Highly active antiretroviral therapy dysregulates proliferation and differentiation of human pre-adipocytes.

AIM: To investigate the mechanism(s) by which potential effects of multi-drug highly-active antiretroviral therapy contributes to lipodystrophy syndrome. METHODS: Preadipocytes from healthy donors were assessed for proliferation and differentiation in the presence of nucleoside reverse transcriptase inhibitors (NRTIs), nonnucleoside reverse transcriptase inhibitors (NNRTIs), and protease inhibitors (PIs) individually and in combination. Effects on proliferation were assessed with a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assay and effects on differentiation were assessed from glycerol-3-phosphate dehydrogenase (GP DH) activity and quantitation of Oil Red O staining for intracellular lipid. Data were analyzed with a randomized block ANOVA with post-hoc Fisher's Least Significant Difference test. RESULTS: Preadipocyte proliferation was inhibited by a combination of NNRTI + NRTI (14% at 48 h, P < 0.001) and PI + NRTI (19% at 48 h, P < 0.001) with additional suppression when ritonavir (RTV) was added (26% at 48 h). The drug combination of atazanavir (ATV) + RTV + emtricitabine (FTC) + tenofovir (TDF) had the greatest inhibitory effect on proliferation at 48 h. Preadipocyte differentiation was most significantly reduced by the efavirenz + FTC + TDF assessed either by GPDH activity (64%) or lipid accumulation (39%), P < 0.001. Combining NRTIs with a PI (ATV + FTC + TDF) significantly suppressed differentiation (GPDH activity reduced 29%, lipid accumulation reduced by 19%, P < 0.01). This effect was slightly greater when a boosting amount of RTV was added (ATV + FTC + TDF + RTV, P < 0.001). CONCLUSION: Although combination antiretroviral therapy is clinically more efficacious than single drug regimens, it also has a much greater inhibitory effect on preadipocyte proliferation and differentiation.

Beta-blockade prevents hematopoietic progenitor cell suppression after hemorrhagic shock.

BACKGROUND: Severe injury is accompanied by sympathetic stimulation that induces bone marrow (BM) dysfunction by both suppression of hematopoietic progenitor cell (HPC) growth and loss of cells via HPC mobilization to the peripheral circulation and sites of injury. Previous work demonstrated that beta-blockade (BB) given prior to tissue injury both reduces HPC mobilization and restores HPC colony growth within the BM. This study examined the effect and timing of BB on BM function in a hemorrhagic shock (HS) model. METHODS: Male Sprague-Dawley rats underwent HS via blood withdrawal, maintaining the mean arterial blood pressure at 30-40 mm Hg for 45 min, after which the extracted blood was reinfused. Propranolol (10 mg/kg) was given either prior to or immediately after HS. Blood pressure, heart rate, BM cellularity, and death were recorded. Bone marrow HPC growth was assessed by counting colony-forming unit-granulocyte-, erythrocyte-, monocyte-, megakaryocyte (CFU-GEMM), burst-forming unit-erythroid (BFU-E), and colony-forming unit-erythroid (CFU-E) cells. RESULTS: Administration of BB prior to injury restored HPC growth to that of naïve animals (CFU-GEMM 59 ± 11 vs. 61 ± 4, BFU-E 68 ± 9 vs. 73 ± 3, and CFU-E 81 ± 35 vs. 78 ± 14 colonies/plate). Beta-blockade given after HS increased the growth of CFU-GEMM, BFU-E, and CFU-E significantly and improved BM cellularity compared with HS alone. The mortality rate was not increased in the groups receiving BB. CONCLUSION: Administration of propranolol either prior to injury or immediately after resuscitation significantly reduced post-shock BM suppression. After HS, BB may improve BM cellularity by decreasing HPC mobilization. Therefore, the early use of BB post-injury may play an important role in attenuating the BM dysfunction accompanying HS.

Quantitative measure of cytotoxicity of anticancer drugs and other agents.

Many anticancer drugs act on cancer cells to promote apoptosis, which includes impairment of cellular respiration (mitochondrial O(2) consumption). Other agents also inhibit cellular respiration, sometimes irreversibly. To investigate the sensitivity of cancer cells to cytotoxins, including anticancer drugs, we compare the profiles of cellular O(2) consumption in the absence and presence of these agents. Oxygen measurements are made at 37 degrees C, using glucose as a substrate, with [O(2)] obtained from the phosphorescence decay rate of a palladium phosphor. The rate of respiration k is defined as -d[O(2)]/dt in a sealed container. Different toxins produce different profiles of impaired respiration, implying different mechanisms for the drug-induced mitochondrial dysfunction. The decrease in the average value of k over a fixed time period, I, is proposed as a characteristic value to assess mitochondrial injury. The value of I depends on the nature of the toxin, its concentration, and the exposure time as well as on the cell type. Results for several cell types and 10 cytotoxins are presented here.