Mechanical properties of native and decellularized reproductive tissues: insights for tissue engineering strategies.

Understanding the mechanical properties and porosity of reproductive tissues is vital for regenerative medicine and tissue engineering. This study investigated the changes in Young's modulus (YM), storage modulus (E'), loss modulus (E"), and porosity of native and decellularized bovine reproductive tissues during the estrous cycle. Testis tunica albuginea had significantly higher YM, E', and E" than the inner testis, indicating greater stiffness and viscoelasticity. Endometrium showed no distinct differences in YM, E', or E" across the estrous cycle or between horns. Ovaries exhibited significant variations in YM, E', E", and porosity, with higher YM and E' in the ipsilateral cortex and medulla during the luteal phase. Decellularized ovarian tissues displayed increased porosity. The oviduct displayed no significant differences in YM or E' in the isthmus, but the contralateral ampulla had reduced YM and E' in the luteal phase. These findings offer valuable insights into the dynamic mechanical properties and porosity of reproductive tissues, facilitating the development of biomimetic scaffolds for tissue engineering applications.

Magnetic resonance imaging of pulmonary ventilation. Initial experiences with a gadolinium-DTPA-based aerosol.

RATIONALE AND OBJECTIVES: The authors investigate whether a modified gadolinium (Gd)-DTPA formulation can be aerosolized and used as a contrast agent for magnetic resonance (MR) ventilation imaging of the lungs. METHODS: Gadolinium-DTPA (gadopentetate dimeglumine, Schering AG, Berlin, Germany, 100 mmol Gd/L) was modified by addition of mannitol (Sigma, Deisenhofen, Germany, 10 mg/mL) and the surface active detergent Lutrol F68 (BASF, Mannheim, Germany, 2 mg/mL). The imaging was performed in an anesthetized rat model after inhalation of the contrast agent aerosol (PulmoSonic, De Vilbiss, Germany, 10-minute nebulization). T1-weighted spin echo images (repetitive time [TR]/echo time [TE] = 40/3 mseconds) were acquired at 2 T (SIS 85; Sisco, Fremont, CA) before and as long as 120 minutes after administration of the contrast agent. RESULTS: The modified Gd-DTPA aerosol elicited high and relatively homogeneous enhancement of the lung directly after nebulization. The enhancement was more pronounced than that obtained with a Gd-DTPA formulation without additives. CONCLUSIONS: Gadolinium-DTPA-based aerosol appears to be a suitable contrast agent for MR ventilation imaging in an experimental animal model. Modification by mannitol (to increase proton density through a slight additional osmotic effect) and a detergent (to reduce droplet size by decreasing surface tension) is suitable and effective in increasing signal intensity compared with Gd-DTPA without modification.

Elimination of gadolinium-ethoxybenzyl-DTPA in a rat model of severely impaired liver and kidney excretory function. An experimental study in rats.

RATIONALE AND OBJECTIVES: The authors investigated whether gadolinium-ethoxybenzyl-DTPA (Gd-EOB-DTPA) can be eliminated in the absence of the two usual excretory pathways (urinary or biliary) and whether a remaining excretory pathway is able to compensate for impaired liver or kidney function. METHODS: The study was performed using two groups of animals: group A animals underwent ligation of the common bile duct, and group B animals underwent ligation of the renal blood vessels. A dose of 0.1 mmol/kg Gd-EOB-DTPA or Gd-DTPA (control) was injected via a tail vein. Bile or urine were collected in fractions of 0 to 1, 1 to 2, 2 to 4, and 4 to 8 hours after administration of either contrast agent. At the end of the experiments, detainment of the contrast agents was determined by measurement of Gd concentrations. RESULTS: Most of the Gd-EOB-DTPA was rapidly cleared from the body: 89.4% +/- 7.5% of the injected dose within 4 hours after bile duct ligation (group A) and 87.0% +/- 6.0% within 1 hour after ligation of renal vessels (group B). Eight hours after injection of Gd-EOB-DTPA, 3.0% +/- 2.4% of the administered dose of this contrast agent was found in the carcasses of group A animals, and 1.3% +/- 0.6% in carcasses of group B animals. By comparison, at 8 hours after injection, 1.9% +/- 3.2% of the injected Gd-DTPA was found in the carcasses of group A animals (no statistical significant difference as compared with Gd-EOB-DTPA), and 96.3% +/- 3.3% in carcasses of group B animals. CONCLUSIONS: In the rat model, the magnetic resonance imaging contrast agent Gd-EOB-DPTA is rapidly and effectively eliminated by virtue of its dual-elimination pathway. The dysfunction of liver or kidney may be fully compensated by the remaining elimination pathway.