Lesions

Care should be taken in handling and using iodine, as contact with the skin can cause lesions iodine vapor is intensely irritating to the eyes and mucus membranes. The maximum allowable concentration of iodine in air should not exceed 1 mg/nu (8-hour time-weighted average -40-hour). 

A II H 11 Its 2HC1 salt (Agr307) opposes the formation of extensive infarct lesions 910... 

Pneumogstis carini pneumonia (PCP), the most common of the opportunistic infections, occurs in more than 80% of AIDS patients (13). Toxoplasmosis, a proto2oan infection of the central nervous system, is activated in AIDS patients when the 004 count drops and severe impairment of ceU-mediated immunity occurs. Typically, patients have a mass lesion(s) in the brain. These mass lesions usually respond well to therapy and can disappear completely. Fungal infections, such as CTyptococcalmeningitis, are extremely common in AIDS patients, and Histop/asma capsulatum appears when ceU-mediated immunity has been destroyed by the HIV vims, leading to widespread infection of the lungs, Hver, spleen, lymph nodes, and bone marrow. AIDS patients are particularly susceptible to bacteremia caused by nontyphoidal strains of Salmonella. Bacteremia may be cleared by using antibiotic therapy. 

Mode of Action. The fundamental biochemical lesion produced by arsenicals is the result of reaction between As " and the sulfhydryl groups of key respiratory enzymes such as pymvate and a-ketoglutarate dehydrogenases. 

Mode of Motion. The cyclodienes, like lindane and toxaphene, affect the nerve axon produciag hyperactivity, convulsions, prostration, and death. The biochemical lesion is the competitive inhibition of the y-aminobutyric acid (GABA) neurotransmitter binding site of the nerve axon. Spray workers with lengthy exposure to dieldrin have suffered from prolonged and repeated central nervous system disturbances produciag epileptiform coavulsioas. Similar disturbances occurred ia workers heavily exposed to chlordecoae. 

There are certain weU-estabUshed facts about olfaction (6). AU normal people can smell. People suffering from brain lesions, injured olfactory nerve, or obstmcted nasal passages may be anosmic. Cases of preferential anosmia, ie, abUity to sense certain smells and not others, are not weU estabUshed. Such cases occur, but Utde is known of them. 

The demonstration that injected or force-fed neonatal rodents given extremely high doses of MSG showed evidence of brain lesions, has led to much additional research to determine any possible link between neurotoxicity and human use of MSG (33). However, no evidence from animal tests indicates that MSG in the diet causes brain damage in humans (34). 

Laser ablation systems hold considerable promise if restenosis (reblocking of the arteries) rates are reduced. The rate as of 1995 is 30%, typically within six months. Mechanical or atherectomy devices to cut, shave, or pulverize plaque have been tested extensively in coronary arteries. Some of these have also been approved for peripheral use. The future of angioplasty, beyond the tremendous success of conventional balloon catheters, depends on approaches that can reduce restenosis rates. For example, if appHcation of a dmg to the lesion site turns out to be the solution to restenosis, balloon catheters would be used for both dilating the vessel and deUvering the dmg. An understanding of what happens to the arterial walls, at the cellular level, when these walls are subjected to the various types of angioplasty may need to come first. 

Ha2ards were discovered by experience. It was soon found that x-rays produced skin bums and lesions that healed only slowly later it was learned that tumors could be produced. Within the medical community, it became clear that guidelines were needed for the use of x-rays, especially for medical workers, who were often present while the x-rays were produced. 

The biodistribution of the ideal radiopharmaceutical would show extremely rapid distribution via the circulatory system to the organs of interest and htfle distribution to others. It would be rapidly extracted by the organ or tissue of interest differentially in a way that reflects the disease process of interest. Ideally, abnormahties should be defined by substantial increases in the concentration of the agent because lesions defined by a decrease from surrounding concentrations, ie, cold-spot imaging, are more difficult to image. 

Kinetics of the biodistribution must be compatible with the practical aspects of hospital routine and imaging capabiUty. In the case of a diagnostic agent, maximal lesion contrast, maximal radioactivity concentrations in tissue of interest, and minimal background radioactivity during the time imaging... 

Instrumentation. The future of radiopharmaceuticals is highly dependent on imaging instmmentation. Instmmental methods can evolve rapidly. Performance and characteristics of these instmments are important in the choice of disease target, lesion size, location, and contrast. 

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