Modified Borggreve-Van Nes-Winkelmann rotationplasty for surgery in developing countries

BACKGROUND

Amputation is still the most common therapy for patients suffering from osteosarcoma in Myanmar, despite the fact that limb salvage surgery e.g. Borggreve-Van Nes-Winkelmann rotationplasty for malignant tumors located within the distal femur or proximal tibia is the current state-of-the-art reconstructive procedure. A safe and reliable operation technique is crucial in order to perform a complex surgical procedure like the rotationplasty in lower-middle income economies with limited infrastructure and resources. The authors present seven cases of patients with osteosarcomas that received a Borggreve-Van Nes-Winkelmann rotationplasty with an evaluation of the procedures focusing on safety and sustainability.

METHODS

From 2019 until 2020, seven young patients with osteosarcomas of the distal femur or proximal tibia were treated with Borggreve-Van Nes-Winkelmann rotationplasties in the Orthopaedic Hospital in Mandalay, Myanmar. As modification of the standard procedure the dissection and subsequent clamping of the femoral artery in order to minimize blood loss as well as the formation of an adipocutaneous flap that minimizes swelling and decreases the pressure on the vessels were successfully performed. This modified procedure resembles a safe and simplified surgical technique that is feasible under the circumstances of lower-middle income economies with good outcomes.

RESULTS

All patients showed good functional and aesthetic results. One of the seven patients needed secondary wound closure due to wound dehiscence.

CONCLUSIONS

A simplified and safe operation technique for the performance of the Van Nes-Borggreve rotationplasty was adapted to the given constraints in lower-middle income economies and proved to be successful. Trial registration All patients approved to participate in the study and have given consent to publication.

Preclinical modeling of a phase 0 clinical trial protocol

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Background: The Exploratory IND program initiated at NCI (“Phase 0”) is designed to evaluate the pharmacodynamic effects (PD) of candidate drugs at the molecular level in the clinic. Trials employ patient biopsies and surrogate tissues (e.g. PBMCs) to determine the quantitative effect of the agent on its putative target, after a minimum number of doses. The approach requires repeated biopsy of the tumor, an understanding of the time-effect window, and some knowledge of the dose level likely to cause a measurable drug effect. Methods: Prior to initiating a Phase 0 study of the PARP (PolyAdenosyl-Ribose Polymerase) inhibitor, ABT-888, we developed a pre-clinical model to mirror the clinical protocol. Colo 829 and A375 xenografts in athymic nude [nu/nu (NCr)] mice were examined for time and dose effect on PARP using a validated, quantitative PAR assay. Extracts of entire xenografts, quartered xenografts and 18 gauge needle biopsies were examined for variability of baseline and post-treatment PAR levels. Results were cross-checked with Western analysis for polyADP-Ribose (PAR)-labeled proteins in treated mice. Pharmacokinetics (PK) were modeled using plasma drug levels. Additional studies examined the influence of previous biopsy, contralateral biopsy, vehicle treatment, and general anesthesia on PAR in xenografts. Results: A single dose of ABT-888 produced a significant decrease in intracellular PAR levels that could be measured 2 to 6 hours post-dose. PAR levels and drug effect on PAR levels were not influenced by repeated needle biopsies. Variation across xenografts was random for single and bilateral xenograft animal models in the ABT-888 treated, vehicle- and topotecan-treated control groups. Animal handling and socialization appeared to elevate baseline PAR levels, which could confound analysis of study results. Conclusions: Pre-clinical modeling of a specific Phase 0 clinical protocol for drug effects and biological variability provided valuable insights into the development, refinement, and analysis of the currently-active NCI Phase 0 clinical trial of ABT-888. Animal studies were conducted in an AAALAC approved facility under an approved IACUC protocol. Funded by NCI Contract N01-CO-12400.

No significant financial relationships to disclose.

Vascular permeability in experimental diabetes is associated with reduced endothelial occludin content: vascular endothelial growth factor decreases occludin in retinal endothelial cells. Penn State Retina Research Group

Blood-retinal barrier (BRB) breakdown is a hallmark of diabetic retinopathy, but the molecular changes that cause this pathology are unclear. Occludin is a transmembrane component of interendothelial tight junctions that may regulate permeability at the BRB. In this study, we examined the effects of vascular endothelial growth factor (VEGF) and diabetes on vascular occludin content and barrier function. Sprague-Dawley rats were made diabetic by intravenous streptozotocin injection, and age-matched animals served as controls. After 3 months, BRB permeability was quantified by intravenous injection of fluorescein isothiocyanate-bovine serum albumin (FITC-BSA), Mr 66 kDa, and 10-kDa rhodamine-dextran (R-D), followed by digital image analysis of retinal sections. Retinal fluorescence intensity for FITC-BSA increased 62% (P < or = 0.05), but R-D fluorescence did not change significantly. Occludin localization at interendothelial junctions was confirmed by immunofluorescence, and relative protein content was determined by immunoblotting of retinal homogenates. Retinal occludin content decreased approximately 35% (P < or = 0.03) in the diabetic versus the control animals, whereas the glucose transporter GLUT1 content was unchanged in rat retinas. Additionally, treatment of bovine retinal endothelial cells in culture with 0.12 nmol/l or 12 nmol/l VEGF for 6 h reduced occludin content 46 and 54%, respectively. These data show that diabetes selectively reduces retinal occludin protein expression and increases BRB permeability. Our findings suggest that the elevated VEGF in the vitreous of patients with diabetic retinopathy increases vascular permeability by downregulating occludin content. Decreased tight junction protein expression may be an important means by which diabetes causes increased vascular permeability and contributes to macular edema.

Histamine reduces ZO-1 tight-junction protein expression in cultured retinal microvascular endothelial cells

We examined ZO-1 protein content in cultured retinal vascular endothelial cells to test the hypothesis that histamine alters tight-junction-protein expression. Histamine (10(-9) -10(-4) M) causes a reversible concentration-dependent reduction of ZO-1 protein content, mediated by both H1 and H2 receptors. Histamine reduces ZO-1 expression within the time associated with increased paracellular permeability. Tight-junction-protein alterations may be a novel explanation for the mechanism by which vasoactive agents increase microvascular permeability.

Hormonal regulation of insulin-like growth factor II and insulin-like growth factor binding protein expression by breast cancer cells in vivo: evidence for stromal epithelial interactions

Insulin-like growth factors (IGFs) I and II are potent mitogens for breast cancer cells. Their proliferative activity is likely to be influenced by their binding proteins (IGFBPs), a family of newly identified proteins. We report here on the in vivo hormonal regulation of mRNAs for IGF-II and IGFBPs in the N-nitrosomethylurea-induced rat mammary tumor, a well-established model of hormone-responsive mammary cancer. IGF-II mRNA levels tended to decrease in regressing tumors following ovariectomy, and they markedly increased upon reactivation of tumor growth with hormone repletion. Ovariectomy induced a drastic increase in IG-FBP-6 mRNA which was reversible with hormone repletion. Similar but more modest changes were observed with IGFBP-2 mRNA. In contrast, IGFBP-3 and IGFBP-4 mRNAs tended to decrease with ovariectomy and increase with hormone repletion. These latter effects, however, were modest, variable, and not statistically significant. In situ hybridization analysis revealed that IGF-II, IGFBP-5, and IGFBP-6 mRNAs were localized in the stromal component of the tumor, whereas IGFBP-2 mRNA was expressed by epithelial cells. We conclude that hormonal regulation of IGFBP expression is heterogeneous, thus suggesting divergent biological functions for these peptides. Our data also emphasize the importance of potential stromal-epithelial interactions in the control of breast cancer cell proliferation by IGFs.

Synchronization of breast cancer cell proliferation in vivo by combined hormonal and polyamine manipulation

Optimal synchronization of breast cancer cell proliferation by hormonal means may be limited by cellular heterogeneity in sensitivity to the multistep activation of growth following initial hormone binding to the receptor. We hypothesized that induced synchronous growth may be improved by combined manipulation of the polyamine (PA) pathway since we have previously shown that PAs are distal effectors of hormonal action on proliferation in breast cancer. To test our hypothesis, we induced an initial phase of hormone and PA depletion (castration plus administration of the PA synthesis inhibitor alpha-difluoromethylornithine) in rats bearing N-nitrosomethylurea induced mammary tumors. This was followed by transition phase of hormone repletion in the presence of alpha-difluoromethylornithine (to push the cells into the proliferative cascade up to the distal step controlled by PA) and finally a phase of hormone and PA repletion. Simultaneously, groups of rats were subjected to hormone/PA depletion/repletion individually. The effects of these manipulations on the labeling indices (LIs) of glandular, myoepithelial, and nonepithelial cells were estimated by autoradiography. The combined hormone/PA manipulation yielded the highest degree of synchronization with LIs of the glandular and myoepithelial cells being approximately 2-fold over intact control after only 2 or 3 days of combined repletion. In contrast, hormone treatment alone restored the LIs of glandular cells only to control levels and minimally influenced those of myoepithelial cells. PA manipulation alone failed to affect the LIs of any cell type. Although the rate of tumor regrowth was highest with the combination treatment, the absolute tumor volumes did not differ significantly at the end of the repletion phase between the three regimens. These results indicate that combined hormone/PA manipulation provides the best "therapeutic window" (LI/tumor volume) for implementation of kinetically based cytotoxic chemotherapy.