Insulin and glucose induced changes in expression level of nucleoside transporters and adenosine transport in rat T lymphocytes

Adenosine is an endogenous agent exerting potent action on the immune system including regulation of lymphocyte functioning. Impaired T lymphocyte functioning is a common feature of diabetes. The aims of this study were to examine the effects of glucose and insulin on nucleoside transporters (NT) expression level and adenosine (Ado) transport in rat T lymphocytes cultured under the defined concentrations of glucose and insulin. Performed experiments revealed that rat T lymphocytes expressed the equilibrative nucleoside transporter type 1 and 2 (rENT1, rENT2) and concentrative nucleoside transporter type 2 (rCNT2). The mRNA levels of rENT2 and rCNT2 were highly dependent on insulin but were not affected by changes in extracellular glucose concentration. Exposition of T cells to 10nM insulin resulted in 73% increase in rENT2 mRNA and 50% decrease in the rCNT2 mRNA level. The level of rENT1 mRNA was sensitive to extracellular glucose concentration but not to insulin. The highest differences among cells cultured in high (20mM) and low (5mM) glucose were observed in equilibrative nitrobenzylthioinosine sensitive adenosine transport, which was lowered by 65% in cells cultured at high glucose. Alterations in adenosine transport were accompanied by changes in adenosine accumulation in the cell. These results indicate that adenosine transport in rat T lymphocytes is independently and differentially regulated by glucose and insulin by means of changes in the nucleoside transporters expression level. Altered adenosine transport has a great impact on its intracellular level. This suggests that under diabetic conditions adenosine action on T lymphocytes might be altered.     

Research achievement award--D. John Faulkner

David John Faulkner, one of the pioneers of marine natural products chemistry and the 2003 recipient of the ASP Research Achievement Award, passed away on November 23, 2002. John was very pleased to learn that he'd been named as the award recipient and was intending to present the ASP Research Achievement Award Address at the annual meeting in July 2003, Chapel Hill, North Carolina. John's untimely death left an unprecedented event in the history of the ASP-a posthumous Research Achievement Award to a deserving individual and an untimely loss for us all. We are bereft of a colleague, a friend, and a mentor, and the opportunity to hear John's words on the occasion of his own award. In tribute to John, we have assembled a retrospective of John's work that is not meant to be a comprehensive review (this would take considerably more space) but a selection of highlights and personal vignettes from some of those that trained in marine natural products under his mentorship. This paper is a written account of the symposium presented by the authors at the ASP Annual Meeting in Chapel Hill, North Carolina, on July 16, 2003.     

(2S,3R)-2-aminododecan-3-ol, a new antifungal agent from the ascidian Clavelina oblonga

A new antifungal agent, (2S,3R)-2-aminododecan-3-ol (1), has been isolated from the ascidian Clavelina oblonga collected in Brazil. The structure of 1 was established by analysis of spectroscopic data, including absolute stereochemistry determined by circular dichroism analysis of the dibenzoyl derivative 2. Compound 1 displayed antifungal activity against Candida albicans ATCC 10231 with a MIC of 0.7 mug/mL and against Candida glabrata with a MIC of 30 microg/mL.     

2-Chlorodeoxyadenosine alone and in combination with cyclophosphamide and mitoxantrone induce apoptosis in B chronic lymphocytic leukemia cells in vivo

The purpose of the study was to determine some apoptotic events in mononuclear cells obtained from peripheral blood of patients with B-cell chronic lymphocytic leukemia (B-CLL) during and after therapy with 2-chlorodeoxyadenosine (2-CdA; C), and the combination of 2-CdA with cyclophosphamide (CC), or 2-CdA with mitoxantrone and cyclophosphamide (CMC). Western blot technique was performed to estimate expression/proteolytic degradation of generally accepted apoptotic markers, i.e., Bcl-2 protein, lamin B, PARP-1, and caspase-3 in leukemic cells isolated from blood samples of patients before treatment and subjected to drug(s) administration. The decrease of antiapoptotic protein Bcl-2 expression and proteolytic cleavage of nuclear proteins--lamin B and PARP-1 were observed in leukemic cells of patients treated according to the above therapy protocols, however, each to a different level among the studied groups. The obtained results indicated also that procaspase-3 was cleaved and activated in leukemic cells of three drug(s) treated groups. However, the cleavage of procaspase-3 and the generation of fragments with mol. mass of 17/20 kDa occurred especially effectively among patients treated according to CMC regimen. The changes in expression/proteolytic degradation of the above selected apoptotic markers, are accompanied by the appearance of apoptotic morphology in leukemic cells originated from blood of patients treated with the above drug(s) in comparison to untreated ones.     

Acute lymphoblastic leukaemia in elderly patients: biological characteristics and therapeutic approaches

Acute lymphoblastic leukaemia (ALL) is a rare disease in the elderly. The prevalence of ALL in patients >60 years of age is reported to be between 16% and 31% of all adult cases. The biology of ALL in older patients seems to be significantly different from that in younger patients and may, at least in part, explain poor treatment outcome. Immunophenotyping and cytogenetic characteristics are among the most important biological differences in comparison with younger adults. The frequency of pre B-cell ALL and common ALL is higher and T-cell ALL subtype is under-represented in elderly populations compared with younger patients. The frequency of the Philadelphia chromosome also seems to increase with age and adversely influences complete remission rate and survival. Few reports on the effectiveness and toxicity of therapeutic programmes concerning exclusively older patients with ALL have been published so far and only some of them were prospective studies. In some of the studies age-adapted approaches have been applied in which protocols processed earlier for younger patients have been adopted for older patients. In such modified protocols chemotherapy was usually less aggressive, especially if it was given for patients with comorbidities and poor performance status. Consequently, in several studies elderly patients received suboptimal treatment. Death during induction chemotherapy was observed in 7-42% of the patients in particular reports. The overall response rate varied from 12% to 85%. The median overall survival (OS) durations in patients who received a curative approach ranged from 3 to 14 months and from 1 to 14 months in patients treated palliatively. Poor performance status, comorbidities and high early mortality during intensive chemotherapy are the main reasons for poor treatment results and short OS time. New therapeutic approaches are necessary to improve the outcome in this age group of patients with ALL.     

Determination of the in vivo effects of cladribine alone and its combination with cyclophosphamide or cyclophosphamide and mitoxantrone on Bax and Bcl-2 protein expression in B-CLL cells

The present study investigated a correlation between expression of Bcl-2 family members, Bax and Bcl-2 (the Bax/Bcl-2 ratio values) in B-CLL cells in vivo and the response of these cells to chemotherapy. Western blot technique combined with videodensitometry was used for Bax and Bcl-2 determination in homogenate, nuclear and postnuclear fractions of mononuclear cells isolated from peripheral blood of B-CLL patients treated with cladribine alone (C), and in combination with cyclophosphamide (CC) or mitoxantrone and cyclophosphamide (CMC). The Bax/Bcl-2 ratio values were changed in B-CLL cells originated from blood samples of patients treated by the three therapy protocols, and was the most elevated in the case of CMC treatment. High degree of B-CLL cell apoptosis induction with cladribine combined with mitoxantrone and cyclophosphamide was confirmed by DNA fragmentation and an appearance of apoptotic morphology among leukemic cells from the blood of patients treated with this form of combined therapy.