Predominance and characteristics of Burkitt lymphoma among children with non-Hodgkin lymphoma in northeastern Brazil

The purpose of this paper was to define the histologic distribution, clinical features, and treatment response of childhood non-Hodgkin lymphoma (NHL) in northeastern Brazil. We reviewed medical records and histopathologic studies of 98 children treated for NHL from 1980 to 1987 at a major pediatric cancer center in Recife, Brazil. Treatment outcome was evaluated in relation to tumor burden (stage and serum LDH) and type of therapy (LSA2L2 vs other multiagent chemotherapy). There was a striking predominance of the small noncleaved cell (Burkitt) subtype, which occurred in 92 of the 98 children and adolescents diagnosed with NHL. Subsequent analyses focused on these patients. The majority (n = 84) had advanced (stage III/IV) disease at diagnosis. The abdomen was the most common site of disease (84 cases); jaw involvement was rare (three cases). Five-year event-free survival (excluding treatment refusals) was significantly better for patients with limited vs advanced stage disease (75 +/- 14% vs 42 +/- 6%; P < 0.04). Elevated serum LDH (>500 U/l) was associated with a poorer outcome (P = 0.008). The type of chemotherapy did not affect EFS (P = 0.95). Only 39% of patients are long-term survivors, reflecting the high rate of septic deaths (25% of patients) and parental refusal/abandonment of therapy (10%). Epstein-Barr virus (EBV) was detected in tumor cells from eight of the 11 cases studied. In clinical presentation, these cases resemble sporadic Burkitt lymphoma, yet in their apparent responsiveness to LSA2L2 therapy and association with EBV, they do not. Childhood NHL in northeastern Brazil is predominantly of the Burkitt subtype, and is associated with clinical features that appear to distinguish it from the endemic and sporadic forms of this tumor. These cases may represent a third or intermediate subtype of Burkitt lymphoma.     

Constitutive expression of mature transforming growth factor beta1 in the liver accelerates hepatocarcinogenesis in transgenic mice

Transforming growth factor beta-1 (TGF-beta1) is a potent inhibitor of hepatocyte growth both in vivo and in vitro. In this study, we analyzed the effects of TGF-beta1 on both naturally occurring and diethylnitrosamine-induced hepatocarcinogenesis using single transgenic TGF-beta1 and double transgenic c-myc/TGF-beta1 mice in which the expression of both transgenes was targeted to the liver. Hepatocellular tumors developed spontaneously in 59% (10 of 17) of the TGF-beta1 mice by 16-18 months of age. Coexpression of TGF-beta1 and c-myc transgenes in the liver accelerated hepatic tumor growth in both the presence and absence of carcinogenic treatment. Moreover, diethylnitrosamine-initiated tumors in the c-myc/TGF-beta1 mice showed a high rate of malignant conversion associated with a reduced expression or lack of TGF-beta receptor type II. The results suggest that overexpression of TGF-beta1 may contribute to liver carcinogenesis and that loss of TGF-beta receptor type II transduced inhibitory growth signals and up-regulation of c-myc are critical steps in liver tumor progression.     

Increased probability of GABA release during withdrawal from morphine

Opioid receptors located on interneurons in the ventral tegmental area (VTA) inhibit GABA(A)-mediated synaptic transmission to dopamine projection neurons. The resulting disinhibition of dopamine cells in the VTA is thought to play a pivotal role in drug abuse; however, little is known about how this GABAA synapse is affected after chronic morphine treatment. The regulation of GABA release during acute withdrawal from morphine was studied in slices from animals treated for 6-7 d with morphine. Slices containing the VTA were prepared and maintained in morphine-free solutions, and GABAA IPSCs were recorded from dopamine cells. The amplitude of evoked IPSCs and the frequency of spontaneous miniature IPSCs measured in slices from morphine-treated guinea pigs were greater than placebo-treated controls. In addition, activation of adenylyl cyclase, with forskolin, and cAMP-dependent protein kinase, with Sp-cAMPS, caused a larger increase in IPSCs in slices from morphine-treated animals. Conversely, the kinase inhibitors staurosporine and Rp-CPT-cAMPS decreased GABA IPSCs to a greater extent after drug treatment. The results indicate that the probability of GABA release was increased during withdrawal from chronic morphine treatment and that this effect resulted from an upregulation of the cAMP-dependent cascade. Increased transmitter release from opioid-sensitive synapses during acute withdrawal may be one adaptive mechanism that results from prolonged morphine treatment.     

Vaccinia DNA topoisomerase I: evidence supporting a free rotation mechanism for DNA supercoil relaxation

The Vaccinia type I topoisomerase catalyzes site-specific DNA strand cleavage and religation by forming a transient phosphotyrosyl linkage between the DNA and Tyr-274, resulting in the release of DNA supercoils. For type I topoisomerases, two mechanisms have been proposed for supercoil release: (I) a coupled mechanism termed strand passage, in which a single supercoil is removed per cleavage/religation cycle, resulting in multiple topoisomer intermediates and late product formation, or (2) an uncoupled mechanism termed free rotation, where multiple supercoils are removed per cleavage/religation cycle, resulting in few intermediates and early product formation. To determine the mechanism, single-turnover experiments were done with supercoiled plasmid DNA under conditions in which the topoisomerase cleaves predominantly at a single site per DNA molecule. The concentrations of supercoiled substrate, intermediate topoisomers, and relaxed product vs time were measured by fluorescence imaging, and the rate constants for their interconversion were determined by kinetic simulation. Few intermediates and early product formation were observed. From these data, the rate constants for cleavage (0.3 s(-1)), religation (4 s(-1)), and the cleavage equilibrium constant on the enzyme (0.075) at 22 degrees C are in reasonable agreement with those obtained with small oligonucleotide substrates, while the rotation rate of the cleaved DNA strand is fast (approximately 20 rotations/s). Thus, the average number of supercoils removed for each cleavage event greatly exceeds unity (delta n = 5) and depends on kinetic competition between religation and supercoil release, establishing a free rotation mechanism. This free rotation mechanism for a type I topoisomerase differs from the strand passage mechanism proposed for the type II enzymes.     

Results of allogeneic bone marrow transplants for leukemia using donors other than HLA-identical siblings

PURPOSE: To compare outcomes of bone marrow transplants for leukemia from HLA-identical siblings, haploidentical HLA-mismatched relatives, and HLA-matched and mismatched unrelated donors. PATIENTS: A total of 2,055 recipients of allogeneic bone marrow transplants for chronic myelogenous leukemia (CML), acute myelogenous leukemia (AML), and acute lymphoblastic leukemia (ALL) were entered onto the study. Transplants were performed between 1985 and 1991 and reported to the International Bone Marrow Transplant Registry (IBMTR). Donors were HLA-identical siblings (n = 1,224); haploidentical relatives mismatched for one (n = 238) or two (n = 102) HLA-A, -B, or -DR antigens; or unrelated persons who were HLA-matched (n = 383) or mismatched for one HLA-A, -B, or -DR antigen (n = 108). HLA typing was performed using serologic techniques. RESULTS: Transplant-related mortality was significantly higher after alternative donor transplants than after HLA-identical sibling transplants. Among patients with early leukemia (CML in chronic phase or acute leukemia in first remission), 3-year transplant-related mortality (+/-SE) was 21% +/- 2% after HLA-identical sibling transplants and greater than 50% after all types of alternative donor transplants studied. Among patients with early leukemia, relative risks of treatment failure (inverse of leukemia-free survival), using HLA-identical sibling transplants as the reference group, were 2.43 (P < .0001) with 1-HLA-antigen-mismatched related donors, 3.79 (P < .0001) with 2-HLA-antigen-mismatched related donors, 2.11 (P < .0001) with HLA-matched unrelated donors, and 3.33 (P < .0001) with 1-HLA-antigen-mismatched unrelated donors. For patients with more advanced leukemia, differences in treatment failure were less striking: 1-HLA-antigen-mismatched relatives, 1.22 (P = not significant [NS]); 2-HLA-antigen-mismatched relatives, 1.81 (P < .0001); HLA-matched unrelated donors, 1.39 (P = .002); and 1-HLA-antigen-mismatched unrelated donors, 1.63 (P = .002). CONCLUSION: Although transplants from alternative donors are effective in some patients with leukemia, treatment failure is higher than after HLA-identical sibling transplants. Outcome depends on leukemia state, donor-recipient relationship, and degree of HLA matching. In early leukemia, alternative donor transplants have a more than twofold increased risk of treatment failure compared with HLA-identical sibling transplants. This difference is less in advanced leukemia.     

Amphiphilic peroxynitrite decomposition catalysts in liposomal assemblies

BACKGROUND: Peroxynitrite (ONOO-), a toxic biological oxidant, has been implicated in many pathophysiological conditions. The water-soluble porphyrins 5,10,15,20-tetrakis(N-methyl-4'-pyridyl)porphinato iron(III) (FeTMPyP) and manganese(III) (MnTMPyP) have recently emerged as potential drugs for ONOO- detoxification, and FeTMPyP has demonstrated activity in models of ONOO- related disease states. We set out to develop amphiphilic analogs of FeTMPyP and MnTMPyP suitable for liposomal delivery in sterically stabilized liposomes (SLs). RESULTS: Three amphiphilic iron porphyrins (termed 1a-c.) and three manganese porphyrins (termed 2a-c.) bound to liposomes and catalyzed the decomposition of ONOO-. The polyethylene-glycol-linked metalloporphyrins 1b. and 2b. proved the most effective of these catalysts, rapidly decomposing ONOO- with second-order rate constants (kcat) of 2.9 x 10(5) M-1 s-1 and 5.0 x 10(5) M-1 s-1, respectively, in dimyristoylphosphatidylcholine liposomes. Catalysts 1b. and 2b. also bound to SLs, and these metalloporphyrin-SL constructs efficiently catalyzed ONOO- decomposition (kcat approximately 2 x 10(5) M-1 s-1). The analogous metalloporphyrins 1a. and 2a., which are not separated from the vesicle membrane surface by polyethylene glycol linkers, were significantly less effective (kcat approximately 3.5 x 10(4) M-1 s-1). CONCLUSIONS: For these amphiphilic analogs of FeTMPyP and MnTMPyP, the polarity of the environment of the metalloporphyrin headgroup is intimately related to the efficiency of the catalyst; a polar aqueous environment is essential for effective catalysis of ONOO- decomposition. Thus, catalysts 1b. and 2b. react rapidly with ONOO- and are potential therapeutic agents that, unlike their water-soluble TMPyP analogs, could be administered as liposomal formulations in SLs. These SL-bound amphiphilic metalloporphyrins may prove to be highly effective in the exploration and treatment of ONOO- related disease states.     

Primary coexistent adenocarcinoma and choriocarcinoma of the stomach. A case report and review of the literature

We report a case of primary gastric choriocarcinoma with liver metastasis. The mixed histologic patterns included adenocarcinoma, undifferentiated carcinoma, and choriocarcinoma. Immunohistologic staining for the beta-subunit of human chorionic gonadotrophin (beta-HCG) showed positive results in the choriocarcinoma, adenocarcinoma, and normal mucosal gland. However, positive HCG cells were present at different intensities in the choriocarcinoma, adenocarcinoma, and normal mucosal gland. The level of HCG was significantly increased in serum. This unusual tumor probably resulted from dedifferentiation of a primary adenocarcinoma or developed directly from the mucosal glands.     

Development of parvalbumin immunoreactivity in the chick Edinger Westphal nucleus

To determine when the calcium-binding protein parvalbumin appears during development, neurons in the chick Edinger Westphal nucleus were examined for parvalbumin immunoreactivity at a variety of embryonic stages. Parvalbumin immunoreactivity appeared on embryonic day 14 (E14, Hamburger and Hamilton stage 40) in predominantly lateral Edinger Westphal neurons. Cytochrome oxidase activity within the nucleus was examined throughout development, as an indicator of physiological activity, and expression of cytochrome oxidase was compared with that of parvalbumin. Cytochrome oxidase activity was found to be uniformly high in all parts of the Edinger Westphal nucleus throughout development. Either the Edinger Westphal nucleus in physiologically active quite early in its development or other energy demands mask the correlation of cytochrome oxidase with electrical activity. Cytochrome oxidase was expressed well before parvalbumin immunoreactivity appeared. Voltage-activated calcium currents were characterized in E12 Edinger Westphal neurons. In both amplitude and composition, E12 calcium currents resemble those of E16 neurons, excluding the possibility that calcium currents appear de novo during or just prior to the appearance of parvalbumin. Both cytochrome oxidase activity and calcium currents are observed in Edinger Westphal neurons well before the appearance of parvalbumin during development. These findings do not exclude the possibility that physiological activity affects the expression of parvalbumin since other factors such as changing patterns of synaptic activity or the appearance of calcium conducting NMDA receptors have yet to be examined. However, they raise the possibility that additional factors such as an intrinsic developmental program or a change in the neuron's basal intracellular calcium requirements may also be involved.