Visual and semi-quantitative analysis of 6-[18F]FDOPA PET/CT in patients with brain tumors and suspected tumor recurrence versus radionecrosis.

INTRODUCTION: Amino acid PET is a tool recommended by the main neuroimaging societies in the differential diagnosis between radionecrosis (RNC) and umour recurrence (TR) in brain tumours, but its use in our country is still limited. The aim of this work is to present our experience with 6-[18F]FDOPA PET/CT (FDOPA) in brain tumours (primary and M1), comparing these results with other published results. MATERIAL AND METHODS: Retrospective study of 62 patients with suspected tumour recurrence (TR): 42 brain metastases (M1) and 20 primary, who underwent FDOPA. Images were analysed visually and semi-quantitatively, obtaining SUVmax and SUVmaxlesion/SUVmaxstriatum (L/S) and SUVmaxlesion/SUVmaxcortex (L/C) ratios. The diagnostic validity of PET was analysed and the best performing cut-off points were calculated. PET results were compared with clinical-radiological follow-up and/or histopathology. RESULTS: TR was identified in 49% of M1 and 76% of brain primaries. The best performing FDOPA interpretation was visual and semi-quantitative, with a sensitivity and specificity in primaries of 94% and 80% and in M1s of 96% and 72% respectively. The cut-off points with the best diagnostic performance were L/C1.44 in M1 and L/C1.55 in primaries. There are discrepant results with other published results. CONCLUSION: FDOPA PET/CT is a useful tool in the differential diagnosis between recurrence and RNC in brain tumours. It is needed a standardization to contribute to homogenise FDOPA results a inter-centre level.

Effects of concurrent exercise on health-related quality of life in middle-aged women.

OBJECTIVE: This study aimed to evaluate the influence of a 16-week concurrent exercise program on health-related quality of life in middle-aged women. METHODS: A total of 150 middle-aged women from the FLAMENCO project (age range 45-60 years) were randomized into a counseling (n = 75) or an exercise (n = 75) group. The exercise group followed a 16-week (3 days/week, 60 min/session) concurrent exercise program (aerobic + resistance training). The counseling group attended conferences on a healthy lifestyle. Participants' health-related quality of life was assessed with the EuroQol plus, a visual analog scale and the 36-item Short Form Health Survey (SF-36), where greater values indicate a better health-related quality of life. RESULTS: The visual analog scale increased by 9.0% in the exercise group, whereas it only increased by 3.5% in the counseling group (p = 0.040). The SF-36 physical function, physical role, bodily pain, vitality and emotional role increased by 5.5%, 11.3%, 10.8%, 9.6% and 8.9%, respectively, in the exercise group, whereas these only increased by 0.6%, decreased by 0.7% and increased by 1.4%, 3.8% and 0.6% in the counseling group (all p < 0.05). CONCLUSIONS: Our results suggest that a 16-week concurrent exercise program adapted for midlife women improved their health-related quality of life. CLINICALTRIALS.GOV IDENTIFIER: NCT02358109. Date of registration: 05/02/2015.

Acute symptomatic seizures and epilepsy after mechanical thrombectomy. A prospective long-term follow-up study.

INTRODUCTION: New treatments for acute ischaemic stroke, such as mechanical thrombectomy, can achieve reperfusion of large ischaemic tissue. Some studies have suggested that reperfusion therapies can increase the risk of suffering acute symptomatic seizure (ASS) and poststroke epilepsy (PSE). The aim of the study was to determine the incidence of ASS and PSE in patients undergoing thrombectomy, and related factors. PATIENTS AND METHODS: This was a retrospective single-centre study including patients with ischaemic stroke and NIHSS> 8 treated with thrombectomy with a follow-up ≥5 years. We evaluated several epidemiological, radiological, clinical and electroencephalographic variables. RESULTS: Of the 344 included patients, 21 (6.1%) presented ASS, 53 (15.40%) died in the acute phase, and 13 (4.46%) died during the first year. The degree of reperfusion (p 0.029), advanced age (p 0.035), and haemorrhagic transformation (p 0.038) increased the risk of suffering ASS, with degree of reperfusion being an independent factor, OR 2.02 (1.21-4.64). The incidence of PSE was 4.12% in the first year, 3.72% in the second, and 1.61% in the fifth. The accumulated incidence at 5 years was 8.93%. Related risk factor for suffering PSE was ASS (p < 0.001), yielding an OR value of 2.00 (1.28-3.145). CONCLUSIONS: Thrombectomy doesn´t increase the risk of ASS. A higher percentage of reperfusion, advanced age, and haemorrhagic transformation are associated with an increased risk of ASS. ASS is a risk factor for suffering PSE. In terms of mortality, having suffered ASS and/or PSE does not increase acute or long-term mortality.

Mediterranean diet, tobacco consumption and body composition during perimenopause. The FLAMENCO project.

OBJECTIVE: To study the association of the adherence to the Mediterranean diet (MD) and tobacco consumption with body composition during perimenopause. STUDY DESIGN AND METHODS: A cross-sectional study in 176 perimenopausal women from the FLAMENCO project. A food frequency questionnaire and the Mediterranean Diet Score were assessed. Body composition was measured using dual-energy X-ray absorptiometry. MAIN OUTCOMES MEASURES: Body mass index (BMI), fat mass (FM), ratio of gynecoid to total fat mass (G/T), ratio of android to gynecoid fat mass (A/G), visceral adipose tissue (VAT) and waist circumference (WC). RESULTS: Intake of whole-grain cereals was associated with lower WC, FM percentage, android FM, VAT and higher G/T (all p < 0.05). Intake of nuts was associated with lower BMI and FM percentage and intake of fruits with lower BMI, WC, total and android FM, FM percentage, A/G, VAT and higher G/T (all p < 0.05). Intake of pulses was associated with lower weight, BMI and android FM. Intake of whole dairy products was associated with lower weight, BMI, WC, total and android FM and VAT (all p < 0.05). Intake of olive oil was associated with lower WC and FM percentage (all p < 0.05). Intake of sweetened beverages was associated with higher weight, BMI, WC, FM percentage, android FM, VAT and total FM (all, p < 0.05). Smokers had a lower MD adherence (p < 0.05). Finally, a greater MD adherence was associated with higher G/T (p < 0.01) and lower A/G (p < 0.05). CONCLUSIONS: A higher MD adherence, avoiding tobacco, an increased consumption of whole-grain cereals, nuts, fruits, pulses, whole dairy products and olive oil, and a lower consumption of sweetened beverages might contribute to a healthier body composition during perimenopause.

[Historical perspective of the studies with the greatest impact on the treatment of gliomas]. / Perspectiva histórica de los estudios con mayor impacto en el tratamiento de los gliomas.

Historically, advances in our knowledge of neuro-oncology and improvements in the survival of patients with brain tumours have been relatively scarce. One of the main turning points can be established from 2005 onwards, when the potential therapeutic role of cytostatics in these tumours was confirmed, thus changing the standard of treatment. Up until that date, only radiation therapy and surgery were considered truly effective treatments. This shift has contributed to the development of new systemic therapies and to an in-depth study of gliomagenesis. Advances in the knowledge of the basic fields of brain tumours have helped improve the design and results of new clinical trials, while clinical outcomes provide feedback and new data to further the understanding of these tumours. However, these promising advances open up new unresolved questions and offer a critical approach to the interpretation of past studies. This review mainly updates the results of trials that changed or modified the clinical practice of the treatment and management of gliomas. Commenting on relevant basic research papers that have not yet been translated into the implementation of changes in the treatment of these patients is excluded.

TITLE: Perspectiva histórica de los estudios con mayor impacto en el tratamiento de los gliomas.Históricamente, los avances en el área de conocimiento de la neurooncología y las mejoras en la supervivencia de los pacientes con tumores cerebrales han sido relativamente escasos. Uno de los principales puntos de inflexión puede establecerse a partir de 2005, cuando se constata el hasta entonces potencial papel terapéutico de los citostáticos en estos tumores, cambiando consiguientemente el estándar de tratamiento. Hasta esa fecha, sólo la radioterapia y la cirugía se consideraban tratamientos realmente eficaces. Este cambio ha contribuido al desarrollo de nuevas terapias sistémicas y a profundizar en el estudio de la gliomagénesis. Los avances en los campos básicos del conocimiento de los tumores cerebrales han ayudado a mejorar el diseño y los resultados de los nuevos ensayos clínicos, al mismo tiempo que los resultados clínicos retroalimentan y ofrecen nuevos datos para seguir avanzando en la comprensión de estos tumores. Sin embargo, estos esperanzadores avances abren nuevas cuestiones aún no resueltas y ofrecen un enfoque crítico a la interpretación de estudios pasados. La presente revisión principalmente actualiza los resultados de los ensayos que cambiaron o modificaron la práctica clínica del tratamiento y el manejo de los gliomas. Se excluyen trabajos relevantes de investigación básica que aún no han tenido traslación en la implementación de cambios en el tratamiento de estos pacientes.

Electronic properties of pure and p-type doped hexagonal sheets and zigzag nanoribbons of InP.

Unlike graphene, a hexagonal InP sheet (HInPS) cannot be obtained by mechanical exfoliation from the native bulk InP, which crystallizes in the zinc blende structure under ambient conditions. However, by ab initio density functional theory calculations we found that a slightly buckled HInPS is stable both in pristine form and when doped with Zn atoms; the same occurred for hydrogen-passivated zigzag InP nanoribbons (ZInPNRs), quasi-one-dimensional versions of the quasi-two-dimensional material. We investigated the electronic properties of both nanostructures, in the latter case also in the presence of an external transverse electric field, and the results are compared with those of hypothetical planar HInPS and ZInPNRs. The band gaps of planar ZInPNRs were found to be tunable by the choice of strength of this field, and to show an asymmetric behavior under weak electric fields, by which the gap can either be increased or decreased depending on their direction; however, this effect is absent from slightly buckled ZInPNRs. The binding energies of the acceptor impurity states of Zn-doped HInPS and ZInPNRs were found to be similar and much larger than that of Zn-doped bulk InP. These latter findings show that the reduction of the dimensionality of these materials limits the presence of free carriers.

Site-specific modulation of white adipose tissue lipid metabolism by oleoyl-estrone and/or rosiglitazone in overweight rats.

In spite of their shared decrease of insulin resistance, oleoyl-estrone [OE], and rosiglitazone show diverging effects on body fat mass and distribution. In this study, we studied whether their effects on white adipose tissue [WAT] were due to a shared or synergistic mechanism of action. Combined effects of OE and rosiglitazone 10-day treatment on WAT lipid, cell mass/number, and the expression of key lipid metabolism and regulatory agents were studied using an adult male overweight rat model. OE decreased WAT cell mass and lipids, parameters not changed by rosiglitazone. The effects of OE and--specially--rosiglitazone were more marked in small-cell WAT (i.e., mesenteric and subcutaneous sites) than in larger cell WAT (retroperitoneal and perigonadal). OE decreased the expressions in WAT of lipogenic enzymes, lipoprotein lipase, PPARs, and SREBP1c, effects symmetrically reversed by rosiglitazone. OE showed no effects on hormone-sensitive lipase expression, which was increased by rosiglitazone. OE strongly inhibited WAT lipogenesis, leaving lipolysis unchanged, thus unbalancing (and helping mobilize) WAT lipid stores. Rosiglitazone acted practically only on small-cell WAT sites, where it favored lipogenesis, but also stimulated lipolysis, which resulted in limited changes in lipid stores. Combination of OE and rosiglitazone induced less fat loss than OE alone.

Medical audit on children with asthma in an Emergency Department.

OBJECTIVE: To carry out a medical audit or evaluation and improvement procedure on the management of children with asthmatic crises in our Emergency Department (ED). MATERIAL AND METHODS: We carried out a retrospective audit between January and March 2007, analysing the medical records of a random sample of 50 patients aged 2-14 years consulting our ED for asthmatic crises. Following the international guides, we first selected 17 explicit indicators divided into four domains: "evaluation", "examination", "diagnostic resources", and "treatment and conditions at discharge". RESULTS: Indicators' compliance proved unequal; it was scarce for cause of asthma crisis (32%); degree of severity (18%); and supportive treatment (24%). Auscultation was registered in 100%, but respiratory frequency only in 49%, and peak flow in 0%. A total of 78% of the patients were treated in the ED, in all cases with beta-mimetic agents, and with systemic corticosteroids in 12%. The result of treatment was registered in only 69% of cases. The medical documentation of resident doctors was not signed by the staff. CONCLUSIONS: We identified the following weak points: failure to determine the degree of severity; lack of specification of the details of the crisis (prior duration, treatment at home, supportive treatment); scant asthma background history; and deficient recording of respiratory frequency and peak flow. We propose improving the anamnesis, recording respiratory frequency, with the introduction of tools to measure peak flow, specification of treatment response, and the development of a simpler and more practical protocol, with the performance of a re-audit.

Influence of oleoyl-estrone treatment on circulating testosterone. Role of 17beta-hydroxysteroid dehydrogenase isoenzymes.

Overweight male rats received oral oleoyl-estrone (OE) for 10 days, and were compared with controls. The expression of 17beta-hydroxysteroid dehydrogenase (17betaHSDH) isoenzymes, and other proteins related to sex hormone metabolism, were analyzed in testicle, liver, adrenals and two white adipose sites: subcutaneous inguinal and epididymal pads using a semiquantitative RT-PCR method. Androstenedione, testosterone, estrone and estradiol levels were measured by HPLC-MS/MS. Isoenzyme expressions were grouped according to their main physiological function (oxidative or reductive) and preferred substrate (androgen or estrogen). As expected, testicle was the main site for synthesis of testosterone and estradiol, and the liver the main organ oxidizing them to androstenedione and estrone. Overall oxidative capacity was 6.5-fold higher than the reductive, and estradiol synthesis and oxidation potential were higher than for testosterone. OE decreased serum androgens, and increased estrone, but not estradiol. This was due to decreased testicle ability to produce testosterone, because of smaller size and decreased 17betaHSDH3 expression, but also to lower availability of precursors. High estrone availability (from OE hydrolysis) does not translate into higher estradiol because of decreased testicle reductive 17betaHSDH expression and decreased aromatase. In consequence, we can assume that OE effects on androgens, and the hypothalamic-pituitary-gonadal axis are limited to testicles.

Intestinal oleoyl-estrone esterase activity in the Wistar rat.

Low-dose oral oleoyl-estrone (OE) (i.e. in dairy products) is hydrolysed to estrone, which promotes growth and fat deposition. However, pharmacological doses of OE are absorbed largely intact and elicit fat losses. Thus, in order to find out how the intestine handles OE, esterase activity (at pH 5, 7 or 8) was measured in rat stomach, duodenum, jejunum, ileum, cecum, large intestine, and liver using OE as substrate. There were no sex-related differences. Pure pancreatic cholesterol-ester esterase hydrolysed OE even in the absence of taurocholate. The differences in the pH-related activity distribution pattern and selective inhibition and taurocholate dependence show that, in addition to the luminal (i.e. pancreatic) cholesterol-ester esterase, other esterases hydrolyse OE; these combined activities may be sufficient to rapidly dispose of pharmacological doses of OE. Female rats received a tritium-labeled OE gavage; the luminal and tissue label content were measured up to 24 h. The high retention of label in the stomach suggest that this may be a significant site of absorption. The rapid decrease of label in intestinal lumen (and rat tissues) shortly after the administration, hint at rapid absorption and disposal. In conclusion, the high OE-esterase activity and early absorption of OE are indicative of upper gastro-intestinal tract absorption skipping most of the medium-tract esterases.

A density-functional study of the possibility of noncollinear magnetism in small Mn clusters using SIESTA and the generalized gradient approximation to exchange and correlation.

We investigated the possibility of noncollinear magnetism in small Mn(n) clusters (n=2-6) using the density-functional method SIESTA with the generalized gradient approximation (GGA) to exchange and correlation. The lowest-energy states identified were collinear, with the atomic spin magnetic moments pointing in the same direction, for Mn(2) and Mn(3), and noncollinear for Mn(4), Mn(5) and, most decidedly, Mn(6). These SIESTA/GGA results, which are compared with those of an earlier SIESTA study that used the local spin density approximation, are qualitatively in keeping with the result obtained by VASP/GGA calculations.

Engineering the magnetic structure of Fe clusters by Mn alloying.

We propose to tailor the magnetic structure of atomic clusters by suitable doping, which produces the nanometric equivalent to alloying. As a proof of principle, we perform a theoretical analysis of Fe(6-x)Mn(x) clusters (x = 0-5), which shows a modulation of the magnetic moment of the clusters as a function of Mn doping and, more importantly, a collinear to noncollinear transition at x = 4.

In the rat, estrone sulphate is the main serum metabolite of oral oleoyl-estrone.

Two different oral doses of oleoyl-estrone: 1 and 10 nmol/g a day were given once to male Wistar rats. The serum levels of free estrone, estrone sulphate, estradiol, and acyl-estrone were measured at intervals up to 72 h after the gavage. Oleoyl-estrone was rapidly absorbed; with the 1 nmol/g dose no changes were observed in plasma acyl-estrone but levels increased dramatically with 10 nmol/g, peaking at 6 h; high acyl-estrone levels were maintained up to 24 h, returning to normalcy at 48 h. With the 10 nmol/g dose, free estrone at most doubled its levels but estrone sulphate concentrations rose by one order of magnitude; in both cases, the increases soon (2 h) reached a plateau that was maintained for almost two days. Estradiol levels remained unchanged except for a transient peak at 2 h at the 10 nmol/g dose. The relationship between free estrone and its sulphate was linear, and those of estrone and estrone sulphate versus acyl-estrone showed the existence of an upper serum concentration limit for both molecules. The results hint at estrone sulphate being an important metabolite of oleoyl-estrone disposal, confirm the limited estrogenic response to oleoyl-estrone administration and agree with a rapid absorption and disposal of oleoyl-estrone, nevertheless maintaining high circulating levels of the ester for a time after its oral administration.

[Ocular myasthenia gravis: diagnostic aspects and evolution]. / Miastenia grave ocular: aspectos diagnósticos y evolución.

INTRODUCTION: Myasthenia gravis lacks a diagnostic gold standard, so diagnosis is supported by the findings of several tests. Conversion from ocular myasthenia gravis (OMG) to a more widespread disease is frequently early. AIMS. To describe and compare the clinical data and findings of the diagnostic tests of patients with OMG and those with a different diagnosis, and to know the conversion rate from OMG to generalized myasthenia. PATIENTS AND METHODS: Descriptive and analytic retrospective study of 44 patients referred for neurophysiological testing through 4 years because of suspected OMG. RESULTS: 12 patients (27%) were diagnosed as having OMG. Evolution time prior to diagnosis tended to be shorter in OMG patients. Isolated ptosis or combined with diplopia was more frequent in OMG, while isolated diplopia was so in other diagnoses (p = 0.003). No thymoma was found. SFEMG jitter of facial muscles was abnormal, including blocking, in all OMG patients (8/8) and normal in the rest (30/30). Edrophonium test was positive in all OMG patients (7/7) and doubtful in another one (1/7). Anti-AChR titers were initially positive in 10/11 OMG patients and 0/17 with other diagnoses. Aponeurotic ptosis and strabismus were the most frequent non-myasthenic etiologies. OMG showed an early generalization in two patients who developed dysarthria. CONCLUSIONS: The low ratio of diagnostic confirmation suggests that in the face of ptosis or diplopia diagnostic testing with a high sensibility for OMG is favoured. Jitter showed the best initial diagnostic performance.

The conjugated linoleic acid ester of estrone induces the mobilisation of fat in male Wistar rats.

We investigated whether the substitution of the fatty acid moiety in oleoyl-estrone (OE) by conjugated linoleic acid, i.e. conjugated linoleoyl-estrone (cLE) may help improve the antiobesity effects of OE. Overweight (17% fat) male rats were treated for 10 days with oral OE or cLE (10 nmol/g per day) and compared with controls receiving only the oily vehicle. Rat weight and food intake were measured daily. After killing by decapitation, body composition and main plasma parameters were analysed. cLE induced marked decreases in body weight, energy intake, carcass energy and body lipid, whilst sparing protein; the effects were not significantly different from those obtained with OE. Energy expenditure was unchanged, but energy intake decreased to 46% (OE) or 55% (cLE) of controls; whole body energy decreased by 29% (OE) or 24% (cLE) in the 10-day period studied. Plasma composition showed almost identical decreases in glucose and cholesterol elicited by OE and cLE, with a more marked decrease in triacylglycerols by OE and no effect of either on NEFA. OE decreased leptin and insulin levels, but the effects of cLE were more marked on both, with similar decreases in adiponectin. It can be concluded that cLE is a new drug of the OE family; its overall effects on energy were akin to those of OE, albeit fractionally less effective at the single dose tested. However, this lower potency on lipid mobilisation does not affect other effects, such as powerful hypercholesterolemic effects or the modulation of adiponectin. And last, but not least, cLE seems to produce a more marked decrease in leptin and insulin than OE, which may reflect a coordinate action of the conjugated linoleic acid moiety and the "OE effect" on target tissues. If that were the case, cLE may constitute an improvement over OE in its action on insulin resistance.

Evolution of magnetism in iron from the atom to the bulk.

The evolution of the magnetic moment in iron clusters containing 20-400 atoms is investigated using first-principles numerical calculations based on density-functional theory and real-space pseudopotentials. Three families of clusters are studied, characterized by the arrangement of atoms: icosahedral, body-centered cubic centered on an atom site, and body-centered cubic centered on the bridge between two neighboring atoms. We find an overall decrease of magnetic moment as the clusters grow in size towards the bulk limit. Clusters with faceted surfaces are predicted to have magnetic moment lower than other clusters with similar size. As a result, the magnetic moment is observed to decrease as function of size in a nonmonotonic manner, which explains measurements performed at low temperatures.

Real space pseudopotential calculations for copper clusters.

Neutral and anion clusters of copper, Cu(n) (n=3-11), are examined using real space pseudopotentials constructed within the local spin density approximation. We predict the ground state structure for each cluster, the binding energy, and the corresponding photoelectron spectra, which we compare to experiment. We find strong final state effects in the photoelectron spectra, especially for the smaller clusters. The binding energy as a function of cluster size tracks well with the measured values, although the magnitude of the binding energy exceeds the experimental values by approximately 20%, as expected for the local spin density approximation.

Combined effects of oral oleoyl-estrone and limited food intake on body composition of young overweight male rats.

OBJECTIVE: The combined effects of limited food intake and OE treatment have been analysed in order to determine whether hypocaloric diets enhance the slimming effects of OE on mature overweight male rats. Two levels of dietary limitation at 50 and 25% of a standard intake were established, roughly corresponding to the human LCDs and VLCDs. DESIGN: Wistar male rats (6 weeks old) were made overweight by a cafeteria diet. After transition to standard diet, they were subjected to food restriction: down to 50 or 25% with respect to the transition period. Half the animals were given daily oral gavages of 10 nmol/g oleoyl-estrone (OE), and the rest received only the vehicle during 10 days. MEASUREMENTS: Changes in weight and body composition: water, lipid, protein or gross energy were determined by comparing the final pool size with that of day 0, calculated from the initial body weight and the composition of untreated rats. Energy and nitrogen balances were estimated. Plasma levels of metabolites and hormones were also measured. RESULTS: OE induced changes in body composition similar to those elicited by a 50% reduction in food, with massive loss of lipid and energy. OE-treated rats ate less than the controls, but additional effects on body composition on reduced diet were minimal. OE improved metabolic homoeostasis: better maintained glycaemia, lower cholesterol and shallower hormonal changes, but at the expense of slightly increased protein mobilisation. CONCLUSIONS: The data presented suggest that no advantages are accomplished by combining OE treatment and hypocaloric diets compared with OE alone, at least under the experimental conditions tested, since the effects were not additive. Despite OE affecting food intake, mechanisms other than that are deemed responsible for the mobilisation of body fat, since intake alone cannot explain the effects on body weight, nor the metabolic and hormonal changes in OE-treated rats. It is concluded that the combination of food restriction and OE may result in unwanted increased protein mobilisation with no synergy between both slimming treatments.

Ab Initio simulations of nonstoichiometric Cd(x)Te(1-x) liquids.

We present ab initio molecular-dynamics simulations for Cd(x)Te(1-x) liquids where the composition is nonstoichiometric. The simulations are performed following Born-Oppenheimer molecular dynamics. The required forces are obtained from a solution of the Kohn-Sham equation using ab initio pseudopotentials. We consider stoichiometries of the form: Cd(x)Te(1-x), where x=0.2, 0.4, 0.6, and 0.8. For each composition of the melt, we consider a range of temperatures near the experimentally determined liquid temperatures. We examine the microstructural properties of the melt, the viscosity, and self-diffusion properties of the liquid as a function of the stoichiometry and temperature. We also perform an analysis of the distribution of the electronic density of states in these liquids. We find that structural changes in the local order, experimentally predicted to occur when the concentration of Cd is increased, are closely related to changes in the electronic properties of the melt.