Ultrasound-guided percutaneous liver biopsy in children. Five-year experience at a tertiary care center.

INTRODUCTION AND AIMS: Percutaneous liver biopsy with histopathologic analysis is a valuable tool for the diagnosis, prognosis, and treatment evaluation of liver diseases. Its ultrasound-guided performance is useful, making the procedure safer and reducing the risk for complications and hospital stay. Our aim was to describe the indications, histopathologic study, and complications associated with the performance of ultrasound-guided percutaneous liver biopsy in pediatric patients. MATERIAL AND METHODS: The study included 102 ultrasound-guided percutaneous liver biopsies performed on patients <16 years of age, within the time frame of January 2014 and December 2019. The information was obtained from electronic files and histopathologic studies and the data were analyzed through descriptive statistics. RESULTS: A total of 102 procedures were carried out on 99 patients. Mean patient age was 72 months and 58.8% of the patients were female. Over 65% of the indications for liver biopsy included autoimmune hepatitis (23.5%), elevated liver enzymes (21.5%), and chronic liver disease (20.5%). Four patients presented with immediate complications (3.9%), three of which were major (2.9%), concurring with that reported in the international literature. CONCLUSIONS: Our study corroborates the importance of ultrasound-guided liver biopsy in the diagnosis and follow-up of pediatric patients. The procedure also had a low complication rate of only 3.9%.

Ultrasound-guided percutaneous liver biopsy in children. Five-year experience at a tertiary care center. / Biopsia hepática percutánea guiada por ultrasonido en pediatría. Experiencia de 5 años en un centro de tercer nivel.

INTRODUCTION AND AIMS: Percutaneous liver biopsy with histopathologic analysis is a valuable tool for the diagnosis, prognosis, and treatment evaluation of liver diseases. Its ultrasound-guided performance is useful, making the procedure safer and reducing the risk for complications and hospital stay. Our aim was to describe the indications, histopathologic study, and complications associated with the performance of ultrasound-guided percutaneous liver biopsy in pediatric patients. MATERIAL AND METHODS: The study included 102 ultrasound-guided percutaneous liver biopsies performed on patients <16 years of age, within the time frame of January 2014 and December 2019. The information was obtained from electronic files and histopathologic studies and the data were analyzed through descriptive statistics. RESULTS: A total of 102 procedures were carried out on 99 patients. Mean patient age was 72 months and 58.8% of the patients were female. Over 65% of the indications for liver biopsy included autoimmune hepatitis (23.5%), elevated liver enzymes (21.5%), and chronic liver disease (20.5%). Four patients presented with immediate complications (3.9%), three of which were major (2.9%), concurring with that reported in the international literature. CONCLUSIONS: Our study corroborates the importance of ultrasound-guided liver biopsy in the diagnosis and follow-up of pediatric patients. The procedure also had a low complication rate of only 3.9%.

New bioanalytical platform based on the use of avidin for the successful exfoliation of multi-walled carbon nanotubes and the robust anchoring of biomolecules. Application for hydrogen peroxide biosensing.

We are reporting an innovative building-block for the development of biosensors based on the non-covalent functionalization of multi-walled carbon nanotubes (MWCNTs) with avidin (MWCNTs-avidin). In this work, at variance with previous reports, avidin has the double role of simultaneously being the exfoliating agent of MWCNTs and the platform for anchoring different biotinylated biomolecules. The optimum dispersion was obtained by sonicating for 5.0 min 0.50 mgmL-1 MWCNTs with 1.00 mgmL-1 avidin solution prepared in 50:50 v/v ethanol/water. As proof-of-concept, we immobilized biotinylated horseradish peroxidase (b-HRP) at glassy carbon electrodes (GCE) modified with MWCNTs-avidin to develop a hydrogen peroxide biosensor using hydroquinone as redox mediator. Surface plasmon resonance, electrochemical impedance spectroscopy, cyclic voltammetry and amperometry demonstrated that, even after the partial denaturation of avidin due to the drastic conditions used to functionalize the MWCNTs, it preserves the biorecognition properties and efficiently interacts with biotinylated horseradish peroxidase (b-HRP). The analytical characteristics of the resulting hydrogen peroxide biosensor are the following: linear range between 1.0 × 10-6 M and 1.4 × 10-5 M, sensitivity of (1.37 ±â€¯0.04) x 105 µAM-1, detection limit of 24 nM and reproducibility of 2.9%. The sensor was challenged with different samples, a mouthwash solution, human blood serum and milk, with very good performance.

Immobilization of DNA on glassy carbon electrodes for the development of affinity biosensors.

The adsorption and electrooxidation of nucleic acids on glassy carbon electrodes are evaluated by using chronopotentiometric stripping analysis. The influence of electrochemical pretreatments, supporting electrolyte, halides and monovalent cations levels as well as the role of the oligonucleotide length and composition, accumulation potential and time on the adsorption and further electrooxidation of oligo(dG)(11) and oligo(dG)(21) are discussed. The adsorption behavior of single and double stranded calf thymus DNA on untreated glassy carbon electrodes is also evaluated. Trace (microg/l) levels of the oligonucleotides and polynucleotides can be readily detected following short accumulation periods with detection limits of 25, 60, 126 and 219 microg/l for oligo(dG)(21), oligo(dG)(11), ss and ds calf thymus DNA, respectively. The confined DNA layers demonstrated to be stable in air, in 0.200 M acetate buffer pH 5.00 and in 0.020 M phosphate buffer pH 7.40+0.50 M NaCl.

FIA-AAS determination of salicylic acid by a solid-phase reactor of copper carbonate incorporated in polyester resin beads.

The determination of salicylic acid was carried out by reaction of the drug with copper carbonate entrapped in a polymeric material in a solid-phase reactor; the released cupric ions were monitored by flame atomic absorption at 324.8 nm. The calibration graph is linear over the range 4.0-75 mug ml(-1) of salicylic acid, with a relative standard deviation of less than 1.5% and a sample throughout of 257 h(-1). The influence of foreign compounds was studied and the method was applied to the determination of salicylic acid content in two different pharmaceutical formulations.

Comparative study of the electrochemical behavior and analytical applications of (bio)sensing platforms based on the use of multi-walled carbon nanotubes dispersed in different polymers.

This review present a critical comparison of the electrochemical behavior and analytical performance of glassy carbon electrodes (GCE) modified with carbon nanotubes (CNTs) dispersed in different polymers: polyethylenimine (PEI), PEI functionalized with dopamine (PEI-Do), polyhistidine (Polyhis), polylysine (Polylys), glucose oxidase (GOx) and double stranded calf-thymus DNA (dsDNA). The comparison is focused on the analysis of the influence of the sonication time, solvent, polymer/CNT ratio, and nature of the polymer on the efficiency of the dispersions and on the electrochemical behavior of the resulting modified electrodes. The results allow to conclude that an adequate selection of the polymers makes possible not only an efficient dispersion of CNTs but also, and even more important, the building of successful analytical platforms for the detection of different bioanalytes like NADH, glucose, DNA and dopamine.

Calcium binding to human platelet integrin GPIIb/IIIa and to its constituent glycoproteins. Effects of lipids and temperature.

Platelet plasma membrane glycoproteins IIb (GPIIb) and IIIa (GPIIIa) form a Ca(2+)-dependent heterodimer. GPIIb/IIIa, which serves as the receptor for fibrinogen and other adhesive proteins at the surface of activated platelets. Using equilibrium dialysis measurements, it was established that both GPIIb and GPIIIa in solution have low-affinity Ca(2-)-binding sites (Kd0.2-0.3 mM), five in GPIIb and two in GPIIIa, and it was confirmed that only the alpha-chain of GPIIb (GPIIb alpha) binds Ca2+. Furthermore, Ca2+ binding was found with two CNBr fragments of GPIIb, GPIIb alpha-(1-285) and GPIIb alpha-(314-489), which carry three out of the four putative Ca(2+)-binding sites. GPIIb/IIIa in solution has a single high-affinity Ca(2+)-binding site (Kd1 80 +/- 30 nM at 21 degrees C), whose degree of saturation regulates the state of association of GPIIb and GPIIIa in the GPIIb/IIIa heterodimer at room temperature, and 3-4 medium-affinity Ca(2+)-binding sites (Kd2 40 +/- 15 microM at 21 degrees C). When GPIIb/IIIa was incorporated into liposomes, Kd1 decreased by an order of magnitude (9 +/- 3 nM at 21 degrees C) and reached the dissociation constant estimated for the high-affinity Ca(2+)-binding sites at the platelet surface [Brass & Shattil (1982) J. Biol. Chem. 257, 1400-1405], whereas Kd2 remained unchanged. The high-affinity Ca(2+)-binding site of GPIIb/IIIa in solution at 4 degrees C has almost the same affinity (Kd1 65 +/- 20 nM) as at 21 degrees C; however, at 37 degrees C, either its affinity decreases enough so as to become experimentally indistinguishable from the medium-affinity Ca(2+)-binding sites determined at this temperature (number of binding sites 3.9 +/- 1.2 mol of Ca2+/mol of GP, Kd 25 +/- 11 microM), or vanishes altogether. Studies on Ca(2+)-dependent dissociation of GPIIIb/IIIa at 37 degrees C in solution seem to support the former interpretation. Further work will be necessary to decide whether the dissociation of GPIIb/IIIa in the platelet membrane at 37 degrees C is regulated by the degree of saturation of the high-affinity Ca(2+)-binding site, as occurs in solution. It is suggested that the high-affinity Ca(2+)-binding site could be related to the putative GPIIIa-binding region in GPIIb (residues 558-747 of the alpha chain).

Amperometric biosensor for the quantification of gentisic acid using polyphenol oxidase modified carbon paste electrode.

The affinity of mushroom polyphenol oxidase (PPO) towards gentisic acid (GA), a metabolite of acetyl salicylic acid (ASA), is demonstrated by spectrophotometry and by electrochemical techniques. The enzyme can selectively recognize GA even in the presence of large excess of ASA and its metabolic derivatives (salicylic acid (SA) and salicyluric acid (SUA)). At -0.150 V, the sensitivity is (6.1+/-0.1)x10(4) NAM(-1), the response is linear up to 2.0x10(-4) M and the detection limit is 5.0x10(-5) M. The kinetic parameters, obtained from Eadie-Hofstee plots, are I(max)=51.4 nA and K(m)(app)=6.7x10(-4) M.

A large-scale procedure for the isolation of integrin GPIIb/IIIa, the human platelet fibrinogen receptor.

The heterodimer GPIIb/IIIa, formed by the Ca(2+)-dependent association of glycoproteins IIb (GPIIb) and IIIa (GPIIIa), is the major integrin at the platelet surface, where it serves as the receptor for fibrinogen and other adhesive proteins and plays a central role in platelet aggregation and in platelet adhesion to the subendothelium. Here we describe a procedure for the isolation of GPIIb/IIIa using as starting material either the whole particulate fraction, obtained by differential centrifugation after hypoosmotic lysis of glycerol-loaded platelets, or any of the fractions obtained by density gradient centrifugation of the whole particulate fraction. The procedure consists simply of differential extraction with Triton X-100 of the starting particulate fraction, anion-exchange chromatography of the 4% Triton X-100 supernatant, and size-exclusion chromatography of the GPIIb/IIIa-rich fraction retained in the ion-exchange column. The use of particulate fractions instead of whole platelets as the starting material for extraction together with differential extraction with Triton X-100 (two steps that are simple and inexpensive to perform) results in the early removal of many unwanted proteins, which otherwise would have to be removed at later stages at the expense of severely impairing the final yield of GPIIb/IIIa. Pure GPIIb/IIIa is obtained with a yield of about 48%, the highest so far reported, calculated with respect to the GPIIb and GPIIIa content in the starting particulate fraction. The final product can be stored in freeze-dried form without apparent changes in its physical and chemical properties.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium and temperature regulation of the stability of the human platelet integrin GPIIb/IIIa in solution: an analytical ultracentrifugation study.

The human platelet integrin GPIIb/IIIa (228 kDa), a Ca-dependent heterodimer formed by the alpha IIb subunit (GPIIb, 136 kDa) and the beta 3 subunit (GPIIIa, 92 kDa), serves as the fibrinogen receptor at the surface of activated platelets. The degree of dissociation of the GPIIb/IIIa heterodimer (s degrees 20*, 8.9 S) into its constituent glycoproteins (GPIIb, 5.8 S; and GPIIIa, 3.9 S) has been assessed by analytical ultracentrifugation in Triton X100 buffers, and its Ca(2+)- and temperature-dependence correlated with Ca(2+)-binding to GPIIb/IIIa and its temperature dependence. At 21 degrees C half-maximal dissociation of GPIIb/IIIa occurs at 5.5 +/- 2.5 x 10(-8) M Ca2+, very close to the dissociation constant of the high affinity Ca-binding site of GPIIb/IIIa (Kd1 8 +/- 3 x 10(-8) M) (Rivas and González-Rodriguez, 1991) and much lower than the Kd of the 3.4 medium affinity Ca-binding sites (Kd2 4 +/- 1.5 x 10(-5) M), which seems to demonstrate that the stability of the heterodimer in solution at room temperature is regulated by the degree of saturation of the high-affinity Ca-binding site. At 4 degrees C, the stability of the heterodimer is apparently Ca(2+)-independent, while at room and physiological temperatures (15-37 degrees C) the degree of dissociation of the heterodimer is regulated by the degree of dissociation of the high- and medium-affinity Ca-binding sites, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular characterization of the human platelet integrin GPIIb/IIIa and its constituent glycoproteins.

Human platelet plasma membrane glycoproteins IIb (GPIIb) and IIIa (GPIIIa) form a Ca(2+)-dependent heterodimer, the integrin GPIIb/IIIa, which serves as the receptor for fibrinogen and other adhesive proteins at the surface of activated platelets. Below the critical micellar concentration of Triton X100 (TtX), the three glycoproteins do not bind appreciably to TtX and form association products of large size. The size-exclusion chromatographic patterns of GPIIb, GPIIIa and GPIIb/IIIa have been obtained at 0.2% TtX, and the molecular properties of the association products and monomer fractions have been determined by analysis of the detergent bound to the glycoproteins, laser-light scattering, sedimentation velocity, and electron microscopy (TEM). The monomer of the GPIIb-TtX complex was identified by the molecular mass (M) of the glycoprotein moiety (125 +/- 15 kDa), the molecular size (9.5 +/- 1.5 nm x 11 +/- 1.5 nm) and globular shape observed by TEM. It has a molecular mass (M*) of 197 +/- 20 kDa, a sedimentation coefficient s degrees 20* of 5.8 +/- 0.1 S, a Stokes radius R s* of 6.8 +/- 0.4 nm, and a frictional ratio f*/fmin* of 1.7 +/- 0.14. The (GPIIb)n-TtX complexes are disulphide-bonded size-heterogeneous association products of GPIIb, tetramers being the smallest species found. GPIIIa has a greater propensity to self-associate than GPIIb, this tendency being lower below 1 mg GPIIIa/ml, 0.1 mM Ca2+, pH 9.0. The (GPIIIa)n-TtX complexes are noncovalent size-heterogeneous association products of GPIIIa, tetramers being the smallest form observed. The monomer of the GPIIIa-TtX complex was identified by the 103 +/- 15 kDa M determined for the glycoprotein moiety, and the 9 +/- 1.5 nm x 10 +/- 1.5 nm size and globular shape observed by TEM. It has a M* of 136 +/- 15 kDa, a s degrees 20* of 3.9 +/- 0.3 S, a Rs* of 6.4 +/- 0.5 nm, a f*/fmin* of 1.9 +/- 0.3, and, when stored at pH 7.4, has a certain tendency to form filamentous association products (20-70 nm x 2-5 nm), as observed by TEM. The GPIIb/IIIa-TtX complex in 0.2% TtX/0.1 mM Ca2+ elutes as a single monomeric fraction, as deduced from the 210 +/- 15 kDa M determined for its glycoprotein moiety and the 12 +/- 1.5 nm x 14 +/- 1.5 nm size of the globular forms observed by TEM.(ABSTRACT TRUNCATED AT 400 WORDS)

An outpatient approach to female sterilization with methylcyanoacrylate.

MCA is a tissue adhesive which can be delivered transcervically to the Fallopian tubes by means of the FEMCEPT device. In the patients treated with this system, both prior to hysterectomy and on an ambulatory basis, there have been no significant complications or side effects. In the most recent series of ambulatory patients treated with the REMCEPT-MCA system, the bilateral tubal closure rate was 78%.

PIP: Clinical trials of methylcyanoacrylate (MCA), a tissue adhesive injected to occlude fallopian tubes for tubal sterilization, were conducted in ambulatory patients and are presented. 3 small series of patients are described; most received .4-ml injections, but 23 of the 131 total subjects received .6-ml injections. Outcome was determined by hysterosalpingography. Bilateral closure rate after 1 treatment in series 1 (n=28) was 64%. In the 2nd series the bilateral closure rate was 54% after 1 injection; after a 2nd injection in the 2nd series, the rate was 78%, but overall the closure rate for this group after 2 injections was 65% (n=102). In the 3rd series, bilateral closure rate was 78% after 1 injection; this series used .6-ml injections and represents a dramatic improvement over the preceding series. Complications include pain at site of injection, mild to moderate cramping, and transient vagal reaction. The procedure takes 5 minutes or less. 2 uterine pregnancies have occurred to date, and no ectopic pregnancies were reported. MCA is a low-viscosity fluid in a monomeric form which rapidly polymerizes when placed in contact with body fluids.