The Effect of Trans-Stifle External Skeletal Fixation and Hyaluronic Acid Therapy on Articular Cartilage in the Dog

Transarticular external skeletal (TES) fixators were applied unilaterally to the stifle joints of 10 young adult dogs. After 4 weeks, the fixators were removed from all dogs. Two dogs were not allowed a remobilization period, whereas 8 dogs were provided with 4 additional weeks of weight-bearing activity in a kennel run. Four dogs were given high-molecular weight hyaluronic acid by intra-articular injection weekly during the remobilization period. Clinical gait evaluations and range of motion were determined during the remobilization period. Articular cartilage samples from both stifle joints of all dogs were evaluated histologically and histochemically. No significant differences in gait scores or range of motion were noted between treated and untreated dogs. Articular cartilage proteoglycan content was reduced after 4 weeks of trans-stifle external skeletal fixation as determined by loss of alcian blue (AB) histochemical staining. Improved homogeneity of histochemical staining was observed after remobilization. However, remobilization was associated with histological damage to the surface and tangential layers of articular cartilage. Remobilization combined with hyaluronic acid (HA) therapy improved histochemical staining and reduced structural damage to articular cartilage when compared with remobilization alone.     

An in vitro method for testing synergistic action of parasiticides using malachite green and formalin as a model system

Abstract. An in vitro technique was developed to screen drugs for toxicity to laboratory cultured protozoans. Drugs were diluted using standard microtitration equipment. An easily cultured protozoan, Tetrahymena pyriformis , was added to the dilutions of drugs and viability was checked daily for 10 days. Drugs used as a model system to test the technique were formalin and malachite green. Effective concentrations of formalin determined by this in vitro technique were close to recommended therapeutic treatment levels for Ichthyophthirius . Malachite green was effective at concentrations in excess of recommended therapeutic treatment levels for Ichthyophthirius . The synergistic effect of formalin and malachite green was demonstrated. This technique can he of use in determining effectiveness of new drugs as parasiticides.     

The Self-Assembly Mechanism of Alkanethiols on Au(111)

The self-assembly mechanism of alkanethiol monolayers on the (111) surface of gold was discovered with the use of an ultrahigh-vacuum scanning tunneling microscope. Monolayer formation follows a two-step process that begins with condensation of low-density crystalline islands, characterized by surface-aligned molecular axes, from a lower density lattice-gas phase. At saturation coverage of this phase, the monolayer undergoes a phase transition to a denser phase by realignment of the molecular axes with the surface normal. These studies reveal the important role of molecule-substrate and molecule-molecule interactions in the self-assembly of these technologically important material systems.