[Mechanism and clinical treatment strategy of heparin resistance].

Heparin resistance is becoming a hot issue of clinical concern. In critically ill patients, heparin resistance can lead to failure of anticoagulation therapy or increase the risk of major bleeding. Prompt recognition of heparin resistance can help to precisely adjust heparin dosage and avoid deterioration and adverse events. Heparin resistance can be mechanistically classified into the antithrombin-mediated and the non-antithrombin-mediated. Common etiologies include heparin-induced thrombocytopenia, severe infections such as severe COVID-19, treatment with extracorporeal circulation or extracorporeal membrane oxygenation (ECMO), and use of factor Xa reversal agents; heparin resistance is now often identified by the concordance of activated partial thromboplastin time (APTT) ratio with anti-FXa. Common clinical management strategies include antithrombin supplementation and replacement of anticoagulant drugs (e.g., direct thrombin inhibitors), but their safety and efficacy still need to be further validated.

[Multidisciplinary regenerative treatment and mechanisms for rescuing a severe calciphylaxis patient with human amnion-derived mesenchymal stem cells].

Calciphylaxis is a rare disease with severe pain and high-mortality due to cutaneous ischemic necrosis and infection that currently lacks proved effective therapies. The occurrence of calciphylaxis in end stage kidney disease (ESKD) patients is known as calcific uremic arteriolopathy (CUA), which is characterized histologically by dermal microvessel calcification, intimal fibroplasia and microthrombosis. Here we innovatively treated a severe CUA patient with human amnion-derived mesenchymal stem cells (hAMSCs). A 34-year-old uremic woman was presented with progressive, painful malodorous ulcers in buttocks and mummified lower limbs. Skin pathological features supported the diagnosis of calciphylaxis. The patient was refractory to conventional multidisciplinary symptomatic therapies. With the approval of our hospital ethics committee, she was treated with hAMSCs including intravenous and local intramuscular injection, and external application of hAMSC culture supernatant to the wound area. During 15-month follow-up, the patient had regeneration of skin and soft tissues, with improved blood biochemical, inflammatory, mineral and bone metabolic indices and immunoregulation effects. After 15-month hAMSC treatment, the score of pain visual analog scale (VAS) decreased from 10 to 0, Bates-Jensen wound assessment tool (BWAT) score decreased from 65 to 13, and wound-quality of life (Wound-QoL) questionnaire score decreased from 68 to 0. We propose that hAMSC treatment is promising for CUA patients. The therapy is potentially involved in the multiple beneficial effects of inhibiting vascular calcification, stimulating angiogenesis and myogenesis, modulating adverse inflammatory and immunologic responses, promoting re-epithelialization and restoring skin integrity.

[Annual review of venous thromboembolism in 2021].

In the past year, significant progress has been made in the field of venous thromboembolism (VTE) including risk assessment and anticoagulation prevention, diagnostic strategies and model exploration, new drug development and disease management. Particularly, major breakthroughs have been made in the prevention of VTE with FXI inhibitors and the prevention of novel coronavirus pneumonia with coagulation alterations and anticoagulation interventions. Here, we reviewed the progress and achievements in the field of VTE in the past year, aiming to provide evidence and ideas for the diagnosis, treatment and future studies of VTE.

LINC00657 promotes malignant progression of oral squamous cell carcinoma via regulating microRNA-150.

OBJECTIVE: Previous studies have shown that LINC00657 is a cancer-promoting gene. However, the role of LINC00657 in oral squamous cell carcinoma (OSCC) has not been reported. This study was designed to investigate the role of LINC00657 in OSCC and its regulatory mechanism. PATIENTS AND METHODS: Quantitative Real Time-Polymerase Chain Reaction (qPCR) was used to detect the levels of LINC00657 and microRNA-150 in 32 pairs of OSCC tissues and normal ones, and the correlation between LINC00657 and clinical indicators and OSCC patient's prognosis was analyzed. qRT-PCR further verified the levels of LINC00657 and microRNA-150 in OSCC cells. In addition, LINC00657 overexpression and knockdown models were constructed using lentivirus in OSCC cell lines Fadu and Tca8113, and Cell Counting Kit-8 (CCK-8), plate clone experiment, and 5-Ethynyl-2'-deoxyuridine (EdU) assay were carried out to evaluate the influence of LINC00657 on the biological functions of OSCC cells. Further, Luciferase reporter gene and recovery experiments were used to explore its potential mechanism. RESULTS: qRT-PCR showed that LINC00657 expression in OSCC tissue specimens was increased in comparison to normal ones. Patients with high LINC00657 expression had higher pathological staging and lower overall survival. Besides, the cell proliferation ability of the LINC00657 silencing group was remarkably decreased, while the opposite result was observed in LINC00657 overexpression group. Subsequently, qRT-PCR demonstrated a significant decrease in microRNA-150 expression in OSCC cell lines and tissues and a negative correlation with LINC00657. Luciferase assay demonstrated that LINC00657 could be targeted by microRNA-150 in certain binding sites. In addition, cell reverse experiment also confirmed that LINC00657 and microRNA-150 can be mutually regulated, thereby jointly modulating the malignant progression of OSCC. CONCLUSIONS: LINC00657, remarkably upregulated in OSCC tissues, showed a close association with the poor prognosis of OSCC patients. Additionally, it may accelerate the malignant progression of OSCC via regulating microRNA-150.

[Progress of researches on animal models of Blastocystis hominis infections].

Blastocystis hominis is a common parasitic protozoa in human and animal intestines; however, its pathogenicity remains controversial. Construction of animal models is of great significance to investigate the pathogenicity, pathogenic mechanisms and drug screening of B. hominis. Experimental animals, mode of infections, parasite strains and host immune status are important factors affecting the successful modeling of B. hominis infections in animals. Hereby, we review the progress of researches on animal models of B. hominis infections, and summarize the influencing factors and application of animal models of B. hominis infections, in order to provides insights into the selection of animals models of B. hominis infections.

Lysophosphatidylethanolamine acyltransferase activity is elevated during cardiac cell differentiation.

We examined if elevation in lysophosphatidylethanolamine acyltransferase activity was associated with elevation in phosphatidylethanolamine content during differentiation of P19 teratocarcinoma cells into cardiac myocytes. P19 cells were induced to undergo differentiation into cardiac myocytes by the addition of 1% dimethylsulfoxide to the medium. Immunofluorescence microscopy revealed the presence of striated myosin at 8 days post-dimethylsulfoxide addition confirming differentiation into cardiac cells. The content of phosphatidylethanolamine was increased 2.1-fold (P<0.05) in differentiated cells compared to undifferentiated cells, whereas the content of phosphatidylcholine was reduced 29% (P<0.05). There were no alterations in the pool sizes of other phospholipids, including cardiolipin. The relative abundance of fatty acids in phospholipids of P19 cells was 18:1 > 18:0 > 16:1 = 18:2 > 16:0 = 14:0 > 20:4 and differentiation did not affect the relative amounts of these fatty acids within individual phospholipids. When cells were incubated with [1,3-(3)H]glycerol, radioactivity incorporated into phosphatidylethanolamine was elevated 5.8-fold, whereas radioactivity incorporated into phosphatidylcholine was unaltered. Ethanolaminephosphotransferase, cholinephosphotransferase and membrane CTP:phosphocholine cytidylyltransferase activities were elevated in differentiated cells compared to undifferentiated cells, whereas membrane and cytosolic phospholipase A2 activities were unaltered. Lysophosphatidylethanolamine acyltransferase activities were elevated 2.4-fold (P<0.05). Lysophosphatidylcholine acyltransferase, monolysocardiolipin acyltransferase, acyl-Coenzyme A synthetase and acyl-Coenzyme A hydrolase activities were unaltered in differentiated cells compared to undifferentiated cells. We postulate that during cardiac cell differentiation, the observed elevation in lysophosphatidylethanolamine acyltransferase activity accompanies the elevation in phosphatidylethanolamine mass, possibly to maintain the fatty acyl composition of this phospholipid within the membrane.

Four trace elements in pregnant women and their relationships with adverse pregnancy outcomes.

OBJECTIVE: Lack of trace elements during pregnancy is detrimental to maternal and fetal health. Our aim is to study the changes in trace element levels in Chinese pregnant women and their association with adverse pregnancy outcomes. PATIENTS AND METHODS: 1568 cases of Chinese pregnant women in remote areas were collected for a prospective cohort study. Serum copper, zinc, calcium and iron levels were measured at pre-pregnancy, 1st trimester (7w-12w), 2nd trimester (24w-28w) and 3rd trimester (35w-40w). RESULTS: (1) Serum copper levels was significantly higher after pregnancy than before, calcium and iron levels decreased, but zinc levels did not change significantly. (2) Copper and zinc deficiency in pregnant women was not a common finding, but lack of iron and calcium was frequently encountered; iron deficiency was especially common in the 3rd trimester (42.27%). (3) Serum zinc and iron levels in patients who either had a miscarriage or a preterm delivery were significantly lower than in the control group (p < 0.05). In patients with premature rupture of membranes, serum zinc levels were significantly lower (p < 0.05). In patients with intrauterine growth restriction (IUGR), serum copper, zinc, calcium and iron were significantly lower (p < 0.05). CONCLUSIONS: Trace elements is closely associated with fetal growth and development during pregnancy. Deficiency can lead to adverse pregnancy outcomes. Therefore, we should have a reasonable diet, replenish trace elements, therefore reducing the occurrence of adverse pregnancy outcomes.

Symmetrical adenovirus minichromosomes have hairpin replication intermediates.

A special class of panhandles (hairpin or foldback structures) arising from the replication of symmetrical adenovirus (Ad) minichromosome dimers and oligomers have been identified by two-dimensional gel electrophoresis. Hairpins provide evidence for replicative intermediates in the pathway for Ad complementary-strand synthesis. Furthermore, larger inverted sequences give Ad minichromosomes a replicative advantage.

[Pulmonary function and artery blood analysis of diabetes mellitus].

The widespread and depth-in investigations on the pulmonary change in DM have been documented abroad. Some revealed that the abnormalities of pulmonary function usually exist in DM. There has been no similar report found in China so far. In this study, ventilation, small airway function (V25 and V50), diffusion capacity and artery blood gas studies have been done in 60 DM and 62 healthy subjects respectively. The results have shown that there is a significant difference between NIDDM group and control group (P less than 0.05) in V50, V25, DLCO and the reduced value of PaO2, and there exists remarkably significant difference between the IDDM group and control group (P less than 0.01) in the decreased values of TLC, FEV1.0%, V50, V25, DLCO, PaCO2 and PaO2.

[Study on the relationship between postmortem interval and the change of absorbance in vitreous humor of rabbit after death].

OBJECTIVE: To seek a exact method of estimating Postmortem interval (PMI). METHODS: This study was preformed to investigate the relationship between postmortem interval and absorbance in vitreous humor of rabbit after death. The absorbance in vitreous humor of 48 rabbits after death were investigated with Model 754 spectrophotometer in apt wavelength (420 nm). RESULTS: There exists positive linear regression association between postmortem interval (Y) and absorbance in vitreous humor (X) (r = 0.98327, P < 0.05), during rabbits after death 0 to 72 hours. The formula of linear regression is Y = 453.30 X + 0.75 (Y = postmortem interval = PMI, X = absorbance in vitreous humor). CONCLUSION: The absorbance in vitreous humor can be as reference indicator to estimate PMI within hour 72.

Efficacy of intravenous lidocaine versus placebo on attenuating cardiovascular response to laryngoscopy and tracheal intubation: a systematic review of randomized controlled trials.

Cardiovascular response to laryngoscopy and tracheal intubation may be harmful in surgical patients with cardiovascular and cerebral diseases. The efficacy of intravenous lidocaine on attenuating the hemodynamic changes remains controversial. This systematic review aims to determine the efficacy of lidocaine versus placebo. PubMed, Embase and Cochrane Library databases were searched for relevant randomized controlled trials (RCTs). The quality of eligible RCTs was evaluated according to the modified Jadad scale. Quantitative analyses were carried out using Review Manager 5 and Stata 10. Thirty-seven trials with 1429 patients of different age groups were included in our meta-analysis. Additional lidocaine resulted in fewer changes in systolic blood pressure (SBP) (mean difference (MD) -4.32 mmHg, 95% confidence interval (CI) -6.21 to -2.43); diastolic blood pressure (DBP) (MD -4.76 mmHg, 95% CI -5.90 to -3.63); mean arterial blood pressure (MAP) (MD -2.72 mmHg, 95% CI: -3.65 to -1.80) and heart rates (HR) (MD -4.28 beats per min, 95% CI -5.83 to -2.72). Subgroup analysis showed that lidocaine was effective in both the elderly and children with the exception of failing to reduce HR in children. Exclusion of poor-quality trials did not change the favor to lidocaine. No significant publication bias across trials was found. Intravenous lidocaine helps reduce cardiovascular responses to laryngoscopy and tracheal intubation in patients of all age groups compared to placebo. Further studies are needed to clarify the effects of dosage and timing of lidocaine on hemodynamic changes.

Metabotropic glutamate subtype 7 and 8 receptors oppositely modulate cardiac nociception in the rat nucleus tractus solitarius.

Recent study from our laboratory has indicated that microinjection of glutamate into the nucleus tractus solitarius (NTS) facilitates the cardiac-somatic reflex induced by pericardial capsaicin. Further, N-methyl-d-aspartate (NMDA) receptors and metabotropic glutamate receptors (mGluRs) mediate this function. However, the roles of the individual receptor subtypes or subunits in modulating cardiac nociception are unknown. Among the three groups of mGluRs, group III mGluRs are the primary mGluR subtype expressed in visceral afferent neurons in the NTS. The present study examined the roles of group III mGluRs and their subtype 7 and 8 receptors (mGluR7 and mGluR8) in modulating the cardiac-somatic reflex induced by pericardial capsaicin, which was monitored by recording electromyogram (EMG) activity from the spinotrapezius muscle in anesthetized rats. Intra-NTS microinjection of a group III mGluR agonist, l-(+)-2-Amino-4-phosphonobutyric acid (l-AP4, at 1, 10, and 20 nmol) or a selective mGluR7 agonist, N,N'-diphenylmethyl-1,2-ethanediamine dihydrochloride (AMN082, at 1, 2, and 4 nmol) both decreased the EMG response in a dose-dependent manner. This decrease was inhibited by the group III mGluR antagonist (RS)-α-Methylserine-O-phosphate (MSOP, at 20 nmol). In contrast, intra-NTS microinjection of a selective mGluR8 agonist, (S)-3, 4-dicarboxyphenylglycine (DCPG, at 6 and 8 nmol), significantly increased the EMG response above control levels. This effect was eliminated by intra-NTS MSOP and by vagal deafferentation. These data suggest that group III mGluRs and mGluR7 in the NTS display an inhibitory effect, while mGluR8 displays a facilitatory effect in modulating cardiac nociception, and this facilitatory effect is dependent on vagal afferents.

Antihypertensive and renoprotective effects of trandolapril/verapamil combination: a meta-analysis of randomized controlled trials.

Both trandolapril and verapamil are effective and widely used antihypertensive agents. The aim of this study was to estimate the efficacy and tolerability of trandolapril/verapamil (Tr/Ve) combination for blood pressure control and renoprotection. PubMed, EMBASE and Cochrane Library were searched for relevant studies. A meta-analysis of all randomized controlled trials (RCTs) meeting the criteria was performed. Twelve RCTs were ultimately included out of 62 studies. (1) Combination versus trandolapril: a greater diastolic blood pressure (DBP) reduction (weighted mean difference (WMD): 3.71, 95% confidence interval (CI): 1.84-5.57); a greater reduction in albuminuria (WMD: 136.77, 95% CI: 12.44-261.09). There were no differences in reduction in systolic blood pressure (SBP), blood pressure response rate or proteinuria. (2) Combination versus verapamil: a greater SBP reduction (WMD: 6.14, 95% CI: 3.59-8.70); a greater DBP reduction (WMD: 2.49, 95% CI: 0.81-4.17); a greater reduction in proteinuria (standardized mean difference: 0.84, 95% CI: 0.22-1.45); a greater reduction in albuminuria (WMD: 255.00, 95% CI: 119.26-390.74). (3) Incidence of all-cause adverse events (AEs) was comparable between combination and monotherapy. The present meta-analysis indicates that Tr/Ve combination provides a superior blood pressure control and a favourable renoprotective effect without an increase of overall AEs than verapamil monotherapy. The combination also shows a slight advantage over trandolapril monotherapy by reducing DBP and albuminuria to a greater extent.

OX40 ligand levels and high-sensitivity C-reactive protein levels in blood from local coronary plaque and the femoral artery in patients with acute coronary syndrome or stable angina.

OX40 ligand (OX40L) and high-sensitivity C-reactive protein (hs-CRP) play important roles in the pathogenesis of atherosclerosis. In this study, consecutive patients with acute coronary syndrome (ACS; n = 90) or stable angina (SA; n = 40) and healthy control subjects (n = 50) were evaluated to assess plasma OX40L and serum hs-CRP levels in local coronary plaque and the femoral artery. OX40L and hs-CRP levels in the femoral artery were significantly higher in patients with ACS compared with controls. OX40L and hsCRP levels in local coronary plaque (OX40L(c) and hs-CRP(c), respectively) were significantly higher in ACS than in SA patients. OX40L and hs-CRP levels were positively correlated with each other and were also correlated with fibrinogen levels. The number of complex lesions was correlated with OX40L(c) and hs-CRP(c) levels. It is concluded that the OX40L(c) level was highly sensitive for evaluating the inflammatory response in ACS and elevated levels of OX40L(c) may be a valuable predictive marker for increased risk of atherosclerotic progression in ACS patients.

Cytidine-5'-diphosphate-1,2-diacyl-sn-glycerol import into mitochondria through mitochondrial membrane contact sites in permeabilized rat liver hepatocytes.

The location of cytidine-5'-diphosphate-1,2-diacylsn-glycerol import into mictochondria was examined in permeabilized rat liver hepatocytes. The model utilized the ability of intact mitochondria to freely import [14C]glycerol-3-phosphate. Import of cytidine-5'-diphosphate-1,2-diacyl-sn-glycerol was measured by the synthesis of phosphatidyl[14C]glycerol. Phosphatidyl [14C]glycerol was synthesized in a time- and concentration-dependent manner in the presence of cytidine-5'-diphosphate-1,2-diacyl-sn-glycerol. The presence of ATP in the incubations stimulated phosphatidyl[14C]glycerol formation. The presence of adriamycin, at concentrations that block import of proteins into mitochondria, inhibited the formation of phosphatidyl [14C]glycerol. In addition, adriamycin, inhibited in vitro biosynthesis of phosphatidyl[14C]glycerol in mitochondrial but not microsomal fractions. 1,4-Dinitrophenol, which may decrease the number of mitochondrial inner and outer membrane contact sites, inhibited formation of phosphatidyl[14C]glycerol in permeabilized hepatocytes. The results demonstrate that cytidine-5'-diphosphate-1,2-diacyl-sn-glycerol may be imported into mitochondria through inner and outer mitochondrial membrane contact sites in hepatocytes.

Biosynthesis of plasmenylethanolamine (1-O-alk-1'-enyl-2-acyl-sn-glycero-3-phosphoethanolamine) in the guinea pig heart.

In this study, the isolated guinea pig heart was pulse-labeled with a precursor of ethanolamine glycerophospholipid, and then chased with the non-radioactive compound for 0-8 h. Labeling with hexadecanol revealed that plasmanylethanolamine was the immediate precursor of plasmenylethanolamine, but a substantial portion of the label was also found in phosphatidylethanolamine. When ethanolamine was used as the precursor, the labeling of plasmenylethanolamine was between 50-65% of the labeling of phosphatidylethanolamine, and this ratio was maintained throughout the perfusion. The ratio of labeling is similar to the ratio of pool sizes of these ethanolamine glycerophospholipid in the heart, which implies that the CDP-ethanolamine pathway is also important for plasmenylethanolamine biosynthesis. The role of diradylglycerol in the synthesis of each ethanolamine glycerophospholipid was also investigated. The ratio of 1-alkenyl-2-acyl glycerol to total diradylglycerol content was 7% in the homogenate and 32% in the microsomes. However, ethanolamine phosphotransferase displayed a distinct selectivity towards 1-alkenyl-2-acyl glycerol. Kinetic studies revealed that the synthesis of phosphatidylethanolamine was inhibited by 1-alkenyl-2-acyl glycerol, but the formation of plasmenylethanolamine was not affected by 1,2-diacylglycerol. In addition, the inhibition of ethanolamine phosphotransferase by 1-alkyl-2-acyl glycerol appears to be an important mechanism for the coordination of plasmenylethanolamine biosynthesis via the desaturase reaction and the CDP-ethanolamine pathway.

Lysophosphatidylcholine inhibits cardiolipin biosynthesis in H9c2 cardiac myoblast cells.

The effect of phospholipase A2 treatment on cardiolipin biosynthesis was investigated in intact H9c2 cardiac myoblasts. Treatment of cells with Naja mocambique mocambique phospholipase A2 reduced the pool sizes of phosphatidylcholine and phosphatidylethanolamine compared with controls. The pool sizes of lysophosphatidylcholine and lysophosphatidylethanolamine were elevated, whereas the pool sizes of cardiolipin and other phospholipids were unaffected by phospholipase A2 treatment. Pulse labeling experiments with [1,3-3H]glycerol and pulse-chase labeling experiments with [1,3-3H]glycerol were performed in cells incubated or preincubated in the absence or presence of phospholipase A2. In all experiments, radioactivity incorporated into cardiolipin was reduced in phospholipase A2-treated cells with time compared with controls, indicating attenuated de novo biosynthesis of cardiolipin. The mechanism for the reduction in cardiolipin biosynthesis in phospholipase A2-treated cells was a decrease in the activity of phosphatidic acid:cytidine-5'-triphosphate cytidylyltransferase, the rate-limiting enzyme of cardiolipin biosynthesis, mediated by elevated cellular lysophosphatidylcholine levels. The results suggest that de novo cardiolipin biosynthesis in H9c2 cells may be regulated by the cellular level of lysophosphatidylcholine.

N-Acetylsphingosine stimulates phosphatidylglycerolphosphate synthase activity in H9c2 cardiac cells.

Cardiolipin and phosphatidylglycerol biosynthesis were examined in H9c2 cells incubated with short-chain ceramides. Incubation of cells with N-acetylsphingosine or N-hexanoylsphingosine stimulated [1, 3-3H]glycerol incorporation into phosphatidylglycerol and cardiolipin, with N-acetylsphingosine having the greater effect. The mechanism for the ceramide-mediated stimulation of de novo phosphatidylglycerol and cardiolipin biosynthesis appeared to be an increase in the activity of phosphatidylglycerolphosphate synthase, the committed step of phosphatidylglycerol and cardiolipin biosynthesis. The presence of the potent protein phosphatase inhibitors calyculin A or okadaic acid attenuated the N-acetylsphingosine-mediated stimulation of phosphatidylglycerolphosphate synthase activity and of phosphatidylglycerol and cardiolipin biosynthesis, indicating the involvement of a ceramide-activated protein phosphatase(s). The presence of 8-(4-chlorophenylthio)-cAMP (CPT-cAMP) stimulated enzyme activity and [1,3-3H]glycerol incorporation into phosphatidylglycerol and cardiolipin. The effects of CPT-cAMP and N-acetylsphingosine on phosphatidylglycerol and cardiolipin biosynthesis and on phosphatidylglycerolphosphate synthase activity were additive. Phosphatidylglycerol biosynthesis from sn-[14C]glycerol 3-phosphate in permeabilized H9c2 cells was stimulated by preincubation with N-acetylsphingosine, and this was attenuated by okadaic acid. N-Acetylsphingosine treatment of cells elevated mitochondrial phospholipase A2 activity. Since the pool sizes of phosphatidylglycerol and cardiolipin were unaltered in these cells, the observed increase in phosphatidylglycerolphosphate synthase activity may be a compensatory mechanism for the N-acetylsphingosine-mediated elevation of mitochondrial phospholipase A2 activity. Finally, addition of tumour necrosis factor alpha to H9c2 cells resulted in an elevation of both phosphatidylglycerolphosphate synthase and phospholipase A2 activities. The results suggest that phosphatidylglycerol and cardiolipin metabolism in H9c2 cells may be regulated by intracellular ceramide signalling.

Differential effects of chloroquine on cardiolipin biosynthesis in hepatocytes and H9c2 cardiac cells.

Chloroquine is a potent lysomotropic therapeutic agent used in the treatment of malaria. The mechanism of the chloroquine-mediated modulation of new cardiolipin biosynthesis in isolated rat liver hepatocytes and H9c2 cardiac myoblast cells was addressed in this study. Hepatocytes or H9c2 cells were incubated with [1,3-(3)H]glycerol in the absence or presence of chloroquine and cardiolipin biosynthesis was examined. The presence of chloroquine in the incubation medium of hepatocytes resulted in a rapid accumulation of radioactivity in cardiolipin indicating an elevated de novo biosynthesis. In contrast, chloroquine caused a reduction in radioactivity incorporated into cardiolipin in H9c2 cells. The presence of brefeldin A, colchicine or 3-methyladenine did not effect radioactivity incorporated into cardiolipin nor the chloroquine-mediated stimulation of cardiolipin biosynthesis in hepatocytes indicating that vesicular transport, cytoskeletal elements or increased autophagy were not involved in de novo cardiolipin biosynthesis induced by chloroquine. The addition of chloroquine to isolated rat liver membrane fractions did not affect the activity of the enzymes of de novo cardiolipin biosynthesis but resulted in an inhibition of mitochondrial cytidine-5'-diphosphate-1,2-diacyl-sn-glycerol hydrolase activity. The mechanism for the reduction in cardiolipin biosynthesis in H9c2 cells was a chloroquine-mediated inhibition of glycerol uptake and this did not involve impairment of lysosomal function. The kinetics of the chloroquine-mediated inhibition of glycerol uptake indicated the presence of a glycerol transporter in H9c2 cells. The results of this study clearly indicate that chloroquine has markedly different effects on glycerol uptake and cardiolipin biosynthesis in hepatocytes and H9c2 cardiac cells.