Glycosaminoglycan in cerebrum, cerebellum and brainstem of young sheep brain with particular reference to compositional and structural variations of chondroitin-dermatan sulfate and hyaluronan

Selective isolation of hyaluronan by solid phase adsorption to silica

A solid phase adsorption method for selective isolation of hyaluronan (HA) from biological samples is presented. Following enzymatic degradation of protein, HA can be separated from sulfated glycosaminoglycans, other unsulfated glycosaminoglycans, nucleic acids, and proteolytic fragments by adsorption to amorphous silica at specific salt concentrations. The adsorbed HA can be released from silica using neutral and basic aqueous solutions. HA ranging in size from ∼9 kDa to MDa polymers has been purified by this method from human serum and conditioned medium of cultured cells.

Methods for isolating and analyzing physiological hyaluronan: a review

The carbohydrate hyaluronan (or hyaluronic acid, HA) is found in all human tissues and biofluids where it has wide-ranging functions in health and disease that are dictated by both its abundance and size. Consequently, hyaluronan evaluation in physiological samples has significant translational potential. Although the analytical tools and techniques for probing other biomolecules such as proteins and nucleic acids have become standard approaches in biochemistry, those available for investigating hyaluronan are less well established. In this review, we survey methods related to the assessment of native hyaluronan in biological specimens, including protocols for separating it from biological matrices and technologies for determining its concentration and molecular weight.

Translating pH-sensitive PROgressive saturation for QUantifying Exchange rates using Saturation Times (PRO-QUEST) MRI to a 3T clinical scanner

PURPOSE

To translate the recently developed PRO-QUEST (Progressive saturation for quantifying exchange rates using saturation times) sequence from preclinical 9.4T to 3T clinical magnetic field strength.

METHODS

Numerical simulations were performed to define the optimal saturation flip angles for PRO-QUEST saturation pulses at 3T and demonstrate the effect of a ∆T₂ error on the exchange rate (k_ex ) estimation at various field strengths. Exchange-dependent relaxation rate (R_ex ) was measured for glutamate solutions in various pH, healthy volunteers and patients with multiple sclerosis (MS). Additionally, concentration-independent ratiometric R_ex maps were produced to evaluate regional signal variations across the brain of human volunteers.

RESULTS

The calculated R_ex significantly correlates with pH in glutamate samples, however, k_ex values are underestimated as compared to those previously obtained at 9.4T. In the ratiometric R_ex map of healthy volunteers, no significant differences are found between grey matter, white matter, and basal ganglia. In patients with MS, white matter lesions are visible in single saturation power R_ex maps whereas only a periventricular lesion is apparent in the ratiometric R_ex map.

CONCLUSION

We demonstrate that quantification of pH sensitive indices using PRO-QUEST is feasible at 3T within clinically acceptable acquisition times. Our initial findings in patients with MS show that pH sensitive indices varied with the type of lesion examined whereas no significant difference was found in healthy volunteers between tissue types, suggesting that it would be worthwhile to apply PRO-QUEST in a larger cohort of patients to better understand its distinct imaging features relative to conventional techniques.

Hyaluronan, neural stem cells and tissue reconstruction after acute ischemic stroke

Focal stroke is a disabling disease with lifelong sensory, motor and cognitive impairments. Given the paucity of effective clinical treatments, basic scientists are developing novel options for protection of the affected brain and regeneration of lost tissue. Tissue bioengineering and stem/progenitor cell treatments have both been individually pursued for stroke neural repair therapies, with some benefit in tissue recovery. Emerging directions in stroke neural repair approaches combine these two therapies to use biopolymers with stem/progenitor transplants to promote greater cell survival in the transplant and directed delivery of bioactive molecules to the transplanted cells and the adjacent injured tissue. In this review the background literature on a combined use of neural stem/progenitor cells encapsulated in hyaluronan gels is discussed and the way this therapeutic approach can affect the important processes involved in brain tissue reconstruction, such as angiogenesis, axon regeneration, neural differentiation and inflammation is clarified. The glycosaminoglycan hyaluronan can optimize those processes and be employed in a successful neural tissue engineering approach.