Serum hyaluronan and its association with unfavorable histology and aggressiveness of heterotransplanted Wilms' tumor

BACKGROUND/PURPOSE: The sera and urine of children with Wilms' tumor (WT) often contain increased concentrations of hyaluronan (HA). The authors developed a heterotransplant model to investigate whether serum HA concentrations could predict the histology and progression of WT. METHODS: Random portions of 8 human WT specimens (7 favorable and 1 unfavorable histology findings) were heterotransplanted into the flanks of severe combined immunodeficient (SCID) mice. After 6 to 20 weeks of observation, animals were killed, and serum HA concentrations, tumor histology, and local invasion were determined. RESULTS: Sera of mice supporting tumor growth had a median HA concentration of 9,379 microg/L (range, 459 to 3,206,176 microg/L) compared with a median HA concentration of 416 microg/L (range, 204 to 782 microg/L) in animals not supporting tumor growth. The highest serum HA concentrations were detected in animals harboring unfavorable histology blastemal-predominant tumors, whereas animals supporting favorable histology epithelial- and stromal-predominant tumors had the lowest serum HA concentrations. In association with markedly increased serum HA, undifferentiated blastemal tumors showed significantly greater growth rates than the more differentiated epithelial or stromal tumors. Additionally, serum HA concentrations were greater in mice with invasive as compared with noninvasive tumors for each histological type. Complete resection of established tumors also resulted in the return of serum HA to preheterotransplant concentrations. Identification of tumor progression was further tested in SCID mice receiving subcutaneous flank injections of the human WT cell line, SK-NEP-1. Significantly greater serum HA concentrations again corresponded with more rapid growth rates and invasiveness. CONCLUSIONS: Serum HA concentrations predict the growth, invasion, and unfavorable histology findings of WT in a heterotransplant model. The authors further speculate that HA may foster an environment conducive to WT aggressiveness.     

Genetic and chromosomal alterations in Kenyan Wilms Tumor

Wilms tumor (WT) is the most common childhood kidney cancer worldwide and poses a cancer health disparity to black children of sub‐Saharan African ancestry. Although overall survival from WT at 5 years exceeds 90% in developed countries, this pediatric cancer is alarmingly lethal in sub‐Saharan Africa and specifically in Kenya (36% survival at 2 years). Although multiple barriers to adequate WT therapy contribute to this dismal outcome, we hypothesized that a uniquely aggressive and treatment‐resistant biology compromises survival further. To explore the biologic composition of Kenyan WT (KWT), we completed a next generation sequencing analysis targeting 10 WT‐associated genes and evaluated whole‐genome copy number variation. The study cohort was comprised of 44 KWT patients and their specimens. Fourteen children are confirmed dead at 2 years and 11 remain lost to follow‐up despite multiple tracing attempts. TP53 was mutated most commonly in 11 KWT specimens (25%), CTNNB1 in 10 (23%), MYCN in 8 (18%), AMER1 in 5 (11%), WT1 and TOP2A in 4 (9%), and IGF2 in 3 (7%). Loss of heterozygosity (LOH) at 17p, which covers TP53, was detected in 18% of specimens examined. Copy number gain at 1q, a poor prognostic indicator of WT biology in developed countries, was detected in 32% of KWT analyzed, and 89% of these children are deceased. Similarly, LOH at 11q was detected in 32% of KWT, and 80% of these patients are deceased. From this genomic analysis, KWT biology appears uniquely aggressive and treatment‐resistant. © 2015 The Authors. Genes, Chromosomes & Cancer Published by Wiley Periodicals, Inc.     

Biological evaluation of intervertebral disc cells in different formulations of gellan gum‐based hydrogels

Gellan gum (GG)‐based hydrogels are advantageous in tissue engineering not only due to their ability to retain large quantities of water and provide a similar environment to that of natural extracellular matrix (ECM), but also because they can gelify in situ in seconds. Their mechanical properties can be fine‐tuned to mimic natural tissues such as the nucleus pulposus (NP). This study produced different formulations of GG hydrogels by mixing varying amounts of methacrylated (GG‐MA) and high‐acyl gellan gums (HA‐GG) for applications as acellular and cellular NP substitutes. The hydrogels were physicochemically characterized by dynamic mechanical analysis. Degradation and swelling abilities were assessed by soaking in a phosphate buffered saline solution for up to 170 h. Results showed that as HA‐GG content increased, the modulus of the hydrogels decreased. Moreover, increases in HA‐GG content induced greater weight loss in the GG‐MA/HA‐GG formulation compared to GG‐MA hydrogel. Potential cytotoxicity of the hydrogel was assessed by culturing rabbit NP cells up to 7 days. An MTS assay was performed by seeding rabbit NP cells onto the surface of 3D hydrogel disc formulations. Viability of rabbit NP cells encapsulated within the different hydrogel formulations was also evaluated by Calcein‐AM and ATP assays. Results showed that tunable GG‐MA/HA‐GG hydrogels were non‐cytotoxic and supported viability of rabbit NP cells. Copyright © 2012 John Wiley & Sons, Ltd.     

Diabetes and orthopaedic surgery: a review

Diabetes mellitus (DM) is common, estimated to affect 425 million people worldwide in 2017. It is a condition that is continually growing in prevalence and is often associated with multiple co-morbidities. Its multi-system effects on the body mean that its management can pose a challenge, even to more experienced clinicians. In orthopaedic practice, diabetic patients are commonly encountered owing to their increased fracture risk and complications of the disease such as diabetic foot. An appropriate knowledge of diabetes, its pathophysiology, immunology and the pharmacology of medications used in its treatment is essential, as the consequences of mismanagement can be grave. Optimal treatment of diabetics can often require the involvement of a wider multidisciplinary team. Complications that can be encountered in the perioperative and postoperative periods include, diabetic ketoacidosis, hyperosmolar hyperglycaemic state, surgical site infection and venous thromboembolism. This review outlines current concepts in the perioperative management of diabetes and its manifestations within orthopaedic surgery, with a focus on outcomes and complications. A review of the available literature reveals conflicting conclusions between studies, with no clear effect or consensus yet established for many issues. There is a need for a greater number of well-designed, high-quality, appropriately powered trials to establish the true effect of diabetes on outcomes in orthopaedic surgery.     

The pediatric surgeon's road to research independence: utility of mentor-based National Institutes of Health grants

Background

The current research environment for academic surgeons demands that extramural funding be obtained. Financial support from the National Institutes of Health (NIH) is historically the gold standard for funding in the biomedical research community, with the R01 funding mechanism viewed as indicator of research independence. The NIH also supports a mentor-based career development mechanism (K-series awards) in order to support early-stage investigators. The goal of this study was to investigate the grants successfully awarded to pediatric surgeon-scientists and then determine the success of the K-series award recipients at achieving research independence.

Methods

In July 2012, all current members of the American Pediatric Surgery Association (APSA) were queried in the NIH database from 1988–2012 through the NIH Research Portfolio Online Reporting Tools. The following factors were analyzed: type of grant, institution, amount of funding, and funding institute or center.

Results

Among current APSA members, there have been 83 independent investigators receiving grants, representing 13% of the current APSA membership, with 171 independent grants funded through various mechanisms. Six percent currently have active NIH funding, with $7.2 million distributed in 2012. There have been 28 K-series grants awarded. Of the recipients of expired K08 awards, 39% recipients were subsequently awarded an R01 grant. A total of 63% of these K-awarded investigators transitioned to an independent NIH award mechanism.

Conclusions

Pediatric surgeon-scientists successfully compete for NIH funding. Our data suggest that although the K-series funding mechanism is not the only path to research independence, over half of the pediatric surgeons who receive a K-award are successful in the transition to independent investigator.     

Importance of catalase in the disposal of hydrogen peroxide within human erythrocytes

The catalase within normal, intact human erythrocytes was completely inactivated with amino triazole. The rate of 14CO2 evolution, when the cells were subsequently incubated with 14C-labeled glucose, provided a measure of the rate at which NADPH was being oxidized by the glutathione peroxidase/reductase system for the disposal of H2O2. This rate was determined in control cells and in catalase-inactivated cells while the cells were exposed to H2O2, which was generated at various constant and predetermined rates by glucose oxidase. The results indicated that catalase handles approximately half of the generated H2O2. The glutathione peroxidase/reductase mechanism accounted for the other half. These results are in agreement with our earlier findings on erythrocytes of a subject with a genetic deficiency of catalase. However, an unexpected result with the present approach was the finding that the increased dependence on the glutathione peroxidase/reductase mechanism did not occur until greater than 98% of the catalase had been inactivated. The latter observation indicates that catalase and the glutathione peroxidase/reductase system function intracellularly in a manner very different from that previously ascribed to them. An explanation of the findings requires that the two methods of H2O2 disposal function in a coordinated way, such as a sequential action in which the glutathione peroxidase/reductase system is the rate-limiting step.     

Paleoclimate and Amerindians: evidence from stable isotopes and atmospheric circulation

Two Amerindian demographic shifts are attributed to climate change in the northwest plains of North America: at approximately 11,000 calendar years before present (yr BP), Amerindian culture apparently split into foothills-mountains vs. plains biomes; and from 8,000-5,000 yr BP, scarce archaeological sites on the open plains suggest emigration during xeric "Altithermal" conditions. We reconstructed paleoclimates from stable isotopes in prehistoric bison bone and relations between weather and fractions of C(4) plants in forage. Further, we developed a climate-change model that synthesized stable isotope, existing qualitative evidence (e.g., palynological, erosional), and global climate mechanisms affecting this midlatitude region. Our isotope data indicate significant warming from approximately 12,400 to 11,900 yr BP, supporting climate-driven cultural separation. However, isotope evidence of apparently wet, warm conditions at 7,300 yr BP refutes emigration to avoid xeric conditions. Scarcity of archaeological sites is best explained by rapid climate fluctuations after catastrophic draining of the Laurentide Lakes, which disrupted North Atlantic Deep Water production and subsequently altered monsoonal inputs to the open plains.     

Antimicrobial Activities of Skincare Preparations from Plant Extracts

In this study, Tithonia diversifolia Helms. (A Gray), Aloe secundiflora (Miller) and Azadirachta indica (A. Juss) plant extracts were used to make herbal soaps while Thevetia peruviana (Schum) seed oil was used to make a herbal lotion for skincare. The soaps were tested for the growth inhibition of Escherichia coli, and Candida albicans. The lotion was evaluated against Staphylococcus aureus and E.coli. Although Tithonia diversifolia soap exhibited the highest inhibitory effect on the test bacterial strains, it had the least inhibition against C. albicans. Results from this study indicated that the ‘Tithonia diversifolia’ soap would have superior skin protection against the tested bacteria but would offer the least skin protection against C. albicans. The herbal lotion inhibited S. aureus and E. coli in a concentration dependent manner, however, the inhibitory effect was more pronounced on S. aureus.