Publications

OBJECTIVE

N, N-Dimethylsphingosine (DMS) is recognized as an inhibitor of sphingosine kinase (SphK), a key enzyme responsible for the formation of sphingosine-1-phosphate (S1P). We previously showed that S1P was cardioprotective and that SphK was critical for myocardial ischemic preconditioning. Although DMS is an endogenous sphingolipid, its effect on cardiac function and cardioprotection at low concentration has not been studied.

METHODS

In Langendorff-perfused wild-type and protein kinase C (PKC)epsilon-null mouse hearts, cardiac function, infarction size, and SphK activity were measured.

RESULTS

Pretreatment with 0.3 microM and 1 microM DMS for 10 min protected against ischemia/reperfusion injury. Cardiac function (LVDP, +/-dP/dtmax) was improved and infarction size was reduced. The cardiac protection induced by DMS was abolished in PKCepsilon-null mouse hearts. Administration of 1 microM DMS ex vivo increased cytosolic SphK activity. This enhanced SphK activity was abolished in PKCepsilon-null mouse hearts. DMS also increased PKCepsilon translocation from the particulate to the cytosolic fraction with no effect on PKCalpha distribution. Co-immunoprecipitation showed that SphK1 interacted with PKCepsilon phosphorylated on Ser729. DMS also increased cytosolic Akt phosphorylation (Ser 473) and Akt translocation from a Triton-insoluble fraction to the cytosol.

CONCLUSIONS

DMS has a biphasic effect on cardioprotection. Higher concentrations (10 microM) are inhibitory, whereas a low concentration (0.3 microM and 1 microM) of DMS protects murine hearts against ischemia/reperfusion injury. DMS activates SphK in the cytosol via a PKCepsilon dependent mechanism. The PKCepsilon-SphK-S1P-Akt pathway is involved in the cardiac protection induced by DMS.

PURPOSE

To determine the recommended phase II dose (RPTD) of the farnesyltransferase (FTase) inhibitor tipifarnib when combined with doxorubicin and cyclophosphamide (AC) in patients with advanced breast cancer, the pathologic complete response (pCR) rate after preoperative treatment with four cycles of the combination in locally advanced breast cancer (LABC), and the effect of tipifarnib on primary tumor FTase enzyme activity in vivo.

PATIENTS AND METHODS

Thirty-two patients with metastatic breast cancer (n = 11) or LABC (n = 21) received AC (doxorubicin 60 mg/m2 and cyclophosphamide 600 mg/m2) administered intravenously on day 1 plus tipifarnib (100, 200, or 300 mg bid for 6 to 14 days) without (n = 2) or with (n = 30) granulocyte colony-stimulating factor (G-CSF) for up to four cycles. Patients with LABC underwent surgery after up to four cycles of the combination.

RESULTS

When combined with AC every 2 weeks plus G-CSF, the RPTD of tipifarnib was 200 mg bid administered on days 2 to 7. Seven (33%) of 21 patients (95% CI, 15% to 55%) with LABC treated with up to four cycles of the combination at the RPTD had a pCR in the breast at surgery. The five patients had serial biopsies that demonstrated at least 50% FTase enzyme inhibition in the primary tumor (median, 100%; range, 55% to 100%) after tipifarnib.

CONCLUSION

Tipifarnib may be safely combined with dose-dense AC using a dose and schedule that significantly inhibits FTase enzyme activity in human breast cancer in vivo and may enhance the pCR rate after four cycles of preoperative dose-dense AC.

Myocardial remodeling after myocardial infarction (MI) is associated with increased levels of the matrix metalloproteinases (MMPs). Levels of two MMP species, MMP-2 and MMP-9, are increased after MI, and transgenic deletion of these MMPs attenuates post-MI left ventricular (LV) remodeling. This study characterized the spatiotemporal patterns of gene promoter induction for MMP-2 and MMP-9 after MI. MI was induced in transgenic mice in which the MMP-2 or MMP-9 promoter sequence was fused to the beta-galactosidase reporter, and reporter level was assayed up to 28 days after MI. Myocardial localization with respect to cellular sources of MMP-2 and MMP-9 promoter induction was examined. After MI, LV diameter increased by 70% (P < 0.05), consistent with LV remodeling. beta-Galactosidase staining in MMP-2 reporter mice was increased by 1 day after MI and increased further to 64 +/- 6% of LV epicardial area by 7 days after MI (P < 0.05). MMP-2 promoter activation occurred in fibroblasts and myofibroblasts in the MI region. In MMP-9 reporter mice, promoter induction was detected after 3 days and peaked at 7 days after MI (53 +/- 6%, P < 0.05) and was colocalized with inflammatory cells at the peri-infarct region. Although MMP-2 promoter activation was similarly distributed in the MI and border regions, activation of the MMP-9 promoter was highest at the border between the MI and remote regions. These unique findings visually demonstrated that activation of the MMP-2 and MMP-9 gene promoters occurs in a distinct spatial relation with reference to the MI region and changes in a characteristic time-dependent manner after MI.

BACKGROUND

Case management (CM) coordinates care for persons with complex health care needs. It is not known whether CM is effective at improving biological outcomes among homeless and marginally housed persons with human immunodeficiency virus (HIV) infection. Our goal was to determine whether CM is associated with reduced acute medical care use and improved biological outcomes in homeless and marginally housed persons with HIV infection.

METHODS

We conducted a prospective observational cohort study in a probability-based community sample of HIV-infected homeless and marginally housed adults in San Francisco, California. The primary independent variable was CM, defined as none or rare (any CM in 25% but 75%). The dependent variables were 3 self-reported health service use measures (receipt of primary care, emergency department visits and hospitalizations, and antiretroviral therapy adherence) and 2 biological measures (increase in CD4(+) cell count of >or=50% and geometric mean HIV load of

RESULTS

In multivariate models, CM was not associated with increased primary care, emergency department use, or hospitalization. Moderate CM, compared with no or rare CM, was associated with an adjusted beta coefficient of 0.13 (95% confidence interval [CI], 0.02-0.25) for improved antiretroviral adherence. Consistent CM (adjusted odds ratio [AOR], 10.7; 95% CI, 2.3-49.6) and moderate CM (AOR, 6.5; 95% CI, 1.3-33.0) were both associated with >or=50% improvements in CD4(+) cell count. CM was not associated with geometric HIV load <400 copies/mL when antiretroviral therapy adherence was included in the model. Study limitations include a lack of randomization.

CONCLUSION

CM may be a successful method to improve adherence to antiretroviral therapy and biological outcomes among HIV-infected homeless and marginally housed adults.