Basic fibroblast growth factor (FGF-2) induced transdifferentiation of retinal pigment epithelium: generation of retinal neurons and glia.

In the present study we report that basic fibroblast growth factor (bFGF, FGF-2) promotes the transdifferentiation of Xenopus laevis larval retinal pigment epithelium (RPE) into neural retina. Using specific antibodies we have examined the cellular composition of the regenerated retinal tissue. Our results show that, in addition to retinal neurons and photoreceptors, glial cells were also regenerated from the transdifferentiated RPE. These results were specific to FGF-2, since other factors that were tested, including acidic FGF (aFGF, FGF-1), epidermal growth factor (EGF), laminin, ECL, and Matrigel, exhibited no activity in inducing retinal regeneration. These results are the first in amphibians demonstrating the functional role of FGF-2 in inducing RPE transdifferentiation. Transplantation studies were carried out to investigate retinal regeneration from the RPE in an in vivo environment. Sheets of RPE implanted into the lens-less eyes of larval hosts transformed into neurons and glial cells only when under the influence of host retinal factors. In contrast, no retinal transdifferentiation occurred if the RPE was implanted into the enucleated orbit. Taken together, these results show that the amphibian RPE is capable of transdifferentiation into neuronal and glial cell-phenotypes and implicate FGF-2 as an important factor in inducing retinal regeneration in vitro.

Reclamation of acetone in plastination laboratories: a simple and inexpensive method.

Since the introduction of the plastination process by von Hagens [Anat Rec 194/2: 247-256, 1979], the cost of acetone used for the dehydration step has been considered an important factor in the cost of plastination. We have developed a three-step method that permits the reuse of acetone. The first step simply consists of storing the contaminated acetone in the freezer and separating the congealed fat by filtration. The second step is vacuum distillation of the acetone and can be conducted with the freezer and vacuum pump (found in any plastination laboratory) with just a few additions. It produces 95-97% pure acetone. The last step uses a desiccant to take away the residual water from the distilled acetone and brings the purity to 99.5%. With this method, we have reduced the amount of acetone to be purchased to a minimum and completely eliminated the cost of discarding used acetone. In addition vaporized acetone released during the impregnation step of plastination is recaptured.

Plastinated canine gastrointestinal tracts used to facilitate teaching of endoscopic technique and anatomy.

Plastinated specimens, when prepared with a design for endoscopic use, can serve as a practical model for teaching. Intact alimentary canals were excised from fresh canine cadayers. Cannulas in excess of the intended endoscope size (9.6 mm diameter) were placed in restrictive openings [cardiac ostium (ostium cardiacum), pyloric ostium (ostium pyloricum) and cecocolic orifice (ostium cecocolicum)]. These cannulas allowed ingesta to be removed and maintained adequate diameters for endoscoping. After flushing out the gastrointestinal contents, specimens were formaldehyde-fixed overnight in a dilated anatomical conformation. Prior to S10/S3 impregnation, fixative was flushed from the specimens and they were dehydrated in acetone. After impregnation, slow cure (elongation of S3 molecules at room temperature) was allowed to proceed for approximately 1 week. The gastrointestinal tracts were maintained in a dilated conformation by a positive pressure air flow. When polymer seepage was minimal, they were cured using small quantities of S6 (final curing agent). The curing agent was contained around the specimen by enclosing the specimens in plastic bags. The plastinated specimens retain their dilated anatomical conformation, and may be used to teach both endoscopic technique and gastrointestinal anatomy.

E12 technique: an aid to study sinuses of psittacine birds.

Infraorbital sinus infections, which form the bulk of upper respiratory tract infections in companion birds, are commonly encountered in clinical practice and often require medical and/or surgical management. The infraorbital sinus with its dorsal drainage into the nasal cavity makes it difficult to treat these infections. The sinus has various compartments throughout the skull, and subcutaneous tissue. As an aid in determining the location and extent of the sinuses of the parrot and macaw, a corrosion cast of the infraorbital sinus was made. Also, computed tomography (CT) images of cadaver heads were completed at 2-mm scans. Prior to sectioning for sheet plastination, the infraorbital sinus of one half of the imaged heads was injected with a mixture of colored epoxy. The specimens were frozen (-25 degrees C) prior to sawing 2-mm-thick sections which corresponded to the CT scans. The sections were dehydrated, impregnated and sheets prepared using the standard E12 technique. The slices were used to identify the compartments of the infraorbital sinuses and to aid identification of such on the CT images.

Diet and growth of children with glycogen storage disease Types I and III.

Patients with glycogen storage disease (GSD) Types I and III were placed on a dietary treatment plan of frequent daytime feedings and continuous drip nocturnal enteral feedings of defined nutrient composition. Specific anthropometric measurements were collected to document and evaluate growth. There were a significant increase in arm muscle area and a relative decrease in triceps skinfold thickness not previously documented in the literature. Study results confirmed previous reports of accelerated growth and improvement of biochemical abnormalities. The dietitian's role in nutrition assessment and dietary management of GSD patients is emphasized.