Novel approach for critical bone defect repair, A

2022 Summer.Includes bibliographical references.Critical bone defects are defined as defects that will not naturally heal over a patient's lifetime, even with surgical stabilization. When these occur in the long bones of the axial skeleton (secondary to trauma, tumor resection, etc.), limb-sparing surgery can be performed to avoid amputation of the limb. This procedure typically involves the installation of a steel locking plate over the defect, along with an endoprosthesis or allograft to fill the void of resected bone. Much progress has been made in the natural bone regeneration using tissue engineering (TE) scaffolds in place of these grafts. Porous hydroxyapatite (HAP) is a well-established bone TE scaffold biomaterial but lacks sufficient mechanical strength when fabricated at porosities shown to best induce osteogenesis. To remedy this, polymers such as polycaprolactone (PCL) are often mixed with HAP to fabricate scaffolds with increase load-bearing capacity. However, the addition of PCL makes the scaffold less osteogenic and dramatically slows the degradation rate of the scaffold. This translates into reduced new bone volume where the PCL cannot be remodeled as new bone is formed. This project involves a pilot clinical trial of a novel method that augments the gold-standard limb-sparing procedure by implanting a 3D printed endoprosthetic "sleeve" device that attaches to the locking fixation plate and contains and protects the brittle HAp scaffold. The PCL sleeve alleviates the dependency on scaffold strength which enables use of the most osteogenic possible biomaterials at ideal porosities to maximize the rate and density of new bone formation. The purpose of the study is to clinically validate the construct design and surgical procedure. Thus far, pilot limb-sparing surgeries have been performed on 4 client-owned dogs, in which sleeve-scaffold devices were installed in the critical defects caused by the removal of osteosarcomas in distal epiphyseal radii. Recombinant human bone morphogenic protein-2 (rhBMP-2) was added to the scaffolds to further encourage osteogenesis. Mechanical tests were performed on both the sleeves alone and the full construct installed in canine cadaver limbs. Results from this testing demonstrate the sleeve's ability to prevent mechanical failure of the HAp scaffolds. Similarly, no scaffold failure has been observed in clinical trial patients, with some having the device installed for greater than 24 weeks. Additionally, pressureometry and gait analysis confirmed excellent return of limb function in these animals. However, to date, no new bone formation has been observed within the scaffold devices, which has likely been inhibited by anti-cancer treatment. Regardless, results from ex vivo testing and the clinical trial validate the construct design and the viability of our novel method for protecting and maintaining brittle bone tissue engineering scaffolds, while aiding in restoration of normal limb function

The effects of ice cream in the diet of young life.

Much work has been done in the past on the nutritional value in young life of different dairy products, all of which experiments have been carried to successful completion by various men at different times. There is, however, no published information demonstrating the comparative values resulting from experimental work in the nutritional value of ice cream as a supplementary diet in infant life. For the purpose of the following experiments, the albino rat, (Mus Norvegicus Albinus) and the Norway rat, (Mus Nor vegicus), together with Guinea Pigs and cats were used. It is a well-known fact that rats exhibit the same sensitivity to surrounding conditions to which they are subjected as does man, and likewise that they respond, to these conditions in a like manner. They are, therefore, ideal subjects for nutritional experimentation. The life of the Albino Rat and the Norway is three and four years respectively, while the average old-age possibilities of man is approximately ninety years. The body composition and the composition of the kidney secretion of the rate are exact in percentage to that of man. Therefore, multiplying the results of these experiments will give the results to be gained for man. It is the purpose of this paper to show the relative nutritional value of ice cream in young life, as demonstrated by simultaneous experiments

The effect of systematic lens parameter variation on the fitting characteristics of RGP lenses

In the art of rigid contact lens fitting, practitioners must be able to make judgements to obtain the desired fit and to overcome wearing problems for the contact lens patient. The new rigid gas permable (RGP) lens materials offer the practitioner opportunity to optimize contact lens design for use in fitting and patient management. Successful fitting techniques using RGP lenses demand careful patient selection, understanding of design principles, and proper material selection. The use of diagnostic fitting and flourescein examination can be powerful tools in reaching a successful fit and management evaluation for your patients. This paper/video will discuss and illustrate the effects of variations in base curve, diameter, power, center thickness, and edge profile. Through use of high resolution biomicroscopy we will demonstrate how varying these parameters will clinically alter the lens-cornea fitting relationship