Role of zidovudine antiretroviral therapy in the pathogenesis of acquired immunodeficiency syndrome-related lymphoma

The role of zidovudine and other antiretroviral agents in the pathogenesis of acquired immunodeficiency syndrome (AIDS)-related lymphomas has been somewhat controversial. In an attempt to elucidate the precise role of antiretroviral agents in the subsequent development of AIDS-related lymphoma, we performed a population-based, case-control study of human immunodeficiency virus (HIV)-seropositive patients with intermediate- or high-grade lymphoma in Los Angeles County, California, in which information regarding use of antiretroviral medications was ascertained. Diagnostic biopsy material was reviewed to confirm intermediate-or high-grade lymphoma. A structured interview, conducted with all cases and controls, included information about use of zidovudine and other antiretroviral agents. A total of 112 HIV-infected homosexual/bisexual men with lymphoma were matched to 112 homosexual/bisexual men with asymptomatic HIV infection; 49 of the lymphoma cases were also matched to 49 additional controls with AIDS, as defined by conditions other than lymphoma. Positive histories of zidovudine use were reported by 44 (39%) lymphoma cases, 24 (21%) asymptomatic HIV controls, and 21 (42%) AIDS controls. The average duration of zidovudine use up to 12 months before lymphoma diagnosis was 19.0 +/- 13.0 months (mean +/- SD) for the lymphoma cases, 12.6 +/- 10.5 months for the asymptomatic controls, and 11.0 +/- 7.1 months for the AIDS controls. When comparing the 49 HIV-positive lymphoma cases with their 49 matched AIDS controls, all of whom were diagnosed with AIDS during the same time period, the matched relative odds of lymphoma associated with prior use of zidovudine was 0.43 (95% confidence interval [CI] = 0.17 to 1.12). In comparing all 112 lymphoma cases with 49 AIDS controls, the unmatched relative odds of lymphoma associated with zidovudine use was 0.93 (95% confidence interval = 0.47 to 1.83). One lymphoma case and no AIDS control cases had a history of didanosine use; no lymphoma case or AIDS control cases had taken zalcitabine. We conclude that zidovudine is not associated with an increased risk of development of lymphoma among HIV-infected homosexual or bisexual men.     

DDAVP in type IIa von Willebrand's disease

1-D-Amino(8-D-arginine)-vasopressin (DDAVP) infusion in three patients with type IIa von Willebrand's disease (vWD) resulted in a normalization of the factor VIII coagulant, factor VIII-related antigen, and von Willebrand factor (vWF) (ristocetin cofactor) activities and the bleeding time. The normalization of these hemostatic parameters persisted for four hours. Over the same time period there was a marked increase in the quantity of the vWF multimers when blood was collected in the presence of protease inhibitors. The vWF multimers present were even larger than the normal. When blood was collected in the absence of protease inhibitors, a smaller increase in the plasma vWF multimers was observed and fewer of the intermediate and larger vWF multimers were seen; multimers larger than those present in normal plasma were not visualized. The platelet vWF multimers and activities did not change with or without inhibitors. These studies suggest that there is a subgroup of patients with type IIa vWD who respond to DDAVP with complete normalization of their hemostatic abnormalities and whose vWF is sensitive to proteolysis.     

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.     

Serum interleukin 2 receptor levels in childhood acute lymphoblastic leukemia

The clinical significance of interleukin 2 receptor (IL2R) concentrations in serum was determined for 344 children with newly diagnosed acute lymphoblastic leukemia (ALL). Serum levels of IL2R in patients (267 to 80,000 U/mL, median 2,007 U/mL) were significantly higher than normal control values (170 to 738 U/mL, median 347 U/mL) (P less than .0001). Measurements in cases of T cell ALL were lower than in the non-T, non-B cases (P = .02). Among the 264 patients with non-T, non-B ALL, but not in those with T cell disease, higher serum IL2R levels (greater than 2,000 U/mL) were associated with a poorer treatment outcome (P = .04). In a multivariate analysis, serum IL2R level contributed independent prognostic information beyond that conveyed by leukocyte count, race, and age (P = .04). One explanation for these results is that soluble IL2R competes with normal lymphocyte- integrated IL2R for the ligand and thus could suppress host antitumor immunity.     

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.     

The mutagenic response at the ouabain resistance locus in T cells of mice exposed to N-ethyl-N-nitrosourea parallels the response at the Hprt locus and correlates with mutation target size

The lymphocyte Hprt gene has been used extensively as a reporter locus to monitor the mutational effects of the exposure of animals to genotoxicants. Implicit in this view of the function of a reporter gene is the assumption that its mutagenic response is representative of that of other genes in the organism. As a test of this hypothesis we compared the frequency of 6-thioguanine-resistant (TGr) mutants at the Hprt locus with the mutant frequency (MF) induced at another locus, the ouabain resistance (Oua) locus. The frequency of spontaneous OUA(R) mutants was estimated to be 1.1x10(-7) (MF between <0.3 and 1.1x10(- 7)), which was approximately 30-fold less than the spontaneous TGr MF. Following treatment with N-ethyl-N-nitrosourea (ENU), the induced OUA(R) MF at each of two dose levels (50 and 150 mg/kg ENU) and two time points (3 and 6 weeks post-exposure) was consistently 8- to 9-fold lower than the corresponding TGr MF. Thus the mutagenic response of the Oua locus closely paralleled that of the Hprt locus, indicating a similarity in their response to ENU. In addition, the Oua locus was 3-4 times more sensitive than the Hprt locus to the mutagenic effect of ENU, as measured by the fold increase in MF over the background level. The number of ENU-mutable sites capable of resulting in a TGr or OUA(R) phenotype, otherwise known as the mutation target size, was estimated to differ by an order of magnitude between the two loci. This difference in target size correlates with, and therefore may largely account for, the difference in induced MF between both loci.      

Hypoglycemic and anti-lipemic effects of the aqueous extract from Cissus sicyoides

Background

Psoriasis is a chronic inflammatory skin disease that can be successfully treated with a mixture of fumaric acid esters (FAE) formulated as enteric-coated tablets for oral use. These tablets consist of dimethylfumarate (DMF) and salts of monoethylfumarate (MEF) and its main bioactive metabolite is monomethylfumarate (MMF). Little is known about the pharmacokinetics of these FAE. The aim of the present study was to investigate the hydrolysis of DMF to MMF and the stability of MMF, DMF and MEF at in vitro conditions representing different body compartments.

Results

DMF is hydrolyzed to MMF in an alkaline environment (pH 8), but not in an acidic environment (pH 1). In these conditions MMF and MEF remained intact during the period of analysis (6 h). Interestingly, DMF was hardly hydrolyzed to MMF in a buffer of pH 7.4, but was rapidly hydrolyzed in human serum having the same pH. Moreover, in whole blood the half-life of DMF was dramatically reduced as compared to serum. The concentrations of MMF and MEF in serum and whole blood decreased with increasing time. These data indicate that the majority of the FAE in the circulation are metabolized by one or more types of blood cells. Additional experiments with purified blood cell fractions resuspended in phosphate buffered saline (pH 7.4) revealed that at concentrations present in whole blood monocytes/lymphocytes, but not granulocytes and erythrocytes, effectively hydrolyzed DMF to MMF. Furthermore, in agreement with the data obtained with the pure components of the tablet, the enteric-coated tablet remained intact at pH 1, but rapidly dissolved at pH 8.

Conclusion

Together, these in vitro data indicate that hydrolysis of DMF to MMF rapidly occurs at pH 8, resembling that within the small intestines, but not at pH 1 resembling the pH in the stomach. At both pHs MMF and MEF remained intact. These data explain the observation that after oral FAE intake MMF and MEF, but not DMF, can be readily detected in the circulation of human healthy volunteers and psoriasis patients.