Highly polarized light from stable ordered magnetic fields in GRB 120308A.

After the initial burst of γ-rays that defines a γ-ray burst (GRB), expanding ejecta collide with the circumburst medium and begin to decelerate at the onset of the afterglow, during which a forward shock travels outwards and a reverse shock propagates backwards into the oncoming collimated flow, or 'jet'. Light from the reverse shock should be highly polarized if the jet's magnetic field is globally ordered and advected from the central engine, with a position angle that is predicted to remain stable in magnetized baryonic jet models or vary randomly with time if the field is produced locally by plasma or magnetohydrodynamic instabilities. Degrees of linear polarization of P ≈ 10 per cent in the optical band have previously been detected in the early afterglow, but the lack of temporal measurements prevented definitive tests of competing jet models. Hours to days after the γ-ray burst, polarization levels are low (P < 4 per cent), when emission from the shocked ambient medium dominates. Here we report the detection of P =28(+4)(-4) per cent in the immediate afterglow of Swift γ-ray burst GRB 120308A, four minutes after its discovery in the γ-ray band, decreasing to P = 16(+5)(-4) per cent over the subsequent ten minutes. The polarization position angle remains stable, changing by no more than 15 degrees over this time, with a possible trend suggesting gradual rotation and ruling out plasma or magnetohydrodynamic instabilities. Instead, the polarization properties show that GRBs contain magnetized baryonic jets with large-scale uniform fields that can survive long after the initial explosion.

Alpha-lipoic acid, but not di-hydrolipoic acid, activates Nrf2 response in primary human umbilical-vein endothelial cells and protects against TNF-α induced endothelium dysfunction.

The antioxidants role in cell response regulation attracted great interest in the last decades and it is undergoing to a profound reconsideration. The mere concept of "biological antioxidant" has been frequently misconceived or misused, possibly leading to the misinterpretation of some experimental observation. Organosulfur compounds in general and α-lipoic acid, a dithiol molecule, can be considered a typical example of the kind. Reduced α-lipoic acid, dehydrolipoic acid has been in fact originally considered a bona fide, reducing, electron donor molecule. A more recent approach, according to stoichiometric and thermodynamic evidences, lead to a reinterpretation of the biochemical role of "antioxidants". The electrophilic nature of oxidized nucleophilic molecules, including α-lipoic acid, renders more plausible a mechanism based on the ability to activate Nrf2/EpRE mediated hormetic response. In this study, we demonstrate that nmolar concentrations of oxidized α-lipoic acid, but not dehydrolipoic acid, protect human umbilical primary endothelial cells (HUVEC) from TNF-α induced dysfunction, inhibit NF-κB activation and block apoptosis following the activation of Nrf2 transcription factor. Our observations corroborate the concept that the major, if not the unique, mechanism by which α-lipoic acid can non-enzymatically exert its reducing activity is related to the electrophilic nature of the oxidized form.

Transcriptome analysis of human primary endothelial cells (HUVEC) from umbilical cords of gestational diabetic mothers reveals candidate sites for an epigenetic modulation of specific gene expression.

Within the complex pathological picture associated to diabetes, high glucose (HG) has "per se" effects on cells and tissues that involve epigenetic reprogramming of gene expression. In fetal tissues, epigenetic changes occur genome-wide and are believed to induce specific long term effects. Human umbilical vein endothelial cells (HUVEC) obtained at delivery from gestational diabetic women were used to study the transcriptomic effects of chronic hyperglycemia in fetal vascular cells using Affymetrix microarrays. In spite of the small number of samples analyzed (n=6), genes related to insulin sensing and extracellular matrix reorganization were found significantly affected by HG. Quantitative PCR analysis of gene promoters identified a significant differential DNA methylation in TGFB2. Use of Ea.hy926 endothelial cells confirms data on HUVEC. Our study corroborates recent evidences suggesting that epigenetic reprogramming of gene expression occurs with persistent HG and provides a background for future investigations addressing genomic consequences of chronic HG.

French marine bark extract pycnogenol as a possible enrichment ingredient for yogurt.

The influence of Pycnogenol, French marine bark extract, added to yogurt preparation on the viability of Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus and on pH, titratable acidity, macro-nutrients, and folate content were evaluated throughout the shelf life of products. At all concentrations studied, Pycnogenol additions neither significantly affected the growth of microorganisms nor caused any modification of nutritional parameters during storage in yogurt. To highlight any possible degradation of Pycnogenol components by yogurt flora, an estimation of total polyphenol contents and an evaluation of some phenolic compounds in yogurt at the greatest concentration of Pycnogenol were carried out at the beginning and at the end of the study. Our data indicates that neither total polyphenol content nor selected phenolic substances (cathechin, epicatechins, chlorogenic acid, and caffeic acid) was affected during the shelf life. In conclusion, these results suggest Pycnogenol as a valuable ingredient to enrich yogurt preparation.

A red orange extract modulates the vascular response to a recreational dive: a pilot study on the effect of anthocyanins on the physiological consequences of scuba diving.

Nutritional antioxidants have been proposed as an expedient strategy to counter the potentially deleterious effects of scuba diving on endothelial function, flow-mediated dilation (FMD) and heart function. Sixteen volunteers performing a single standard dive (20 min at 33 m) according to US Navy diving procedures were randomly assigned to two groups: one was administered with two doses of 200 mg of an anthocyanins (AC)-rich extract from red oranges, 12 and 4 h before diving. Anthocyanins supplementation significantly modulated the effects of diving on haematocrit, body water distribution and FMD. AC administration significantly reduces the potentially harmful endothelial effects of a recreational single dive. The lack of any significant effect on the most common markers of plasma antioxidant capacity suggests that the mechanism underlying this protective activity is independent of the putative antioxidant effect of AC and possibly involves cellular signalling modulation of the response to high oxygen.

In vitro inhibition of the activity of phosphorylase kinase, protein kinase C and protein kinase A by caffeic acid and a procyanidin-rich pine bark (Pinus marittima) extract.

Caffeic acid (CA) is a common constituent of human diet while pine bark extract (PBE) is utilized either as nutritional supplement or as phytochemical remedy for different diseases. CA and PBE, are reported as efficient antioxidants and more recently have been described to modulate cellular response to oxidative challenge and to possess many other biological activities, i.e. anti-inflammatory, antimutagenic, antitumoral effects. In order to investigate in depth the mechanism of action of these polyphenols, the effects of CA and PBE on the activity of some protein kinases involved in the regulation of fundamental cellular processes were studied in vitro: phosphorylase kinase (PhK), protein kinase A (PKA), protein kinase C (PKC). PBE at the concentration of 20 microg/ml (corresponding to 69 microM catechin equivalents) inhibited PKA, PhK and PKC by about 90, 59, 57%, respectively, while 100 microM CA inhibited by 37, 52 and 54%, respectively. Considerable inhibitions have been still observed at even lower concentrations of CA and PBE. For PhK and PKA, the inhibition follows a non-competitive mechanism. CA also inhibits PKC activity in a partially purified cellular extract. The results suggest a possible involvement of CA and PBE in modulation of cellular functions.

Evaluation of the efficacy and tolerability of nitrendipine in reducing both pressure and left ventricular mass in hypertensive type 2 diabetic patients.

OBJECTIVE: To evaluate the efficacy and tolerability of nitrendipine in comparison with captopril in hypertensive diabetic patients with left ventricular hypertrophy (LVH). RESEARCH DESIGN AND METHODS: A total of 75 patients enrolled in this study presented stable type 2 diabetes (not treated with insulin) and mild-to-moderate hypertension with a left ventricular mass > or = 75 g/m2 by two-dimensional echocardiography. After a 4-week washout period, 38 patients were assigned to treatment with captopril, and 37 patients to nitrendipine (random allocation). The duration of follow-up was 36 weeks. RESULTS: Patients of both groups were similar with regard to the duration of diabetes and hypertension, systolic and diastolic blood pressure at rest, degree of LVH, metabolic control, and albumin excretion rate (AER). Both drugs were equally effective in reducing systolic and diastolic blood pressure (captopril: from 165 +/- 13/100 +/- 4 to 147 +/- 11/87 +/- 4 mmHg; nitrendipine: from 167 +/- 17/100 +/- 5 to 143 +/- 9/86 +/- 4 mmHg; P < 0.05) and in reversing LVH (nitrendipine: from 87 +/- 2 to 81 +/- 1 g/m2; captopril: from 89 +/- 2 to 85 +/- 2 g/m2; P = 0.0001). Neither the left ventricular end-diastolic volume index nor the left ventricular ejection fraction changed significantly during the treatment period. CONCLUSION: Nitrendipine is as effective as captopril in reducing both systolic and diastolic blood pressure and in reversing LVH. Neither drug showed any negative side effects on fasting plasma glucose and glycated hemoglobin (HbA1c) levels, and both maintain constant AERs.

The presence of retinopathy in patients with secondary diabetes following pancreatectomy or chronic pancreatitis.

The incidence of diabetic retinopathy was evaluated by means of fluorescein angiography in 54 patients with diabetes secondary to chronic pancreatitis or to pancreatectomy. Thirty-one percent of the patients had background retinopathy; none had proliferative retinopathy. The percentage of patients with retinopathy was the same in groups with or without a family history of diabetes. There was no correlation between the degree of metabolic control, the levels of C-peptide, glucagon, growth hormone, and the presence of retinopathy. Retinopathy was correlated with the duration of diabetes. In conclusion, diabetes caused by pancreatitis or pancreatectomy has a significant prevalence of retinopathy, which has more benign characteristics and slower evolution than the retinopathy in patients with primary diabetes.

Procyanidins extracted from Pinus maritima (Pycnogenol): scavengers of free radical species and modulators of nitrogen monoxide metabolism in activated murine RAW 264.7 macrophages.

Nitrogen monoxide (NO) has diverse physiological roles and also contributes to the immune defense against viruses, bacteria, and other parasites. However, excess production of NO is associated with various diseases such arthritis, diabetes, stroke, septic shock, autoimmune, chronic inflammatory diseases, and atheriosclerosis. Cells respond to activating or depressing stimuli by enhancing or inhibiting the expression of the enzymatic machinery that produce NO. Thus, maintenance of a tight regulation of NO production is important for human health. Phytochemicals have been traditionally utilized in ways to treat a family of pathologies that have in common the disregulation of NO production. Here we report the scavenging activity of Pycnogenol (the polyphenols containing extract of the bark from Pinus maritima) against reactive oxygen and nitrogen species, and its effects on NO metabolism in the murine macrophages cell line RAW 264.7. Macrophages were activated by the bacterial wall components lipopolysaccharide (LPS) and interferon (IFN-gamma), which induces the expression of large amounts of the enzyme nitric oxide synthase (iNOS). Preincubation of cells with physiological concentrations of Pycnogenol significantly decreased NO generation. It was found that this effect was due to the combination of several different biological activities, i.e., its ROS and NO scavenging activity, inhibition of iNOS activity, and inhibition of iNOS-mRNA expression. These data begin to provide the basis for the conceptual understanding of the biological activity of Pycnogenol and possibly other polyphenolic compounds as therapeutic agents in various human disorders.

Procyanidins extracted from pine bark protect alpha-tocopherol in ECV 304 endothelial cells challenged by activated RAW 264.7 macrophages: role of nitric oxide and peroxynitrite.

A co-culture system was used to study the effect of reactive nitrogen species (RNS) generated by RAW 264.7 macrophages grown on filters and activated by lipopolysaccharide and interferon-gamma, on the alpha-tocopherol levels in ECV 302 endothelial cells. The results indicate that: RNS generated by activated macrophages or by direct administration of peroxynitrite lead to a significant loss of alpha-tocopherol in endothelial cells; pre-incubation with procyanidin extracted from pine bark (Pycnogenol) protects alpha-tocopherol of endothelial cells and enhances by about 15% basal endogenous levels of alpha-tocopherol. These results demonstrate flavonoids participate in the cellular antioxidant network and suggest that Pycnogenol may play an important role in the protection of endothelium from oxidative stress induced by reactive nitrogen species.

Antioxidant activity and biologic properties of a procyanidin-rich extract from pine (Pinus maritima) bark, pycnogenol.

There is growing interest in the biologic activities of plant extracts such as that obtained from the bark of the French maritime pine Pinus maritima, Pycnogenol. Pycnogenol (PYC) is a standardized extract composed of a mixture of flavonoids, mainly procyandins and phenolic acids. Studies indicate that PYC components are highly bioavailable. Uniquely PYC displays greater biologic effects as a mixture than its purified components do individually indicating that the components interact synergistically. PYC has been reported to have cardiovascular benefits, such as a vasorelaxant activity, angiotensin-converting enzyme (ACE) inhibiting activity, and the ability to enhance the microcirculation by increasing capillary permeability. Investigations of the cellular mechanisms of these therapeutic effects have demonstrated that PYC has strong free radical-scavenging activity against reactive oxygen and nitrogen species. The oligomeric components of PYC contribute significantly to the ESR free radical signal. PYC also participates in the cellular antioxidant network as indicated by its ability to regenerate the ascorbyl radical and to protect endogenous vitamin E and glutathione from oxidative stress. PYC modulates NO metabolism in activated macrophages by quenching the NO radical and inhibiting both iNOS mRNA expression and iNOS activity. The spectrum of different effects of NO in the circulation and the nervous system suggest the potential applications of PYC in immune and circulatory disorders as well as in neurodegenerative disease. PYC can bind to proteins, altering their structure and thereby modulating the activity of key enzymes and proteins involved in metabolic pathways. PYC effects redox-sensitive signal transduction pathways and alters gene expression. Aspects of PYC's activity are presented and discussed together with possible future implications and directions in the field of flavonoid research.

Modulation of ceramide-induced NF-kappaB binding activity and apoptotic response by caffeic acid in U937 cells: comparison with other antioxidants.

Ceramide acts as second messenger in the signal transduction triggered by a variety of stress stimuli and extracellular agents. Stress response through ceramide is involved in the development of many human diseases, such as atherosclerosis, inflammation, neurodegenerative disorders, and acquired immunodeficiency syndrome. Dietary polyphenols have been reported to exert a beneficial effect on the onset and development of most of these human chronic-degenerative pathologies. However, the mechanisms underlying this beneficial effect are mostly not understood at the present. To investigate the ability of polyphenols in modulating fundamental cellular functions, we studied the effect of caffeic acid, a widespread phenolic acid largely present in human diet, in the modulation of ceramide-induced signal transduction pathway leading to apoptosis in U937 cells, in comparison with other established antioxidants of nutritional interest (N-acetylcysteine, d-alpha-tocopherol acetate and ascorbic acid). Our results indicate that caffeic acid efficiently inhibits both ceramide-induced NF-kappaB binding activity and apoptosis at micromolar concentration. Other antioxidants tested are totally ineffective in inhibiting apoptosis, although affecting NF-kappaB activation. Caffeic acid was found to inhibit protein tyrosine kinase activity, suggesting that this mechanism can be on the basis of the inhibition of apoptosis. Our results suggest that dietary caffeic acid might modulate ceramide-induced signal transduction pathway and NF-kappaB activation through either antioxidant and nonantioxidant mechanisms.

Intestinal damage induced by zinc deficiency is associated with enhanced CuZn superoxide dismutase activity in rats: effect of dexamethasone or thyroxine treatment.

Zinc has a wide spectrum of biological activities and its deficiency has been related to various tissue dysfunctions and alterations of normal cell metabolism. Zinc also plays an important role in the antioxidant cellular defenses being a structural element of the non-mitochondrial form of the enzyme superoxide dismutase (CuZnSOD). We have already reported that Zn deficiency induces severe alterations in the rat intestine, that are reverted by treatment with dexamethasone (Dex) or thyroxine (T4). Here we report a paradoxical increase of CuZnSOD activity in rat intestine after 20 and 40 days of zinc deficiency. The increase of CuZnSOD activity is not due to an upregulation of gene expression because both Northern and Western blot analysis indicate that CuZnSOD mRNA and protein levels are not affected by zinc deficiency. A significant increase of lipid peroxidation was also observed in duodenum and jejunum associated with zinc deficiency. Treatment with either Dex or T4 to zinc-deficient rats protects against intestinal oxidative damage and results in SOD activity similar to control rats. Because glutathione peroxidase and catalase activities decreased in zinc deficiency, we speculate that the increase in SOD activity may be associated with an accumulation of hydrogen peroxide that may activate inflammatory molecules, further worsening tissue damage.

Ferulic acid excretion as a marker of consumption of a French maritime pine (Pinus maritima) bark extract.

French maritime pine (Pinus maritima) bark extract (PBE) is a polyphenol-rich food supplement patented under the name of Pycnogenol and known to have strong antioxidant activity and different beneficial effects on human health. Although its biological properties have begun to be extensively studied both in vitro, in laboratory animals and more recently in humans, little is known about its bioavailability. The present study investigated the urinary excretion of free and conjugated ferulic acid, present in quantitatively detectable amounts in PBE, after oral PBE administration to human subjects. Eleven healthy adult subjects (4 women and 7men) consumed either a single dose (200 mg PBE) or two doses of PBE (100 and 200 mg, respectively) within a 48-h interval. Two days before the oral administration of PBE and during the urine sample collection period volunteers adhered to a diet low in polyphenols. Aliquots of all urine production were collected over 24 h. Free and conjugated ferulic acid was assessed in urine by HPLC using diode array detection. A close association between the dietary intake of PBE and the urinary excretion of ferulic acid was detected. Moreover, the results indicate that a considerable proportion of ferulic acid is excreted as glucuronide or sulfate after PBE consumption, varying over the range 2 to 20% between individuals. The kinetics of excretion associated with the administration of 100 mg PBE was quite similar to that obtained after 200 mg PBE. A a biphasic trend was evident in a number of subjects. All subjects studied here displayed a significant, although variable level of excretion of ferulic acid after supplementation with PBE, Thus, the data provide evidence that at least a part of the phenolic components of PBE are absorbed, metabolized, and eliminated by humans.

Bcl-2 overexpression in the HaCaT cell line is associated with a different membrane fatty acid composition and sensitivity to oxidative stress.

Different mechanisms have been proposed for the activity of the Bcl-2 proto-oncogene product. A bona fide antioxidant activity and a pro-oxidant setting up of the cell have been suggested using different experimental models, yet many uncertainties exist about the biochemical mechanism of Bcl-2 action. In the present paper, we report the characterization of the cellular response to mild oxidative stress of a cultured cell line of immortalized keratinocytes (HaCaT), overexpressing the Bcl-2 oncogene product. A sublethal oxidative stress was induced by 1 h treatment with 200 microM tert-butyl-hydroperoxide (t-BOOH). Following peroxide treatment, the formation of reactive oxygen species was lower in Bcl-2 expressing cells, suggesting a better capacity to counter oxidative stress. Total Superoxide Dismutase activity was induced by oxidative t-BOOH treatment in bcl-2 transfected cells, which also accumulated less damage to membrane lipids and proteins, as assessed by TBA-RS and carbonyl formation respectively. On the other hand, the formation of 4-hydroxy-nonenal, a more specific marker of peroxidative damage to polyunsaturated fatty acids, was higher in bcl-2 transfected cells than in control cells. Bcl-2 over-expression was also associated with significant changes in the fatty acid composition of cell membranes. Transfected cells presented a higher proportion of mono-unsaturated fatty acids and omega6 poly unsaturated fatty acids and a lower proportion of penta-enoic PUFA, thus resulting in a higher unsaturation index with respect to control cells. Changes in protein kinase C activity were also associated to bcl-2 expression, possibly resulting from the differences in membrane fatty acid composition. These data may be an important background for the understanding of Bcl-2 involvement in the control of apoptotic response as well as in the induction of antioxidant cell defenses against oxidative stress.

Interaction between cultured endothelial cells and macrophages: in vitro model for studying flavonoids in redox-dependent gene expression.

This article focused on two methods to measure the activity of NF-kB. Both methods evalute "post-IkB phosphorylation" stages in the NF-kB activation cascade. In fact, EMSA performed with nuclear extracts provides an information only on NF-kB nuclear translocation and its ability to bind kB-DNA sequences. Likewise, the reporter gene assay is limited to assessing NF-kB-dependent gene expression no matter the mechanism that originally activated NF-kB. Nevertheless, the latter assay represents a more physiological and more reproducible way of measuring NF-kB activity in mammalian cells than the EMSA does. In order to obtain further insights into NF-kB signal transduction pathways, investigating IkB degradation and phosphorylation are recommended. The cloning and characterization of IkB kinases provided new testing possibilities based on measure of their activity.

The effect of zinc and vitamin A supplementation on immune response in an older population.

OBJECTIVE: To determine if either supplemental vitamin A, zinc, or both increases cell-mediated immune response in an older population. DESIGN: A double-blind, randomized, controlled trial of supplementation with vitamin A and zinc. SETTING: Casa Di Riposo Roma III, a public home for older people in Rome, Italy. SUBJECTS: The health and nutritional status of 178 residents were evaluated. One hundred thirty-six residents agreed to participate in the trial and were randomized into four treatment groups, and 118 of these residents completed the trial. INTERVENTION: The four treatments consisted of: (1) Vitamin A (800 micrograms retinol palmitate); (2) Zinc (25 mg as zinc sulfate); (3) Vitamin A and Zinc (800 micrograms retinol palmitate and 25 mg as zinc sulfate); (4) Placebo capsules containing starch. MAIN OUTCOME MEASUREMENTS: Immune tests-counts of leucocytes, lymphocytes, T-cell subsets, and lymphocyte proliferative response to mitogens-were measured before and after supplementation. RESULTS: Zinc increased the number of CD4 + DR + T-cells (P = .016) and cytotoxic T-lymphocytes (P = .005). Subjects treated with vitamin A experienced a reduction in the number of CD3 + T-cells (P = .012) and CD4 + T-cells (P = .012). CONCLUSIONS: These data indicate that zinc supplementation improved cell-mediated immune response, whereas vitamin A had a deleterious effect in this older population. Further research is needed to clarify the clinical significance of these findings.

Increased sodium influx and calcium uptake in erythrocytes in hyperthyroidism: role of abnormal membrane lipid levels.

The study was designed to examine the effects of thyroid hormones on red blood cell (RBC) membrane phospholipids and ion transport. We demonstrated that in untreated Graves' disease, an alteration in the phospholipid pattern is present at cellular levels, with a concomitant derangement in membrane permeability defined as (22)Na influx and (45)Ca uptake. Thionamide therapy replaced the normal membrane permeability, presumably as a consequence of restoring the normal phospholipid membrane composition. We conclude that thyroid hormones are able to induce a quick breakdown of a large number of membrane components such as membrane phospholipids.

Relative expansion of extracellular water in obese vs. normal children.

This preliminary communication reports data regarding the distribution between intracellular (ICW) and extracellular (ECW) water compartments in a group of 21 prepubertal young obese children of both sexes in comparison with a group of 18 normal children weight matched for age. Our data indicate that obesity is associated with a highly significant relative expansion of extracellular water (ECW/ICW = 0.61 +/- 0.19 and 0.76 +/- 0.09 in control and obese subjects, respectively; P < 0.0015). This observation, which has been already reported in adult women, suggests that some disturbances of water homeostasis have an early onset and stress the need for an early control of energy imbalance in children. These findings are of great concern also in the field of human body composition, suggesting the opportunity for a critical reevaluation of the assumed constancy of some human body characteristics. Body composition methodologies developed for "normal" populations would require adjustment for use in the obese population, since a considerable error would be introduced.

Relationship between fat-free mass and urinary excretion of creatinine and 3-methylhistidine in adult humans.

The urinary excretion of endogenous creatinine (CRTN) and 3-methylhistidine (3-MH) has been proposed as a predictor of fat-free mass (FFM) in healthy subjects. In this study, we report the relationship between FFM, estimated by densitometry plus deuterium dilution, and daily urinary excretion of CRTN and 3-MH in a sample of 20 healthy adult subjects of both sexes. 3-MH and CRTN were measured in 2 days of urine collection, which followed 4 days of meat-free diet. Meat-free diet was maintained throughout the period of urine collection. The mean of 2 days of excretion of 3-MH was 237.7 +/- 87.3 (SD) and 138.9 +/- 31.2 mumol/day in men and women, respectively. The mean CRTN excretion was 1.51 +/- 0.22 and 0.98 +/- 0.15 g/day in men and women, respectively. CRTN excretion was found well associated with FFM (R2 = 0.89; P < 0.0001), whereas 3-MH was lightly associated with FFM (R2 = 0.33; P < 0.01). Residuals from the regression of 3-MH vs. FFM were found to be correlated with CRTN excretion and FFM (R2 = 0.57 and 0.67, respectively), suggesting that muscularity and the absolute amount of lean mass are relevant for the error in predicting FFM from 3-MH excretion. Data confirm that urinary CRTN excretion can be an expedient indirect method for evaluating body composition in healthy adult subjects. Data also suggest that the relationship between 3-MH and FFM is complex, limiting the possibility of predicting body composition from the excretion of this metabolite.