Morphological modification of MWCNT functionalized with HNO3/H2SO4 mixtures

The acidic oxidation with HNO3/H2SO4 mixtures is widely reported as an effective method to functionalize multi-walled carbon nanotubes (MWCNT). Although effective, a bad control of the oxidation conditions frequently cause serious modifications of carbon nanotube network, limiting further potential applications. Investigations about the effect of functionalization operating conditions on the morphological, chemical and chemical-physical properties of MWCNT can be useful for a proper setting of oxidation reactions of MWCNT according to their specific applications. In this work the effect of HNO3/H2SO4 ratio on the morphological and chemical-physical properties and on the degree of functionalization of MWCNT was investigated. Electron microscopy, thermogravimetric, X-ray diffraction, titration and water dispersion analyses clearly revealed that the increase of the amount of concentrated sulphuric acid in the HNO3/H2SO4 mixture lead to an increase of the amount of functional groups on the MWCNT surface but also to an increase of structural damage in terms of tube cutting and generation of additional defects in the graphitic network of pristine

Coumarin-conjugated multiwalled carbon nanotubes for potential biological applications: development and characterization

This work presents a novel cascade of chemical functionalization of multiwalled carbon nanotubes which allows the conjugation with differently substituted coumarins. Aim of the present work is to synthesize new materials able to rescue cells from the adverse effect of CNT particles since pristine CNTs are practically insoluble and tend to accumulate inside cells, organs and tissues. Moreover, it was reported that single walled CNTs particles show an adverse effect on keratinocytes through an oxidative mechanism, leading to NF-kB activation. The conjugation with coumarins, known superoxide anion scavengers, could switch the cytotoxicity of the new materials. The cascade functionalization of MWCNTs by sequential steps of carboxylation, acylation, amine modification and finally, coumarin conjugation have been performed and the synthesis and the chemical properties of several f-MWCNTs-coumarins have been exploited.

Optimized CVD production of CNT-based nanohybrids by Taguchi robust design

Taguchi's robust design method is for the first time employed to optimize many aspects of the production of nanohybrids based on C nanotubes by iron-catalyzed chemical vapor deposition in i-C4H10 + H2 atmosphere. By analyzing the outcomes of the catalytic process in terms of selectivity, carbon yield, purity and crystalline arrangement of the hybrid-forming nanotubes, the influence is ranked of the following parameters: synthesis temperature (500-700 degrees C), support material (alumina, magnesia or sodium-exchanged montmorillonite), calcination- (450-750 degrees C) and reduction-(500-700 degrees C) temperatures of the 15 wt% Fe-catalyst. In the experiments initially performed for this purpose, the growth process had, on average, scarce selectivity (2 in a scale 1-5) and poor yield (130 wt%); carbonaceous deposits exhibited unsatisfactory graphitization degree (Raman D/G intensity ratio > 1.5) and contained large amounts of metal impurities (14 wt%) and amorphous carbon (5 wt%). The indications emerging from Taguchi approach to the process optimization are critically examined. The experimental conditions chosen for carrying out test experiments allow achieving excellent selectivity (5) or large yield (760 wt%), hybrids with well-graphitized nanotubes (D/G intensity ratio < 0.6), nearly free of metallic (0.3 wt%) or amorphous (0.4 wt%) inclusions, with consequent possibility of satisfying the different requisites that the specific application to be addressed may require.

Deregulation of PERK in the autoimmune disease pemphigus vulgaris occurs via IgG-independent mechanisms

BACKGROUND

Serum and IgG isolated from patients with the autoimmune blistering disease pemphigus vulgaris (PV) trigger complex intracellular pathways in keratinocytes, including alterations of the cell cycle and metabolism, which ultimately lead to cell-cell detachment (acantholysis). We have shown previously that one of the earliest pathogenic events in PV is the activation of protein kinases, including the PKR-like endoplasmic reticulum (ER) kinase PERK.

OBJECTIVES

In the present study we investigated in more detail the role of PERK in the pathogenesis of PV.

METHODS

PERK levels were assessed by Western blotting and in-cell enzyme-linked immunosorbent assay, and PERK expression was silenced by siRNA technology. The effects of PV sera/IgG on keratinocyte cultures were investigated by flow cytometry, MTT and adhesion assays.

RESULTS

We show that PERK is activated in keratinocytes exposed to PV serum, as demonstrated by an increase in phosphorylated PERK levels and phosphorylation of eIF2α. Decreased expression of PERK by siRNA reduced the effects of PV serum on the cell cycle and keratinocyte viability, two key events in PV pathophysiology. As impairment of metabolic activity in PV is partially due to non-IgG serum factors, we then investigated the activation of PERK in keratinocytes incubated with whole PV serum, purified PV IgG and IgG-depleted PV serum. The data demonstrated that PV sera depleted of IgG, but not PV IgG, triggered PERK phosphorylation and this correlated with a marked reduction of metabolic activity in keratinocytes exposed to IgG-free serum. Knockdown of PERK by siRNA abrogated the changes in the cell cycle and apoptosis induced by IgG-depleted PV serum. Finally, the reduction of metabolic activity observed in keratinocytes exposed to IgG-depleted PV serum was almost absent in PERK-deficient cells.

CONCLUSIONS

Taken together, the results demonstrate that activation of PERK participates in the reduction of metabolic activity and cell viability seen in PV and that this phenomenon depends on non-IgG factors. PERK activation may represent a novel signalling mechanism linking ER stress and acantholysis in PV.

Note: Electrical resolution during conductive atomic force microscopy measurements under different environmental conditions and contact forces

Conductive atomic force microscopy experiments on gate dielectrics in air, nitrogen, and UHV have been compared to evaluate the impact of the environment on topography and electrical measurements. In current images, an increase of the lateral resolution and a reduction of the conductivity were observed in N(2) and, especially, in UHV (where current depends also on the contact force). Both effects were related to the reduction/elimination of the water layer between the tip and the sample in N(2)/UHV. Therefore, since current measurements are very sensitive to environmental conditions, these factors must be taken into consideration when comparisons between several experiments are performed.

Scaling laws for multi-walled carbon nanotube growth by catalyzed chemical vapor deposition

The synthesis of C nanotubes by catalyzed chemical vapor deposition at 600 degrees C is investigated, using yield and purity degree of C deposits to monitor the reaction outcome. From the reaction, carried out in C4H10-H2-He environment over Al2O3 supported Fe catalysts, multi-walled C nanotubes are attained, which, after purification, are analyzed by routinely-used diagnostics techniques. In order to clarify the role of the growth parameters, various experiments are performed changing flow rates of reactive gases, as well as, amount, metal load and reduction temperature of Fe/Al2O3 catalysts in the ranges 15-90 cc/min, 0.25-2.00 g, 10-40 wt% and 500-700 degrees C, respectively. Correspondingly, carbon yield varies between 47 wt% and 913 wt%, while purity degree between 56 wt% and 93 wt%. Owing to the lack of any correlation between these changes, it is initially quite difficult to envisage the effect, produced by any change of the growth conditions, on the final reaction outcome. The problem is solved by applying a semi-empirical approach, through which the "original" growth variables are combined to give dimensionless arguments (scaling laws for the reaction parameters), able to account for all the variation of yield and purity in the ranges considered. As final result, the growth issue can be easily predicted because carbon yield and purity degree can be approximated through very simple functions of the "new" process variables.

Influence of carbon source and Fe-catalyst support on the growth of multi-walled carbon nanotubes

Catalytic activity of iron based catalysts in the production of multi-walled carbon nanotubes (MWCNTs) has been investigated. The effect of the carbon source (ethane or isobutane), catalyst support (Al2O3 or SiO2), iron loading, catalyst reduction temperature and reaction temperature on yield and quality of carbon products has been examined. The structural and morphological properties of catalyst and carbon products obtained have been analyzed by means of scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy (RS), thermogravimetric analysis (TGA) and X-ray powder diffraction (XRD). The iron-based catalysts supported on alumina seem to be efficient systems for the production of carbon nanotubes from chemical vapor deposition (CVD) of isobutane with very interesting yields. The opportune calibration of reaction parameters, such as iron loading and reaction temperature, can in fact drive the synthesis toward the formation of high quality CNTs.

Improving the electrical performance of a conductive atomic force microscope with a logarithmic current-to-voltage converter

A new configuration of conductive atomic force microscope (CAFM) is presented, which is based in a standard CAFM where the typical I-V converter has been replaced by a log I-V amplifier. This substitution extends the current dynamic range from 1-100 pA to 1 pA-1 mA. With the broadening of the current dynamic range, the CAFM can access new applications, such as the reliability evaluation of metal-oxide-semiconductor gate dielectrics. As an example, the setup has been tested by analyzing breakdown spots induced in SiO2 layers.

At least three phosphorylation events induced by pemphigus vulgaris sera are pathogenically involved in keratinocyte acantholysis

Intercellular adhesion among keratinocytes is guaranteed by desmosomes. Disruption of desmosomal integrity leads to cell-cell detachment or acantholysis, as it classically occurs in pemphigus vulgaris (PV), an autoimmune blistering disease of skin and mucous membranes. While purified PV IgG seems to trigger intracellular signaling that crucially involves p38 MAPK, keratinocyte acantholysis induced by whole PV serum may recruit a number of additional signals. In this study, the Pro-Q Diamond Phosphoprotein Assay was used to investigate the overall changes in protein phosphorylation levels in an in vitro model of PV. We showed that keratinocytes exposed to whole PV sera underwent at least three early and transient phosphorylation events. Two bands with apparent molecular masses of 35 and 45 kDa were found to be phosphorylated within 1 min after incubation with PV sera. A third band of about 80 kDa reached the peak of phosphorylation level after 3 hours. Morphologic evidence of cell shrinkage and acantholysis were late events and did not correlate temporally with kinase activation, suggesting that cytoskeleton reorganization is a downstream phenomenon. Interestingly, pharmacological abrogation of PV-specific protein phosphorylation was able to inhibit the cell-cell detachment, rounding up, and redistribution of Dsg3 in keratinocytes. Thus, at least three phosphorylation events are pathogenically involved in pemphigus acantholysis.

Mucocutaneous pemphigus vulgaris carrying high-titre antidesmoglein 1 antibodies with skin lesions resembling pemphigus erythematosus

Patients with pemphigus vulgaris (PV) who have both antidesmoglein (Dsg)1 and anti-Dsg3 antibodies usually develop flaccid blisters on skin and mucous membranes. We report a case of PV with crusting skin lesions resembling pemphigus erythematosus, the localized variant of pemphigus foliaceus (PF). Notably, the patient had high titres of anti-Dsg1 IgG, as assessed by ELISA. We then established an in vitro model of pemphigus, and found that patient's serum was able to induce suprabasilar acantholysis in mouse skin culture. However, epidermal splitting also occurred within the granular layer, suggesting that the pathogenic potential of such a high-titre anti-Dsg1 serum was intermediate between PV and PF. Thus, the levels of anti-Dsg1 antibodies could play a role in determining the clinical phenotype of pemphigus.

Phenomenological model for the confined dynamics in semicrystalline polymers: the multiple alpha relaxation in cold-crystallized poly(ethylene terephthalate)

The segmental relaxation in poly(ethylene terephthalate), crystallized from either an isotropic or a cold-drawn glass, is investigated by means of dielectric spectroscopy. It is shown that there exist two distinct alpha relaxation modes: a slow one, characterized by a rather wide frequency interval, and a faster, much narrower one. A simple phenomenological model is developed in order to analyze the polarization autocorrelation functions phi(t)'s associated with these relaxation modes. The model is based on the idea that the growth of crystalline domains causes a progressive confinement of the amorphous regions where, eventually, the observed alpha processes take place. The mechanism of confinement is accounted for by applying to the case of constrained density fluctuations, well known concepts introduced by Adam and Gibbs [J. Chem. Phys. 43, 139 (1965)] concerning the relaxation dynamics in liquids close to the glass transition. Randomness on confining conditions is then introduced, leading to the derivation of analytical expressions which are used afterwards to fit the asymptotic behavior of the phi's for long-time tails. It is found that the slow, broad alpha process takes place in regions where the confining effect of crystals is strong, whereas the amorphous domains relaxing via the fast mode are those where the confinement effect of crystals is weak. The analysis of the phi's by means of this model allows us to relate the fitting exponents to the dispersion in the free energy associated with structural rearrangement.

[Diagnostic and therapeutic guidelines for entero-cutaneous fistulas. Personal experience and literature review]

The entero-cutaneous fistulas (ECF) are abnormal communications between intestine and abdominal skin. They can occur spontaneously, or after an injury or a surgical procedure. They are associated with a high rate of morbidity and mortality. Spontaneous fistulas can mainly occur in patients affected by cancer, inflammatory bowel disease, diverticulitis, appendicitis, as a result of radiotherapy or injuries. Surgical procedures, carried out in case of neoplastic diseases, inflammatory bowel disease, adhesions removal, represent the primary cause in the development of a postoperative fistulas. Malnourishment, poor general conditions of the patient, high output fistula along with anatomical site of development, and the presence of abscesses, represent the negative factors influencing the spontaneous healing of fistulas. The experience reported here is about three ECF cases occurred after surgery and treated only with medical therapy. The first case is a woman in good general conditions who underwent surgery to remove a recurrent retroperitoneal myxoid liposarcoma situated in the right lower quadrant. The patient had never undergone surgery for an intestinal resection. The other two patients analyzed were affected by sepsis and metabolic unbalance and had developed a fistula after colonic resection. Fluids and electrolytes adjustments and sepsis management have preceded any other kind of therapy. Continuous infusion with somatostatin, fast, proton pump inhibitors and loperamide have been taken up to decrease secretions and intestinal motility. Total parenteral nutrition has been essential to recover nutritional status and improve patients' general conditions. In order to heal and protect peri-fistula skin we have used sterile washing solutions, absorbable ionic exchange resin, silver and polyurethanes based medications and colostomy bags adhesive systems. Since surgical treatment of ECF is associated with high rates of morbidity and mortality, conservative treatment should always be taken into consideration. When conservative treatment fails, delayed surgical intervention has been related to a higher rate of success. The purpose of this study is to describe diagnostic and therapeutic guidelines to general surgeons, like ourselves, whenever they have to deal with ECF cases.

Effect of ewe feeding system (grass v. concentrate) on intramuscular fatty acids of lambs raised exclusively on maternal milk

Twenty pregnant Comisana ewes were divided into two groups of 10. One group was allowed to graze a vetch pasture (grass). The second group of animals was housed collectively in a pen and was given hay and concentrates (concentrate). After lambing, all the ewes were allowed to stay with the respective lambs between 18:00 h and 07:00 h of the following day in two different pens. Therefore all the lambs were raised exclusively on maternal milk. The lambs were slaughtered at 38 days of age. Milk and lamb meat (longissimus dorsi muscle) fatty acids were analysed. Ewes on grass produced milk with a lower (P< 0·001) proportion of saturated fatty acids and with a higher proportion of both monounsaturated (P< 0·05) and polyunsaturated fatty acids (P< 0·01) than ewes given concentrates. Trans-vaccenic acid was significantly higher (P< 0·001) in milk from grass-fed animals compared with ewes given concentrates. Linoleic acid (C18: 2 n-6) tended to be higher (P= 0·06) in milk from ewes on concentrates while linolenic acid (C18: 3 n-3) was significantly higher (P< 0·001) in milk from animals grazing pasture. Conjugated linoleic acid (cis-9, trans-11 C18: 2) was almost double in milk from grass-fed ewes compared with animals given concentrates (P< 0·001). Regarding lamb tissue, trans-vaccenic acid (C18: 1 trans-11) was higher (P= 0·01) in the fat from lambs raised by grazing ewes. Linoleic acid (C18: 2 n-6) was at higher concentration (P< 0·001) in the fat from lambs raised by ewes given concentrates. Linolenic acid (C18: 3 n-3) was increased three-fold (P< 0·001) in the fat of lambs from the grass group compared with lambs suckled by ewes given concentrates. The isomer cis-9, trans-11 of conjugated linoleic acid was present at double concentration (P< 0·001) in the fat from animals raised by grazing ewes. Eicosapentaenoic (C20: 5 n-3; EPA) and docosaesaenoic (C22: 6 n-3; DHA) acids were higher (respectivelyP< 0·001 andP= 0·01) in the intramuscular fat from lambs from the grass group compared with animals from the concentrate group. The n-6/n-3 ratio was lower (P< 0·001) in the meat from lambs raised by grazing ewes. Overall this trial showed that ewe feeding system strongly affects intramuscular fatty acids even in lambs raised exclusively on maternal milk.

[Anastomotic configuration as a risk factor in the recurring onset after intestinal resection for Crohn's disease: our point of view]

Crohn's disease is an inflammatory chronic intestinal disease characterized of an high level of postoperative recurrence. Actually surgical treatment is not decisive; patients can undergo several operations during their lives, running the risk of coming up against the syndrome of short bowel. The main disease frequently appears in the segment ileo-caecal, while the site more often affected by the recurrence seems to be the stump close to the anastomosis. General, local and not specific factors should influence the recurrence level. Among the general factors, cigarette smoking would have a leading role in the recurrences onset. Giving up smoking and a treatment with 5-ASA (amino-salicylic acid) help to reduce the risk of Crohn's recurrences after surgery. During the treatment of this pathology the wide intestinal resections are not justified because the anastomotic recurrence after resection seems to be influenced not by the presence of remaining lesions but by the type of realized anastomosis. Although they disagree about the type of anastomosis to adopt, the authors agree identifying the anastomotic stenosis as the main factor which determines the recurrences. Stenosis, in fact, determining fecal stasis and, therefore, the increase of the pressure at the intestinal wall level, causes ischemia of this same wall. Ischemia puts up the risk of fistulas and anastomotic dehiscence. The mechanical or manual ileo-colic side-to-side anastomosis, assuring a wide lumen, drops to the minimum the risk of stenosis compared with the end-to-end and end-to-side configurations. And then, the side-to-side ileo-colic anastomosis avoiding the intestinal compartmentation between ileo and colon, guarantees less reflow in the small bowel of bacteria and colic metabolite. In this way the inflammatory process which brings to the fresh outbreak of the disease on the mucosa of the near anastomotic head faints. In the light of this thesis, most of the authors, including the writer, agree about making the side-to-side anastomoses in the intestinal resections for the Crohn's disease.

Doxorubicin coupled to lactosaminated albumin: Effects on rats with liver fibrosis and cirrhosis

BACKGROUND

The conjugate of doxorubicin with lactosaminated human albumin has the potential of increasing the doxorubicin efficacy in the treatment of hepatocellular carcinomas expressing the asialoglycoprotein receptor. However, coupled doxorubicin also accumulates in the liver, which might damage hepatocytes.

AIMS

To verify whether coupled doxorubicin impairs liver function in rats with liver fibrosis and cirrhosis.

METHODS

Coupled doxorubicin was administered using the same schedule which exerted an antineoplastic effect on rat hepatocellular carcinomas (4-weekly injections of doxorubicin at 1 microg/g). Liver fibrosis/cirrhosis was produced by carbon tetrachloride (CCl4) poisoning. Liver samples were studied histologically. Serum parameters of liver function and viability were determined.

RESULTS

In normal rats, administration of coupled doxorubicin neither caused microscopic changes of hepatocytes nor modified serum liver parameters. In rats with fibrosis/cirrhosis, although a selective doxorubicin accumulation within the liver followed coupled doxorubicin administration, the drug did not have a detrimental effect on the histology of the liver and, among serum liver tests, only alanine aminotransferase and aspartate aminotransferase levels were moderately modified.

CONCLUSIONS

Coupled doxorubicin can be administered to rats with liver fibrosis/cirrhosis without inducing a severe liver damage. If further studies will confirm the efficacy and safety of this compound, coupled doxorubicin therapy may open a new perspective in the treatment of hepatocellular carcinoma.

[Nearly total thyroidectomy: versus total thyroidectomy: our experience]

AIM

Generally, the classification of thyroidectomy as benign pathology is: multinodular toxic goitre, simple goitre, toxic adenoma, Base-dow disease, Hashimoto's tyroiditis Subtotal thyroidectomy provides for the removal of the gland except for a bilateral residue of about 6-10 g, near total thyroidectomy provides for the near total removal of the gland except for a residue inferior to 5 grams. Near total thyroidectomy has taken the place of the subtotal thyroidectomy.

METHODS

In two years, in our institute, there have been exeuted: 96 near total thyrodectomies, 96 total thyroidetomies, 8 lobectomies ad two revues for recurrencies.

RESULTS

In 2 cases there have been haemorrhagies after nearly total thyroidetomy. Only in 1 case we practiced tracheotomy for follicular carcinoma infiltering thiroidic cartilage. In 2 cases treated with nearly total thyroidetomy and in 4 cases treated with total thyroidetomy, there has been temporary hypoparathyroidism. In no case treared wih nearly total thyroidetomy and in 2 cases treated with total thyroidetomy, there has been permanent hypo-parathyroidism. In 5 cases treated with total thyroidetomy and in no case treated with nearly total thyroidetomy, there has been, monolateral, temporary paralysis of the inferior laryngeal nerve that solved in 6 months for 3 patients and in 2 months for 2 patients.

CONCLUSIONS

There has not been permanent paralysis of the mono or bilateral inferior laryngeal nerve. Even if the surgical approach to the benign disease is now orientated to the total thyroidectomy, a more conservative surgery is, in our opinion, justified when a malignant pathology is excluded and considering also the low effect of recurrencies and hypothyroidism.