β3-adrenergic receptor activation plays an important role in the depressed myocardial contractility via both elevated levels of cellular free Zn2+ and reactive nitrogen species

Role of β₃-AR dysregulation, as either cardio-conserving or cardio-disrupting mediator, remains unknown yet. Therefore, we examined the molecular mechanism of β₃-AR activation in depressed myocardial contractility using a specific agonist CL316243 or using β₃-AR overexpressed cardiomyocytes. Since it has been previously shown a possible correlation between increased cellular free Zn²⁺ ([Zn²⁺]_i) and depressed cardiac contractility, we first demonstrated a relation between β₃-AR activation and increased [Zn²⁺]_i, parallel to the significant depolarization in mitochondrial membrane potential in rat ventricular cardiomyocytes. Furthermore, the increased [Zn²⁺]_i induced a significant increase in messenger RNA (mRNA) level of β₃-AR in cardiomyocytes. Either β₃-AR activation or its overexpression could increase cellular reactive oxygen species (ROS) and reactive nitrogen species (RNS) levels, in line with significant changes in nitric oxide (NO)-pathway, including increases in the ratios of pNOS3/NOS3 and pGSK-3β/GSK-3β, and PKG expression level in cardiomyocytes. Although β₃-AR activation induced depression in both Na⁺- and Ca²⁺-currents, the prolonged action potential (AP) seems to be associated with a marked depression in K⁺-currents. The β₃-AR activation caused a negative inotropic effect on the mechanical activity of the heart, through affecting the cellular Ca²⁺-handling, including its effect on Ca²⁺-leakage from sarcoplasmic reticulum (SR). Our cellular level data with β₃-AR agonism were supported with the data on high [Zn²⁺]_i and β₃-AR protein-level in metabolic syndrome (MetS)-rat heart. Overall, our present data can emphasize the important deleterious effect of β₃-AR activation in cardiac remodeling under pathological condition, at least, through a cross-link between β₃-AR activation, NO-signaling, and [Zn²⁺]_i pathways. Moreover, it is interesting to note that the recovery in ER-stress markers with β₃-AR agonism in hyperglycemic cardiomyocytes is favored. Therefore, how long and to which level the β₃-AR agonism would be friend or become foe remains to be mystery, yet.     

Efficiency considerations for the purely tapered interference fit (TIF) abutments used in dental implants

A tapered interference fit provides a mechanically reliable retention mechanism for the implant-abutment interface in a dental implant. Understanding the mechanical properties of the tapered interface with or without a screw at the bottom has been the subject of a considerable amount of studies involving experiments and finite element (FE) analysis. In this paper, approximate closed-form formulas are developed to analyze the mechanics of a tapered interference fit. In particular, the insertion force, the efficiency, defined as the ratio of the pull-out force to insertion force, and the critical insertion depth, which causes the onset of plastic deformation, are analyzed. It is shown that the insertion force is a function of the taper angle, the contact length, the inner and outer radii of the implant, the static and the kinetic coefficients of friction, and the elastic modulii of the implant/abutment materials. The efficiency of the tapered interference fit, which is defined as the ratio of the pull-out force to insertion force, is found to be greater than one, for taper angles that are less than 6 deg when the friction coefficient is 0.3. A safe range of insertion forces has been shown to exist. The lower end of this range depends on the maximum pull-out force that may occur due to occlusion in the multiple tooth restorations and the efficiency of the system; and the upper end of this range depends on the plastic deformation of the abutment and the implant due to interference fit. It has been shown that using a small taper angle and a long contact length widens the safe range of insertion forces.     

Serum interleukin-18 and nitric oxide activity in bladder carcinoma

BACKGROUND: Both interleukin-18 and nitric oxide are multifunctional molecules that are involved in the different steps of carcinogenesis. METHODS: In the present study, we measured serum interleukin-18 and nitric oxide activity in 51 bladder cancer patients with different tumor stage and grade, and in 8 healthy controls. Serum nitrite-nitrate levels were measured as an index of nitric oxide generation. RESULTS: Serum interleukin-18 levels were significantly higher in bladder cancer patients when compared to the control subjects (p > 0.05). Serum interleukin-18 levels were found to be higher in patients with Ta stage than patients with T1 and T2, T3, T4 stages and in patients with grade 1 tumors than patients with grade 2 and grade 3 tumors, but this was not statistically significant (p > 0.05). There was no significant difference in serum nitrite + nitrate levels between bladder cancer patients and control subjects. CONCLUSIONS: Elevated serum interleukin-18 levels in bladder carcinoma patients may be a result of host defence mechanism against the growth and progression of bladder cancer cells.     

The effects of dietary boric acid and borax supplementation on lipid peroxidation,antioxidant activity,and DNA damage in rats

The aims of this study were to clarify the effects of high dietary supplementation with boric acid and borax, called boron (B) compounds, on lipid peroxidation (LPO), antioxidant activity, some vitamin levels, and DNA damage in rats. Thirty Sprague Dawley male rats were divided into three equal groups: the animals in the first group (control) were fed with a standard rodent diet containing 6.4 mg B/kg, and the animals in the experimental group were fed with a standard rodent diet added with a supra-nutritional amount of boric acid and borax (100 mg B/kg) throughout the experimental period of 28 days. The B compounds decreased malondialdehyde (MDA), DNA damage, the protein carbonyl content (PCO) level in blood, and glutathione (GSH) concentration in the liver, Cu–Zn superoxide dismutase (SOD), and catalase (CAT) activity in the kidney. The B compounds increased GSH concentration in blood and the vitamin C level in plasma. Consequently, our results demonstrate that B supplementation (100 mg/kg) in diet decreases LPO, and enhances the antioxidant defense mechanism and vitamin status. There are no differences in oxidant/antioxidant balance and biochemical parameters except for serum vitamin A and liver GSH concentration, between the boron compounds used in this study.     

Sleep stage and obstructive apneaic epoch classification using single-lead ECG

Background  

Polysomnography (PSG) is used to define physiological sleep and different physiological sleep stages, to assess sleep quality and diagnose many types of sleep disorders such as obstructive sleep apnea. However, PSG requires not only the connection of various sensors and electrodes to the subject but also spending the night in a bed that is different from the subject's own bed. This study is designed to investigate the feasibility of automatic classification of sleep stages and obstructive apneaic epochs using only the features derived from a single-lead electrocardiography (ECG) signal.     

Immunoglobulin G depletion from human serum with metal-chelated beads under magnetic field

Magnetic poly(ethylene glycol dimethacrylate-N-methacryloyl-(L)-histidine methyl ester) [mag-poly(EGDMA-MAH) beads, 50-100 microm in diameter, were produced by suspension polymerization for affinity depletion of immunoglobulin G (IgG) from human serum. Cu2+ ions were complexed directly via MAH groups (Cu2+ loading: 4.1 micromol/g). IgG depletion studies were performed by magnetically stabilized fluidized bed column. Acetate, Tris-HCl, MES and phosphate buffers all allow adsorption of similar quantities of IgG (27.3-45.6 mg/g). MOPS and HEPES allow higher adsorption quantities (79.6 mg/g and 74.1mg/g, respectively). Maximum adsorption capacities in MOPS buffer were 46.8 mg/g for mag-poly(EGDMA-MAH) and 102.1mg/g for Cu2+ chelated mag-poly(EGDMA-MAH) beads. The adsorption capacity decreased drastically from 102.1mg/g to 30.7 mg/g with the increase of the flow rate from 0.2 ml/min to 3.5 ml/min. The elution studies were performed by 1.0M NaCl. The elution results demonstrated that the adsorption of IgG to the adsorbent was reversible. To test the efficiency of IgG depletion from human serum, proteins in the serum and eluted portion were analyzed by two-dimensional gel electrophoresis. The depletion efficiency for IgG was above 99.4%. Eluted proteins include mainly IgG, and a small number of non-albumin proteins such as apo-lipoprotein A1, sero-transferrin, haptoglobulin and alpha1-antitrypsin. When anti-HSA-sepharose adsorbent is used together with our metal-chelated mag-beads, IgG and HSA can be depleted in a single step.     

Shotgun alanine scanning shows that growth hormone can bind productively to its receptor through a drastically minimized interface

The high affinity binding site (Site1) of the human growth hormone (hGH) binds to its cognate receptor (hGHR) via a concave surface patch containing about 35 residues. Using 167 sequences from a shotgun alanine scanning analysis of Site1, we have determined that over half of these residues can be simultaneously changed to an alanine or a non-isosteric amino acid while still retaining a high affinity interaction. Among these hGH variants the distribution of the mutation is highly variable throughout the interface, although helix 4 is more conserved than the other binding elements. Kinetic and thermodynamic analyses were performed on 11 representative hGH Site1 variants that contained 14-20 mutations. Generally, the tightest binding variants showed similar associated rate constants (k(on)) as the wild-type (wt) hormone, indicating that their binding proceeds through a similar transition state intermediate. However, calorimetric analyses indicate very different thermodynamic partitioning: wt-hGH binding exhibits favorable enthalpy and entropy contributions, whereas the variants display highly favorable enthalpy and highly unfavorable entropy contributions. The heat capacities (DeltaCp) on binding measured for wt-hGH and its variants are significantly larger than normally seen for typical protein-protein interactions, suggesting large conformational or solvation effects. The multiple Site1 mutations are shown to indirectly affect binding of the second receptor at Site2 through an allosteric mechanism. We show that the stability of the ternary hormone-receptor complex reflects the affinity of the Site2 binding and is surprisingly exempt from changes in Site1 affinity, directly demonstrating that dissociation of the active signaling complex is a stepwise process.     

A New Method for Purification of Carbonic Anhydrase Isozymes by Affinity Chromatography

A new affinity gel for purification of carbonic anhydrase isozymes was prepared using EUPERGIT C-250L derivatized with p-aminobenzenesulfonamide, an inhibitor of carbonic anhydrase. The binding capacity of the affinity gel was determined at different temperatures, pH values, elution buffers, and ionic strengths. Human carbonic anhydrase isozymes (HCA I and HCA II) and bovine carbonic anhydrase (BCA) were purified in high yields from erythrocytes.