Increased cytosine DNA-methyltransferase activity is target-cell-specific and an early event in lung cancer.

The association between increased DNA-methyltransferase (DNA-MTase) activity and tumor development suggest a fundamental role for this enzyme in the initiation and progression of cancer. A true functional role for DNA-MTase in the neoplastic process would be further substantiated if the target cells affected by the initiating carcinogen exhibit changes in enzyme activity. This hypothesis was addressed by examining DNA-MTase activity in alveolar type II (target) and Clara (nontarget) cells from A/J and C3H mice that exhibit high and low susceptibility, respectively, for lung tumor formation. Increased DNA-MTase activity was found only in the target alveolar type II cells of the susceptible A/J mouse and caused a marked increase in overall DNA methylation in these cells. Both DNA-MTase and DNA methylation changes were detected 7 days after carcinogen exposure and, thus, were early events in neoplastic evolution. Increased gene expression was also detected by RNA in situ hybridization in hypertrophic alveolar type II cells of carcinogen-treated A/J mice, indicating that elevated levels of expression may be a biomarker for premalignancy. Enzyme activity increased incrementally during lung cancer progression and coincided with increased expression of the DNA-MTase activity are strongly associated with neoplastic development and constitute a key step in carcinogenesis. The detection of premalignant lung disease through increased DNA-MTase expression and the possibility of blocking the deleterious effects of this change with specific inhibitors will offer new intervention strategies for lung cancer.     

Thrombocytopenia associated with pregnancy in a patient with type IIB von Willebrand's disease

Thrombocytopenia may accompany variant (type IIB) von Willebrand's disease (vWD) and is thought to result from binding of the abnormal von Willebrand factor (vWF) to the patient's platelets with subsequent platelet aggregate formation and clearance. We have studied a patient with type IIB vWD who became thrombocytopenic during two pregnancies. During the third trimester of pregnancy, her platelet counts dropped to 20,000 to 30,000/microL, and an increase in the intermediate-sized vWF multimers was seen on agarose gel electrophoresis. During this time her platelet-rich plasma showed spontaneous platelet aggregation, and her plasma caused spontaneous aggregation of normal washed platelets. Antibody to platelet glycoprotein Ib completely blocked the spontaneous platelet aggregation, while antibody to platelet glycoprotein IIb/IIIa did not block the response at the concentrations used. Inhibitors of platelet function that elevate platelet cyclic AMP also blocked the response, but aspirin had no effect on the spontaneous platelet aggregation. The patient illustrates that the platelet counts in one individual can vary greatly in type IIB vWD and that the thrombocytopenia that occurs can appear under physiologic conditions that stimulate the endogenous production of the patient's abnormal vWF. The mechanisms leading to spontaneous platelet aggregation and thrombocytopenia appear to be similar to those described for other patients with type IIB vWD.     

Epileptic spasms without hypsarrhythmia in infancy and childhood: tonic spasms as a seizure type

Epileptic spasms were defined by the International League Against Epilepsy Task Force on Classification and Terminology in 2001 as a specific seizure type. Epileptic spasms without hypsarrhythmia have been described in some series of patients, occurring either in infancy or childhood. More prolonged epileptic spasms without hypsarrhythmia were previously defined as a different seizure type, and referred to as “tonic spasm seizures”. Here, we present a 5‐year‐old boy who started having epileptic spasms without hypsarrhythmia at 8 months of age, effectively treated with oxcarbazepine. With the withdrawal of medication, epileptic spasms returned. Video‐EEG monitoring revealed high‐voltage slow waves superimposed by low‐voltage fast activity, followed by an electrodecremental phase and a burst of asymmetric fast activity, time‐locked to clinical tonic spasm seizures. Brain MRI showed left temporal atrophy with temporal pole grey/white matter junction blurring and ictal PET‐CT showed left basal frontal hypermetabolism. Seizures were refractory to several AEDs and vigabatrin was introduced with seizure cessation. Despite efforts to classify epileptic spasms, these are still considered as part of the group of unknown seizure types. In some cases, a focal origin has been suggested, leading to the term “periodic spasms” and “focal spasms”. In this case, epileptic spasms without hypsarrhythmia, associated with tonic spasms, may be a variant of focal spasms and might be considered as an epileptic syndrome. [Published with video sequence]     

Biologic and prognostic significance of the presence of more than two mu heavy-chain genes in childhood acute lymphoblastic leukemia of B precursor cell origin

We examined the arrangement of the mu heavy-chain immunoglobulin (Ig) genes in the leukemic blast cell DNA of 93 children with acute lymphoblastic leukemia (ALL). All cases met morphologic and cytochemical criteria for ALL, lacked detectable T cell surface antigens, and expressed HLA-DR (Ia) antigens. Eighty-three of the 93 patients (89%) were positive for the common acute lymphoblastic leukemia antigen (CALLA), and 20 of 91 (22%) tested had detectable cytoplasmic immunoglobulin. As expected, the heavy-chain lg gene was rearranged in all cases, and the pattern of rearrangements was variable; 23 had one allele rearranged and one in the germ line configuration; 15 had one rearranged and one deleted; and 37 had two rearranged. Unexpectedly, in 18 patients the presence of more than two mu gene-hybridizing bands was detected. Combinations of enzymes and heavy-chain gene probes were used to confirm that the extra bands were not the result of underdigestion of the DNA or DNA restriction site polymorphism. In eight of the 18 patients, we identified an extra chromosome 14 as a possible cause of the extra bands' hybridizing to the mu heavy-chain constant-region probe. In the remaining ten patients, the presence of three or four bands hybridizing with the mu probe suggests the presence of two populations of leukemic cells that may have arisen either by separate leukemic transformation events or by clonal evolution of one clone into two related lines. Although preliminary (2-year follow-up), our data suggest that childhood ALL of B lineage with more than two mu heavy-chain genes, but without extra copies of chromosome 14, may be more resistant to therapy.     

Factor VIII/von Willebrand factor protein: sensitivity of periodic acid Schiff stain to carbohydrate deficiency

We have investigated the periodic acid Schiff (PAS) Coomassie staining ratio of the human factor VIII/von Willebrand factor (fVIII/vWf) protein. The PAS-Coomassie staining ratio is consistent over 8 days. The PAS-Coomassie ratio of fVIII/vWf protein purified from different starting materials does not appear to be significantly different. The PAS stain can detect as little as 300 ng of carbohydrate in the fVIII/vWf protein. Desialation did not affect the PAS-Coomassie ratio, while removal of penultimate galactose resulted in a marked reduction in the PAS-Coomassie ratio. This reduction was further accentuated with the removal of N-acetylglucosamine. The smaller multimers of the fVIII/vWf protein have a reduced sialic acid and PAS-Coomassie staining ratio. This difference does not appear to be related to the sialic acid deficiency but may be related to the distribution or organization of the carbohydrate moieties on the smaller fVIII/vWf multimers.     

Delayed diagnosis and elevated mortality in an urban population with HIV and lung cancer: implications for patient care

OBJECTIVE: Lung cancer is more common in HIV-infected patients than in the general population. We examined how effectively lung cancer was being diagnosed in our HIV-infected patients. METHODS: Retrospective study assessing clinical diagnosis of lung cancer in HIV-infected patients at Johns Hopkins Hospital between 1986 and 2004. RESULTS: Ninety-two patients were identified. Compared to HIV-indeterminate patients (n=4973), HIV-infected individuals were younger with more advanced cancer. CD4 counts and HIV-1 RNA levels indicated preserved immune function. Mortality was higher in HIV-infected patients, with 92% dying of lung cancer (hazard ratio, 1.57; 95% confidence interval, 1.25-1.96), compared to HIV-uninfected patients. Advanced stage and black race were associated with worse survival. After adjustment for these factors, HIV infection was not associated with increased mortality (hazard ratio, 1.04; 95% confidence interval, 0.83-1.32). Of 32 patients followed in our HIV clinic, 60% of chest radiographs had no evidence of neoplasm within 1 year of diagnosis compared to only 1 (4%) of 28 chest computed tomography scans. Nonspecific infiltrates were observed in 9 patients in the same area that cancer was subsequently diagnosed. CONCLUSIONS: HIV-infected lung cancer patients have shortened survival mainly due to advanced stage. Low clinical suspicion and overreliance on chest radiographs hindered earlier detection. Aggressive follow-up of nonspecific pulmonary infiltrates in these patients is warranted.     

Transient low doses of DNA-demethylating agents exert durable antitumor effects on hematological and epithelial tumor cells

Reversal of promoter DNA hypermethylation and associated gene silencing is an attractive cancer therapy approach. The DNA methylation inhibitors decitabine and azacitidine are efficacious for hematological neoplasms at lower, less toxic, doses. Experimentally, high doses induce rapid DNA damage and cytotoxicity, which do not explain the prolonged time to response observed in patients. We show that transient exposure of cultured and primary leukemic and epithelial tumor cells to clinically relevant nanomolar doses, without causing immediate cytotoxicity, produce an antitumor "memory" response, including inhibition of subpopulations of cancer stem-like cells. These effects are accompanied by sustained decreases in genomewide promoter DNA methylation, gene reexpression, and antitumor changes in key cellular regulatory pathways. Low-dose decitabine and azacitidine may have broad applicability for cancer management.