3D printable fully biomass-based composite using poly(furfuryl alcohol) as binder and cellulose as a filler.

Nowadays, composite materials are widely used in different sectors owing to their improved mechanical and functional properties compared to bulk materials and efficient manufacturing processes. Nevertheless, the majority of these materials are still petroleum-based, which is incompatible with the recent environmental awareness. As a result, in the current study, a fully biomass-based composite material was produced employing poly(furfuryl alcohol) (PFA) as a bio-based matrix coupled with cellulose powder as fillers and processing aid agent. The addition of cellulose powder increased the viscosity of the uncured composite paste and conferred it a shear-thinning thixotropic making it suitable for 3D printing using the liquid deposition modeling technique (LDM). After curing, the combination of these raw materials yields a renewable and cost-effective composite for additive manufacturing by the LDM technique with high interlayer and interfilament adhesion, good mechanical performances, and adequate shape fidelity.

New fluorinated montmorillonites for the preparation of UV-cured coatings.

Montmorillonite was modified by means of a cation exchange reaction with two fluorinated ammonium salts, containing either a fluoroalkylic or a perfluoropolyether chain. The introduction of the fluorinated ammonium salts into the clay mineral galleries led in both cases to an increase of the interlayer distance, as revealed from the XRD spectra. However, the surfactant conformation achieved was different: a double layer structure was formed by the fluoroalkylic modifier, a paraffinic structure was present when the perfluoropolyether surfactant was used. This led to different results when the organoclays were dispersed into a typical UV curable dimethacrylate: a good degree of intercalation was achieved only with the clay modified by the fluoroalkylic surfactant.

Norepinephrine activity, as measured by MHPG, is associated with menopausal hot flushes.

OBJECTIVES: Baseline norepinephrine levels, as measured by a metabolite (plasma 3-methoxy-4-hydroxyphenolglycol, MHPG), have been reported to increase in women who experience hot flushes. However, norepinephrine is also discharged in a counter-regulatory attempt to increase brain glucose as normal daily variations occur. The purpose of this analysis is to examine the relationship between hot flush frequency and MHPG under conditions of experimental glucose manipulation. METHODS: A repeated-measures experimental design study was conducted with ten postmenopausal women taking hormone therapy between the ages of 38 and 55 years. In a 30-h experimental protocol, participants received normal saline and 20% glucose intravenous infusions on sequential days and were monitored for hot flushes and blood glucose changes. MHPG levels were evaluated before and after each experimental condition as a biomarker of norepinephrine activity. RESULTS: Although hot flush frequency was significantly different between infusion periods, mean MHPG levels were not statistically different (normal saline period, 3.1 ng/ml; glucose infusion, 3.2 ng/ml). No distinct patterns of MHPG change were found in this sample. CONCLUSIONS: In this study, there was no consistent pattern of MHPG increase or decrease in the women experiencing hot flushes.

Acute induction of epileptiform discharges by pilocarpine in the in vitro isolated guinea-pig brain requires enhancement of blood-brain barrier permeability.

Systemic application of the muscarinic agonist, pilocarpine, is commonly utilized to induce an acute status epilepticus that evolves into a chronic epileptic condition characterized by spontaneous seizures. Recent findings suggest that the status epilepticus induced by pilocarpine may be triggered by changes in the blood-brain barrier (BBB) permeability. We tested the role of the BBB in an acute pilocarpine model by using the in vitro model brain preparation and compared our finding with in vivo data. Arterial perfusion of the in vitro isolated guinea-pig brain with <1 mM pilocarpine did not cause epileptiform activity, but rather reduced synaptic transmission and induced steady fast (20-25 Hz) oscillatory activity in limbic cortices. These effects were reversibly blocked by co-perfusion of the muscarinic antagonist atropine sulfate (5 microM). Brain pilocarpine measurements in vivo and in vitro suggested modest BBB penetration. Pilocarpine induced epileptiform discharges only when perfused with compounds that enhance BBB permeability, such as bradykinin (n=2) or histamine (n=10). This pro-epileptic effect was abolished when the BBB-impermeable muscarinic antagonist atropine methyl bromide (5 microM) was co-perfused with histamine and pilocarpine. In the absence of BBB permeability enhancing drugs, pilocarpine induced epileptiform activity only after arterial perfusion at concentrations >10 mM. Ictal discharges correlated with a high intracerebral pilocarpine concentration measured by high pressure liquid chromatography. We propose that acute epileptiform discharges induced by pilocarpine treatment in the in vitro isolated brain preparation are mediated by a dose-dependent, atropine-sensitive muscarinic effect promoted by an increase in BBB permeability. Pilocarpine accumulation secondary to BBB permeability changes may contribute to in vivo ictogenesis in the pilocarpine epilepsy model.

The influence of water on the intercalation of epoxy monomers in Na-montmorillonite.

The intercalation of a typical UV-curable epoxy monomer (CE) in unmodified montmorillonite and the effect of hydration on the intercalation reaction are studied. Montmorillonite in the sodium form was submitted to a controlled hydration/dehydration cycle and the water content was checked by TGA/XRD analyses. The structure of the hydrated Na+-montmorillonite was determined from the values of the basal spacings and from the water content of the hydrated form: a coordination of four water molecules per Na ion was found, corresponding to a minimum of energy calculated by molecular dynamics simulation. When dispersing the clay in the CE monomer, the anhydrous Na+-montmorillonite did not show any intercalation; on the contrary the hydrated form showed an increase of the basal spacing. A possible mechanism to explain the intercalation of the CE monomers is proposed.

Improved method for the measurement of large neutral amino acids in biological matrices.

A high-performance liquid chromatographic method for measuring neutral amino acids in rat sera, brain tissues, and perfusates was developed by using o-phthalaldehyde sulfite as a pre-column derivatization reagent. With the present method, it was possible to separate the neutral amino acids within a single run in 25 min, while the acidic amino acids were eluted near or at the solvent front. The recovery was above 88.8% with a relative standard deviation (RSD) below 4.2%. The within- and between-day assay reproducibility for the determination of rat serum amino acids showed RSDs below 1.35 and 7.61%, respectively. In the present study, the neutral amino acids were assayed with high sensitivity, accuracy and good reproducibility in a relatively short time and on a small sample size.

Cutaneous uptake of 14C-HD vapor by the hairless guinea pig.

The hairless guinea pig (HGP) is used by our laboratory to model the human cutaneous response to sulfur mustard (HD), bis(2-chloroethylsulfide), exposure. We determined the HD content in the skin of HGP after a 7-min exposure to vapors saturated with a mixture of HD and 14C-HD. Concentration/time (CT) values in the range of 2 micrograms/cm2/min were determined by counting skin 14C disintegrations per min (dpm) in animals euthanized immediately after exposure. These values are similar to human penetration rates obtained by other investigators. A rate curve monitoring the reduction in skin 14C dpm was developed for animals euthanized between 0 and 24 hr post- exposure. This curve showed the greatest change after 1 hr. The epidermal (62%) to dermal (38%) ratio of 14C at 24 hr was measured for two animals. We saw no site preference for HD penetration among the 8 sites used. The 14C content of template adhesive tape was determined to follow HD distribution. These results contribute to a better understanding of the cutaneous response to HD in the HGP model.

Cutaneous exposure to bis-(2-chloroethyl)sulfide results in neutrophil infiltration and increased solubility of 180,000 Mr subepidermal collagens.

Exposure to bis-(2-chloroethyl)sulfide (BCES; "sulfur mustard") causes delayed formation of slowly healing skin blisters. Although the histopathology of BCES injury is well characterized [reviewed in Smith et al., J Am Acad Dermatol 32: 767-776, 1995], little is known of the cutaneous toxicity at the molecular level. To identify biological markers of exposure, epidermal and subepidermal extracts were prepared from 48 individual hairless guinea pigs (HGP) at successive 3-hr intervals following exposure to BCES vapor, and compared using gel electrophoresis, and lectin- and antisera-binding. Inflammation was assessed by measuring edema and myeloperoxidase activity. Edema reached peak levels at 15-18 hr and remained elevated above controls at 24 hr. Recruitment of neutrophils, deduced from increased myeloperoxidase, occurred as early as 3 hr after BCES exposure with maximum infiltration at 6-12 hr. Binding of concanavalin-A lectin revealed increased amounts, relative to contralateral control sites, of two approximately 180,000 Mr polypeptides in subepidermal protein extracts from the BCES-exposed skin obtained > or = 12 hr after exposure. This alteration was not found in epidermal protein extracts prepared from the same animals. Based upon the determined amino acid compositions, both polypeptides had significant collagenous triple helical content (>75%). They could be distinguished immunologically from collagen types I, III, and IV by using polyclonal antisera. We conclude that exposure of HGP skin to BCES results in an early neutrophil infiltration that precedes epidermal-dermal separation and selective alterations of the subepidermal extracellular matrix.

Hypochlorite solution as a decontaminant in sulfur mustard contaminated skin defects in the euthymic hairless guinea pig.

Hypochlorite solutions are thought to be efficacious when used to topically decontaminate intact skin. However, few studies have examined the efficacy of decontamination of chemically contaminated wounds. Therefore, we compared the decontamination efficacy of sodium hypochlorite (0.5% and 2.5% solutions), calcium hypochlorite (0.5% and 2.5% solutions) and sterile water to untreated controls in wounds exposed to sulfur mustard (HD). Anesthetized euthymic hairless guinea pigs (EHGP) (n = 6) were exposed to 20 mg/kg (approximately 0.4 LD50) HD in a full-thickness 8 mm surgical biopsy skin defect (i.e., wound). Each animal was subsequently decontaminated, after a two-minute intra-wound exposure to liquid HD, with nothing or one of the decontamination solutions. Decontamination efficacy was determined by the visual grading of the HD-traumatized wound lesion and by comparison of the expected HD-induced leukocyte suppression. Leukocyte suppression was inconsistent in all animals; therefore, the visual grading was the only viable evaluation method. No significant differences were observed among wounds decontaminated with any of the solutions. However, the skin surrounding non-decontaminated (but exposed) control animals showed the least visual pathology. The lesions induced following decontamination are presumed to be due to the mechanical flushing of HD onto the peri-lesional skin, or by chemical damage induced by the solution, or HD-solution interaction. Further studies are required to best delineate the optimal decontamination process for HD contaminated wounds.

Pyridoxal phosphate as an antisickling agent in vitro.

Although pyridoxal phosphate is known to inhibit gelation of purified hemoglobin S, antisickling activity has never been demonstrated for intact erythrocytes. We incubated washed erythrocytes at 37 degrees C either in buffer alone, or with added pyridoxal phosphate or pyridoxal, washed these cells, suspended them in untreated buffer, and compared the percent modified hemoglobin, the oxygen affinity, and the extent of sickling under hypoxia. Pyridoxal phosphate modified intracellular hemoglobin more slowly than pyridoxal. Pyridoxal phosphate lowered the oxygen affinity of normal cells, but had no effect on oxygen binding by sickle cells. Pyridoxal increased the oxygen affinity of normal and sickle erythrocytes equally. Pyridoxal phosphate significantly inhibited sickling of sickle or sickle trait erythrocytes (P less than 0.001). Inhibition of sickling by pyridoxal phosphate was largely independent of oxygen binding; whereas inhibition of sickling by pyridoxal was almost entirely dependent on increased oxygen binding. Although pyridoxal phosphate and pyridoxal both inhibit sickling by modification of hemoglobin S, they differ in the kinetics of whole cell modification, the effect on oxygen affinity of intact cells, and the mechanism of action of the antisickling activity.

Modification of intracellular hemoglobin with pyridoxal and pyridoxal 5'-phosphate.

The aldehyde forms of vitamin B6, pyridoxal and pyridoxal 5'-phosphate (PLP) have aroused interest as antisickling agents because of their ability to modify hemoglobin (Hb) and their low toxicity. To study their rate of formation and stability inside red cells, pyridoxal-Hb and PLP-Hb were measured in lysates from treated normal and sickle erythrocytes using isocratic high pressure liquid chromatography on Bio-Rex 70. The validity of this assay was confirmed by isoelectric focussing, fluorescence scans of reduced globin, and treatment of cells with pyridoxal 14C. Optimal conditions were described for treatment of whole blood with pyridoxal and washed erythrocytes with PLP. Although there was competition between 2,3-DPG and PLP, but not pyridoxal, for binding to Hb, depletion of 2,3-DPG prior to treatment was unnecessary. No special requirements were noted for the anticoagulants or buffers used. Sickle erythrocytes formed PLP-Hb more rapidly than normal erythrocytes, but pyridoxal-Hb appeared at the same rate in both types of erythrocytes. During incubation of treated erythrocytes in untreated plasma, the stability of pyridoxal-Hb varied inversely with the hematocrit, but PLP-Hb was stable at all hematocrits tested. The absence of hemolysis during a 4 day incubation of treated normal red cells implies that treatment with pyridoxal or PLP did not severely impair red cell metabolism.

Measurement of serum T4 concentration by high performance liquid chromatography.

Although RIA techniques for the measurement of serum T4 have been extremely useful, this methodology has several disadvantages, including the requirement for the use of radioisotopes, various levels of thyronine cross-reactivity, and the ability to measure only a single iodothyronine in one assay. We have developed a high performance liquid chromatography (HPLC) method for quantitating serum T4 that utilizes the detection of dansyl-T4 compounds and obviates the problems described for RIA techniques. Serum samples were extracted with ethanol and then chloroform, reacted with dansyl chloride, and, after n-heptane extraction, placed directly on column. Utilizing this technique, dansyl-T4 was easily separated and identified. The sensitivity of detection of the dansylated-T4 in serum was 1 microgram/dl, and linearity was observed when increasing standard T4 concentrations were employed. Sensitivity to 10 ng/dl (100 fmol on column) was achieved when T4 was added to buffer. The coefficients of variation were 4.8% and 2.1% for normal and high serum samples, respectively. When 39 random serum samples were anayzed both by HPLC and RIA, there was concordance of these techniques, since the derived correlation coefficient was 0.94. In summary, the present study demonstrates that serum T4 concentrations can be measured by HPLC and that these measurements agree remarkably well with those obtained by RIA. Because of the inherent advantages of HPLC methodology over that of RIA, this technique of measurement of T4 may have wide applicability to the measurement of iodothyronines.

Normal valine disposal in obese subjects with impaired glucose disposal: evidence for selective insulin resistance.

Insulin has major effects on both glucose and branched chain amino acid metabolism. To determine whether the insulin resistance of obesity equally affects both glucose and branched chain amino acid metabolism, we measured the ability of obese and normal subjects to dispose of intravenous bolus dose of glucose (25 g) or L-valine (4 g). Basal plasma glucose levels were the same in the 18 normal and 17 obese (163 plus or minus 8% of ideal body weight) subjects, but basal plasma insulin levels were higher in the obese group (15 plus or minus 2 vs 6 plus or minus 1 microU/ml; p less than 0.001). The obese group had a slower glucose disappearance rate after glucose challenge (0.84 plus or minus 0.06 vs. 1.11 plus or minus 0.07 hr(-1); p less than 0.01) despite having a greater serum insulin response to the glucose load (26 plus or minus 4 vs 11 plus or minus 1 insulin area units; p less than 0.01), confirming insulin resistance. In contrast, disposal of a valine load was the same in normal and obese subjects, as assessed by initial and second phase exponential disappearance rates, metabolic clearance rates of valine, and volumes of distribution. In normal men, disposal rates of glucose and valine after simultaneous administration of both substances were slower than corresponding disposal rates determined when each substance was given alone. We conclude that obese subjects with impaired glucose disposal have normal valine disposal, suggesting that the insulin resistance of obesity can be selective in its effect on different metabolic systems. Glucose and valine also appear to mutually antagonize each other's disposal.