牵张应变诱导人牙周膜细胞凋亡过程中caspase蛋白酶表达的初步研究

目的研究在牵张应变诱导人牙周膜细胞凋亡过程中caspase蛋白酶表达的变化。方法对体外培养的人牙周膜细胞分别施加20%牵张应变6、24 h,采用流式细胞术测定细胞凋亡率,采用免疫印迹技术检测caspase-3、-5、-7、-8、-9的蛋白表达,并采用分光光度比色法测定caspase-3、-5、-8、-9的蛋白酶活性变化。结果 20%牵张应变加载6、24 h可诱导人牙周膜细胞发生凋亡。caspase-3的蛋白表达及蛋白酶活性和caspase-7的蛋白表达在24 h牵张应变作用下较对照组增加,caspase-5、-8、-9的蛋白表达及蛋白酶活性在6、24 h牵张应变作用下较对照组增加。结论 20%牵张应变能诱导体外培养的人牙周膜细胞凋亡,此过程中伴随发生了caspase-3、-5、-7、-8、-9蛋白酶的活化。     

IL-2 and IL-7 but not IL-12 protect natural killer cells from death by apoptosis and up-regulate bcl-2 expression.

Human natural killer cells (NK) respond to interleukin-2 (IL-2) with augmented cytolytic activity, cytokine secretion and cell proliferation. Here we show that IL-2 protects NK cells from death by apoptosis (programmed cell death; PCD). Highly purified NK cells (CD3- CD56+) were isolated from peripheral blood lymphocytes (PBL) of either control donors or of an asymptomatic donor with 60% NK cells. Glucocorticosteroids (GCS) induced PCD in NK cells, as shown by nuclear condensation and DNA fragmentation. IL-2 completely prevented GCS-induced PCD in a dose-dependent manner without overcoming GCS-induced inhibition of NK cell proliferation. The IL-2 protective effect was mediated through the p75 beta chain of the IL-2R, as neutralizing monoclonal antibody (mAb) to the p75 beta chain but not to the p55 alpha chain completely abolished the IL-2 anti-apoptotic activity. In addition to IL-2, the cytokines IL-7 and IL-12 have been reported to regulate NK cell functions. Our present data showed that IL-7 but not IL-12 rescued NK cells from apoptosis, but to a lesser extent than IL-2. Although IL-4 had a marginal protective effect, IL-1, IL-3, IL-6, IL-8, interferon-gamma (IFN-gamma) and IFN-alpha, tumour necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta) and granulocyte-macrophage colony-stimulating factor (GM-CSF) displayed no significant activity. Finally, we report that IL-2 and IL-7 enhanced bcl-2 expression in NK cells, suggesting the existence of a bcl-2-dependent survival pathway. In addition to regulating various functions, it is concluded that IL-2 and IL-7 have the ability to prevent PCD in NK cells.     

Inhibition of caspases prevents cell death of hippocampal CA1 neurons, but not impairment of hippocampal long-term potentiation following global ischemia.

An essential role for caspases in programmed neuronal cell death has been demonstrated in various in vitro studies, and synthetic caspase inhibitors have recently been shown to prevent neuronal cell loss in animal models of focal cerebral ischemia and traumatic brain injury, respectively. The therapeutic utility of caspase inhibitors, however, will depend on preservation of both structural and functional integrity of neurons under stressful conditions. The present study demonstrates that expression and proteolytic activity of caspase-3 is up-regulated in the rat hippocampus after transient forebrain ischemia. Continuous i.c.v. infusion of the caspase inhibitor N-benzyloxycarbonyl-Asp(OMe)-Glu(OMe)-Val-Asp(OMe)-fluoromethyl ketone significantly attenuated caspase-3-like enzymatic activity, and blocked delayed cell loss of hippocampal CA1 neurons after ischemia. Administration of N-benzyloxycarbonyl-Asp(OMe)-Glu(OMe)-Val-Asp(OMe)-fluoromethyl ketone, however, did not prevent impairment of induction of long-term potentiation in post-ischemic CA1 cells, suggesting that caspase inhibition alone does not preserve neuronal functional plasticity.     

Apoptosis induced by paclitaxel via Bcl-2, Bax and caspases 3 and 9 activation in NB4 human leukaemia cells is not modulated by ERK inhibition

We have studied the role of pivotal bio-molecules involved in signalling of cytotoxic effects induced by paclitaxel (Ptx) on acute promyelocytic human leukaemia NB4 cells. A time-dependent increase in cell death and DNA cleavage was observed after 30 μM Ptx treatment. Cell death induction by Ptx proceeds mainly as programmed cell death as shown by annexin V-FITC, reaching up to 30% of apoptotic cells after 24 h. Significant reductions of p53, changes in Bax and Bcl-2 and activation of caspases 3 and 9 were observed as the treatment was applied for long times. Ptx treatments produced NFkB depletion with expression levels abolished at 19 h what could be involved in reduction of survival signals. Phosphorylation of intracellular kinases showed that pERK1/2 decreased significantly at 19 h of Ptx treatment. When these cells were preincubated for 90 min with 20 μM PD98059, 2′-amino-3′-methoxyflavone, an inhibitor of ERK phosphorylation, a slight reduction of cell viability was observed in comparison to that produced by Ptx alone. Pretreatment with PD98059 neither activated caspases nor significantly increased the apoptotic effect of Ptx. Taken together, our data reveal that the inhibition of ERK phosphorylation does not seem to be an essential pathway for bursting an increased induction of apoptosis by Ptx. Decrease of p53 and Bcl-2, fragmentation of DNA, increase of Bax and, finally, activation of caspases 3 and 9 in NB4 leukaemia cells make the apoptotic process induced by Ptx irreversible. Application of Ptx in leukaemia cells shows therefore a promising potential with particular effects on different leukaemia cell types.     

Localization of apoptotic and proliferating cells and mRNA expression of caspases and Bcl-2 in gonads of chicken embryos

The aim of the present study was to analyze participation of apoptosis and proliferation in gonadal development in the chicken embryo by: (1) localization of apoptotic (TUNEL) and proliferating (PCNA immunoassay) cells in male and female gonads and (2) examination of mRNA expression (RT-PCR) of caspase-3, caspase-6 and Bcl-2 in the ovary and testis during the second half of embryogenesis and in newly hatched chickens. Apoptotic cells were found in gonads of both sexes. At E18 the percentage of apoptotic cells (the apoptotic index, AI) in the ovarian medulla and the testis was lower (p < 0.05) than in the ovarian cortex. In the ovarian medulla, the AI at E18 was lower (p < 0.05) than on E12. In the testis, the AI was significantly lower (p < 0.05) at E18 than at E15 and 1D. The percentage of proliferating cells (the proliferation index: PI) within the ovary significantly increased from E15 to 1D in the cortex, while proliferating cells in the medulla were detected only at E15. In the testis, the PI gradually increased from E12 to 1D. The mRNA expression of caspase-3 and -6 as well as Bcl-2 was detected in male and female gonads at days 12 (E12), 15 (E15) and 18 (E18) of embryogenesis and the day after hatching (1D). The expression of all analyzed genes on E12 was significantly higher (p < 0.05) in female than in male gonads. This difference was also observed at E15 and E18, but only for the caspase-6. The results obtained showed tissue- and sex-dependent differences in the number of apoptotic and proliferating cells as well as mRNA expression of caspase-3, -6 and Bcl-2 genes in the gonads of chicken embryos. Significant increase in the number of proliferating cells in the ovarian cortex and lack of these cells in the ovarian medulla (stages E12, E18, 1D) simultaneous with decrease in the intensity of apoptosis only in the medulla indicates that proliferation is the dominant process involved in the cortical development, which constitutes the majority of the functional structure of the fully developed ovary. No pronounced changes in the expression of apoptosis-related genes found during embryogenesis suggest that they cannot be considered as important indicators of gonad development. The molecular mechanisms of the regulation of balance between apoptosis and proliferation in developing avian gonads need to be further investigated.     

Inhibition by prostaglandin E(2) of anaphylatoxin C5a- but not zymosan-induced prostanoid release from rat Kupffer cells

The proinflammatory anaphylatoxin C5a induces the release of prostanoids, ie, prostaglandins (PG) and thromboxane (TX), from the resident liver macrophages (Kupffer cells [KC]). Because KC themselves express prostanoid receptors, prostanoids--besides having paracrine functions--might regulate their own release in an autocrine loop. So far, such a possible feedback regulation has not been investigated systematically, probably because of methodological difficulties to measure newly synthesized prostanoids in the presence of added prostanoids. Here, after prelabeling of phospholipids with [(14)C]arachidonate, cellularly formed [(14)C]prostanoids were determined in the presence of added unlabelled prostanoids by thin layer chromatography. In cultured KC, recombinant rat C5a (rrC5a) rapidly increased PGD(2), PGE(2), and TXA(2) release, which was strongly reduced by PGE(2), but neither by PGD(2) nor by the TXA(2) analog U46619. The inhibitory effect of PGE(2) was mimicked by cAMP, indicating that the G(s)-coupled PGE(2) receptors type 2 or 4 were involved. Zymosan also enhanced prostanoid release from KC, but with slightly slower kinetics; this action was neither inhibited by PGE(2) nor by cAMP. Also in perfused rat livers, rrC5a enhanced prostanoid release from KC as shown by prostanoid overflow and thereby indirectly increased glucose output from hepatocytes. Again, PGE(2), but not PGD(2), inhibited rrC5a-elicited prostanoid overflow. This resulted in a complete inhibition of rrC5a-induced, prostanoid-mediated glucose output. Thus, PGE(2) can inhibit specifically the C5a-induced prostanoid release from KC via a feedback mechanism and thereby limit prostanoid-mediated hepatocellular defense reactions, eg, glucose release.     

Th1 and Th2 CD4+ T cell clones specific for Plasmodium chabaudi but not for an unrelated antigen protect against blood stage P. chabaudi infection

The host protective immune response to blood stage malaria infection was studied using Plasmodium chabaudi chabaudi (P. chabaudi) in NIH mice. It has been shown previously that CD4⁺ cells are critically required for protection against erythrocytic infection. Mice lacking a functional CD4⁺ cell compartment suffer unremitting patent primary parasitemias for at least 60 days after infection. Here, we report that the adoptive transfer of eight P. chabaudi-specific CD4⁺ T cell clones of either the T_h1 or T_h2 type to mice rendered CD4-depleted by adult thymectomy and anti-CD4 monoclonal antibody therapy fully restored the ability of recipients to control challenge infection. Control T_h1 and T_h2 clones specific for an unrelated antigen, ovalbumin, were unable to confer a comparable level of protection in CD4-depleted mice, even though they received regular doses of the antigen. These data demonstrate that protective immunity to asexual P. chabaudi parasites can be mediated through immune CD4⁺ T cell clones of either the T_h1 or the T_h2 subset.     

Chronic inhibition of glycogen synthase kinase-3 protects against rotenone-induced cell death in human neuron-like cells by increasing BDNF secretion

Mitochondrial dysfunction is a common feature of many neurodegenerative disorders. Likewise, activation of glycogen synthase kinase-3 (GSK-3) has been proposed to play an important role in neurodegeneration. This multifunctional protein kinase is involved in a number of cellular functions and we previously showed that chronic inhibition of GSK-3 protects neuronal cells against mitochondrial dysfunction-elicited cell death, through a mechanism involving increased glucose metabolism and the translocation of hexokinase II (HKII) to mitochondria. Here, we sought to gain deeper insight into the molecular basis of this neuroprotection. We found that chronic inhibition of GSK-3, either genetically or pharmacologically, elicited a marked increase in brain-derived neurotrophic factor (BDNF) secretion, which in turn conferred resistance to mitochondrial dysfunction through subcellular re-distribution of HKII. These results define a molecular pathway through which chronic inhibition of GSK-3 may protect neuronal cells from death. Moreover, they highlight the potential benefits of enhanced neurotrophic factor secretion as a therapeutic approach to treat neurodegenerative diseases.     

NuMA and nuclear lamins are cleaved during viral infection--inhibition of caspase activity prevents cleavage and rescues HeLa cells from measles virus-induced but not from rhinovirus 1B-induced cell death

Nuclear matrix is a structural framework of important nuclear processes. We studied the effect of two different types of viral infections on nuclear matrix. HeLa cells were infected with human rhinovirus 1B (HRV 1B) or measles virus (MV), and Nuclear Mitotic Apparatus protein (NuMA) and lamins A/C and B were used as markers for internal nuclear matrix and peripheral nuclear lamina, respectively. We show that NuMA, lamins, and poly(ADP-ribose) polymerase-1 are cleaved during viral infection in a virus family-specific manner suggesting that these viruses activate different sets of proteases. Morphologically, NuMA was excluded from the condensed chromatin, lamins showed a folded distribution, and both proteins finally remained around the nuclear fragments. A general caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (z-VAD-FMK) prevented the nuclear disintegration and the cleavage of the proteins studied. Interestingly, z-VAD-FMK rescued MV-infected but not HRV 1B-infected cells from cell death. These results show for the first time that NuMA and lamins are specific target proteins during virus-induced programmed cell death.     

骨髓间充质干细胞通过上调EPO表达减轻缺氧损伤引起的PC12细胞凋亡

 目的：观察骨髓间充质干细胞（BM-MSCs）对氯化钴（CoCl2）诱导的PC12细胞缺氧损伤及凋亡的影响并探讨其作用机制。方法：将PC12细胞分为以下几组：空白对照组、CoCl2处理组、BM-MSCs-siCTL+CoCl2处理组和BM-MSCs-siEPO +CoCl2处理组。应用MTT、流式细胞术（FCM）及Hoechst  33258染色法检测BM-MSCs对CoCl2诱导的细胞活性下降及凋亡的影响。采用逆转录PCR（RT-PCR）和Western blotting检测BM-MSCs的促红细胞生成素（EPO）表达情况。同时通过RT-PCR法检测PC12细胞的Bcl-2与Bax表达情况。此外应用分光光度法检测caspase-9和-3活性。结果：MTT结果显示BM-MSCs共培养能够提高PC12细胞活力, 0.6 mmol/L CoCl2单独处理组24 h和48 h细胞存活率仅为（43.0±6.4）%和（33.8±5.7）%,1∶15细胞比BM-MSCs共培养24 h和48 h后细胞存活率明显上升,分别为（77.9±3.8）%和（75.2±9.7）%（P＜0.01）。RT-PCR 和Western blotting显示0.6 mmol/L CoCl2处理24 h和48 h明显诱导BM-MSCs的EPO表达上调,而EPO siRNA可完全抑制BM-MSCs的EPO表达（P＜0.01）。FCM及Hoechst 33258结果表明CoCl2处理能诱导PC12细胞损伤及凋亡,BM-MSCs-siCTL与PC12细胞共培养可有效抑制CoCl2的细胞毒性作用,减少细胞缺氧性损伤及凋亡,而EPO siRNA可明显阻断BM-MSCs的抗细胞凋亡作用（P＜0.01）。 RT-PCR结果显示BM-MSCs共培养组PC12细胞的Bcl-2表达较CoCl2处理组明显升高,而Bax表达较CoCl2处理组明显降低;EPO siRNA明显抑制BM-MSCs介导的Bcl-2表达升高和Bax表达降低（P＜0.01）。分光光度法结果显示BM-MSCs-siCTL共培养组的caspase-9和-3活性较CoCl2处理组明显降低,而BM-MSCs-siEPO共培养组的caspase-9和-3活性较BM-MSCs-siCTL共培养组明显增加（P＜0.01）。结论：BM-MSCs共培养能抑制CoCl2诱导的PC12细胞凋亡,其细胞保护作用的机制可能与其上调EPO的表达有关。     

Bcl-2 prevents death of factor-deprived cells but fails to prevent apoptosis in targets of cell mediated killing.

'Programmed cell death' has been used to describe the death of cells killed by cytotoxic T cells or growth factor deprivation. Although bcl-2 can prevent death of cells deprived of growth factor, it failed to protect cells against T cell killing. In spite of bcl-2 expression, the DNA of targeted cells was degraded into nucleosome-sized fragments. Therefore the early steps in apoptosis induced by factor deprivation differ from those triggered by cytotoxic T cells, although they share a common final pathway featuring degradation of the DNA and loss of cytoplasmic membrane integrity.     

Phagocytosis of apoptotic eosinophils but not neutrophils by bronchial epithelial cells

BACKGROUND: We have previously demonstrated that human bronchial epithelial cells engulf apoptotic eosinophils. OBJECTIVES: To compare and contrast the phagocytic capabilities of monocyte-derived macrophage and primary airway epithelial cells for apoptotic granulocytes. RESULTS: Here we compared phagocytosis of human apoptotic eosinophils and neutrophils by small and large airway epithelial cells (SAEC and LAEC) and monocyte-derived macrophages. Confocal microscopy of F-actin staining and scanning and transmission electron microscopy revealed phagocytic cup formation around apoptotic eosinophils by airway epithelial cells (AEC) membranes with evidence of their digestion. Resting and cytokine-stimulated AEC did not recognize and ingest apoptotic neutrophils. The latter were phagocytosed by macrophages that exhibited greater ingestion of and higher capacity for, apoptotic eosinophils over apoptotic neutrophils. Cytochalasin D completely abolished uptake of apoptotic eosinophils by SAEC, LAEC or macrophage monolayers. Ligation of epithelial cell CD44 receptors for 24 h increased phagocytosis of apoptotic eosinophils by SAEC and LAEC with a potency comparable with that of IL-1. Phagocytosis was a specific receptor-mediated process involving integrin- (alphavbeta3, alphavbeta5, CD36), phosphatidylserine receptor- and lectin-dependent mechanisms. No significant differences were observed in avarice for apoptotic eosinophils by SAEC or LAEC either resting, CD44 monoclonal antibodies- or cytokine- stimulated, or in their usage and expression of recognition receptors. CONCLUSION: These findings further suggest and define an important role for the bronchial epithelium in the selective removal of apoptotic eosinophils from the airways in asthma.     

Flagella-mediated bacterial motility accelerates but is not required for Salmonella serotype Enteritidis invasion of differentiated Caco-2 cells

The relative contributions of the flagellum and the flagella-associated bacterial motility in the invasion of Caco-2 cells by Salmonella serotype Enteritidis were investigated using an fliC mutant defective in flagellin production and a motA mutant that carries flagella but is non-motile. Infection assays demonstrated that, at 1 h of infection, both the fliC and the motA mutants were severely impaired in bacterial invasion compared to the parental strain. Infection assays at 3 h infection demonstrated virtually equal invasion levels for both non-motile mutants and the parental strain. Together these data suggest that flagella-mediated bacterial motility accelerates the invasion of Salmonella but is not required for the invasion event per se.     

IL-2 enhances polyclonal IgM but not IgM-rheumatoid factor synthesis by activated human peripheral blood B cells.

IgM-rheumatoid factor (RF) is thought to be involved in the pathogenesis of rheumatoid arthritis (RA). Several cytokines are known to regulate immunoglobulin synthesis. In this study the effects of IL-2 on polyclonal IgM and IgM RF synthesis were compared. Cytokines were added to peripheral blood B cells from normal subjects and patients with RA after activation by Staphylococcus aureus Cowan 1 (SAC). The addition of IL-2, but not IL-4 or IL-6, resulted in significant enhancement of IgM synthesis in cultures from both healthy subjects and patients with RA. Similar degrees of enhancement were seen in both peripheral blood mononuclear cell and highly purified B cell cultures. IgM-RF was synthesized after activation in cultures from healthy subjects and spontaneously in cultures from RA patients. In contrast to polyclonal IgM synthesis, IL-2 failed to augment IgM-RF synthesis in cell cultures from either healthy subjects or RA patients. This study demonstrates different effects of IL-2 on IgM and IgM-RF synthesis.     

An embryonic source of Ly1 but not conventional B cells.

Ly1+ B cells differ from conventional B cells with respect to their anatomical localization, cell surface marker expression, and antibody repertoire suggesting that they may constitute a functionally distinct subset of B cells. To determine whether Ly1+ B cells also have a developmentally distinct site of origin we grafted various fetal primordia into adult severe combined immunodeficient (scid) mice and analyzed their potential to give rise to T and B cells. We demonstrated that fetal omentum, but not spleen or thymus grafts, reconstituted exclusively Ly1 B cells (including the Ly1 sister population) as well as a population of IgM and IgA producing plasma cells in the spleen and gut, respectively. Although thymus grafts regularly reconstituted T cells, thymus plus fetal omentum cografts gave rise to a population of Ly1+ B cells as well as T cells which were also derived from omentum. However, in neither omentum nor omentum plus thymus cografts were conventional B cells detected. These results provide the first evidence that Ly1 B cells but not conventional B cells are generated from the fetal omentum.     

Pimecrolimus leads to an apoptosis-induced depletion of T cells but not Langerhans cells in patients with atopic dermatitis

BACKGROUND: Apart from the long-used corticosteroids, topical calcineurin inhibitors (tacrolimus, pimecrolimus) represent novel therapeutic options for the treatment of atopic dermatitis. OBJECTIVE: This study was designed to investigate the pathophysiological target cells and mode of action of pimecrolimus in atopic skin. METHODS: Twenty-two patients were randomly assigned to treatment with pimecrolimus cream 1%, matching vehicle cream, or beta-methasone-17-valerate (BMV) cream 0.1% in a randomized, double-blind, vehicle-controlled, parallel group clinical trial. Treatment was given twice daily for 3 weeks. Cryostat sections of skin biopsies were taken before as well as at selected time points after initiation of therapy. For certain experiments, healthy volunteers were topically treated with the creams described twice a day on 5 consecutive days. Epidermal sheets were prepared from suction blisters. For in vitro experiments, untreated, healthy human skin was obtained from patients undergoing plastic surgery. The effect of pimecrolimus and BMV on Langerhans cells (LCs), inflammatory dendritic epidermal cells, and T cells was investigated by using immunofluorescence and flow-cytometry techniques. RESULTS: While topical BMV treatment depleted LCs in healthy and atopic skin, pimecrolimus did not affect their number. Correlating with the disappearance of inflammatory cells, we observed a depletion of inflammatory dendritic epidermal cells and T cells on pimecrolimus and BMV treatment. Furthermore, we show that pimecrolimus depletes T cells by the induction of apoptosis. CONCLUSION: In summary, our data show that pimecrolimus reduces pathological T cells in atopic dermatitis skin via apoptosis, whereas LCs remain unaffected.     

Neuroprotection of microglia conditioned media from apoptotic death induced by staurosporine and glutamate in cultures of rat cerebellar granule cells

Microglia, the immune cells of the mammalian CNS, have often been indicated as dangerous effector cells for their activation in response to traumatic CNS injuries or immunological stimuli and for their involvement in many chronic neurodegenerative diseases. Recently, several in vitro and in vivo studies have emphasized that microglial activity is essential in promoting neuronal survival. We have tested the efficacy of media directly conditioned by microglia or conditioned by microglia after having been exposed to apoptotic neurons, towards neuroprotection of rat cerebellar granule cells (CGCs) challenged with staurosporine or glutamate. Apoptotic death of CGC caused by staurosporine, as well as by a mild excitotoxic stimulus delivered through sub-chronic glutamate treatment, was significantly counteracted by microglia conditioned media. On the other hand, an acute excitotoxic insult delivered through a short pulse of glutamate exposure in the absence of magnesium and resulting in a mix of apoptotic and necrotic death was only marginally counteracted by microglia conditioned media. The present results extend the available information regarding the neuroprotective role of microglia and support the usefulness of employing the culture approach for perspective identification of neuroprotective factors released by these cells. Furthermore, the use of media previously exposed to apoptotic neurons to elicit the neuroprotective response of microglia, indicate the feasibility to re-create also in the isolated culture conditions, at least some of the elements at the basis of neuron/microglia cross-talk.     

Inhibition of TNF-alpha induced cell death in human umbilical vein endothelial cells and Jurkat cells by protocatechuic acid

The Chinese herb radix Salviae miltiorrhizae (RSM) is used in traditional Chinese medicine as a treatment for cardiovascular and cerebrovascular diseases. Several components of the plant extract from salvia mitorrhiza bunge have been determined previously, one of which is protocatechuic acid (PAC). It has been found, in the study, that PAC inhibited TNF-α-induced cell death of human umbilical vein endothelial cells (HUVECs) and Jurkat cells in a concentration of 100μM when applied 2 h prior to TNF-α exposure. Molecular studies revealed that PAC activated NF-κB with a maximum effect after 30 min of treatment. Inhibition of NF-κB action by MG132 and NF-κB inhibitory peptide suppressed the cell-protective effect of PAC. Further, degradation of lkBα occurred in response to PAC treatment. The results provide evidence that activation of NF-κB plays an important role in mediating the cell-protecting effect of PAC on HUVECs and Jurkat cells. Further studies are required to test whether PAC, a component of radix salviae miltiorrhizae, could be useful in preventing in vivo cell death resulting from cardiovascular or cerebrovascular diseases.