Cytogenetic interactions of contrast media and antineoplastic drugs.

The cytogenetic interactions of ionic (diatrizoate, ioxaglate) and nonionic (iohexol) contrast media (CM) with antineoplastic drugs cyclophosphamide (CPA) and carmustine (CARM) were evaluated in a rat bone marrow cell model. Male Wistar rats were anesthetized with a 6% chloral hydrate solution and divided into five groups of five rats each. In protocol 1, three groups of rats received diatrizoate, ioxaglate, and iohexol (2.5 mL/kg) intravenously within 30 seconds. The remaining two groups were similarly injected with CPA and CARM (10 mg/kg). Control animals were injected with nonpyrogenic sterile water or saline solution. After 12 and 24 hours, the animals were killed with an overdose of chloral hydrate, and bone marrow smears were prepared for determining chromosomal damage in polychromatic erythrocytes (PCEs) by a micronucleus test. In protocol 2, CPA and CARM were injected, and 15 minutes later, bolus injections of diatrizoate, ioxaglate and iohexol were given through the same route. Both ionic and nonionic CM induced significant numbers of micronuclei in PCEs (P less than .05). CPA caused a severe cytogenetic effect, whereas CARM did not produce a significant number of micronuclei in PCEs compared with control. In protocol 2 experiments, antagonism with CPA and synergism with CARM was demonstrable. Clinical implication of the cytogenetic interactions between CM and antineoplastic drugs remains to be established.

Electroencephalography in herpes simplex encephalitis.

The EEG in the acute stage of herpes simplex encephalitis (HSE) can show a variety of abnormalities, including uni- or bilateral periodic sharp waves or attenuation of amplitude, focal or generalized slow waves or epileptiform discharges, or electrical seizures. No specific EEG patterns are pathognomonic for HSE, but a focal or lateralized EEG abnormality in the presence of encephalitis is highly suspicious of HSE. In the acute stage, EEG appears to be more sensitive than computerized tomography or radioisotope brain scanning. The EEG findings tend to differ in the course of illness, and the periodic discharges occur only during the acute stage. The EEG findings in either the acute stage or long-term follow-up do not predict the chance of survival or severity of disability, and EEG changes appear to lag behind the clinical changes. EEG results can become normal in both adults and neonates when the acute stage is over.