Evaluation of Submucosally Injected Polyethylene Glycol-Based Hydrogel and Bovine Cross-Linked Collagen in the Canine Urethra using Cystoscopy, Magnetic Resonance Imaging and Histopathology

Comprehensive Review on Hydrogels

The conventional drug delivery systems have a long list of issues of repeated dosing and toxicity arising due to it. The hydrogels are the answer to them and offer a result that minimizes such activities and optimizes therapeutic benefits. The hydrogels proffer tunable properties that can withstand degradation, metabolism, and controlled release moieties. Some of the areas of applications of hydrogels involve wound healing, ocular systems, vaginal gels, scaffolds for tissue, bone engineering, etc. They consist of about 90% of the water that makes them suitable bio-mimic moiety. Here, we present a birds-eye view of various perspectives of hydrogels, along with their applications.

Intracranial abscess formation in an adult alpaca: a case report

Background

Intracranial abscess formation is an extremely rare and sporadically documented disease in South American Camelids (SACs). Herein we report the first case of otogenic brain abscess formation in this species.

Case presentation

A 4 years old female alpaca was presented to our veterinary hospital with a 6 month history of neurologic disorder symptoms, mainly head tilt to the right and emaciation. A comprehensive workup (ultrasound and computed tomography) revealed irreversible cranial nerve abnormalities, extensive lesions in the region of external, middle and internal right ear including destruction of bony structures (tympanic bulla, parts of temporal bone) and severe brain deformation caused by an intracranial abscess. The lesion was up to 6x7x4 cm and occupying almost 40% of the cranial cavity. No pathological findings were evident in other organs or structures. The late referral of the alpaca at this advanced stage of destructive disease precluded surgical intervention.

Conclusions

This case report describes the clinical signs, diagnostic procedures and pathological findings in an adult female alpaca suffering from cranial nerve abnormalities caused by a massive otogenic brain abscess. Camelids suffering from otitis may not present with clinical signs until the pathology is severe. The importance of considering intracranial abscess formation as differential diagnosis in SACs showing the merest hint of nerve deficits cannot be emphasized enough in order to diagnose such pathological processes at an early and treatable stage.

Cellulose-based hydrogel materials: chemistry, properties and their prospective applications

Hydrogels based on cellulose comprising many organic biopolymers including cellulose, chitin, and chitosan are the hydrophilic material, which can absorb and retain a huge proportion of water in the interstitial sites of their structures. These polymers feature many amazing properties such as responsiveness to pH, time, temperature, chemical species and biological conditions besides a very high-water absorption capacity. Biopolymer hydrogels can be manipulated and crafted for numerous applications leading to a tremendous boom in research during recent times in scientific communities. With the growing environmental concerns and an emergent demand, researchers throughout the globe are concentrating particularly on naturally derived hydrogels due to their biocompatibility, biodegradability and abundance. Cellulose-based hydrogels are considered as useful biocompatible materials to be used in medical devices to treat, augment or replace any tissue, organ, or help function of the body. These hydrogels also hold a great promise for applications in agricultural activity, as smart materials and some other useful industrial purposes. This review offers an overview of the recent and contemporary research regarding physiochemical properties of cellulose-based hydrogels along with their applications in multidisciplinary areas including biomedical fields such as drug delivery, tissue engineering and wound healing, healthcare and hygienic products as well as in agriculture, textiles and industrial applications as smart materials.

Assessment of in vivo degradation profiles of hyaluronic acid hydrogels using temporal evolution of chemical exchange saturation transfer (CEST) MRI

Hyaluronic acid (HA) hydrogels have found a wide range of applications in biomedicine: regenerative medicine to drug delivery applications. In vivo quantitative assessment of these hydrogels using magnetic resonance imaging (MRI) provides an effective, accurate, safe, and non-invasive translational approach to assess the biodegradability of HA hydrogels. Chemical exchange saturation transfer (CEST) is an MRI contrast enhancement technique that overcomes the concentration limitation of other techniques like magnetic resonance spectroscopy (MRS) by detecting metabolites at up to two orders of magnitude or higher. In this study, HA hydrogels were synthesized based on different crosslinking agents and assessed using CEST MRI to investigate the in vivo degradation profiles of these gels in a mouse subcutaneous injection model over a three-month period. Nature of crosslinking agents was found to influence their degradation profiles. Since CEST MRI provides a unique chemical signature to visualize HA hydrogels, our studies proved that this technique could be used as a guide in the hydrogel optimization process for drug delivery and regenerative medicine applications.

Cystoscopy in dogs and cats

Cystoscopy has become an important and widely available component of the diagnostic evaluation of diseases of the lower urinary tract in dogs and cats. In addition, a large number of cystoscopic guided procedures have been described that can be used to treat disease processes that were previously treatable only with invasive surgical procedures. This article reviews the indications and contraindications for cystoscopy, cystoscopy equipment and techniques for male and female dogs and cats, potential complications associated with cystoscopy, and management options for these complications.

X-ray Phase Contrast Allows Three Dimensional, Quantitative Imaging of Hydrogel Implants

Three dimensional imaging techniques are needed for the evaluation and assessment of biomaterials used for tissue engineering and drug delivery applications. Hydrogels are a particularly popular class of materials for medical applications but are difficult to image in tissue using most available imaging modalities. Imaging techniques based on X-ray Phase Contrast (XPC) have shown promise for tissue engineering applications due to their ability to provide image contrast based on multiple X-ray properties. In this manuscript, we investigate the use of XPC for imaging a model hydrogel and soft tissue structure. Porous fibrin loaded poly(ethylene glycol) hydrogels were synthesized and implanted in a rodent subcutaneous model. Samples were explanted and imaged with an analyzer-based XPC technique and processed and stained for histology for comparison. Both hydrogel and soft tissues structures could be identified in XPC images. Structure in skeletal muscle adjacent could be visualized and invading fibrovascular tissue could be quantified. There were no differences between invading tissue measurements from XPC and the gold-standard histology. These results provide evidence of the significant potential of techniques based on XPC for 3D imaging of hydrogel structure and local tissue response.