Laparoscopic abdominal cysts fenestration using harmonic scalpel

The use of ultrasonically activated scalpel for tissue cutting and coagulation is a potential replacement for electrosurgery, which can be related to different complications. Its working principle is to transform the electric power into the mechanical longitudinal movement of the working part of the instrument, by a piezoelectric transducer situated in the hand piece. Between October 2000 and June 2004, six patients with abdominal cysts were treated by laparoscopy, using the harmonic scalpel. The average age was 40.8 (ranging from 15-60) years. Laparoscopic abdominal cyst fenestration was performed in five patients, and laparoscopic cholecystectomy and abdominal cyst fenestration were done in one patient during the same operation. The average duration of the operation was 40 (ranging from 25-70) minutes and hospital stay was 2.8 (ranging from 1-5) days. Laparoscopic abdominal cyst fenestration using the harmonic scalpel is a safe and successful operation, with good results including all the advantages of the minimally invasive surgery.     

Lipid-protein interactions in human plasma LDL evidenced by magnetic resonance

Low density lipoprotein (LDL) particles exhibit extremely complex three-dimensional structural organization which is still not understood at the molecular level. The aim of this study was to provide the experimental evidence of a direct non-covalent interaction of the protein part with the lipid matrix. The approach was based on the combination of (1)H NMR (600 MHz) spectroscopy with thiol-specific spin labeling of the protein (apoB). It is shown that the spectral peaks assigned to the methyl head groups of phosphatidylcholine and sphingomyelin in the (1)H spectra of LDL exhibit line broadening when otherwise free thiol groups of apoB are covalently modified by methanethiosulfonate spin label. The effect is similar in the presence of water soluble paramagnetic compound. These results indicate that fragments of apoB, which are part of the receptor binding region, are directly in contact with the solvated phospholipid head groups of the lipid matrix.     

Insights in starch acetylation in sub- and supercritical CO2

An in-depth study on the acetylation of starch with acetic anhydride (Ac₂O) and sodium acetate (NaOAc) as the catalyst in pressurized carbon dioxide (scCO₂) in a broad pressure range (8–25 MPa) and a temperature of 90 °C is provided. Highest degrees of substitution (DS) of 0.29 (1 h reaction time) and 0.62 (24 h reaction time) were found near the critical point of the mixture (15 MPa). The phase behavior of the system CO₂, starch and acetic anhydride (Ac₂O) was studied in a high pressure view cell. The critical points were a clear function of the temperature and increased from the range of 9.4–10 MPa to 14.5–14.8 MPa when going from 50 to 90 °C (Ac₂O mole fraction at the critical point in the range of 0.08–0.09). Acetylation experiments with a range of starch particles sizes showed a clear relation between the DS and the particle size.     

Uterine artery embolization for the treatment of uterine fibroids

Uterine artery embolization can be regarded as a less invasive procedure for the treatment of fibroids compared with myomectomy, hysterectomy, and laparoscopic myolysis. The aim of this study was the evaluation of safety and efficacy of uterine artery embolization and of womens' opinion about this treatment. After gynecological examination sixty-nine premenopausal women underwent uterine artery embolization. All procedures but four were technically successful; three women underwent unilateral embolization because of vascular malformation and one of them had an allergic reaction to contrast medium. Of the 69 patients: 58 went home the day after embolization, and 11 within first week. The follow-up examinations after 3, 6 and 12 month showed a significant reduction of uterine and fibroid volume with significant improvement of bleeding. Therefore, according to this report, uterine artery embolization is a successful, minimal invasive treatment of myoma that preserves the uterus and requires shorter hospitalization and recovery times than surgery.     

A model for the activation of plasma membrane calcium pump isoform 4b by calmodulin

Overexpression of the plasma membrane calcium pump (PMCA) isoform 4b by means of the baculovirus system enabled us, for the first time, to study the kinetics of calmodulin binding to this pump. This was done by stopped-flow fluorescence measurements using 2-chloro-(amino-Lys(75))-[6-[4-(N,N-diethylamino)phenyl]-1,3,5-triazin-4-yl]calmodulin (TA-calmodulin). Upon mixing with PMCA, the fluorescence of TA-calmodulin changed along a biphasic curve: a rapid and small increase in fluorescence was followed by a slow and large decrease that lasted about 100 s. The experiment was done at several PMCA concentrations. Global fitting nonlinear regression analysis of these results led to a model in which PMCA is present in two forms: a closed conformation and an open conformation. Calmodulin reacts with both conformations but reacts faster and with higher affinity for the open conformation. Measurements of the ATPase activity of PMCA under similar conditions revealed that the open form has higher ATPase activity than the closed one. Contrasting with the reaction with the whole pump, TA-calmodulin reacted rapidly (in about 2 s) with a calmodulin-binding peptide made after the sequence of the calmodulin-binding domain of PMCA (C28). Results of TA-calmodulin binding to C28 are explained by a simpler model, in which only an open conformation exists.     

Changes in structure and stability of calbindin-D(28K) upon calcium binding

Calbindin-D(28K) is a biologically important protein required for normal neural function and for the transport of calcium in epithelial cells of the intestine and kidney. We have used fluorescence and circular dichroism (CD) spectroscopy to characterize the effects of calcium binding on the structure and stability of calbindin. Ca(2+) titration monitored by fluorescence spectroscopy reveals the presence of two classes of calcium-binding sites with association constants approximately 10(7.5) and approximately 10(8.9)M(-1). CD spectra in the far-UV spectral range show minor changes upon Ca(2+) titration, implying that the secondary structure of calbindin-D(28K) is not greatly affected. On the basis of the CD spectra in the near-UV spectral range, we conclude that the tertiary structure is more sensitive to Ca(2+) addition. The most significant change occurs between pCa 7.0 and pCa 8.0. The variations in the protein thermostability are correlated with those in the near-UV CD spectra. The enthalpy changes upon heat denaturation of calbindin in the apo-state are characteristic of proteins containing several weakly interacting domains with similar thermodynamical properties. Thus, calcium binding by calbindin-D(28K) largely affects the local structure around the aromatic residues and the thermal stability of the protein; the changes in the secondary structure are insignificant.     

Formation of the killer Ig-like receptor repertoire on CD4+CD28null T cells

Killer Ig-like receptors (KIRs) are expressed on CD4(+)CD28(null) T cells, a highly oligoclonal subset of T cells that is expanded in patients with rheumatoid arthritis. It is unclear at what stage of development these T cells acquire KIR expression. To determine whether KIR expression is a consequence of clonal expansion and replicative senescence, multiple CD4(+)CD28(null) T cell clones expressing the in vivo dominant TCR beta-chain sequences were identified in three patients and analyzed for their KIR gene expression pattern. Based on sharing of TCR sequences, the clones were grouped into five clone families. The repertoire of KIRs was diverse, even within each clone family; however, the gene expression was not random. Three particular receptors, KIR2DS2, KIR2DL2, and KIR3DL2, had significant differences in gene expression frequencies between the clone families. These data suggest that KIRs are successively acquired after TCR rearrangement, with each clone family developing a dominant expression pattern. The patterns did not segregate with the individual from whom the clones were derived, indicating that peripheral selection in the host environment was not a major shaping force. Several models were examined using a computer algorithm that was designed to simulate the expression of KIRs at various times during T cell proliferation. The computer simulations favored a model in which KIR gene expression is inducible for a limited time during the initial stages of clonal expansion.     

The metal-binding properties of DREAM: evidence for calcium-mediated changes in DREAM structure.

DREAM, an EF-hand protein, associates with and modulates the activity of presenilins and Kv4 potassium channels in neural and cardiac tissues and represses prodynorphin and c-fos gene expression by binding to DNA response elements in these genes. Information concerning the metal-binding properties of DREAM and the consequences of metal binding on protein structure are important in understanding how this protein functions in cells. We now show that DREAM binds 1 mol of calcium/mol of protein with relatively high affinity and another 3 mol of calcium with lower affinity. DREAM binds 1 mol of magnesium/mol of protein. DREAM, pre-loaded with 1 mol of calcium, binds 1 mol of magnesium, thus demonstrating that the magnesium-binding site is distinct from the high affinity calcium-binding site. Analysis of metal binding to mutant DREAM protein constructs localizes the high affinity calcium-binding site and the magnesium-binding site to EF-hands 3 or 4. Binding of calcium but not magnesium changes the conformation, stability, and alpha-helical content of DREAM. Calcium, but not magnesium, reduces the affinity of apo-DREAM for specific DNA response elements in the prodynorphin and c-fos genes. We conclude that DREAM binds calcium and magnesium and that calcium, but not magnesium, modulates DREAM structure and function.     

Pentadecapeptide BPC 157 and its effects on a NSAID toxicity model: diclofenac-induced gastrointestinal, liver, and encephalopathy lesions

AimsWe attempted to fully antagonize the extensive toxicity caused by NSAIDs (using diclofenac as a prototype).Main methodsHerein, we used the stable gastric pentadecapeptide BPC 157 (GEPPPGKPADDAGLV, MW 1419), an anti-ulcer peptide shown to be efficient in inflammatory bowel disease clinical trials (PL 14736) and various wound treatments with no toxicity reported. This peptide was given to antagonize combined gastrointestinal, liver, and brain toxicity induced by diclofenac (12.5 mg/kg intraperitoneally, once daily for 3 days) in rats.Key findingsAlready considered a drug that can reverse the toxic side effects of NSAIDs, BPC 157 (10 μg/kg, 10 ng/kg) was strongly effective throughout the entire experiment when given (i) intraperitoneally immediately after diclofenac or (ii) per-orally in drinking water (0.16 μg/mL, 0.16 ng/mL). Without BPC 157 treatment, at 3 h following the last diclofenac challenge, we encountered a complex deleterious circuit of diclofenac toxicity characterized by severe gastric, intestinal and liver lesions, increased bilirubin, aspartate transaminase (AST), alanine transaminase (ALT) serum values, increased liver weight, prolonged sedation/unconsciousness (after any diclofenac challenge) and finally hepatic encephalopathy (brain edema particularly located in the cerebral cortex and cerebellum, more in white than in gray matter, damaged red neurons, particularly in the cerebral cortex and cerebellar nuclei, Purkinje cells and less commonly in the hippocampal neurons).SignificanceThe very extensive antagonization of diclofenac toxicity achieved with BPC 157 (μg-/ng-regimen, intraperitoneally, per-orally) may encourage its further use as a therapy to counteract diclofenac- and other NSAID-induced toxicity.     

The breakup of intravascular microbubbles and its impact on the endothelium

Encapsulated microbubbles (MBs) serve as endovascular agents in a wide range of medical ultrasound applications. The oscillatory response of these agents to ultrasonic excitation is determined by MB size, gas content, viscoelastic shell properties and geometrical constraints. The viscoelastic parameters of the MB capsule vary during an oscillation cycle and change irreversibly upon shell rupture. The latter results in marked stress changes on the endothelium of capillary blood vessels due to altered MB dynamics. Mechanical effects on microvessels are crucial for safety and efficacy in applications such as focused ultrasound-mediated blood–brain barrier (BBB) opening. Since direct in vivo quantification of vascular stresses is currently not achievable, computational modelling has established itself as an alternative. We have developed a novel computational framework combining fluid–structure coupling and interface tracking to model the nonlinear dynamics of an encapsulated MB in constrained environments. This framework is used to investigate the mechanical stresses at the endothelium resulting from MB shell rupture in three microvessel setups of increasing levels of geometric detail. All configurations predict substantial elevation of up to 150 % for peak wall shear stress upon MB breakup, whereas global peak transmural pressure levels remain unaltered. The presence of red blood cells causes confinement of pressure and shear gradients to the proximity of the MB, and the introduction of endothelial texture creates local modulations of shear stress levels. With regard to safety assessments, the mechanical impact of MB breakup is shown to be more important than taking into account individual red blood cells and endothelial texture. The latter two may prove to be relevant to the actual, complex process of BBB opening induced by MB oscillations.