Heterogeneity of Human γδ T Cells and Their Role in Cancer Immunity

The γδ T cells are unconventional lymphocytes that function in both innate and adaptive immune responses against various intracellular and infectious stresses. The γδ T cells can be exploited as cancer-killing effector cells since γδ TCRs recognize MHC-like molecules and growth factor receptors that are upregulated in cancer cells, and γδ T cells can differentiate into cytotoxic effector cells. However, γδ T cells may also promote tumor progression by secreting IL-17 or other cytokines. Therefore, it is essential to understand how the differentiation and homeostasis of γδ T cells are regulated and whether distinct γδ T cell subsets have different functions. Human γδ T cells are classified into Vδ2 and non-Vδ2 γδ T cells. The majority of Vδ2 γδ T cells are Vγ9δ2 T cells that recognize pyrophosphorylated isoprenoids generated by the dysregulated mevalonate pathway. In contrast, Vδ1 T cells expand from initially diverse TCR repertoire in patients with infectious diseases and cancers. The ligands of Vδ1 T cells are diverse and include the growth factor receptors such as endothelial protein C receptor. Both Vδ1 and Vδ2 γδ T cells are implicated to have immunotherapeutic potentials for cancers, but the detailed elucidation of the distinct characteristics of 2 populations will be required to enhance the immunotherapeutic potential of γδ T cells. Here, we summarize recent progress regarding cancer immunology of human γδ T cells, including their development, heterogeneity, and plasticity, the putative mechanisms underlying ligand recognition and activation, and their dual effects on tumor progression in the tumor microenvironment.

Integrating balanced mevalonate pathway into chromosome for improving lycopene production in Escherichia coli / 生物工程学报

Isoprenoids are all derived from two five-carbon building blocks called isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), which are synthesized either by the mevalonate (MVA) pathway or 2-C-methyld-D-erythritol-4-phosphate (MEP) pathway. In this study, the MVA pathway genes were integrated into the chromosome of LYC101, in which the expression of key genes in the MEP synthesis pathway and lycopene synthesis pathway were optimized by artificial regulatory parts, to further improve the production of isoprenoids in Escherichia coli. The plasmids pALV23 and pALV145 were screened from a plasmid library that constructed by using the RBS library to link the genes of the MVA pathway, which greatly increased the production of β-carotene. The effects of plasmids pALV23 and pALV145 on the lycopene production in low and high lycopene production strain, LYC001 and LYC101, were compared, respectively. The production of lycopene was increased by plasmids pALV23 and pALV145 in both strains. In high lycopene production strain LYC101, pALV23 produced more lycopene than pALV145. Then, the MVA gene together of promoter of pALV23 was integrated into the chromosome of LYC101 at poxB site using method of homologous recombination helped by CRISPR-Cas9 system, resulted in genetically stable strain, LYC102. The yield of lycopene of LYC102 was 40.9 mg/g DCW, 1.19-folds higher than that of LYC101, and 20% more than that of LYC101 with pALV23. Simultaneous expression of MVA pathway and MEP pathway in recombinant E. coli can effectively increase the yield of terpenoids. In this study, a plasmid-free, genetically stable, high-yielding lycopene strain was constructed, which could be used for industrialization. Also, the platform strain can be used for the synthesis of other terpenoids.

Miopatía por estatinas y vitamina D / Statin-Related Myopathy and Vitamin D

Las estatinas son fármacos habitualmente seguros y bien tolerados, muy eficaces para la prevención de trastornos cardiovasculares. La presencia de mialgias, poco frecuente, pero con incidencia dispar en diversos reportes, es una de las causas de abandono de su uso. También las distintas denominaciones (mialgia, miopatía, rabdomiólisis) y la subjetividad de cada paciente para referirlas han creado confusión en el tema. Se ha comenzado a reportar asociación entre niveles de vitamina D sérica disminuida y mayor riesgo de miopatía, por un lado, y trabajos donde pacientes que las abandonaban a causa de mialgias, con deficiencia de vitamina D, pueden tolerarlas una vez que se suplementa la vitamina hasta valores deseables. La presencia de polimorfismos en genes de enzimas que metabolizan o transportan a las estatinas es otro factor claramente relacionado con miopatía. Es posible que el déficit de vitamina D deba ser considerado un factor de riesgo para desarrollar miopatía por estatinas, como lo serían también la administración simultánea de fármacos que se metabolizan por la misma vía de citocromo P450, o la presencia de los polimorfismos mencionados. En conclusión, el hallazgo de tener deficiencia de vitamina D se asocia a miopatía por estatinas, o que es un factor de riego para desarrollarla, abre nuevas perspectivas para un gran número de pacientes que abandonan este tratamiento debido a esta patología. (AU)

Statins are usually safe and well tolerated drugs, very effective for preventing cardiovascular complications. The rare presence of myalgia, with different incidence as reported by several studies, is one of the causes of lack of drug compliance. Also the different symptoms referred (myalgia, myopathy, rhabdomyolysis) and the lack of objetivity of each patient when referring to the symptoms, have created confusion in this matter. Associations between decreased vitamin D levels and increased risk of myopathy has been reported. Indeed, studies describing patients with vitamin D deficiency who are not compliant due to myalgia show that they become tolerant to the drugs once the vitamin is supplemented to desirable values. The presence of gene polymorphisms for enzymes that metabolize or transport statins is another factor clearly related to myopathy. Therefore, we should consider vitamin D deficiency and other conditions such as the simultaneous administration of drugs that are metabolized by the same cytochrome P450 pathway, or the presence of mentioned polymorphisms as a risk factor for developing myopathy due to statins. In conclusion, the finding that vitamin D deficiency is associated with statin myopathy, or is a risk factor its develpoment, opens new perspectives for a large number of patients who leave this treatment due to this condition. (AU)

Statins and bonehealth: a mini review / Estatinas y salud ósea: una minirevisión

Statins are a widely prescribed class of medications that inhibit similar pathways as the anti-resorptive bisphosphonate drugs. Statins target the mevalonate pathway by blocking HMG-CoA reductase. Several recent meta-analyses concluded statins are osteoprotective in the general population. Here we present current literature exploring the mechanisms underlying the putative osteoprotective effects of statins. We also review recent clinical studies, ranging from observational cohort studies to randomized clinical trials, testing the effect of statins on bone health in various populations. (AU)

Las estatinas son un grupo de drogas prescriptas en forma habitual, con la capacidad de bloquear vías de señalización similares a las inhibidas por los amino-bisfosfonatos. Las estatinas inhiben la vía del mevalonato, a través del bloqueo de diferentes enzimas. Varios metaanálisis recientes llevaron a la conclusión de que las estatinas tienen capacidad osteoprotectora en la población general. En esta revisión presentamos la literatura actual describiendo los mecanismos que subyacen en el potencial efecto osteoprotector de las estatinas, como así también estudios observacionales y clínicos aleatorizados sobre el efecto de estatinas en la salud ósea en diversas poblaciones. (AU)

Novel non-apoptotic cell death: ferroptosis / 영남의대학술지

Ferroptosis is a newly recognized type of cell death that results from iron-dependent lipid peroxidation and is different from other types of cell death, such as apoptosis, necrosis, and autophagic cell death. This type of cell death is characterized by mitochondrial shrinkage with an increased mitochondrial membrane density and outer mitochondrial membrane rupture. Ferroptosis can be induced by a loss of activity of system Xc− and the inhibition of glutathione peroxidase 4, followed by the accumulation of lipid reactive oxygen species (ROS). In addition, inactivation of the mevalonate and transsulfuration pathways is involved in the induction of ferroptosis. Moreover, nicotinamide adenine dinucleotide phosphate oxidase and p53 promote ferroptosis by increasing ROS production, while heat shock protein beta-1 and nuclear factor erythroid 2-related factor 2 inhibit ferroptosis by reducing iron uptake. This article outlines the molecular mechanisms and signaling pathways of ferroptosis regulation, and explains the roles of ferroptosis in human disease.

Novel non-apoptotic cell death: ferroptosis / 영남의대학술지

Ferroptosis is a newly recognized type of cell death that results from iron-dependent lipid peroxidation and is different from other types of cell death, such as apoptosis, necrosis, and autophagic cell death. This type of cell death is characterized by mitochondrial shrinkage with an increased mitochondrial membrane density and outer mitochondrial membrane rupture. Ferroptosis can be induced by a loss of activity of system Xc− and the inhibition of glutathione peroxidase 4, followed by the accumulation of lipid reactive oxygen species (ROS). In addition, inactivation of the mevalonate and transsulfuration pathways is involved in the induction of ferroptosis. Moreover, nicotinamide adenine dinucleotide phosphate oxidase and p53 promote ferroptosis by increasing ROS production, while heat shock protein beta-1 and nuclear factor erythroid 2-related factor 2 inhibit ferroptosis by reducing iron uptake. This article outlines the molecular mechanisms and signaling pathways of ferroptosis regulation, and explains the roles of ferroptosis in human disease.

Effects of Bisphosphonates on Glucose Transport in a Conditionally Immortalized Rat Retinal Capillary Endothelial Cell Line (TR-iBRB Cells)

The objective of the present study was to elucidate the effect of bisphosphonates, anti-osteoporosis agents, on glucose uptake in retinal capillary endothelial cells under normal and high glucose conditions. The change of glucose uptake by pre-treatment of bisphosphonates at the inner blood-retinal barrier (iBRB) was determined by measuring cellular uptake of [3H]3-O-methyl glucose (3-OMG) using a conditionally immortalized rat retinal capillary endothelial cell line (TR-iBRB cells) under normal and high glucose conditions. [3H]3-OMG uptake was inhibited by simultaneous treatment of unlabeled D-glucose and 3-OMG as well as glucose transport inhibitor, cytochalasin B. On the other hand, simultaneous treatment of alendronate or pamidronate had no significant inhibitory effect on [3H]3-OMG uptake by TR-iBRB cells. Under high glucose condition of TR-iBRB cells, [3H]3-OMG uptake was increased at 48 h. However, [3H]3-OMG uptake was decreased significantly by pre-treatment of alendronate or pamidronate compared with the values for normal and high glucose conditions. Moreover, geranylgeraniol (GGOH), a mevalonate pathway intermediate, increased the uptake of [3H]3-OMG reduced by bisphosphonates pre-treatment. But, pre-treatment of histamine did not show significant inhibition of [3H]3-OMG uptake. The glucose uptake may be down regulated by inhibiting the mevalonate pathway with pre-treatment of bisphosphonates in TR-iBRB cells at high glucose condition.

Improving isoprene production by engineered heterologous mevalonate pathway in Escherichia coli / 生物工程学报

Isoprene is an important precursor of synthetic rubber material. In our previous study, metabolic engineered Escherichia coli strain (BW-01) was constructed and used to produce isoprene. Based on the theory of protein budget, using synthetic biology strategies including the increased copy number of genes and rare codons, we regulated the expression of key enzyme to improve isoprene production in Escherichia coli strain. Under shake-flask conditions, isoprene productivity of the engineered strain (BW-07) increased by 73% compared with BW-01, reached 761.1 mg/L. It provides a reference for further studies.

Enhancing ergosterol production in Pichia pastoris GS115 by overexpressing squalene synthase gene from Glycyrrhiza uralensis / 中国天然药物

The present study was designed to determine the effects of copy number variations (CNVs) of squalene synthase 1(SQS1) gene on the mevalonate (MVA) pathway. SQS1 gene from G. uralensis (GuSQS1) was cloned and over-expressed in Pichia pastoris GS115. Six recombinant P. pastoris strains containing different copy number of GuSQS1 were constructed. HPLC was used to assay the level of ergosterol in all transgenic P. pastoris strains containing GuSQS1. HPLC analysis showed that the contents of ergosterol in all of the transgenic P. pastoris containing GuSQS1 were higher than that in the negative control. And with the increase of copy number of GuSQS1, the content of ergosterol showed an increasing-decreasing-increasing pattern. The contents of ergosterol in 10-copy-GuSQS1 P. pastoris and 47-copy-GuSQS1 P. pastoris were significantly higher than that in the rest recombinant P. pastoris strains. In conclusion, the CNVs of GuSQS1 influence the content of secondary metabolites in the MVA pathway. The present study provides a basis for over-expressing GuSQS1 and increasing the content of glycyrrhizin in G. uralensis cultivars.

Cloning and characterization of a cDNA coding 3-hydroxy-3-methylglutary CoA reductase involved in glycyrrhizic acid biosynthesis in Glycyrrhiza uralensis / 药学学报

The roots of Glycyrrhiza uralensis are widely used in Chinese medicine for their action of clearing heat, detoxicating, relieving cough, dispelling sputum and tonifying spleen and stomach. The reason why Glycyrrhiza uralensis has potent and significant actions is that it contains various active secondary metabolites, especially glycyrrhizic acid. In the present study, we cloned the cDNA coding 3-hydroxy-3-methylglutary CoA reductase (HMGR) involved in glycyrrhizic acid biosynthesis in Glycyrrhiza uralensis. The corresponding cDNA was expressed in Escherichia coli as fusion proteins. Recombinant HMGR exhibited catalysis activity in reduction of HMG-CoA to mevalonic acid (MVA) just as HMGR isolated from other species. Because HMGR gene is very important in the biosynthesis of glycyrrhizic acid in Glycyrrhiza uralensis, this work is significant for further studies concerned with strengthening the efficacy of Glycyrrhiza uralensis by means of increasing glycyrrhizic acid content and exploring the biosynthesis of glycyrrhizic acid in vitro.

Dental Considerations of the Bisphosphonate-related Osteonecrosis of the Jaw / 대한골다공증학회지

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a disease entity which is rare, but is a serious side effect of bisphosphonate therapy. Several professional associations have published position papers on BRONJ; in 2009, the Korean position statement was reported as a collaborative effect between the Korean Endocrine Society, Korean Society of Bone Metabolism, Korean Society of Osteoporosis, and Korean Association of Oral and Maxillofacial Surgeons. Diagnostic criteria and treatment strategies for BRONJ are now being established through a thorough investigation and cooperation amongst numerous specialties. Still obscure, it is suggested that the pathogenesis of BRONJ is due to the inhibition of farnesyl pyrophosphate synthase of the osteoclastic mevalonate pathway, thus disturbing the cytoskeletal motility for the fusion of mononuclear cells into a multinucleated giant cell or the establishment of a ruffled border. Eventually, such changes will be followed by inactivation and apoptosis of osteoclasts, leading to decreased bone resorption. The incidence of BRONJ is known to be as low as 0.01~0.001% of the entire population, but BRONJ is as high as 1 in 300 in the case of dental intervention of patients on bisphosphonate therapy. It is important for clinicians to remember in requesting a dental consultation for a patient on bisphosphonate therapy that oral cavity has a special environment for wound healing. Routine minor trauma caused by foreignbodies, such as hard food, is compensated by an appropriate wound healing mechanism involving rapid bone turnover due to the rich vascular supply of the oral mucosa. Bisphosphonate will disturb this normal wound healing as a consequence of decreased bone turnover. It should also be kept in mind that the disturbed wound healing is further complicated by the presence of normal microflora in the oral cavity and by the unique anatomic condition of the thin oral mucosa covering the the mandible, most mobile skeleton in the head and neck area. The potency of the bisphosphonates (intravenous bisphosphonate), local factors, such as local dental intervention (especially dental extraction), and systemic factors, such as patient age (old age), have statistical significance for all BRONJ risk factors. Although the recognition of BRONJ by clinicians has been inadequate until now, the growing body of evidence is unveiling the detailed aspects of BRONJ. Continued investigation and extensive cooperation of related specialties will elucidate the nature of the disease, thus enhancing the quality of life of patients on bisphosphonate therapy.

HMG CoA Reductase Inhibitors Inhibit HCV RNA Replication of HCV Genotype 1b but Not 2a

Replication of hepatitis C virus (HCV) is regulated by statin, one of 3-hydroxy-3-methylglutaryl CoA reducatase (HMG CoA reductase) inhibitors that block mevalonate pathway and cholesterol biosyntheis, which has been used usefully for health improvement and disease control in clinic. In order to know which statin can be used to inhibit HCV replication, we examined the effects of HCV genotype 1b replication by 6 kinds of statins with different structure. We treated six statins to HCV genotype 1b replicon cell. Atorvastatin, simvastatin, fluvastatin, mevastatin, and lovastatin inhibited HCV RNA replication and HCV protein expression in HCV genotype 1b replicon cells, though pravastatin did not affect HCV replication. In order to know whether inhibition of HCV replication by statin is depended on HCV genotype, we treated the statins to HCV genotype 2a producing cells, and investigated HCV RNA replication and HCV protein expression. HCV RNA replication and protein expression was not affected in HCV genotype 2a producing cells by treatment of statins and cholesterol inhibitor. These results suggest that HMG-CoA reductase and cholesterol inhibitors might be used depending on HCV genotype. In addition, inhibition of HCV genotype 1b replication by statins has been depended on structure of various statins which should be seriously selected for HCV clinic. In future, we will study on inhibition of another HCV genotype replication by HMG-CoA reductase and cholesterol inhibitors.

Effects of simvastatin on DNA synthesis in rat cardiac fibroblasts / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effects of simvastatin (Sim) and the interference by mevalonate (MVA) against its effect on DNA synthesis in rat cardiac fibroblasts (CFs).</p><p><b>METHODS</b>CFs were isolated from neonatal SD rats by trypsin digestion and growth-arrested CFs were stimulated with Sim and/or MVA at varied concentrations for different time lengths, and the DNA synthesis in the cells was measured by (3)H-thymidine ((3)H-TdR) incorporation assay.</p><p><b>RESULTS</b>Sim decreased (3)H-TdR incorporation in the CFs in a concentration-dependent manner, and (3)H-TdR incorporation was significantly lower in cells treated with 1 x 10(-6) and 1 x 10(-5) mol/L Sim (1,175+/-202.66 and 771+/-164.86 cpm/2000 cells, respectively) than in the control cells (1,608+/-204.32 cpm/2000 cells, P<0.01). As the treatment time with 1 x 10(-5) mol/L Sim prolonged (for 6, 12, 18, 24, 36, 42, and 48 h), (3)H-TdR incorporation in CFs decreased gradually, showing an obvious inverse correlation with the treatment time (r=-919, P<0.01). (3)H-TdR incorporation in cells treated with 1 x 10(-6) to 1 x 10(-3) mol/L MVA and 1 x 10(-5) mol/L Sim rose steadily as MVA concentration increased. A significant difference in the incorporation was found between cells treated with both 1 x 10(-4)/1 x 10(-3) mol/L MVA and 1 x 10(-5) mol/L Sim (1,612+/-308.57 and 1,995+/-353.83 cpm/2000 cells, respectively) and the cells with 1 x 10(-5) mol/L Sim treatment alone (P<0.01); difference was also noted between cells treated with 1 x 10(-5) mol/L MVA and the control cells (P<0.05), but treatment with 1 x 10(-6) mol/L MVA did not produce much difference in comparison with the control cells (P>0.05) With the increase of treatment time (for 6, 12, 18, 24, 36, 42, 48 h), 1 x 10(-3) mol/L MVA caused steady increase in (3)H-TdR incorporation in the CFs, showing a significant positive correlation with the treatment time (r=0.968, P<0.01).</p><p><b>CONCLUSION</b>Sim can decrease DNA synthesis in rat CFs and postpone the occurrence of myocardial fibrosis, which can be reversed by MVA.</p>

Cloning and analysis of cDNA encoding key enzyme gene (dxr) of the non-MVA pathway in Taxus chinensis cells / 生物工程学报

Two distinct routes (classical mevalonate pathway and a novel mevalonate-independent pathway) are utilized by plants for the biosynthesis of isopentenyl diphosphate, the universal precursor of isoprenoids (Fig. 1). Present researches indicated that taxol was synthesized mainly via non-mevalonate pathway, but not genetic evidence was showed. The second step in non-mevalonate pathway involves an intramolecular rearrangement and subsequent reduction of deoxyxylulose phosphate to yield 2-C-methyl-D-erythritol-4-phosphate, and 1-Deoxy-D-xylulose-5-phosphate reductoisomerase (DXR) with responsibility for this reaction was considered as a key enzyme. As a tool for the isolation of genes in terpenoid biosynthesis in plants, total RNA was prepared from Taxus chinensis suspension cells, a cell type highly specialized for diterpene (taxol). A reverse transcription-PCR strategy based on the design of degenerated oligonucleotides was developed for isolating the gene encoding a gymnosperm homolog of this enzyme from Taxus chinensis. Through sequence analysis by Blast P online, the resulting cDNA showed highly homologous to 1-deoxy-D-xylulose 5-phosphate reductoisomerases, with 95% identification compared with Arabidopsis thaliana (Q9XFS9), 94% with Mentha x piperita (Q9XESO), 80% with Synechococcus elongatus (Q8DK30), 78% with Synechocystis sp. PCC 6803 (Q55663) and Nostoc sp. PCC 7120 (Q8YP49), and 73% with Synechococcus leopoliensis (Q9RKT1). Deduced amino acid sequences were also analyzed by PROSITE, ClustalX (1.81) and Phylio (3.6 alpha), and data present evidence for the existence of this deoxyxyluose phosphate reductoisomerase in Taxus chinensis. This is the first report of the dxr gene cloned from gymnosperm.

An overview of the non-mevalonate pathway for terpenoid biosynthesis in plants.

Terpenoids are known to have many important biological and physiological functions. Some of them are also known for their pharmaceutical significance. In the late nineties after the discovery of a novel non-mevalonate (non-MVA) pathway, the whole concept of terpenoid biosynthesis has changed. In higher plants, the conventional acetate-mevalonate (Ac-MVA) pathway operates mainly in the cytoplasm and mitochondria and synthesizes sterols, sesquiterpenes and ubiquinones predominantly. The plastidic non-MVA pathway however synthesizes hemi-, mono-, sesqui- and di-terpenes, along with carotenoids and phytol chain of chlorophyll. In this paper, recent developments on terpenoids biosynthesis are reviewed with respect to the non-MVA pathway.

Antiproliferative Effect of Lovastatin on Vascular Smooth Muscle Cell

BACKGROUND AND OBJECTIVES: This study was performed to investigate the antiproliferative effect of lovastatin on vascular smooth muscle cell, especially to determine whether lovastatin induces apoptosis in vascular smooth muscle cell and the products of mevalonate pathway can reverse the antiproliferative effect of lovastatin. METHODS AND MATERIALS: Lovastatin only and lovastatin with one of the products of mevalonate pathway such as isopentenyl adenine, farnesol, mevalonate, cholesterol were added respectively in cultured rat vascular smooth muscle cells stimulated with 10% fetal calf serum. DNA synthesis was measured by tritiated-thymidine incorporation. Cell number was determined by hemocytometric counting. Cells were Giemsa-stained to evaluate morphological changes of apoptosis. Extracted DNA from the cells treated with lovastatin was assessed by gel electrophoresis. RESULTS: 1)Lovastatin inhibited DNA synthesis and cell proliferation in a dose-dependent manner. 2)The inhibitory effects of lovastatin could be reversed almost completely by mevalonate, partially by farnesol. 3)Lovastatin-treated vascular smooth muscle cells showed typical morphological changes of apoptosis. 4)A distinct ladder of DNA bands was visualized by gel electrophoresis of the DNA from the cells treated with lovastatin. CONCLUSION: Mevalonate metabolism is essential for vascular smooth muscle cell proliferation. The antiproliferative effect of lovastatin may result from the induction of apoptosis in vascular smooth muscle cells.

Effect of mevalonate on in vitro reactivity of human lymphocytes stimulated by phytohemagglutinin, concanavalin A and pokeweed mitogen

Patients with mevalonic aciduria accumulate mevalonate in their and present unexplained crises of fever, lymphadenopathy, edema and mucocutaneous manifestations. In the present study, we investigated the action of mevalonate on in vitro proliferation of human lymphocytes unstimulated and stimulated by phytohemagglutinin (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM) in order to assess possible immunomodulatory activities which could explain these symptoms. The mitogen-induced lymphocyte response was evaluated from the extent of the incorporation of 3H-thymidine into cellular DNA in vitro. Our results show that mevalonate in doses up to 5 mM does not affect human lymphocyte transformation. Furthermore, mevalonate does not reverse the suppression of lymphocyte blastogenesis caused by cortisol (100 ng/ml). These results indicate that this compound or its metabolites do not affect directly lymphocyte responsiveness.

The Effect of Lovastatin(Mevacor(R)) in Patients with Hypercholesterolemia

Lovastatin is a potent inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, which catalyzes the conversion of hydroxymethylglutaryl-coenzyme A to mevalonate, anearly and rate-limiting step in the synthesis of cholesterol. We studied the therapeutic effect and safety of lovastatin in 18 patients with nonfamilial primary hypercholesterolemia. Patients received 20mg/day lovastatin therapy as a single evening dose. If the total cholesterol level exceeded 200mg/dl after 2weeks of lovastatin therapy, the dosage of lovastatin was doubled. Mean percent total cholesterol level reductions from baseline were 26.4% and 31.9% after 4, and 8 weeks of lovastatin therapy respectively. Mean percent HDL-cholesterol level increase from baseline were 12% and 13% after 4, and 8 weeks of lovastatin therapy respectively. Adverse effects attributable to lovastatin were mild and temporary and no patient was withdrawn from therapy. We concluded that lovastatin was a well tolerated and effective agent for the treatment of nonfamilial primary hypercholesterolemia. Further studies are needed to establish the long-term safety and effectiveness of this drug.