Systemic Delivery and Biodistribution of Cisplatin in Vivo.

Cisplatin is widely used to treat a variety of cancers. However, ototoxicity and nephrotoxicity remain serious side effects of cisplatin-based chemotherapy. In order to inform the study of cisplatin's off-target effects, a new drug-fluorophore conjugate was synthesized that exhibited utility as a tracer to determine the cellular uptake and in vivo distribution of cisplatin. This probe will serve as a useful tool to facilitate investigations into the kinetics and biodistribution of cisplatin and its associated side effects in preclinical models after systemic administration.

Effect of N-acetylcysteine route of administration on chemoprotection against cisplatin-induced toxicity in rat models.

Dosing and route of administration of N-acetylcysteine (NAC) for protection against cisplatin (CDDP) nephrotoxicity was investigated in rats. Two models of toxicity were tested: a single high dose of CDDP (10 mg/kg intraperitoneally (IP)), and multiple low dose treatments (1 mg/kg IP twice a day for 4 days, 10 days rest, then repeated). NAC (50-1,200 mg/kg) was given to the rats by IP, oral (PO), intravenous (IV) and intra-arterial (IA) routes. Renal toxicity was determined by blood urea nitrogen (BUN) and creatinine (CR) levels 3 days after treatment. Blood collected 15 min after NAC was analyzed for total NAC. Both models of CDDP administration produced renal toxicity. In the single dose CDDP model, NAC 400 mg/kg given IP and PO produced no renal protection as measured by BUN (131.8 +/- 8.2 and 123.3 +/- 8.2, respectively) or CR (2.3 +/- 0.38 and 1.77 +/- 0.21, respectively). IV NAC reduced nephrotoxicity, (BUN 26.3 +/- 6.8, CR 0.47 +/- 0.15). NAC 50 mg/kg IA gave better protection than IV. In the repeated-dose CDDP model, nephrotoxicity was blocked by 800 mg/kg NAC given IV but not IP. Blood concentrations of total NAC showed a dose response after IV NAC, but high dose NAC (1,200 mg/kg) by the PO route gave very low levels of NAC. Thus the protective properties of NAC are affected by the dose and route of administration.

Delivery of chemotherapy and antibodies across the blood-brain barrier and the role of chemoprotection, in primary and metastatic brain tumors: report of the Eleventh Annual Blood-Brain Barrier Consortium meeting.

Although knowledge of molecular biology and cellular physiology has advanced at a rapid pace, much remains to be learned about delivering chemotherapy and antibodies across the blood-brain barrier (BBB) for the diagnosis and treatment of central nervous system (CNS) disease. A meeting, partially funded by an NIH R13 grant, was convened to discuss the state of the science, current knowledge gaps, and future directions in the delivery of drugs and proteins to the CNS, for the treatment of primary and metastatic brain tumors. Meeting topics included CNS metastases and the BBB, and chemoprotection and chemoenhancement in CNS disorders. The discussions regarding CNS metastases generated possibilities of chemoprotection as a means not only to decrease treatment-related toxicity but also to increase chemotherapy dose intensity. The increasing incidence of sanctuary brain metastasis from breast cancer, in part due to the difficulty of monoclonal antibodies (mAbs) such as herceptin to cross the BBB, was one of the most salient "take home" messages of the meeting.

Protection against cisplatin-induced toxicities by N-acetylcysteine and sodium thiosulfate as assessed at the molecular, cellular, and in vivo levels.

Cisplatin (CDDP) is a common, highly toxic chemotherapeutic agent. This study investigates chemoprotective effects of N-acetylcysteine (NAC) and sodium thiosulfate (STS) on in vitro and in vivo CDDP toxicities. For ototoxicity studies, CDDP (6 mg/kg) was administered to rats via a retrograde carotid artery infusion. Auditory brainstem response thresholds at 4 to 20 kHz were tested before and 7 days post-treatment. STS (8 g/m(2) i.v.) was administered at 4, 8, or 12 h after CDDP. For nephrotoxicity studies, rats were treated with CDDP intraperitoneally (10 mg/kg) before or after NAC (400 mg/kg) or STS (8 g/m(2)), and blood urea nitrogen (BUN) and creatinine concentrations were measured after 3 days. In vitro cytotoxicity and chemoprotection in human tumor cell lines were assessed by cell viability and immunoblotting assays. Rats treated with STS 4 h after CDDP exhibited no hearing change. The STS 8-h group had less otoprotection, whereas 12-h rats had ototoxicity. CDDP induced high BUN and creatinine, corresponding to renal tubule toxicities. All NAC-treated animals showed normal BUN and reduced creatinine levels compared with CDDP alone and no histopathological evidence of nephrotoxicity. Delayed STS treatment was not consistently protective against nephrotoxicity. STS administration fully protected against the in vitro cytotoxic and apoptotic effects of CDDP if added within 2 h of CDDP, but chemoprotection decreased if STS administration was 4 h, and was minimal by 6 h, after CDDP. Thus, the chemoprotection route and timing of administration can be manipulated to maintain CDDP antitumor efficacy while protecting against toxicities.

Strategies for prevention of toxicity caused by platinum-based chemotherapy: review and summary of the annual meeting of the Blood-Brain Barrier Disruption Program, Gleneden Beach, Oregon, March 10, 2001.

OBJECTIVES: To summarize the findings relevant to otolaryngology from the annual meeting of the Blood-Brain Barrier Disruption Consortium in Gleneden Beach, Oregon, March 10, 2001. STUDY DESIGN: Summaries are provided by the speakers, as well as related data from the published literature. Findings in otology and oncology regarding ototoxicity that were discussed at the meeting are included. RESULTS: Data considered included physiological research, animal studies, and clinical trials that relate to platinum-based chemotherapy and prevention of toxicity. CONCLUSIONS: The dose-limiting side effects of platinum-based chemotherapy are preventable, but questions about the effect of the protective agents on oncological efficacy remain. Strategies for prevention of chemotherapy-induced toxicity include temporal or anatomical separation of cisplatin or carboplatin from sodium thiosulfate, D-methionine, or N-acetyl-cysteine. Clinical application of these methods has begun. The mechanisms presumably involve free radicals or drug conjugation, or both. Understanding the role of free radicals in medicine is likely to become important in the future.

A description of the upper thoracic autonomic nervous system in the rhesus monkey (Macaca mulatta).

The purpose of this study was to describe the autonomic innervation of the carotid sinus and heart in the rhesus monkey. Nine male rhesus monkeys (Macaca mulatta) and one male crab-eating macaque (M. fascicularis) were carefully dissected from the origin of the vagus nerves and superior cervical ganglia to the level of the fourth thoracic ganglion. The specimens were either freshly killed or obtained no later than 24 hours post mortem. The macaque monkeys were found to possess an innervation pattern that displayed features common to dog (connections between the vagus nerves and middle cervical ganglia), baboon (distinct cervical sympathetic and cervical vagal nerve trunks), and man (nerves projecting from the middle cervical and stellate ganglia to the heart). Distinct inferior cervical and first thoracic ganglia were never seen, but rather, large and well defined stellate ganglia were found. The macaque innervation pattern, when considered as a whole, most closely resembled the baboon.