Unraveling the Physiological Mechanisms Underlying the Intracultivar Variability of Water Use Efficiency in Vitis vinifera "Grenache"

Selecting genotypes with a better capacity to respond and adapt to soil water deficits is essential to achieve the sustainability of grapevine cultivation in the context of increasing water scarcity. However, cultivar changes are very poorly accepted, and therefore it is particularly interesting to explore the intracultivar genetic diversity in water use efficiency (WUE). In previous studies, the cultivar "Grenache" has shown up to 30% variability in WUE. This research aimed to confirm the intracultivar variability and to elucidate the traits underlying this variability in the response to a water deficit by analyzing the growth rates, water relations, osmotic potential, leaf morphology, leaf gas exchange and carbon isotope discrimination in nine "Grenache" genotypes grown in pots during two seasons. The results showed lower differences in WUE and carbon isotope ratio than in previous field studies, but fairly good consistency in genotype ranking. Leaf mass area and osmotic potential did not underlie differences in stem water potential and in stomatal conductance. Overall, stomatal regulation and photosynthetic capacity seem to underlie differences in WUE among genotypes with an important environmental influence. These results confirm the ability to select clones with higher WUE and present an opportunity for the genetic improvement of WUE in grapevines.

Polarization-driven self-organization of silver nanoparticles in 1D and 2D subwavelength gratings for plasmonic photocatalysis

One of the main challenges in plasmonics is to conceive large-scale, low-cost techniques suitable for the fabrication of metal nanoparticle patterns showing precise spatial organization. Here, we introduce a simple method based on continuous-wave laser illumination to induce the self-organization of silver nanoparticles within high-index thin films. We show that highly regular and homogeneous nanoparticle gratings can be produced on large areas using laser-controlled self-organization processes. This very versatile technique can provide 1D and 2D patterns at a subwavelength scale with tunable features. It does not need any stabilization or expensive devices, such as those required by optical or electron lithography, and is rapid to implement. Accurate in-plane and in-depth characterizations provide valuable information to explain the mechanisms that lead to pattern formation and especially how 2D self-organization can fall into place with successive laser scans. The regular and homogeneous 2D self-organization of metallic NPs with a single laser scan is also reported for the first time in this article. As the reported nanostructures are embedded in porous TiO₂, we also theoretically explore the interesting potential of organization on the photocatalytic activity of Ag-NP-containing TiO₂ porous films, which is one of the most promising materials for self-cleaning or remediation applications. Realistic electromagnetic simulations demonstrate that the periodic organization of silver nanoparticles can increase the light intensity within the film more than ten times that produced with randomly distributed nanoparticles, leading as expected to enhanced photocatalytic efficiency.

Reorganizing and shaping of embedded near-coalescence silver nanoparticles with off-resonance femtosecond laser pulses

We demonstrate that 2D distributions of non-spherical near-coalescence silver nanoparticles (NPs) embedded in an ultrathin dielectric film can be reorganized, shaped and aligned by exposure to ultrashort laser pulses. As-grown samples prepared by pulsed laser deposition show a broad absorption band with a surface plasmon resonance (SPR) at 650 nm, which can be blue-shifted down to 440 nm and transformed to show polarization anisotropy. In situ white light probing of the spectral sample transmission allows control during irradiation of the position and polarization anisotropy of the SPR, effectively controlling particle reorganization and shaping. Using the high spatial resolution of the optical probe technique (better than 10 μm), the dependence of the nanoparticle shape and distribution on the local fluence can be studied in a single irradiated region. The results inferred from the spectral measurements have been confirmed by TEM studies, showing the formation of nanoparticles with prolate shape, preferential alignment along the polarization axis of the laser and a narrow size distribution. This simple and efficient approach for NP shaping and the straightforward extension to multilayer systems offer excellent perspectives for optical encoding, multidimensional data storage and fabrication of complex, polarization-sensitive spectral masks starting from thin films with near-coalescence distributions of NPs.

Interrelationships between dietary carbohydrates, B cell function and rate of ketogenesis during underfeeding in obese patients

Six matched groups of obese patients underwent 3-week selective hypocaloric regimens which consisted of a 240 or 480 kcal/day liquid formula diets for groups 1-4 and an 800 kcal/day conventional diet for groups 5 and 6. Carbohydrate intake ranged from 19 to 112 g/day so that for each energy level two different amounts of carbohydrates were administered. Body weight loss was similar in groups 1-4 and significantly lower in groups 5 and 6. During treatment fasting serum insulin (but not serum C-peptide) levels and the daily urine excretion rate of C-peptide showed quite a similar fall in all groups. Fasting glucagon levels did not change. The rate of ketogenesis which developed during each nutritional treatment was inversely related to the amount of dietary carbohydrates; moreover, a significant correlation was found between percent variation of ketoacids and those of fasting IRI (r = -0.42; p less than 0.01) and glucose (r = -0.52; p less than 0.01) concentrations, but not with those of fasting C-peptide and its daily urine excretion rate. In conclusion, it seems that during underfeeding (1) low- and high-carbohydrate-containing regimens are substantially equipotent stimuli secretagogues of insulin secretion, and (2) carbohydrate (or glucose) availability affects ketogenesis even through noninsulin-mediated mechanisms.

A controlled trial using ephedrine in the treatment of obesity

A double-blind controlled study was performed in unselected obese outpatients to assess the effects of ephedrine on weight loss. Patients were treated for 3 months with placebo (group I), 25 mg t.i.d. or 50 mg t.i.d. of ephedrine hydrochloride orally administered (groups II and III, respectively). Dietary treatment consisted of 1000 kcal/day for females and 1200 kcal/day for males. The three groups were matched for age, sex, body mass index and pre-treatment spontaneous caloric intake. Weight loss was similar in all groups. Patients in group III (ephedrine 150 mg/day) showed significantly more side effects than the placebo group. These results do not seem to favour the hypothesis that ephedrine, a thermogenic agent, may be effective in the therapy of unselected simple obesity. On the other hand, it cannot be excluded that the drug may be useful in obese patients in whom defective thermogenesis may be clearly demonstrated.

Effect of 'physiological' doses of triiodothyronine replacement on the hormonal and metabolic adaptation to short-term semistarvation and to low-calorie diet in obese patients

In four groups of obese patients matched for Body Mass Index (BMI), we studied the effects of different 3-week semi-starvation treatments followed by an 8-week hypocaloric (1008 kcal, protein 20%, carbohydrate 40%) diet with or without low doses of T3 therapy. Dietary intake (formula diet) in the semi-starvation period was 480 kcal, with 66 g protein (P) and 51 g carbohydrate (CHO) in groups I and III and with 33 g P and 84 g CHO in groups II and IV. Moreover, groups III and IV were given low doses (20 micrograms twice a day) of T3 while groups I and II received a placebo. During semi-starvation periods, a similar fall in BMI values was found in all groups, while during the low-calorie diet, T3-treated patients showed the greater BMI reduction. During semi-starvation, nitrogen balance was significantly more negative in low-protein than in high-protein-treated groups; differences between T3-treated (III and IV) and control (I and II) groups were not significant over this relatively short treatment period. No differences in 24 h urinary 3-methylhistidine or alanine excretion were evident between the four groups. During the entire period of study, daily urine creatinine excretion did not change in any group. In conclusion, in our study low-dose T3 therapy was seen to favour weight loss during low-calorie diet although negative effects on protein metabolism were not excluded, particularly when relatively small amounts of protein were administered.

Seasonal variations of total and free thyroid hormones in healthy men: a chronobiological study

The seasonal variations of iodothyronines and TSH serum concentrations were evaluated in 24 healthy subjects of both sexes. Using a 12 month cosine function, a significant circannual rhythm was found in T3, T4 and free T4 whose maximal values were found in September for T3, in August for T4 and in October for free T4. No significant seasonal variations in free T3 or TSH were found. Some circannual but not sinusoidal changes were found for reverse T3 and TBG. A positive linear correlation between T4, T3 and reverse T3 changes was observed, indicating that the sinusoidal oscillations of these hormones were in phase with each other. Relative weight was significantly lower in summer than in winter, though spontaneous caloric intake and physical activity did not change. A slight but significant correlation was found between relative weight and T4, free T4 and reverse T3 values measured during the period of study.

Clinical application of the 24-H urinary C-peptide excretion rate and its relationship to metabolic control in diabetics

In this study, we evaluated in normal subjects, insulin-dependent (IDD) and non-insulin-dependent (NIDD) diabetics, the diurnal urinary C-peptide excretion rate (CPR-U) and its relationship to serum C-peptide concentration and glucose:C-peptide molar ratio, and to the common parameters of metabolic control. The CPR-U (and CPR-U/g creatinine) were significantly lower in IDD and higher in NIDD compared to control subjects. Moreover, a good and significant correlation with serum C-peptide concentrations and the glucose:C-peptide ratio in diabetic subjects as well as in controls and diabetics considered together was found. A slight but significant correlation was present in diabetic subjects between CPR-U and body mass index (r = 0.45), 24-h glycosuria (r = 0.36), HbA1 levels (r = 0.31), post-prandial glucose concentrations (r = 0.26) and per cent glucose variation after each meal (r = 0.34). No differences were found in CPR-U and the degree of metabolic control between obese and non-obese NIDD. In conclusion, CPR-U may be a useful and simple method of defining the secretory activity of the B-cell. Metabolic control in diabetics is slightly correlated to the degree of B-cell function as evaluated by the diurnal excretion rate of C-peptide in urine.

Relationships between iodothyronine peripheral metabolism and ketone bodies during hypocaloric dietary manipulations

Relationships between iodothyronine and metabolic substrate metabolism during undernutrition were evaluated in four normal subjects who fasted for 48h (Group I) and in four groups (II to V) of obese patients who underwent selective dietary manipulations: 360 calories [carbohydrate (CHO) 40 g/day]; 800 calories containing respectively 19 g/day - ketogenic - (K) and 112 g/day - non ketogenic - (NK) of CHO; and a step-diet programme (during which total calories were progressively reduced from 2500 to 500). Serum T3 levels decreased significantly and constantly during fasting, 360 and 800 K studies, and transiently during the 800 NK diet. During the step-diet programme, a significant fall was found only when 1250 K or less were given. Conversely, serum reverse T3 rose significantly and constantly during 360 and 800 K diets, while a transient increase was found during the 800 NK diet. During the step-diet programme reverse T3 rose only when 750 calories were given. Ketogenesis developed in all studies but one (800 NK), and in the step-diet programme significantly below the 1000 calorie step. Other substrate modifications in each study were also evaluated. Serum T3 levels showed a significant correlation with ketone bodies (KB) in all the ketogenic studies, while no correlation was found in non ketogenic study (800 NK). During the step-diet programme ketone bodies and iodothyronine modifications appeared to be related to the amount of calories. Based on these results, we suggest a relationship between the dietary-induced modifications of iodothyronine metabolism and the development of ketogenesis.

Effect of dietary carbohydrates during hypocaloric treatment of obesity on peripheral thyroid hormone metabolism

The effect of different hypocaloric carbohydrate (CHO) intakes was evaluated in 8 groups of obese patients in order to assess the role of the CHO and the other dietary sources in modulating the peripheral thyroid hormone metabolism. These changes were independent of those of bw. Serum T3 concentrations appear to be more easily affected than those of reverse T3 by dietary manipulation and CHO content of the diet. A fall in T3 levels during the entire period of study with respect to the basal levels occurred only when the CHO of the diet was 120 g/day or less, independent of caloric intake (360, 645 or 1200 calories). Moreover, reverse T3 concentrations were found increased during the entire period of study when total CHO were very low (40 to 50 g/day) while they demonstrated only a transient increase when CHO were at least 105 g/day (with 645 or more total calories). Indeed, our data indicate that a threshold may exist in dietary CHO, independent of caloric intake, below which modifications occur in thyroid hormone concentrations. From these results it appears that the CHO content of the diet is more important than non-CHO sources in modulating peripheral thyroid hormone metabolism and that the influence of total calories is perhaps as pronounced as that of CHO when a "permissive" amount of CHO is ingested.