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Biomedical subjects

D Benjamin

Publications and source records attributed to D Benjamin.

At least 127 records · Page 7Linked to original sources
PubMed1994

Absence of the XIST gene from late-replicating isodicentric X chromosomes in leukaemia.

The mechanism of X-inactivation in man is thought to involve a specific cis-acting locus within the X-inactivation centre at Xq13 (1,2). The XIST gene (X inactive specific transcript) at Xq13 is ubiquitously expressed only from the inactive X and as such may be involved in or influenced by the X-inactivation process (3,4). We have localised the breakpoints on two acquired isodicentric X chromosomes associated with leukaemia to a 450 kilobase region of DNA within Xq13, which result in deletion of the XIST gene. We have demonstrated that these chromosomes remain inactive and that there is no evidence of XIST expression from the remaining intact X chromosomes. The data suggest that XIST is not required for the maintenance of X-inactivation on these somatically rearranged X chromosomes.

Anemia, Refractory, with Excess of Blasts↗
PubMed1994

Treatment of newly diagnosed children and adolescents with acute myeloid leukemia: a Childrens Cancer Group study.

PURPOSE: The objectives of this study were to determine if the addition of etoposide, thioguanine, and dexamethasone to daunorubicin and cytarabine (five-drug regimen) during induction would improve remission induction rates and survival of children with acute myeloid leukemia (AML) when compared with the standard regimen of cytarabine and daunorubicin (7 + 3) and whether allogeneic bone marrow transplantation (BMT) or intensive chemotherapy consolidation with or without maintenance would give a superior outcome. PATIENTS AND METHODS: A total of 591 assessable children with AML entered Childrens Cancer Group (CCG) trial 213 between January 1986 and February 1989. The status of patients as of September 1, 1992 forms the basis of this report. The results were compared with previous AML studies. RESULTS: The projected survival rate of all patients at 5 years is 39% (event-free survival [EFS] rate, 31%), which is superior to that of the prior CCG study (P = .01). The induction rate was 79% for 7 + 3 and 76% for the five-drug regimen (not significant). Comparisons of BMT to chemotherapy favored BMT, but these differences do not always reach statistical significance (eg, 5-year disease-free survival [DFS] rate, 46% v 38% [P = .06] with donor available and 54% v 37% [P = .002] if treated according to protocol intent). No benefit for maintenance therapy was found and, in some comparisons, it was inferior to discontinuation of therapy (5-year survival rate, 46% v 68%, P < .01). CONCLUSION: The 5-year EFS rate of patients with AML is 31% and has improved. The five-drug induction regimen is no better than standard induction, BMT appears superior to chemotherapy, and maintenance therapy was not beneficial.

Adolescent↗
PubMed1994

Human B cell interleukin 10.

Interleukin 10 (IL-10) is a novel lymphokine which exhibits strong DNA and amino acid sequence homology to BCRF1, an open reading frame in the Epstein-Barr virus genome. Using a wide panel of EBV positive and EBV negative cell lines, it has been shown that EBV positive B cell lines derived from patients with AIDS and Burkitt's lymphoma (AABCL) secrete large quantities of B cell IL-10, compared with EBV-positive B cell lines obtained from patients with undifferentiated lymphomas of Burkitt's and non-Burkitt's types. In contrast, EBV-negative B cell lines do not express IL-10 by Northern blot analysis, ELISA or even PCR. B cell IL-10 is confined to a narrow window in the B cell differentiation pathway, and whereas IL-10 expression is detected in mature and preplasmacytic stages, none of the pro-B, pre-B, or myeloma cell lines produce IL-10. EBV exerts direct effect on the production of B cell IL-10, and purified tonsillar B cells infected with EBV were triggered to secrete IL-10. The large amount of IL-10 secreted by B cells derived from AIDS-related lymphomas suggests that HIV-1 also exerts direct effect on IL-10 secretion. B cell IL-10 may function as autocrine growth factor for B cell lymphomas, and both IL-10 and BCRF1 seem to be involved in the pathophysiology of non-Hodgkin's lymphomas.

Amino Acid Sequence↗
PubMed1993

Naltrexone reverses ethanol-induced dopamine release in the nucleus accumbens in awake, freely moving rats.

The effect of the opioid receptor antagonist, naltrexone, on ethanol-induced changes in extracellular dopamine and serotonin in the nucleus accumbens was investigated using in vivo microdialysis in awake, freely moving rats. Locally applied ethanol (5% infused transprobe) resulted in substantial increases in dopamine in dialysate. Administration of naltrexone (cumulative dosing with 0.25-1.0 mg/kg i.p.) during ethanol administration dose-dependently reversed ethanol-induced increases in extracellular dopamine and its metabolite homovanillic acid but not serotonin. These data demonstrate an essential role for the endogenous opioid system in stimulation of dopamine release by ethanol in a brain area associated with reward and support the opioid system as a prime target for pharmacological modulation of the rewarding effects and consumption of ethanol.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1993

Characteristics of endogenous peptides eluted from the class I MHC molecule HLA-B7 determined by mass spectrometry and computer modeling.

Microcapillary HPLC electrospray ionization tandem mass spectrometry was used to sequence 15 peptides eluted from HLA-B7. Sequence alignment implicated four peptide positions in specific interactions with the class I molecule, and their importance was confirmed using synthetic peptides. Because no crystal structure for HLA-B7 was available, computer-assisted modeling was used to understand novel aspects of peptide binding specificity and to accurately predict the effect of defined changes in peptide structure. The results demonstrate that mass-spectrometric sequencing coupled with computer-assisted modeling can be used in the absence of a crystal structure to make accurate predictions concerning requirements for peptide binding to class I molecules. These techniques may be valuable to predict or engineer T cell epitopes.

Amino Acid Sequence↗