Drug-induced esophageal injury. Histopathological study in a rabbit model.

The purpose of this animal study was to investigate the histopathologic consequences of esophageal exposure to a variety of medications known to be injurious to the human esophagus. Twenty-four New Zealand white rabbits were utilized. Tablets or control plastic beads were secured to a silk suture thread and positioned in the rabbit esophagus through a proximal esophagostomy and a gastrostomy. Test medications were allowed to dissolve passively on the surface of the esophageal mucosa in the anesthetized rabbits. After 1 hr of drug exposure, the rabbits were killed and the esophagus removed and examined. No gross abnormalities were detected with the exception of a mild degree of erythema at some of the exposure sites. All medications and control beads produced microscopic mucosal changes when compared to suture controls. The beads and test medications caused thinning of the epithelium and increased subepithelial edema (P less than 0.05). Two changes, however, were unique to animals exposed to test medications: fraying and/or splitting of the epithelium and the presence of balloon cells (P less than 0.05). Balloon cells represent damaged squamous epithelial cells recognizable by their distended, globoid shape. The prevalence of balloon cells ranged from 22% to 89% of sites exposed to drug and was most commonly associated with potassium. Of all drugs reported to cause injury to the human esophagus, potassium chloride has been reported to produce the most severe lesions, including esophageal stricture and perforation.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro adherence of bacteria to prosthetic grafting materials.

Adherence of bacteria to prosthetic grafting material is thought to play an important role in the ultimate development of prosthetic infections. To evaluate the role of bacterial adherence in the initiation and colonization of prosthetic materials, Proplast II, Gore-Tex, and silicone were evaluated for adherence of Escherichia coli and Staphylococcus aureus. Bacteria were radio labeled and incubated with the study material. Adherence was determined by scintillation. Adherence to Proplast II and Gore-Tex reached a maximum at approximately 45 minutes of incubation and demonstrated a detachment phenomenon with E. coli. Similar results were noted with S. aureus, but with a maximal attachment at approximately 30 minutes. Interestingly, bacterial attachment to silicone continued to increase throughout the time of the incubation. In addition, adherence of S. aureus was at a faster rate than E. coli. Attachment of bacteria is a multifactorial process. However, the PTFE graft demonstrates a slower rate of attachment, lower total number of attached bacteria, and faster detachment. The importance of this phenomenon may help explain the foreign body effect of increased susceptibility to infection of foreign materials.

Toxicity of nalidixic acid on candida albicans, Saccharomyces cerevisiae, and Kluyveromyces lactis.

The antibacterial drug nalidixic acid (Nal) can suppress the growth of Candida albicans at levels of the drug normally found in urine. Growth suppression increases as drug levels are increased, and Nal also causes a similar proportional inhibition of the synthesis of all cellular macromolecules. However, growth temperature (25 versus 37 C) and the divalent cations Mg(2+) and Mn(2+) can increase C. albicans resistance to Nal. Also, nitrogen depletion of Candida shows that Nal-treated and untreated cells exhibit no difference in leucine uptake during readaptation to nitrogen. In Nal-treated, nitrogen-starved cells, ribonucleic acid and deoxyribonucleic acid (DNA) biosynthesis are less affected than in unstarved Nal-treated cells, but of the two nucleic acids DNA synthesis is the most affected. Nal-resistant strains of C. albicans exhibit a slight toxicity for macromolecular synthesis. Nal treatment of a synchronized population of Saccharomyces cerevisiae results in an increase in the culture mean doubling time of, at most, 20%, but Nal causes the loss of synchronous cell division. With a synchronized population of Kluyveromyces lactis, Nal causes an increase in the mean doubling time of upwards of 300%, with synchrony of cell division being maintained. It is known that S. cerevisiae asynchronously synthesizes mitochondrial DNA during the cell cycle, whereas with K. lactis it is synchronous. Thus, with C. albicans Nal toxicity is dependent both on the dose and the physiological state of the cell. Furthermore, Nal inhibits growth of yeast with synchronous mitochondrial DNA synthesis more adversely than yeast with asynchronous mitochondrial DNA synthesis.