ERK1/2 inhibition prevents contraction-induced increase in plasma membrane FAT/CD36 content and FA uptake in rodent muscle

AIM

The purpose of this experiment was to investigate the role of extracellular signal-regulated kinase 1/2 (ERK1/2) signalling in the contraction-induced increase in muscle FA uptake.

METHODS

Male Wistar rats (n = 41) were randomly assigned to either a resting or stimulated group. Within each group, animals were randomly assigned to receive PD-98059, an inhibitor of MAP/ERK kinase 1/2 (MEK1/2), a kinase upstream of ERK1/2 and perfused with 550 microM palmitate, [(14)C]palmitate, 7 mM glucose, and no insulin. In the stimulated group, electrical stimulation (ES) of supramaximal trains of 100 ms was delivered every 2 s for 20 min.

RESULTS

ERK1/2 phosphorylation was increased by 50% (P < 0.05) during ES but the contraction-induced increase was prevented by the addition of PD-98059. Glucose uptake increased by 3.6-fold (P < 0.05) from rest to ES in muscle perfused without PD-98059 and was not affected by the addition of PD-98059 either at rest (P > 0.05) or during ES (P > 0.05). For a matched palmitate delivery, ES increased palmitate uptake by 35% (P < 0.05). PD-98059 had no effect on palmitate uptake at rest but completely abolished the increase in palmitate uptake during ES. Plasma membrane FAT/CD36 protein content was increased by 38% during ES (P < 0.05) but the contraction-induced increase was prevented by the addition of PD-98059. AMPK activity was increased by ES (P < 0.05) but was unaffected by PD-98059.

CONCLUSION

These results show for the first time that the increase in FA uptake and in plasma membrane FAT/CD36 protein content is mediated, at least in part, by the ERK1/2 signalling pathway during muscle contraction.

Evaluation of ferromagnetism and magnetic resonance imaging artifacts of the Strecker tantalum vascular stent

A woven tantalum vascular stent (Strecker stent) was tested for ferromagnetism at 4.7 T and underwent magnetic resonance imaging (MRI) in vitro and in vivo at 1.5 T to evaluate the production of magnetic susceptibility artifacts. No ferromagnetism was detected. Spin-echo, phase reconstruction, and gradient echo images revealed a low level of susceptibility artifacts both in vitro and in vivo. Our findings demonstrate the feasibility of using MRI to evaluate blood vessels noninvasively following tantalum stent placement.

Treatment of chronic lymphocytic leukemia using chlorambucil and prednisone with or without cycle-active consolidation chemotherapy. A Southeastern Cancer Study Group Trial

Patients with untreated chronic lymphocytic leukemia (CLL) received protocol treatment with 6 months of chlorambucil (CB) (30 mg/M2) and prednisone (P) (80 mg/d X 5) every 2 weeks. Complete and partial responders (CR, PR) were then randomized to consolidation with six more courses of CB and P or to four courses of cytosine arabinoside (25 mg/M2 every 12 hours X 8, subcutaneously) and cyclophosphamide (25 mg/M2 every 12 hours X 8, orally) every three weeks. Of the 178 eligible patients entered, 138 (78%) were evaluable for induction therapy which produced a 22% hematologic CR and an overall response rate (CR + PR) of 74%. Eighty-two patients received adequate consolidation, at the end of which 43 were in CR. No difference was seen in response or survival between the two consolidation treatments. Responders had longer survival than nonresponders (P = 0.0001) even when a 6-month "guarantee time" was excluded, but there was no survival difference between CR and PR. Thus, intermittent CB and P is a well-tolerated, useful therapy for CLL but the addition of cyclophosphamide and cytosine arabinoside does not improve results.

Randomized trial of cyclophosphamide, doxorubicin, and 5-fluorouracil alone or alternating with a "cycle active" non-cross-resistant combination in women with visceral metastatic breast cancer: a Southeastern Cancer Study Group project

Patients with visceral patterns of metastatic breast cancer were stratified according to dominant metastatic site and performance status and then randomized to therapy with cyclophosphamide, doxorubicin, and 5-fluorouracil (CAF) or CAF alternating with a "cell-cycle active" regimen including cytosine arabinoside, methotrexate with leucovorin rescue, and oncovin ( CAMELEON ). One hundred eighty-seven patients were randomized; response rate for CAF was 44% and for CAF + CAMELEON , 40%. Durations of disease control and survival were not significantly different. Toxicity of CAF was as anticipated with predominant granulocytopenia, vomiting, and alopecia. Toxicity of CAMELEON was less severe than that of CAF, and CAF toxicity was not worsened by preceding courses of CAMELEON ; however, the CAF- CAMELEON regimen was cumbersome and complex leading to both physician and patient noncompliance. Contrary to the preliminary results of a pilot study, and preliminary reports of the present trial suggesting benefit for the CAF- CAMELEON regimen the present randomized trial does not confirm any significant benefit of CAF- CAMELEON over CAF alone in patients with visceral metastatic breast cancer although this conclusion must be viewed in light of the high inevaluability rate due to patient and physician noncompliance.

Long-term survival in adult acute lymphoblastic leukemia: follow-up of a Southeastern Cancer Study Group trial

Current observation was obtained for adults treated on a protocol for acute lymphoblastic leukemia, which was open from 1972 to 1978, in order to determine the long-term outcome and to evaluate potential prognostic factors. Long-term survival (five + years) was seen in 32% (25/79) of patients who achieved complete remission; 16/79 remain in first remission and 2/79 are currently in second remission. Young age (less than 40) and female sex were significant prognostic factors for long-term survival, but the basis for this advantage is unclear. Further improvements in chemotherapy are needed.

Alternating sequential combination chemotherapy in the management of advanced Hodgkin's disease. A Southeastern Cancer Study Group trial

The Southeastern Cancer Study Group has explored the use of alternating sequential combination chemotherapy in advanced Hodgkin's disease. Two hundred twelve evaluable patients were randomly assigned to treatment with the six-drug combination, BCNU, cyclophosphamide, vinblastine, procarbazine, prednisone, and bleomycin (BCVPP-Bleo) or with the same drugs alternating in monthly cycles with doxorubicin, dacarbazine, and bleomycin. Both regimens produced complete response rates of approximately 73%. The duration of remission and survival were similar for the two treatment regimens. Although our sequence of combinations does not rigorously meet the criteria for "non-cross-resistant" our results do not lend support to the hypothesis that alternating sequential non-cross-resistant drug combinations improves the outcome in advanced Hodgkin's disease.

Vindesine and mitomycin C in metastatic breast cancer. A Southeastern Cancer Study Group Trial

64 eligible women with previously treated metastatic breast cancer received mitomycin C plus vindesine chemotherapy. Dosage was based on investigators' estimate of patients' bone marrow reserve. There were 19 evaluable patients in the good marrow reserve category, with two complete and three partial responses (26%). In the poor marrow reserve category there were 29 evaluable patients with four partial responses (14%). The 26% response rate in patients with good marrow reserve is consistent with results obtained with this and similar combinations by other investigators.

Late intensification therapy in adult acute lymphoid leukemia. The Southeastern Cancer Study Group Experience

One hundred ninety-two evaluable patients were treated on a multicenter protocol for adult acute lymphoid leukemia to determine in a prospective randomized fashion if late intensification chemotherapy beginning after about six months of treatment would improve remission duration and survival. The complete remission rate was 60%. The median remission duration was 13.5 versus 25.9 months (P = 0.31) for standard maintenance therapy and late intensification, respectively, and the median survival was 17.5 versus 34.7 months (P = 0.19) respectively. Although there was a suggestion that the late intensification strategy was helpful, relapse proved to be common during the early phases of treatment; thus, insufficient numbers of patients were available at the randomization point to conclusively address the possible value of late intensification. Intensive therapy earlier in remission should be evaluated.

Phase II evaluation of teniposide (VM-26) in metastatic breast carcinoma. A Southeastern Cancer Study Group trial

The Southeastern Cancer Study Group performed a Phase II study of teniposide in previously treated patients with metastatic breast cancer. No responses were observed in 11 evaluable patients who received teniposide 60 mg/m2 by IV infusion for five consecutive days every three weeks. Toxicity was primarily gastrointestinal and hematologic and was frequently severe. This study demonstrated no therapeutic activity for teniposide when given in this dose and schedule to patients with heavily pretreated metastatic breast cancer.

Randomized comparison of tamoxifen versus diethylstilbestrol in estrogen receptor-positive or -unknown metastatic breast cancer: a Southeastern Cancer Study Group trial

In a randomized study 115 postmenopausal women with advanced breast cancer who were estrogen receptor-unknown or -positive were treated initially with tamoxifen or diethylstilbestrol (DES). Their pretreatment characteristics showed no significant difference. The frequency of response was identical with tamoxifen and DES, showing a complete response rate of 2% versus 2% and a partial response rate of 4% versus 8%, respectively; stable disease was present in 78% versus 73% of the patients, respectively. The median time to disease progression (5 vs 6 months) and median survival depending on initial hormone therapy (34 vs 35 months) were identical for tamoxifen and DES, respectively. Gastrointestinal toxicity was more frequent and more severe with DES than tamoxifen. Responses were seen with withdrawal of each agent and on crossover to the alternative agent. Our conclusions are that: DES and tamoxifen are equally effective in treating metastatic breast cancer in the postmenopausal patient who is estrogen receptor-positive or -unknown; withdrawal and crossover responses are seen with both agents; side effects are minimal but more frequent with DES; and on the basis of cost-effectiveness DES is the preferable agent.

Ineffectiveness of levamisole in prolonging remission or survival of women treated with cyclophosphamide, doxorubicin, and 5-fluorouracil for good-risk metastatic breast carcinoma: a Southeastern Cancer Study Group Trial

A total of 97 women with good-risk metastatic breast cancer received therapy with cyclophosphamide, doxorubicin, and 5-FU; half of these patients were randomly allocated to receive levamisole, 2.5 mg/kg, 2 days of each week in addition to chemotherapy, while the other half received an identical placebo. Good-risk patients consisted of those with bone-only metastasis, or local chest wall recurrence with or without bone metastasis. No significant difference in response rate, duration of disease control, or survival was observed between the groups. No major toxicity was associated with levamisole.

Continuous-infusion diaziquone in acute myeloid leukemia: a Southeastern Cancer Study Group trial

Diaziquone (AZQ) is a synthetic quinone with considerable activity against L1210 leukemia and potent myelosuppressive activity in man. To test the efficacy and toxicity of AZQ administered by continuous infusion, a phase II multi-institutional trial was undertaken by the Southeastern Cancer Study Group. Eligible adults with acute myeloid leukemia (AML) received AZQ at a dose of 28 mg/m2 daily by continuous infusion for 5 days. Patients failing to achieve complete remission received a second course utilizing the same dose and schedule. Of 25 evaluable patients with relapsed or refractory AML, three achieved complete response (12%) and two achieved partial response (8%). All patients experienced marked myelosuppression. Severe or life-threatening infection was observed in 15 (56%) patients. Clinical or postmortem evidence of central nervous system hemorrhage was encountered in three (12%) patients with severe refractory thrombocytopenia. Minimal nonhematologic toxicity was observed, suggesting that further studies of this agent in combination regimens and possibly for marrow transplantation preparation in patients with acute leukemia are warranted.

Amsacrine in refractory adult acute leukemia: a pilot study of the Southeastern Cancer Study Group

A phase II pilot study of amsacrine in refractory adult acute leukemia was conducted by the Southeastern Cancer Study Group from May 1979 to August 1980. Amsacrine, 90 mg/m2, was given daily for 5-8 days to 45 patients with acute myeloblastic leukemia, 15 patients with acute lymphoblastic leukemia, and six patients with blastic transformation of chronic granulocytic leukemia. Of the 66 patients entered in the study, 59 (89%) were evaluable for response. Complete remissions were observed in eight of 41 evaluable patients with acute myeloblastic leukemia (20%) and in three of 12 with acute lymphoblastic leukemia (25%). Remissions were short-lived (median, 7.9 weeks; range, 2-27). Toxic effects included the expected myelosuppression (100%), as well as moderate to severe stomatitis (46%), hyperbilirubinemia (30%), and supraventricular tachycardia (1.5%). This cooperative group pilot study confirms previous reports from single institutions that amsacrine is a useful drug in the treatment of refractory adult acute leukemia and is worthy of further study.