Sphingolipid Metabolism in Glioblastoma and Metastatic Brain Tumors: A Review of Sphingomyelinases and Sphingosine-1-Phosphate

Glioblastoma (GBM) is a primary malignant brain tumor with a dismal prognosis, partially due to our inability to completely remove and kill all GBM cells. Rapid tumor recurrence contributes to a median survival of only 15 months with the current standard of care which includes maximal surgical resection, radiation, and temozolomide (TMZ), a blood-brain barrier (BBB) penetrant chemotherapy. Radiation and TMZ cause sphingomyelinases (SMase) to hydrolyze sphingomyelins to generate ceramides, which induce apoptosis. However, cells can evade apoptosis by converting ceramides to sphingosine-1-phosphate (S1P). S1P has been implicated in a wide range of cancers including GBM. Upregulation of S1P has been linked to the proliferation and invasion of GBM and other cancers that display a propensity for brain metastasis. To mediate their biological effects, SMases and S1P modulate signaling via phospholipase C (PLC) and phospholipase D (PLD). In addition, both SMase and S1P may alter the integrity of the BBB leading to infiltration of tumor-promoting immune populations. SMase activity has been associated with tumor evasion of the immune system, while S1P creates a gradient for trafficking of innate and adaptive immune cells. This review will explore the role of sphingolipid metabolism and pharmacological interventions in GBM and metastatic brain tumors with a focus on SMase and S1P.

Mycobacterium avium complex infections in patients with the acquired immunodeficiency syndrome

Disseminated infection with Mycobacterium avium complex developed in 67 patients with the acquired immunodeficiency syndrome (AIDS) who were followed at Memorial Sloan-Kettering Cancer Center. Twenty-nine patients were treated with two or more antimycobacterial drugs for a mean of 6 weeks, and 7 patients received therapy for less than 1 month. Most patients received ansamycin, clofazimine, and ethionamide or ethambutol. Clinical improvement did not occur in treated patients, and microbiologic cure was never obtained. Mycobacterial bacteremia persisted in 24 of 26 treated patients. Colony counts of M. avium complex in sequential blood cultures decreased in 3 patients. Every autopsied patient with M. avium complex infection diagnosed before death, whether treated or not, had disseminated M. avium complex infection at autopsy.

Effect of adding sodium taurocholate to selective media on the recovery of Clostridium difficile from environmental surfaces

The recovery of Clostridium difficile on a medium containing cefoxitin, cycloserine, fructose, and egg yolk was compared with that on media containing one of three preparations of sodium taurocholate. In aerobic environments contaminated with C. difficile, media containing either crude taurocholate from Mann Research Laboratories, New York, N.Y., or pure taurocholate from Sigma Chemical Co., St. Louis, Mo., recovered organisms significantly more often than did cefoxitin-cycloserine-fructose-egg yolk agar.

Epidemiology of colitis induced by Clostridium difficile in hamsters: application of a bacteriophage and bacteriocin typing system

The epidemiology of colitis induced by Clostridium difficile in hamsters was studied with a new bacteriophage and bacteriocin typing system. Fatal enterocolitis was induced by administration of N-formimidoyl thienamycin. Environmental cultures were obtained repeatedly throughout the experiments. Thirteen percent of 90 healthy hamsters were already colonized with C difficile on arrival from the supplier. Mortality from enterocolitis after antibiotic administration was 75% and was not diminished by use of a laminar-flow facility. The same uncommon bacteriocin type (83/1309/2329) of toxigenic C difficile that colonized hamsters on arrival was recovered from the cecal contents of all hamsters dying with enterocolitis and from most environmental isolates. Previously uncolonized , antibiotic-treated hamsters placed into cages where animals had died from enterocolitis also developed enterocolitis with the same bacteriocin type (83/1309/2329), an outcome suggesting acquisition of C difficile from the environment.