Heat-Induced Conformational Unfolding of Fatty Acid-Free and Fatted Camel Serum Albumin: A Comparative Study

Albumin is a multifunctional non-glycosylated, negatively charged plasma protein, with extraordinary ligand-binding and transport properties, antioxidant functions, and enzymatic activities. Physiologically, albumin transports free fatty acids in plasma and contributes in maintaining colloid osmotic pressure. Recent progresses in using albumin as a versatile protein carrier for drug targeting and for improving the pharmacokinetic profile of peptide or protein-based drugs, increased the attempts for improving albumin stability. Studying the thermal stability of camel albumin may provide us not only new clues for designing recombinant albumins, but also molecular insights on camel physiology. This study aims to determine the thermal stability of camel albumin. Fatted camel serum albumin (FCSA) was purified from blood via combination of Cohn’s method and anion-exchange chromatography. Activated charcoal treatment was used to obtain defatted camel serum albumin (CSA). Fluorescence spectroscopy and differential scanning calorimetry (DSC) were used to study thermal denaturation of this protein. The set of fluorescence spectra were deconvoluted using the convex constraint analysis method (CCA). The results from deconvolution of fluorescence spectroscopy and DSC showed three and two components for CSA and FCSA, respectively. The bimodal DSC transition can be attributed to a crevice between domains I and II and formation of two independent thermodynamic domains. The crevice formation can be prevented by fatty acid binding between domains I and II. The calculated values of ?H _v/?H _cal, approximately 0.4 for CSA and near 1 for FCSA, confirmed the presence of at least one intermediate in thermal unfolding of CSA and the absence of the intermediate for FCSA. The obtained midpoint transition temperature (T _m) of FCSA was about 20 °C higher than that of CSA. Such enormous stabilizing effect may be attributed to the fact that fatty acid serves as glue which preserves different domains beside each other and prevents formation of the mentioned intermediate.     

Do Women's Voices Provide Cues of the Likelihood of Ovulation? The Importance of Sampling Regime

The human voice provides a rich source of information about individual attributes such as body size, developmental stability and emotional state. Moreover, there is evidence that female voice characteristics change across the menstrual cycle. A previous study reported that women speak with higher fundamental frequency (F0) in the high-fertility compared to the low-fertility phase. To gain further insights into the mechanisms underlying this variation in perceived attractiveness and the relationship between vocal quality and the timing of ovulation, we combined hormone measurements and acoustic analyses, to characterize voice changes on a day-to-day basis throughout the menstrual cycle. Voice characteristics were measured from free speech as well as sustained vowels. In addition, we asked men to rate vocal attractiveness from selected samples. The free speech samples revealed marginally significant variation in F0 with an increase prior to and a distinct drop during ovulation. Overall variation throughout the cycle, however, precluded unequivocal identification of the period with the highest conception risk. The analysis of vowel samples revealed a significant increase in degree of unvoiceness and noise-to-harmonic ratio during menstruation, possibly related to an increase in tissue water content. Neither estrogen nor progestogen levels predicted the observed changes in acoustic characteristics. The perceptual experiments revealed a preference by males for voice samples recorded during the pre-ovulatory period compared to other periods in the cycle. While overall we confirm earlier findings in that women speak with a higher and more variable fundamental frequency just prior to ovulation, the present study highlights the importance of taking the full range of variation into account before drawing conclusions about the value of these cues for the detection of ovulation.     

Nanoparticles and cancer therapy: Perspectives for application of nanoparticles in the treatment of cancers

Rapid growth in nanotechnology toward the development of nanomedicine agents holds massive promise to improve therapeutic approaches against cancer. Nanomedicine products represent an opportunity to achieve sophisticated targeting strategies and multifunctionality. Nowadays, nanoparticles (NPs) have multiple applications in different branches of science. In recent years, NPs have repetitively been reported to play a significant role in modern medicine. They have been analyzed for different clinical applications, such as drug carriers, gene delivery to tumors, and contrast agents in imaging. A wide range of nanomaterials based on organic, inorganic, lipid, or glycan compounds, as well as on synthetic polymers has been utilized for the development and improvement of new cancer therapeutics. In this study, we discuss the role of NPs in treating cancer among different drug delivery methods for cancer therapy.     

Modulation of functionally significant conformational equilibria in adenylate kinase by high concentrations of trimethylamine oxide attributed to volume exclusion

The effect of an inert small molecule osmolyte, trimethyl amine N-oxide (TMAO), upon the conformational equilibria of Escherichia coli adenylate kinase was studied using time-resolved FRET. The relative populations of open and closed clefts between the LID and the CORE domains were measured as functions of the concentrations of the substrate ATP over the concentration range 0–18 mM and TMAO over the concentration range 0–4 M. A model was constructed according to which the enzyme exists in equilibrium among four conformational states, corresponding to combinations of open and closed conformations of the LID-CORE and AMP-CORE clefts. ATP is assumed to bind only to those conformations with the closed LID-CORE cleft, and TMAO is assumed to be differentially excluded as a hard spherical particle from each of the four conformations in accordance with calculations based upon x-ray crystallographic structures. This model was found to describe quantitatively the dependence of the fraction of the closed LID-CORE cleft upon the concentrations of both ATP and TMAO over the entire range of concentrations with just five undetermined parameters.     

Development of Controlled-Release Matrix Tablet of Risperidone: Influence of Methocel®- and Ethocel®-Based Novel Polymeric Blend on <Emphasis Type="Italic">In Vitro</Emphasis> Drug Release and Bioavailability

Controlled-release (CR) matrix tablet of 4 mg risperidone was developed using flow bound dry granulation–slugging method to improve its safety profile and compliance. Model formulations F1, F2, and F3, consisting of distinct blends of Methocel® K100 LV-CR and Ethocel® standard 7FP premium, were slugged. Each batch of granules (250–1,000 μm), obtained by crushing the slugs, was divided into three portions after lubrication and then compressed to 9-, 12-, and 15-kg hard tablets. In vitro drug release studies were carried out in 0.1 N HCl (pH 1.2) and phosphate buffer (pH 6.8) using a paddle dissolution apparatus run at 50 rpm. The CR test tablet, containing 30% Methocel® and 60% Ethocel® (F3) with 12-kg hardness, exhibited pH-independent zero-order release kinetics for 24 h. The drug release rate was inversely proportional to the content of Ethocel®, while the gel layer formed of Methocel® helped in maintaining the integrity of the matrix. Changes in the hardness of tablet did not affect the release kinetics. The tablets were reproducible and stable for 6 months at 40 ± 2°C/75 ± 5% relative humidity. Risperidone and its active metabolite, 9-hydroxyrisperidone, present in the pooled rabbit’s serum, were analyzed with HPLC-UV at λ_max 280 nm. The CR test tablet exhibited bioequivalence to reference conventional tablet in addition to the significantly (p < 0.05) optimized peak concentration, C_max, and extended peak time, T_max, of the active moiety. There was a good association between drug absorption in vivo and drug release in vitro (R² = 0.7293). The successfully developed CR test tablet may be used for better therapeutic outcomes of risperidone.KEY WORDS: controlled release, dry granulation slugging method, risperidone     

Bioengineered human arginase I with enhanced activity and stability controls hepatocellular and pancreatic carcinoma xenografts

Hepatocellular carcinoma (HCC) and pancreatic carcinoma (PC) cells often have inherent urea cycle defects rendering them auxotrophic for the amino acid l-arginine (l-arg). Most HCC and PC require extracellular sources of l-arg and undergo cell cycle arrest and apoptosis when l-arg is restricted. Systemic, enzyme-mediated depletion of l-arg has been investigated in mouse models and human trials. Non-human enzymes elicit neutralizing antibodies, whereas human arginases display poor pharmacological properties in serum. Co(2+) substitution of the Mn(2+) metal cofactor in human arginase I (Co-hArgI) was shown to confer more than 10-fold higher catalytic activity (k(cat)/K(m)) and 5-fold greater stability. We hypothesized that the Co-hArgI enzyme would decrease tumor burden by systemic elimination of l-arg in a murine model. Co-hArgI was conjugated to 5-kDa PEG (Co-hArgI-PEG) to enhance circulation persistence. It was used as monotherapy for HCC and PC in vitro and in vivo murine xenografts. The mechanism of cell death was also investigated. Weekly treatment of 8 mg/kg Co-hArgI-PEG effectively controlled human HepG2 (HCC) and Panc-1 (PC) tumor xenografts (P = .001 and P = .03, respectively). Both cell lines underwent apoptosis in vitro with significant increased expression of activated caspase-3 (P < .001). Furthermore, there was evidence of autophagy in vitro and in vivo. We have demonstrated that Co-hArgI-PEG is effective at controlling two types of l-arg-dependent carcinomas. Being a nonessential amino acid, arginine deprivation therapy through Co-hArgI-PEG holds promise as a new therapy in the treatment of HCC and PC.     

Method and strain rate dependence of Achilles tendon stiffness

Tendon stiffness is calculated by dividing changes in tendon force by tendon elongation. For this purpose, participants are commonly asked to perform a maximal muscle contraction (“active” method). Alternatively tendon elongation can be achieved by means of a passive joint rotation (“passive” method). The purpose of this study was to compare Achilles tendon stiffness obtained from both methods across different tendon strain rates. Twenty adults performed a series of ramped maximum isometric plantarflexions of different durations. Passive ankle rotations of different angular velocities were also performed. Achilles tendon stiffness was obtained from a combination of motion analysis, isokinetic dynamometry and ultrasonography and compared across methods at three strain rates. At all strain rates, tendon stiffness obtained from the active method was 6% greater compared to the passive method. In spite of this systematic bias, there was good agreement between the methods. Intraclass correlation coefficients were greater than 0.98, and more than 95% of data points fell into the 95% confidence intervals. This agreement will be acceptable in many research contexts. We also found a linear increase in tendon stiffness with increasing strain rate, which must be taken into consideration when interpreting or reporting tendon stiffness.     

Pharmacodynamic equivalence of a decapeptyl 3-month SR formulation with the 28-day SR formulation in patients with advanced prostate cancer

AIMS: The objective of the study was to assess the pharmacodynamic equivalence of LHRH analogue triptorelin 3-month and 28-day SR formulations. METHODS: Patients with documented locally advanced or metastatic prostate cancer were randomized to receive one injection of the 3-month formulation (n = 63) or three injections at 28-day intervals of the 28-day formulation (n = 68). Group-chemical castration rates defined as the percentage of patients reaching a testosterone plasma level 相似文献   

Interaction of arsenic trioxide As2O3 with DNA and RNA

Arsenic salts have been used for centuries to treat a variety of medical conditions ranging from infectious disease to cancer. More recently, trivalent arsenic trioxide was found to exhibit high antitumor activity towards hematological malignancies. Even though much is known about antitumor activity and DNA damage by As2O3, there has been no report on the interaction of arsenic trioxide with isolated DNA or RNA. Therefore, it was of interest to examine the interaction of As2O3 with DNA and RNA in aqueous solution at physiological pH. FTIR and UV-visible difference spectroscopic methods were used to characterize the nature of drug-DNA and drug-RNA interactions and to determine the As binding site, the binding constant, the sequence selectivity, the helix stability, and the biopolymer secondary structure in the As2O3-polynucleotide complexes in vitro. The FTIR spectroscopic studies were conducted with As2O3-polynucleotide (phosphate) ratios of 1/40, 1/20, 1/10, and 1/5, with a final DNA (P) or RNA (P) concentration of 6.25 mmol/l. Spectroscopic results showed As2O3 binds to DNA and RNA at G-C, A-T, and A-U bases, and no interaction with the backbone PO2 group. As2O3-DNA and -RNA adducts showed one type of binding with overall binding constant of K(As2O3-DNA) = 1.24 x 10(5) M(-1) and K(As2O3-RNA) = 2.60 x 10(5) M(-1). The As2O3-polynucleotide complexation is associated with a partial biopolymer aggregation and no major alterations of B-DNA or A-RNA structure.