Guanidinoacetic acid provides superior cardioprotection to its combined use with betaine and (or) creatine in HIIT-trained rats.

This study aimed to determine how guanidinoacetic acid (GAA) or its combined administration with betaine (B) or creatine (C) influences the cardiac function, morphometric parameters, and redox status of rats subjected to high-intensity interval training (HIIT). This research was conducted on male Wistar albino rats exposed to HIIT for 4 weeks. The animals were randomly divided into five groups: HIIT, HIIT + GAA, HIIT + GAA + C, HIIT + GAA + B, and HIIT + GAA + C + B. After completing the training protocol, GAA (300 mg/kg), C (280 mg/kg), and B (300 mg/kg) were applied daily per os for 4 weeks. GAA supplementation in combination with HIIT significantly decreased the level of both systemic and cardiac prooxidants ( O 2 - , H2O2, NO 2 - , and thiobarbituric acid reactive substances) compared with nontreated HIIT (p < 0.05). Also, GAA treatment led to an increase in glutathione and superoxide dismutase levels. None of the treatment regimens altered cardiac function. A larger degree of cardiomyocyte hypertrophy was observed in the HIIT + GAA group, which was reflected through an increase of the cross-sectional area of 27% (p < 0.05) and that of the left ventricle wall thickness of 27% (p < 0.05). Since we showed that GAA in combination with HIIT may ameliorate oxidative stress and does not alter cardiac function, the present study is a basis for future research exploring the mechanisms of cardioprotection induced by this supplement in an HIIT scenario.

A five-compartment biokinetic model for 90 Y-DOTATOC therapy.

PURPOSE: Neuroendocrine tumors (NETs) are now routinely treated by radiopeptide targeted therapy using somatostatin receptor-binding peptides such as 90 Y- and 177 Lu-DOTATOC. The objective of this work was to develop a biokinetics model of 90 Y labelled DOTATOC, which is applied in the therapy of NETs to estimate doses in kidney and tumor. METHODS: A multi-compartment model described by two sets of differential equations, one set for the actual 30-min infusion and the other set for the post-infusion period was developed and activities were measured by liquid scintillation counting in blood (compartment 1) and the urine (compartment 3). The inter-compartment transfer coefficients, λij , were varied to yield the best fit of the calculated to the measured time-activity data and the 90 Y-DOTATOC time-activity data in the five-compartments comprising the human body were thus determined. The resulting time-activity curves were integrated over the interval from 0 to 72 h post administration to obtain the number of radioactive decays in each compartment and, in case of the kidneys and tumor, then multiplied by the self-dose 90 Y beta particle absorbed fraction, determined by Monte Carlo (MC) simulation, the kidney and tumor absorbed doses. RESULTS: Transfer coefficients λij , were determined for five-compartments for all patients. Time- activity curves of 90 Y-DOTATOC in 14 patients were determined, and two typical ones are shown graphically. Absorbed doses in the tumor and kidneys, obtained by the developed method, were determined. The mean absorbed dose in a kidney per unit of administered activity is 1.43 mGy/MBq (range 0.73-2.42 mGy/MBq). The tumor dose was determined as 30.94 mGy/MBq (range 20.05-42.31 mGy/MBq). CONCLUSION: Analytical solution of a biokinetic model for 90 Y-DOTATOC therapy enabled determination of the transfer coefficients and derivation of time-activity curves and kidney and tumor absorbed doses for 14 treated patients. The model can be applied to other radionuclides where elimination is predominantly through urine, which is often the case in radiopharmaceuticals.

Hyperelastic behavior of porcine aorta segment under extension-inflation tests fitted with various phenomenological models.

Most of hyperelastic models for the constitutive modeling of the typical mechanical behaviour of the arterial wall tissue in literature are based on the test data from different animals and arteries. This paper is concerned with the material parameter identification of several phenomenological hyperelastic models by fitting the data from five extension-inflation tests of the porcine aorta segment, carried out in our laboratory. A membrane approximation is used to compute stresses and strains achieved during experiments, with usual assumption of material incompressibility. Three orthotropic two-dimensional strain-energy functions, based on use of the Green-Lagrange strains, are fitted to the test data: the well-known Fung's exponential model; the classical polynomial model with seven constants; and the logarithmic model; and also, two three-dimensional models are employed: polyconvex anisotropic exponential hyperelastic model and the convex isotropic exponential rubber-like hyperelastic constitutive law depending on the first invariant of the right Cauchy-Green deformation tensor. It has been found that isotropic model overestimates values of stresses in axial, and underestimates values of stresses in circumferential direction of artery segment, due to pronounced tissue anisotropy. Also, all two-dimensional models considered give good and similar prediction, while the polyconvex model demonstrates slightly lower performance in the axial direction of artery.

Histamine index and clinical expression of rheumatoid arthritis activity.

BACKGROUND/AIM: Many arguments prove the pathophysiologic role of histamine in the process of remodeling and joint destruction in rheumatoid arthritis. The aim of our study was to find out if there was a relation between histamine concentration in synovial fluid and blood with clinical expression of disease activity. METHODS: Histamine concentration in synovial fluid and blood was determinated in 19 patients with rheumatoid arthritis. Histamine concentration measurement was based on the Shore's fluorometric method. Histamine index (HI) was evaluated as a ratio between histamine concentration in synovial fluid and blood. Disease activity score, DAS 28 (3), with three variables (erythrocyte sedimentation rate, the number of swelled joints and the number of tender joints) was also evaluated. RESULTS: Our results showed that there was no significant difference in concentration of histamine in synovial fluid and blood related to disease activity. However, there was a significiant difference in the histamine index which was increased proportionally with disease activity. CONCLUSION: Our study indicates that histamine index could be useful in estimation of rheumatoid arthritis activity.