A pilot trial of continuous infusion 5-fluorouracil with levamisole for adjuvant therapy of colon cancer.

The relatively high response rate demonstrated with the use of continuous infusion 5-Fluorouracil (CIFU) 200 to 300 mg/m2 per day in disseminated colon cancer is the rationale behind a NCI-sponsored intergroup trial (INT 0153) for postoperative adjuvant therapy of stage III colon cancer. Because CIFU necessitates a significant reduction in the dose of the modulator leucovorin compared with bolus 5-FU, a pilot study of continuous infusion 5-FU in several doses with levamisole was conducted to determine any unexpected toxicity of this combination, and to assess completion rates of levamisole was conducted to determine any unexpected toxicity of this combination, and to assess completion rates of this dose intensive schedule. CIFU, scheduled as two 12-week cycles, was administered at 250 mg/m2 per day. Pending toxicity at the initial dose, CIFU was to be escalated (300 mg/m2) or de-escalated (200 mg/m2). All but one patient entered on this trial completed 24 weeks of adjuvant CIFU+levamisole. Eight patients (57%) completed 24 weeks of therapy with the 2-week scheduled break. One of these 8 patients required a dose reduction without interrupting the schedule. Six patients had toxicity from the CIFU, which obliged us to interrupt the schedule. Limiting toxicities were stomatitis and hand-foot syndrome. No dose-limiting hematologic toxicity was encountered. Three patients (21%) had catheter problems that required replacement. These data suggest that up to 30% of patients started on this regimen may require dose reduction, shorter infusion courses with rest breaks, or both to complete 24 weeks of adjuvant treatment in order to achieve desired dose intensity.

Longitudinal study of the microbiology of endemic trachoma.

A longitudinal study of trachoma in 100 members of nine Tanzanian families was conducted to assess the sources of variation in the laboratory identification of trachoma and the changes that might occur over time. Multiple conjunctival swabs were collected every 3 months for 1 year and examined by direct fluorescent-antibody cytology (DFA), enzyme immunoassay, or microimmunofluorescence serology for tear antichlamydial antibodies. DFA specimens collected 5 min apart had a discordance rate of 10% and this is attributable to sampling variation. DFA specimens collected 2 days or more apart show a 25% discordance rate. This suggests a biologic variation in shedding in addition to sampling variation. Good correlation existed between the DFA and the enzyme immunoassay. Tear serology was quite specific in predicting the presence of clinical disease and correlated with the other two antigen detection tests, although it does not seem to offer any practical advantages. These studies indicate that there is considerable variation in the shedding of chlamydia by people living in trachoma-endemic areas.

Stereoisomers of soman (pinacolyl methylphosphonofluoridate): inhibition of serum carboxylic ester hydrolase and potentiation of their toxicity by CBDP (2-(2-methylphenoxy)-4H-1,3,2-benzodioxaphosphorin-2-oxide) in mice.

The interaction of C(+/-)P(+/-)-soman (pinacolyl methylphosphonofluoridate) and its individual stereoisomers with serum carboxylic-ester hydrolase and potentiation of their toxicity by a carboxylic-ester hydrolase inhibitor CBDP (2-(2-methylphenoxy)-4H-1,3,2-benzodioxaphosphorin-2-oxide) was investigated. C(+/-)P(+/-)-Soman and the individual stereoisomers all inhibited purified mouse serum carboxylic-ester hydrolase to different degrees. C(+/-)P(+/-)-Soman and the C(-)P(-)- and C(+)P(-)-isomers had Ki values of 30.6, 18.7, and 35.7 nM, respectively, and C(-)P(+)- and C(+)P(+)-isomers had Ki values of 1412 and 2523 nM, respectively. In toxicity experiments CBDP (0.5 mg/kg; iv 1 hr prior to soman) pretreatment potentiated the toxicity of C(+/-)P(+/-)-, C(+)P(-)-, and C(-)P(-)-soman to a similar degree. Thus, it appears that the toxic stereoisomers of soman have a similar affinity for mouse serum carboxylic-ester hydrolase, and CBDP pretreatment does not enhance selectively the toxicity of one stereoisomer over the other.

Antibody to myelin constituents: a possible factor in induction of cell-mediated demyelination.

Results from this laboratory have demonstrated that 14C-labeled myelin opsonized with antibodies raised to purified CNS myelin in rabbit is phagocytized by cultured macrophages in larger amounts than untreated myelin or myelin opsonized with preimmune serum. The cultured macrophages produced high amounts of radioactive cholesterol ester and triglyceride from the antibody-treated myelin while much less was formed from preimmune serum-treated or untreated myelin. Antiserum to galactocerebroside also greatly enhanced the formation of radioactive cholesterol ester, while that to myelin basic protein as well as to other myelin constituents had little or no effect. Serum from Lewis rats with acute EAE 13-14 days after immunization with whole CNS myelin also stimulated radioactive cholesterol ester formation compared to serum from Freund's adjuvant-injected controls (FAC). Serum from EAE rats as a result of myelin basic protein injection was as active as that from rats with whole myelin injection. No galactocerebroside antibody could be demonstrated in the EAE sera, although a strong immunostaining to myelin basic protein and proteolipid protein was demonstrated. IgG prepared from EAE serum also showed stimulatory effects compared to IgG from FAC serum, but much of the activity was lost, and the possibility that other factors may be involved is discussed. These experiments provide evidence that myelin phagocytosis and digestion by macrophages is enhanced by the presence of antibody to myelin. In EAE this antibody may leak into CNS with the breakdown of the blood-brain barrier.(ABSTRACT TRUNCATED AT 250 WORDS)

Opsonization with antimyelin antibody increases the uptake and intracellular metabolism of myelin in inflammatory macrophages.

In most demyelinating diseases, macrophages are believed to be active agents of myelin destruction. In experimental encephalomyelitis, these cells appear to strip off and ingest the myelin lamellae, and myelin debris has been observed within the cell body. We show here in vitro conditions in which rat peritoneal macrophages phagocytose and metabolize CNS myelin lipids. Purified rat myelin, prelabeled in vivo with [14C]acetate, was incubated with preimmune serum or rabbit antiserum to rat CNS myelin and added to macrophage monolayers. Myelin opsonized with antimyelin antibodies was more readily phagocytosed and metabolized by cultured macrophages than untreated myelin or that preincubated with preimmune serum. In the presence of macrophages, levels of myelin polar lipids and cholesterol decreased, whereas radioactive cholesterol ester and triglyceride accumulated. Up to five times as much radioactive cholesterol ester and about twice as much triglyceride accumulated in macrophage cultures containing antibody-treated myelin as in cultures fed preimmune serum-treated myelin or in those incubated with untreated myelin. Both the fatty acid and the cholesterol from cholesterol ester contained radioactive label; therefore, both were derived at least partly from the radioactive myelin lipid. Antiserum to myelin purified from peripheral nerve was almost as effective as that to CNS myelin in stimulating cholesterol metabolism, whereas antiserum to galactocerebroside was about 70% as active. Antiserum to basic protein had less effect, whereas antiserum to the myelin-associated glycoprotein and proteolipid protein was inactive. Of the polar lipids, ethanolamine phosphatide was most degraded in both the antiserum- and preimmune serum-treated myelin, with the diacyl form and plasmalogen form degraded about equally. These experiments indicate that myelin-specific antibodies in inflammatory CNS lesions may participate in and stimulate macrophage-mediated demyelination.