The art of simplicity: Water-soluble porphyrin-like carbon dots self-assemble into mesmerizing red glow.

In this new study, we present an intriguing development in the field of theranostics: the simplistic self-assembly of red-emissive amphiphilic porphyrin-like carbon dots (P-CDs). By harnessing their exceptional photophysical properties, we have revealed a strong candidate as the ideal photosensitizer (PS) for applications, particularly in the realm of imaging. Spanning a remarkable size average between 1-4 nm, these particles exhibit both highly stable and unparalleled emission characteristics between 650 and 715 nm in water in comparison to current carbon dots (CDs) available. Lastly, these CDs were fairly non-toxic when tested against normal human cell lines as well as were found to have favorable imaging capabilities in zebrafish embryo.

Advancing glioblastoma imaging: Exploring the potential of organic fluorophore-based red emissive carbon dots.

Over time, the interest in developing stable photosensitizers (PS) which both absorb and emit light in the red region (650 and 950 nm) has gained noticeable interest. Recently, carbon dots (CDs) have become the material of focus to act as a PS due to their high extinction coefficient, low cytotoxicity, and both high photo and thermal stability. In this work, a Federal and Drug Association (FDA) approved Near Infra-Red (NIR) organic fluorophore used for photo-imaging, indocyanine green (ICG), has been explored as a precursor to develop water-soluble red emissive CDs which possess red emission at 697 nm. Furthermore, our material was found to yield favorable red-imaging capabilities of glioblastoma stem-like cells (GSCs) meanwhile boasting low toxicity. Additionally with post modifications, our CDs have been found to have selectivity towards tumors over healthy tissue as well as crossing the blood-brain barrier (BBB) in zebrafish models.

Investigation into Red Emission and Its Applications: Solvatochromic N-Doped Red Emissive Carbon Dots with Solvent Polarity Sensing and Solid-State Fluorescent Nanocomposite Thin Films.

In this work, a NIR emitting dye, p-toluenesulfonate (IR-813) was explored as a model precursor to develop red emissive carbon dots (813-CD) with solvatochromic behavior with a red-shift observed with increasing solvent polarity. The 813-CDs produced had emission peaks at 610 and 698 nm, respectively, in water with blue shifts of emission as solvent polarity decreased. Subsequently, 813-CD was synthesized with increasing nitrogen content with polyethyleneimine (PEI) to elucidate the change in band gap energy. With increased nitrogen content, the CDs produced emissions as far as 776 nm. Additionally, a CD nanocomposite polyvinylpyrrolidone (PVP) film was synthesized to assess the phenomenon of solid-state fluorescence. Furthermore, the CDs were found to have electrochemical properties to be used as an additive doping agent for PVP film coatings.

Carbon nanotube electrodes for electrochemiluminescence biosensors.

The present application is based on the use of carbon nanotubes (CNTs) for biomolecular analysis using electrochemiluminescence (ECL) detection technique [1]-[9]. For this purpose we have grown self standing cylinder-shaped blocks of multi-wall CNTs (MWCNTs) by means of a catalytic chemical vapour deposition system, fed by camphor and ferrocene gases. The blocks were subsequently back-contacted and encapsulated into epoxy resin as electrical insulator and sealant, for their use as voltammetric electrodes. A ruthenium-complex solution has been used as ECL label. It has been observed a periodical light emission that lasts for hundreds of cycles, likely due to the CNTs structure. Thanks to a data-processing algorithm which exploits this behavior, the experiments show that it is possible to obtain a great increase in detection limit as compared to the common working metal electrodes (for example Au or Pt).

Thermal and electronic properties of macroscopic multi-walled carbon nanotubes blocks.

Massive carpets of well packed, vertically aligned and very long multiwall carbon nanotubes were synthesized by an efficient thermal Chemical Vapour Deposition process. Electrical properties of the material were evaluated, both in terms of "global" characteristics (bulk resistivity) and in terms of "local" properties (Scanning Tunnel Spectroscopy measurements) for as-grown and annealed at different temperatures samples. The behaviour of bulk resistivity as a function of temperature was evaluated in the range 3-300 K, with a four-probe technique. The resistivity shows a linear dependence with the square root of temperature in the investigated range. From the electrical analyses, it was found that the quality of the MWNTs was improved by the annealing process, since the resistivity decreases. Heat transport properties were evaluated by the laser flash technique in order to study thermal diffusivity. Moreover high temperature behavior of the specific heat capacity of single and multi-wall carbon nanotubes, was measured up to 800 K with a Differential Scanning Calorimeter.

Hydrogen adsorption in several types of carbon nanotubes.

In this work, we aim to study the hydrogen adsorption in several kinds of carbon nanotubes grown under different process conditions and to correlate the findings with the morphological microstructure and physical properties of these materials. The growth conditions and the behaviour with respect to hydrogen interaction of various carbon nanotubes are discussed, to establish microstructure-process-property relationships. In particular, we have analyzed several types of carbon nanotubes, namely one single-walled and five multi-walled having different tube diameter (due to different deposition techniques and conditions), different defectiveness and submitted to different surface treatments. To better understand the differences among the various samples, they have been investigated using field emission scanning electron microscopy and high resolution transmission electron microscopy for the morphological and structural characteristics, thermo-gravimetric analysis for the sample purity and Brunauer-Emmett-Teller analysis for the surface area. The experimental measurements on the ability of the different types of carbon nanotubes to adsorb and/or releasing hydrogen have been performed at 77 K with a volumetric Sievert analytical tool. Our findings clearly demonstrate a direct correlation between the exposed surface area and adsorbed hydrogen capacity, which confirms their linear relationship observed previously. For instance, single-walled nanotubes with surface area density of approximately 800 m2/g have showed hydrogen storage of approximately 1.7 wt% at a pressure of 35 atm. Adsorption process seems to be perfectly reversible. The adsorption values have been compared with a simple model, in order to evaluate the potentialities for carbon-based nanomaterials in future hydrogen storage applications.

Hydrogen adsorption in several types of carbon nanotubes.

In this work, we aim to study the hydrogen adsorption in several kinds of carbon nanotubes grown under different process conditions and to correlate the findings with the morphological microstructure and physical properties of these materials. The growth conditions and the behaviour with respect to hydrogen interaction of various carbon nanotubes are discussed, to establish microstructure-process-property relationships. In particular, we have analyzed several types of carbon nanotubes, namely one single-walled and five multi-walled having different tube diameter (due to different deposition techniques and conditions), different defectiveness and submitted to different surface treatments. To better understand the differences among the various samples, they have been investigated using field emission scanning electron microscopy and high resolution transmission electron microscopy for the morphological and structural characteristics, thermo-gravimetric analysis for the sample purity and Brunauer-Emmett-Teller analysis for the surface area. The experimental measurements on the ability of the different types of carbon nanotubes to adsorb and/or releasing hydrogen have been performed at 77 K with a volumetric Sievert analytical tool. Our findings clearly demonstrate a direct correlation between the exposed surface area and adsorbed hydrogen capacity, which confirms their linear relationship observed previously. For instance, single-walled nanotubes with surface area density of approximately 800 m2/g have showed hydrogen storage of approximately 1.7 wt% at a pressure of 35 atm. Adsorption process seems to be perfectly reversible. The adsorption values have been compared with a simple model, in order to evaluate the potentialities for carbon-based nanomaterials in future hydrogen storage applications.

Physiological levels and action of dehydroepiandrosterone in Yucatan miniature swine.

The biological role of dehydroepiandrosterone (DHEA) and its less active sulphated conjugate DHEAS was investigated in two experiments using Yucatan miniature swine. In experiment 1, plasma levels of both DHEA(S) among males were greater than female pigs that ranged in age from 0.3 to 84 mo old (P < 0.0001). In males, DHEA(S) were related inversely to serum triglycerides; DHEA was positively related to triglycerides in females (P < 0.01). In experiment 2, four 2-yr old male pigs, used as their own control, showed a 5% decrease in body weight, 11% increase in energy expenditure, 88% increase in lipid, and 100% decrease in glucose utilization (P < 0.0001) in response to DHEA vs. placebo treatments when adjusted for body weight. Plasma DHEA(S) were not different between treatment conditions. Glucose tolerance and plasma insulin levels were not different from controls. In vivo response to norepinephrine indicated beta-adrenergic sensitivity was altered by DHEA. Present findings suggest DHEA and/or its hormone products are important in modulating energy expenditure and lipid utilization for energy in male animals. The role of DHEA in energy metabolism and the difference between sexes warrant further investigation.

Cyclic food restriction, insulin and mammary cell proliferation in the rat.

We reported recently that weight cycling significantly increased the incidence of mammary cancer in virgin female rats that were pretreated with N-methyl-N-nitrosourea. The present study investigated the effect of weight cycling on mammary epithelial cell proliferation and its relationship to changes in plasma insulin, estrogen, progesterone and urinary corticosterone in 30 female virgin Sprague-Dawley rats. Animals were fed a modified AIN-76A diet containing 24.6% corn oil by weight. Weight-cycled (WC) rats were food restricted daily by either 33% or 50% of non-restricted controls for 1 week followed by 3 weeks compensatory refeeding and weight recovery over 18 weeks or 4.5 weight cycles. WC rats consumed 6-10% less food than controls (P = 0.01) but showed a 71-89% greater efficiency of food utilization for growth (P < 0.0001) than controls. There were no differences in total weight gain during treatment. Mammary lobuloalveolar and ductal cell proliferation of WC rats, measured by 5-bromo-2'deoxyuridine labelling, increased in a dose-response fashion, P = 0.03, P = 0.06 respectively in comparison to controls. Energy and substrate utilization measured by indirect calorimetry indicated WC animals expended less energy (P = 0.005) and utilized less glucose (P = 0.0001) and protein (P = 0.006) during restriction, and less lipid during recovery (P = 0.05) than controls. There were no significant differences in hormone levels between groups. Multiple regression analysis with plasma insulin, estrogen, progesterone and urinary corticosterone as independent variables (r = 0.947, r2 = 0.897, P = 0.003) showed that plasma insulin was the only significant predictor (P < 0.01) of mammary cell proliferation. In accord with this observation, tyrosine-phosphorylated activation of insulin receptor substrate-1, detected by immunoprecipitation and Western immunoblot analysis in mammary tumors of WC rats from our previous study, was 3-5 times greater than in non-restricted controls (P < 0.01). Present findings suggest that weight cycling in rats increases risk of breast cancer development via insulin stimulated mammary cell proliferation.

Cyclic food restriction alters substrate utilization and abolishes protection from mammary carcinogenesis female rats.

We tested the hypothesis that cyclic food restriction abolishes protection against mammary carcinogenesis. Virgin female Sprague Dawley rats (n = 159) were injected intraperitoneally with 25 mg/kg n-methyl-n-nitrosourea at 50 d of age. Eleven days later, rats were given free access to a 24.6 g fat/100 g AIN-76A diet (ad lib-c), fed in two meals (me-c), or fed in two meals restricted in weight by 33% for 1 wk followed by 3 wk of compensatory refeeding (me-r) for 18 wk or 4.5 restriction cycles. Energy and substrate utilization of 15 rats from each group was measured by indirect calorimetry. The me-r rats ate and weighed less (P < 0.0001), had a greater efficiency of food utilization (P < 0.01), and had a 12% higher incidence of mammary cancer (P < 0.0001) than ad lib-c rats after adjusting for the effect of final body weight. Resting metabolic rate was not different among groups, but me-r rats used less glucose during restriction and more glucose and less lipid for energy during body weight recovery than me-c rats (P < 0.0001). Increased energy efficiency and the shift in utilization of glucose and fatty acids followed closely the effects of cyclic food restriction and meal feeding on mammary carcinogenesis.

Survival of diabetic patients on peritoneal dialysis or hemodialysis.

Our objective was to analyze the survival of diabetic patients on renal replacement therapy and to compare their survival on extracorporeal and on peritoneal dialysis. All data regarding diabetic patients admitted to dialysis between 1 January 1983 and 31 December 1993 were collected by means of individual patient questionnaires sent to all of the 44 regional Renal Units (100% answers) of Lombardy, Italy. Cox proportional hazards model, stepwise procedure, was applied in order to select the covariates significantly associated with survival. Age (at baseline), sex, type of diabetes, initial modality of treatment (hemodialysis or peritoneal dialysis), and initial clinical risk factors (malignancies, serious heart disease, vascular disease, cirrhosis of the liver, cachexia) were considered. Descriptive analysis of survival was performed using the Kaplan-Meier technique. The survival of all diabetic patients (895) was 86.5% at one year, 52% at three years, and 34% at five years. The main causes of the 488 deaths of diabetic patients were cardiovascular diseases (56%), cachexia (18%), and infections (11%). The relative death risk of patients on peritoneal dialysis versus those on hemodialysis, after taking into account the main comorbid conditions, did not significantly differ from 1, as estimated by the Cox proportional hazards regression model. Five-year survival of diabetic patients was 34%, and no differences were found between peritoneal dialysis and hemodialysis as far as mortality is concerned.

Increased lipolysis to beta-adrenergic stimulation after dehydroepiandrosterone treatment in rats.

Young adult male rats were treated with 4 mg dehydroepiandrosterone (DHEA)/100-g diet for 4 wk or were fed the same purified diet unadulterated (51 carbohydrate:20 fat: 23.5 protein; wt/wt). After 1 wk body weight and fat mass of the DHEA-fed rats were significantly less than the controls. By the end of week 3, fat-free mass of the DHEA rats was less than the controls. Neither food intake nor resting metabolism, measured by indirect calorimetry, was different between groups. Isolated epididymal adipocytes of DHEA rats were significantly smaller and isoproterenol (x 10(7) M) stimulation of glycerol release was 53% greater (P < 0.01) than the controls. Basal rate of glycerol release increased significantly for both groups in response to the adenosine inhibitor adenosine deaminase; there were no significant interaction effects. Inhibition of lipolysis by the adenosine analogue phenylisopropyladenosine was similar between groups. Findings support the hypothesis that DHEA reduces adiposity directly by increased lipolysis, but the mechanism of action does not involve a change in the antilipolytic function of adenosine.

Dietary modulation of pancreatic carcinogenesis: calories and energy expenditure.

Physical activity (exercise) is a lifestyle factor that has received little attention with regard to its role in the etiology and/or prevention of cancer. These studies examined the effects of treadmill exercise on the early stages of pancreatic carcinogenesis initiated by azaserine in rats. Male Lewis rats were treated with azaserine at 2 weeks of age and weaned to experimental protocols at 3 weeks of age. Two experiments were undertaken; treadmill exercise began at 6 weeks of age (Experiment 1) or at 13 weeks of age (Experiment 2). Rats were exercised for 15-20 min/day and for 3-5 days/week. Treadmill speed and angle of incline were adjusted to afford a range of exercise intensities. The development of putative preneoplastic lesions of the pancreatic acinar cells (henceforth termed foci) was evaluated by quantitative stereological analysis using light microscopy. In Experiment 1, exercise resulted in a known paradoxical reduction in food intake by about 15% of the intake of the sedentary group fed ad libitum. The burden of azaserine-induced foci was decreased by approximately 37%, and this was attributed to the well known effects of reduced caloric intake in these young, rapidly growing rats. In Experiment 2, the higher intensity treadmill exercise group had an increased focal burden, compared to their sedentary pair-fed controls. Importantly, this enhancement occurred despite a reduction in food intake and body fat stores in this treadmill exercise group. These experiments demonstrate that exercise may suppress or promote carcinogenesis, depending upon the stage in the life cycle of the animal.

Effects of diet and exercise on the in vivo rates of the triglyceride-fatty acid cycle in adipose tissue and muscle of the rat.

The effects of feeding a low-protein diet (5 percent w/w) and daily exercise on the rates of substrate (futile) cycling between triglyceride and fatty acids (TG-FA cycle) were studied in rats in vivo using a radiochemical assay that involves following the incorporation of tritium from 3H-H2O into the fatty acid and glycerol moieties of triglyceride. Sixty-four rats were fed either a purified control diet (COND) consisting of 70 percent carbohydrate, 20 percent protein, 5 percent fat or an experimental low protein (LPD) diet consisting of 80 percent carbohydrate, 5 percent protein and 10 percent fat (w/w) and were either exercised six days weekly or remained sedentary for six weeks. Both LPD and exercise training (EXT) were found to increase significantly the rate of TG-FA substrate cycling above the rates observed in dietary and sedentary control groups. The LPD increased significantly the rate of cycling in interscapular brown adipose (IBAT), while adipose (WAT) and diaphragm muscle. EXT increased the rates of substrate cycling in soleus, heart, and diaphragm muscle and WAT. Rate of cycling in cardiac or skeletal muscle was one-twentieth that found in adipose tissue. There were also sex differences in the rate of substrate cycling. Substrate cycling in soleus and heart muscle of male animals were consistently higher than respective female treatment groups. Sedentary and EXT LPD animals weighed significantly less than but consumed a similar amount of food to the respective COND animals. These data provide the first in vivo evidence that the rate of substrate cycling can be increased by diet or by exercise training. The possible importance of TG-FA and other substrate cycles on efficiency of energy metabolism and etiology of obesity are discussed.

Fasting energy metabolism of the Yucatan miniature pig.

The fasting metabolic rates (FMR) of Yucatan miniature swine were determined using an open-circuit indirect respiration calorimeter. Mature nulliparous females had a mean FMR of 93 kcal/kg BW.75 and did not change significantly during the estrous cycle. This value is comparable to that observed in mature domestic swine. The calculated metabolizable energy requirement for maintenance for the Yucatan sow is 116 kcal/kg BW.75. Growing Yucatan boars had FMR of 127, 119 and 101 kcal/kg BW.75 at 15, 21 and 38 weeks of age, respectively, and were similar to values for comparably aged domestic swine. The calculated estimate for the metabolizable energy requirement for maintenance for Yucatan boars ranged from 158 kcal at 15 weeks of age to 126 kcal/kg BW.75 for 38 week old animals. Based on the similarity between the FMR of the Yucatan miniature swine in the present study and values published for standard size commercial hogs, it is concluded that the metabolic rates of these breeds of pig are similar. It is suggested that the daily energy needs of the Yucatan miniature pig may be met using values published for production livestock having similar physiological condition when adjusted for the smaller body size of the Yucatan breed.