Dextran-induced acute renal failure after microvascular muscle transplantation

Multidisciplinary Practice Variations of Anti-Thrombotic Strategies for Free Tissue Transfers

Background: Venous thrombosis, the leading cause of free flap failure, may have devastating consequences. Many anti-thrombotic agents and protocols have been described for prophylaxis and treatment of venous thrombosis in free flaps. Methods: National surveys were distributed to microsurgeons (of both Plastics and ENT training) and hematology and thrombosis specialists. Data were collected on routine screening practices, perceived risk factors for flap failure, and pre-, intra-, and post-operative anti-thrombotic strategies. Results: There were 722 surveys distributed with 132 (18%) respondents, consisting of 102 surgeons and 30 hematologists. Sixty-five surgeons and 9 hematologists routinely performed or managed patients with free flaps. The top 3 perceived risk factors for flap failure according to surgeons were medical co-morbidities, past arterial thrombosis, and thrombophilia. Hematologists, however, reported diabetes, smoking, and medical co-morbidities as the most important risk factors. Fifty-four percent of physicians routinely used unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) as a preoperative agent. Surgeons routinely flushed the flap with heparin (37%), used UFH IV (6%), or both (8%) intra-operatively. Surgeons used a range of post-operative agents such as UFH, LMWH, aspirin, and dextran while hematologists preferred LMWH. There was variation of management strategies if flap thrombosis occurred. Different strategies consisted of changing recipient vessels, UFH IV, flushing the flap, adding post-operative agents, or a combination of strategies. Conclusions: There are diverse practice variations in anti-thrombotic strategies for free tissue transfers and a difference in perceived risk factors for flap failure that may affect patient management.

Polymeric Nanoparticles in Gene Therapy: New Avenues of Design and Optimization for Delivery Applications

The field of polymeric nanoparticles is quickly expanding and playing a pivotal role in a wide spectrum of areas ranging from electronics, photonics, conducting materials, and sensors to medicine, pollution control, and environmental technology. Among the applications of polymers in medicine, gene therapy has emerged as one of the most advanced, with the capability to tackle disorders from the modern era. However, there are several barriers associated with the delivery of genes in the living system that need to be mitigated by polymer engineering. One of the most crucial challenges is the effectiveness of the delivery vehicle or vector. In last few decades, non-viral delivery systems have gained attention because of their low toxicity, potential for targeted delivery, long-term stability, lack of immunogenicity, and relatively low production cost. In 1987, Felgner et al. used the cationic lipid based non-viral gene delivery system for the very first time. This breakthrough opened the opportunity for other non-viral vectors, such as polymers. Cationic polymers have emerged as promising candidates for non-viral gene delivery systems because of their facile synthesis and flexible properties. These polymers can be conjugated with genetic material via electrostatic attraction at physiological pH, thereby facilitating gene delivery. Many factors influence the gene transfection efficiency of cationic polymers, including their structure, molecular weight, and surface charge. Outstanding representatives of polymers that have emerged over the last decade to be used in gene therapy are synthetic polymers such as poly(l-lysine), poly(l-ornithine), linear and branched polyethyleneimine, diethylaminoethyl-dextran, poly(amidoamine) dendrimers, and poly(dimethylaminoethyl methacrylate). Natural polymers, such as chitosan, dextran, gelatin, pullulan, and synthetic analogs, with sophisticated features like guanidinylated bio-reducible polymers were also explored. This review outlines the introduction of polymers in medicine, discusses the methods of polymer synthesis, addressing top down and bottom up techniques. Evaluation of functionalization strategies for therapeutic and formulation stability are also highlighted. The overview of the properties, challenges, and functionalization approaches and, finally, the applications of the polymeric delivery systems in gene therapy marks this review as a unique one-stop summary of developments in this field.

Scandinavian clinical practice guideline on choice of fluid in resuscitation of critically ill patients with acute circulatory failure

BACKGROUND

The task force on Acute Circulatory Failure of the Scandinavian Society of Anaesthesiology and Intensive Care Medicine produced this guideline with recommendations concerning the use of crystalloid vs. colloid solutions in adult critically ill patients with acute circulatory failure.

METHODS

Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology was used to grade the quality of evidence and to determine the strengths of the recommendations. As efficacy and harm may vary in different subpopulations of patients with acute circulatory failure, we produced recommendations for general intensive care unit (ICU) patients and those with sepsis, trauma and burn injury.

RESULTS

For general ICU patients and those with sepsis, we recommend using crystalloids for resuscitation rather than hydroxyethyl starch and we suggest using crystalloids rather than gelatin and albumin. For patients with trauma we recommend to use crystalloids for resuscitation rather than colloid solutions. For patients with burn injury we provide no recommendations as there are very limited data from randomised trials on fluid resuscitation in this patient population.

CONCLUSIONS

We recommend using crystalloid solutions rather than colloid solutions for resuscitation in the majority of critically ill patients with acute circulatory failure.

Drug-eluting scaffold to deliver chemotherapeutic medication for management of pancreatic cancer after surgery

Traditional post-surgical chemotherapy for pancreatic cancer is notorious for its devastating side effects due to the high dosage required. On the other hand, legitimate concerns have been raised about nanoparticle-mediated drug delivery because of its potential cytotoxicity. Therefore, we explored the local delivery of a reduced dosage of FOLFIRINOX, a four-drug regimen comprising oxaliplatin, leucovorin, irinotecan, and fluorouracil, for pancreatic cancer using a biocompatible drug-eluting scaffold as a novel chemotherapy strategy after palliative surgery. In vitro assays showed that FOLFIRINOX in the scaffold caused massive apoptosis and thereby a decrease in the viability of pancreatic cancer cells, confirming the chemotherapeutic capability of the drug-eluting scaffold. In vivo studies in an orthotopic murine xenograft model demonstrated that the FOLFIRINOX in the scaffold had antitumorigenic and antimetastatic effects comparable with those achieved by intraperitoneal injection, despite the dose released by the scaffold being roughly two thirds lower. A mechanistic study attributed our results to the excellent ability of the FOLFIRINOX in the scaffold to destroy the CD133⁺CXCR4⁺ cell population responsible for pancreatic tumorigenesis and metastasis. This clinically oriented study gives rise to a promising alternative strategy for postsurgical management of pancreatic cancer, featuring a local chemotherapeutic effect with considerable attenuation of side effects.

Upper limb replantation

Since the first successful salvage of an amputated finger using microsurgical anastomoses in 1965, replantation has been widely used in these decades and is now firmly established as a viable treatment option in traumatic limb amputation. The current concepts of replantation surgery for upper limb amputation are discussed in this review article in terms of history of replantation, present indications for the procedure, pre-theater care, technical refinements, postoperative management and functional outcome. In this article, we demonstrated that the advent of microsurgery has led to replantation of almost every amputated part of the upper limb possible. Replantation of digits and the hand can restore not only circulation but also function and cosmetic appearance. However, major amputations remain a challenge and the functional outcome is often disappointing, albeit the success rate of replantation exceeds 80%. Proper patient selection, adequate pre-theater preservation, good operative skill and postoperative care, as well as tight cooperation among the patient, the surgeon, and the rehabilitation therapist will help to achieve a better final functional outcome.

Toxicological considerations when creating nanoparticle-based drugs and drug delivery systems

INTRODUCTION

The biggest challenge faced by the scientific community involved in drug development is to deliver safe and effective dosage of drugs without causing systemic toxicity. Therefore, novel nano-based delivery vehicles specifically targeting tumors but not normal tissues are urgently needed.

AREAS COVERED

Nanoparticles have beneficial aspects but can be toxic themselves, which is always a concern for any drug or delivery agent. This review examines and details the toxicological aspects that should be considered when planning to use nanoparticles in animals or in man for drug delivery or imaging. Subjects discussed in this review include i) overviews of applications of various nanoparticles for drug delivery and imaging; ii) toxicological aspects to consider when selecting particular nanoparticles for use in various applications in animals or man; iii) hurdles faced when examining nanoparticle toxicity; and iv) current approaches for assessing nanoparticle toxicity.

EXPERT OPINION

Nanotechnology has significant potential for advancing therapeutic efficacy and imaging in cancer; however, these agents can be toxic. Therefore, toxicity needs to be considered when selecting nanoparticles for a particular application. Methods for assessing nanoparticle toxicity need to be improved and standardized across all nanotechnology platforms in order to speed up the application of nanoparticle use in humans.

Osmotic nephrosis: acute kidney injury with accumulation of proximal tubular lysosomes due to administration of exogenous solutes

Osmotic nephrosis describes a morphological pattern with vacuolization and swelling of the renal proximal tubular cells. The term refers to a nonspecific histopathologic finding rather than defining a specific entity. Osmotic nephrosis can be induced by many different compounds, such as sucrose, hydroxyethyl starch, dextrans, and contrast media. It has a broad clinical spectrum that includes acute kidney injury and chronic kidney failure in rare cases. This article discusses the pathological characteristics, pathogenesis, and various clinical entities of osmotic nephrosis.

Renal impact of fluid management with colloids: a comparative review

BACKGROUND AND OBJECTIVES

Colloids such as hydroxyethyl starch (HES), gelatin, dextran and albumin are useful for maintaining renal perfusion and function. The comparative renal effects of colloids have not been previously reviewed.

METHODS

Computer searches of the MEDLINE and EMBASE bibliographic databases and the Cochrane Library were conducted using the search terms: colloids; hetastarch; gelatin; dextrans; serum albumin; kidney failure; cardiac surgical procedures; and kidney transplantation. Relevant studies were also sought through hand searching and examination of reference lists. Results of identified studies were qualitatively summarized with account taken for potential confounding factors.

RESULTS

The three artificial colloids HES, gelatin and dextran all exhibited troublesome renal side-effects. Randomized trials have demonstrated adverse renal effects of HES in sepsis and surgery. Undesirable renal effects are common to all available HES solutions regardless of molecular weight, substitution or C2/C6 ratio. While some of its effects may be less severe than those of HES, gelatin also can adversely affect the kidney. A negative renal impact of dextran is well-established, although this colloid is now less extensively used than formerly. As the normal endogenous colloid, albumin exhibits a wide margin of renal safety, although albumin overdose needs to be avoided. Albumin also appears to exert protective effects on the kidney such as inhibition of apoptosis and scavenging of reactive oxygen species.

CONCLUSIONS

Colloids display important differences in their actions on the kidney. These contrasting renal effects should be considered in making fluid management decisions.

Anticoagulation therapy in microsurgery: a review

The advent of microsurgical tissue transfer including replantation greatly has expanded the scope of reconstructive surgery. There are few recent innovations in anticoagulation therapies for microsurgery, however, and anastomotic thrombosis remains an occasional cause of surgical failure. No consensus exists on the ideal anticoagulation protocol for microsurgery. This article reviews major pharmacologic modalities of anticoagulation, delineates the mechanism of action and study of efficacy of each agent, and compares the risks and benefits of popular anticoagulation therapies. Finally, it examines available human outcomes-based data and attempts to provide a glimpse of the future direction of microsurgical anticoagulation research.