Reductive dechlorination of tetrachloroethene in marine sediments: Biodiversity and dehalorespiring capabilities of the indigenous microbes.

Chlorinated compounds pose environmental concerns due to their toxicity and wide distribution in several matrices. Microorganisms specialized in leading anaerobic reductive dechlorination (RD) processes, including Dehalococcoides mccartyi (Dhc), are able to reduce chlorinated compounds to harmless products or to less toxic forms. Here we report the first detailed study dealing with the RD potential of heavy polluted marine sediment by evaluating the biodegradation kinetics together with the composition, dynamics and activity of indigenous microbial population. A microcosm study was conducted under strictly anaerobic conditions on marine sediment collected near the marine coast of Sarno river mouth, one of the most polluted river in Europe. Tetrachloroethene (PCE), used as model pollutant, was completely converted to ethene within 150 days at reductive dechlorination rate equal to 0.016 meq L(-1) d(-1). Consecutive spikes of PCE allowed increasing the degradation kinetics up to 0.1 meq L(-1)d(-1) within 20 days. Strictly anaerobiosis and repeated spikes of PCE stimulated the growth of indigenous Dhc cells (growth yield of ~7.0 E + 07 Dhc cells per µM Cl(-1) released). Dhc strains carrying the reductive dehalogenase genes tceA and vcrA were detected in the original marine sediment and their number increased during the treatment as demonstrated by the high level of tceA expression at the end of the microcosm study (2.41 E + 05 tceA gene transcripts g(-1)). Notably, the structure of the microbial communities was fully described by Catalysed Reporter Deposition Fluorescence In Situ Hybridization (CARD-FISH) as wells as the dynamics of the dechlorinating bacteria during the microcosms operation. Interestingly, a direct role of Dhc cells was ascertained suggesting the existence of strains adapted at salinity conditions. Additionally, non-Dhc Chloroflexi were retrieved in the original sediment and were kept stable over time suggesting their likely flanking role of the RD process.

A novel missense mutation in the gene for lipoprotein lipase resulting in a highly conservative amino acid substitution (Asp180-->Glu) causes familial chylomicronemia (type I hyperlipoproteinemia).

A previously undescribed single missense mutation (C-->G) was detected within exon 5 of the LPL gene in two members of an Italian family affected with type I hyperlipoproteinemia. This mutation causes a highly conservative amino acid replacement (Asp-->Glu) at position 180 of the mature LPL protein resulting in a virtual absence of LPL enzyme activity and LPL enzyme mass in postheparin plasma. Adipose tissue mRNA concentrations and mRNA sizes were not affected. Both patients were homozygous for the mutation, whereas the parents were heterozygous. Comparison of the expression of the mutated cDNA and the wildtype cDNA in cos-7 cells revealed proper transcription and translation of the mutated clone into an immunologically detectable protein. The mutated LPL protein was secreted from the cells in a manner similar to that of wild-type LPL and bound to heparin-Sepharose with identical properties. However, the mutated enzyme, in contrast to wildtype LPL, exhibited no detectable lipolytic activity against a triglyceride substrate. Our results demonstrate that even a highly conservative amino acid replacement outside the proposed active site of LPL is incompatible with proper enzyme function.

Regional differences in adrenoreceptor status of adipose tissue in adults and prepubertal children.

The relative anatomical distribution of adipose tissue in central (abdominal) vs. peripheral (extremity) depots is highly correlated with the risk of adiposity-related morbidities, such as hypertension, cardiovascular disease, and diabetes mellitus. In adults, comparisons of the functional status of plasma membrane adrenergic receptors indicate that abdominal adipocytes are more responsive to the lipolytic action of beta 1-adrenergic agonists, while gluteal adipocytes are more responsive to the antilipolytic action of alpha 2-adrenergic agonists. To determine whether such regional differences in adipocyte adrenoreceptor status are present before puberty, we obtained needle biopsy samples of abdominal and gluteal sc adipose tissue in the post-absorptive state from 13 prepubertal children and 47 adults of varying body compositions (obese vs. lean). Lipolysis rates were measured in the basal state and in the presence of 10(-7) M norepinephrine (a mixed alpha- and beta-adrenergic agonist) and 10(-7) M isoproterenol (a beta-adrenergic agonist). In children, there were no significant regional differences in either the basal rate of lipolysis or the responses to adrenergic lipolytic and antilipolytic stimuli. In lean and obese adults, gluteal sc adipose tissue was strikingly more responsive to antilipolytic alpha-adrenergic stimulation (P less than 0.0001) and less responsive to lipolytic beta-adrenergic stimuli (P less than 0.005) compared to abdominal tissue. Abdominal sc adipocytes from children had a significantly lower rate of basal lipolysis (P less than 0.01) and were more responsive to alpha 2-adrenergic (antilipolytic) stimuli (P less than 0.05) than abdominal adipocytes in adults. These results suggest that peripubertal endocrine changes may mediate the striking regional differences in adrenoreceptor status of adult adipose tissue, and that a decrease in the preponderance of alpha 2-receptors (antilipolytic) in abdominal adipose tissue may account in part for the relative loss of central vs. peripheral fat that occurs during puberty.

Calorie restriction and iopanoic acid effects on thyroid hormone metabolism.

We measured the effects of iopanoic acid on thyroid hormone metabolism in obese men during severe calorie restriction to study the nutrition regulation of thyroid hormone metabolism. Eight morbidly obese men received a weight-maintenance diet followed by 6 wk of 600 kcal/d. During underfeeding, patients received iopanoic acid or placebo for 2-wk periods in a double-blind crossover fashion. Underfeeding alone (UF) produced a 28.3% decline in the serum triiodothyronine (T3) concentration, and iopanoic acid plus underfeeding (IOP) produced a 49.5% decline in T3 concentration from baseline. Serum reverse T3 concentrations increased 289% during IOP compared with UF alone (p less than 0.001). Serum TSH concentration was unchanged by underfeeding but increased twofold during IOP treatment. Thyroid hormone kinetics demonstrated a decrease in T3 production during IOP compared with UF. These findings suggest that calorie restriction regulates T3 production by modulating only type I 5'-deiodinase activity.

Refeeding after fasting in rats: effects of duration of starvation and refeeding on food efficiency in diet-induced obesity.

Rats with diet-induced obesity starved for 8, 15, and 25 d lost liver and muscle glycogen, excess protein, and fat in proportion to duration of starvation. Fat-cell size decreased but fat-cell number did not. Upon refeeding, body fat was only partly restored, with further increase in adipocyte hyperplasia occurring in the starved obese rats. In contrast, fat-cell size was restored to near that of the prefasting value in the starved controls (dry-food-fed, fasted 4 d) after refeeding. With refeeding, food efficiency increased only if starvation had caused a reduction of adipocyte size below normal. Change in food efficiency was not associated with decreases in total carcass protein, specific tissue proteins, or glycogen stores but was correlated with degree of adipocyte filling. It is possible that adipose tissue status somehow modulates energy-dissipating mechanisms.

Regional changes in adrenergic receptor status during hypocaloric intake do not predict changes in adipocyte size or body shape.

The anatomic distribution of fat is related to the risk for obesity-associated morbidity. Among individuals with equal degrees of relative adiposity, those with an upper-body preponderance of fat distribution (android) have higher rates of diabetes, stroke, ischemic heart disease, and early death than those with preferential deposition of adipose tissue in lower portions of the body (hips, thighs, buttocks; gynecoid. There are well-documented anatomic site-related differences in the relative activities of the adrenergic receptors (beta 1----lipolysis; alpha 2----antilipolysis) that control lipolysis. We assessed modifications of the status of alpha 2- and beta 1-adrenergic receptor and subreceptor function in small fragments of adipose tissue obtained by needle biopsy from the gluteal and abdominal subcutaneous regions of five android, seven gynecoid, and six uniformly obese women during a period of weight maintenance (4 weeks) (T1), and after 15% weight loss on an 840 kcal/d diet (T2). Measurements of body shape and adipocyte size were made and related to changes in the metabolism of these adipocytes. The waist-to-hip ratio (WHR) was used to define these three types of regional distribution of fat in these obese subjects: android = WHR greater than 0.86; gynecoid = WHR less than or equal to 0.76; uniform = WHR greater than 0.76 less than or equal to 0.86. WHR was not significantly altered by weight loss in any of the three groups. Although significant effects of time and/or anatomic site on in vitro responses to isoproterenol, norepinephrine, clonidine, forskolin, and dibutyryl cAMP were found, these did not correlate with intra-individual changes in anthropometry or adipocyte size.(ABSTRACT TRUNCATED AT 250 WORDS)

Resting energy expenditure, body composition, and excess weight in the obese.

This study investigated differences between measured and predicted resting energy expenditure (REE) in 80 women who averaged 104.6 kg in weight and were 49 kg and 88% overweight. Body composition analysis showed that 68% of the excess weight was fat and 32% was fat-free mass (FFM). Normalized for height, total body potassium (TBK) was 113 +/- 15% and total body water (TBW) was 133 +/- 21% of values in nonobese controls. The health of the FFM, defined as the potassium content per kg of FFM, was 84 +/- 13% of normal. Measured and predicted REE were only modestly related (r = +.59), and only 59% of measured REEs were within 10% of predicted values. A stepwise multiple regression indicated that weight was the single best predictor of measured REE and that the size of the FFM made a significantly greater contribution to REE than did the size of the fat mass. Commonly used equations for the prediction of REE are not appropriate for moderately or severely obese patients. Caloric prescription for weight reduction must be tailored to individuals rather than recommending the same caloric intake to persons with varying metabolic rates.

Body composition in adolescents: estimation by total body electrical conductivity.

This comparative study, conducted on 28 boys and girls of widely varying fatness, was designed to validate a new whole-body composition method [total body electrical conductivity (TOBEC)], based on bioelectrical properties of the human body. A significant correlation [r = 0.911; standard error of the estimate (SEE) = 5.3 kg] was demonstrated between the transformed TOBEC scores (TOBEC0.5 X Ht) and lean body mass (LBM) determined by hydrodensitometry and corrected for individual variations in hydration (LBMd + W). TOBEC determinations also correlated well with 1) total body water determined by deuterium oxide dilution (r = 0.877; SEE = 4.5 liters), 2) total body potassium determined by means of a 4 pi whole-body counter (r = 0.860; SEE = 430.7 meq), 3) LBM derived from skinfold thicknesses (r = 0.850; SEE = 5.8 kg). The residuals of the regression between LBMd + W and TOBEC scores did not show any significant correlation with either the potassium or the water content of the LBM. The results indicate that TOBEC is a simple, rapid, reliable, and noninvasive technique for delineating changes in body composition that occur in children during growth.

Naltrexone and human eating behavior: a dose-ranging inpatient trial in moderately obese men.

To investigate the effects of the long-acting opiate antagonist naltrexone on spontaneous human eating behavior, eight moderately obese male paid volunteers were housed in a hospital metabolic unit for 28 days and offered palatable foods ad lib by a platter service method. Under double-blind conditions, equally divided doses of 100, 200 and 300 mg naltrexone, or an acetaminophen placebo, were administered twice daily in tablet form for 3-day periods each, according to a Latin Square design. The doses of naltrexone resulted in decreases of daily caloric intake from placebo level, but these reductions were neither statistically significant nor dose-related. When the averaged effects of the doses were compared to placebo, five subjects showed intake reductions but the overall intake reduction of 301.5 +/- 198.1 kcal/day (mean +/- SEM) was not statistically significant. Naltrexone administration failed to selectively alter intakes of individual meals and snacks or macronutrient consumption patterns. During active drug periods, subjects lost 0.62 +/- 0.22 lb over 3 days, while during the placebo period, subjects gained 0.46 +/- 0.68 lb. However, there was no reliable change of basal metabolic rate as a function of naltrexone administration. The present results, which indicate that naltrexone administration is relatively ineffective in reducing food intake and inducing body weight loss in obese humans, are thus in contrast with reports that administration of opiate antagonist agents promote significant reductions of food intake and attenuations of body weight gain in experimental animals.

Estimation of human body composition by electrical impedance methods: a comparative study.

This study 1) further validated the relationship between total body electrical conductivity (TOBEC) and densitometrically determined lean body mass (LBMd) and 2) compared with existing body composition techniques (densitometry, total body water, total body potassium, and anthropometry) two new electrical methods for the estimation of LBM: TOBEC, a uniform current induction method, and bioelectrical impedance analysis (BIA), a localized current injection method. In a sample of 75 male and female subjects ranging from 4.9 to 54.9% body fat the correlation between LBMd and LBM predicted from TOBEC by use of a previously developed regression equation was extremely strong (r = 0.962), thus confirming the validity of the TOBEC method. LBM predicted from BIA by use of prediction equations provided with the instrument also correlated with LBMd (r = 0.912) but overestimated LBM compared with LBMd in obese subjects. However, no such systematic error was apparent when new prediction equations derived from this heterogeneous sample of subjects were applied. Thus the TOBEC and BIA methods, which are based on the differing electrical properties of lean tissue and fat and which are convenient, rapid, and safe, correlate well with more cumbersome human body composition techniques.

Energy depot replenishment in rats during refeeding after fasting: effect of exercise.

The effect of progressive moderate exercise on body weight gain, visceral and muscle protein stores, and thyroid hormone levels during an 8-day refeeding period after 65 h of starvation was studied in 2-month-old male Sprague-Dawley rats. Twenty-four animals were divided into three groups and acclimated for 5 days while being fed with ordinary Purina Chow. After the fasting phase, a group of rats was killed in order to provide base-line information concerning fasting-induced changes in body composition; a sedentary group was fed Purina Chow ad libitum; and a treadmill-exercised group was pair fed with the sedentary rats. During the refeeding phase, the exercised animals regained significantly less weight than the sedentary animals (p less than 0.001), but the two groups did not differ significantly with respect to visceral, muscle, eviscerated carcass, and skin protein. Total body fat content was lower in the exercised than the sedentary group. The thyroid hormone levels were not significantly different for the two refed groups. These results indicate that exercise during refeeding may alter the pattern of body weight gain during refeeding after fasting such that the replenishment of adipose tissue stores is reduced without compromising the restoration and growth of lean tissue.

Thermic effect of food during graded exercise in normal weight and obese men.

The thermic effect of food during incremental cycle ergometer exercise was compared in six normal weight and six obese men (mean +/- SEM 104 +/- 5% and 160 +/- 11% ideal body weight, respectively). Graded exercise tests were performed after a 12-h fast and 60 min after the start of a 910 kcal mixed meal, on separate days. The thermic of food during exercise, which is the fed minus the fasting oxygen consumption (VO2), was significantly greater for the normal than the obese men at submaximal intensities from O (unloaded cycling) to 100 W (p less than 0.05). The mean slope of the regressions of VO2 (ml . min-1) on power output (W), which reflects the rate of increase in energy expended relative to increases in external work performed, did not differ significantly between the fed and fasting conditions for either group, but the mean (+/- SEM) intercept was significantly higher for the normal, but not the obese men, in the fed than the fasting state (599 +/- 53 versus 497 +/- 47 ml O2 . min-1 for the normal men and 819 +/- 126 versus 821 +/- 145 ml O2 . min-1 for the obese men). These results indicate that the thermic effect of food during exercise, which is virtually absent in the obese men, does not increase significantly across submaximal power outputs for the normal men and therefore does not reflect a significant reduction in efficiency.

Comparison in man of total body electrical conductivity and lean body mass derived from body density: validation of a new body composition method.

This article reports a study in which total body electrical conductivity (TOBEC) measurements and lean body mass (LBM) estimated from hydrostatic weighing in human subjects were compared. The TOBEC method provides a new approach to assessment of human body composition that is based on the principle that the electrical conductivity of lean tissue is far greater than that of fat. In a sample of 32 men and women varying widely in age (20 to 53 years), body weight (45 to 155 kg), and adiposity (9.5 to 53.0% body fat), the TOBEC measurement was found to be extremely reliable (r = 0.999) and to correlate highly with hydrostatically estimated LBM (r = 0.903, P less than 0.0001). When the TOBEC scores were transformed to provide a single variable; namely, the subject's height times the square root of the TOBEC score, a higher correlation with LBM was obtained (r = 0.943). Taking gender into account further enhanced the prediction of LBM from TOBEC (r = 0.951). These observations strongly reinforce the results of a previous investigation in which high correlations were found between TOBEC and both total body potassium and total body water. Accordingly, this new method promises to provide a useful technique for the evaluation of body composition that is at once simple, rapid, objective, and noninvasive.

Measurement of total body electrical conductivity: a new method for estimation of body composition.

A new method for the estimation of body composition in human subjects is described which entails the measurement of total body electrical conductivity. The method is based on the principle that the electrical conductivity of lean tissue is far greater than that of fat. Comparative studies in 19 adults of widely varying fatness have demonstrated excellent correlations between the total electrical conductivity of the subjects and both their total body water (r = 0.87) and total body potassium (r = 0.86). This noninvasive method, which is safe, simple, rapid, and convenient, should prove useful in the nutritional assessment of individuals and populations.

Refeeding after fasting in the rat: effects of dietary-induced obesity on energy balance regulation.

Obesity was induced in male Sprague-Dawley rats by overfeeding a cafeteria-style diet. The obesity was characterized by both adipocyte hypertrophy and hyperplasia. Body weight was then reduced by starvation to match that of control animals that had been fed ordinary Purina Chow. The previously obese rats were then refed to match the same body weight as controls, or given the same amount of Purina Chow as consumed by the controls. This resulted in a remaining moderate obesity, now due only to adipocyte hyperplasia with normal fat cell size. The previously obese rats needed less energy to keep their body weight equal to controls, and they spontaneously ate less than controls. They were, however, less food efficient because they did not accumulate as much energy in fat and protein depots during the period of refeeding as the controls did, and consequently must have transformed more energy into heat. This is in sharp contrast to nonobese animals subjected to a similar experimental procedure. Lipogenic enzymes and lipoprotein lipase activity in adipose tissue as well as plasma insulin concentrations were elevated in overfed rats but normalized during refeeding of Chow after fasting.

Refeeding after fasting in the rat: energy substrate fluxes and replenishment of energy stores.

Rats were fasted and refed and concentrations of plasma glucose, glycerol, triglyceride, insulin, and glucagon as well as glucose kinetics after injection of labeled glucose and glycerol were determined. In addition, concentrations and synthesis in vivo (from tritiated water) and in vitro of glycogen, triglycerides, and protein were followed in liver, muscle, and adipose tissues. The refeeding state after fasting was characterized by a decrease in glucose and triglyceride concentrations in plasma. Glucose turnover rate was increased. Protein losses were repleted, first in the liver then in muscle tissue. Synthesis of glycogen and lipid increased above control in liver and adipose tissue. These results are compatible with an increased outflux during refeeding of different energy substrates from plasma into the depleted protein and energy stores to an extent causing lower concentration of these substrates. Such phenomena might be of importance for energy intake regulation during the phase.

Nitrogen loss and urinary creatinine excretion during fasting in massive obesity.

Six (5 f, 1 m) massively obese, otherwise healthy subjects, were submitted for 4 weeks to a very-low-calorie diet (VLCD): 80 kcal, 335 kJ = 2.6 g N/day (17 g protein, 0 CHO and fat). Daily urinary creatinine excretion (UCE) and weekly nitrogen loss (NL) were determined during the whole period of treatment. Both NL and UCE decreased from the second week of treatment indicating a progressive sparing effect on lean body mass (LBM). A positive correlation (r = 0.991, P less than 0.001) was observed between mean daily UCE and NL, indicating that NL during prolonged fasting in obesity is possibly influenced by the lean body mass of the individual.

Protein-sparing modified fast in the treatment of severe obesity: weight loss and nitrogen balance data.

Nitrogen balance has been measured in 25 (16 f, 9m) patients with severe obesity submitted for four weeks to total fasting (TF) or different versions of protein-sparing modified fast (PSMF). The hospitalized patients, divided into four age-matched groups, were treated as follows:Group 1, were submitted to TF; Group 2 were treated by 80 kcal-PSMF (17 g protein=2.6 g N, traces of fat and carbohydrate); Group 3 were submitted to 180 kcal-PSMF (40 g protein = 6.4 g N, 2 g fat, traces carbohydrate) and Group IV, to 80/180 kcal-PSMF (80 kcal during the 1st and 2nd week and 180 kcal during the 3rd and 4th week of treatment). Weight loss was similar (-11 kg) in Gps 1, 2 and 4; lower (-8 kg) in Gp 3. Mean daily Nitrogen loss was significantly lower (P < 0.05) in Gps 3 and 4 than in Gps 1 and 2. Nitrogen loss was significantly reduced from the 3rd week onward in Gps 1 (P < 0.005), 2 (P < 0.05) and 4 (P < 0.002). During 180 kcal-PSMF nitrogen loss was significantly lower (P < 0.005) only when this dietary regimen was preceded by 80 kcal-PSMF for two weeks (Gp 4). These observations suggest a new approach to the treatment of severe obesity by PSMF and show that is is possible to further reduce the early catabolic phase which commonly arises during this type of therapy.