Purine synthesis de novo in cultured lymphoblast cells derived from patients with gout

Summary Rates of de novo purine synthesis in lymphoblast cell cultures derived from ten patients with gout were compared with those from control individuals. Since the rate of de novo purine synthesis was dependent on the growth rate of the culture, an assay procedure was developed to account for the variation in lymphoblast growth rates and to permit valid quantitative comparison between purine synthesis in each cell line. Clear differences were demonstrated between the rates of purine synthesis in cells from normal control subjects and those from patients with a deficiency of hypoxanthine-guanine phosphoribosyltransferase activity (HPRT-deficient). Lymphoblasts from the gouty patients showed purine synthesis either within the normal range or intermediate between this and the HPRT-deficient cells. In patients having normal renal function, de novo purine synthesis of lymphoblast cells correlated with the degree of urate production as reflected by the urinary excretion of urate over a 24 h period. Three patients, with demonstrable excessive production of urate in vivo, exhibited increased purine synthesis in lymphoblasts. This increased synthesis did not appear to result from any of the enzyme mutations currently recognized as responsible for abnormal purine metabolism.     

Management of gout and hyperuricemia: Multidisciplinary consensus in Taiwan

Gout is an inflammatory disease manifested by the deposition of monosodium urate (MSU) crystals in joints, cartilage, synovial bursa, tendons or soft tissues. Gout is not a new disease, which was first documented nearly 5,000 years ago. The prevalence of gout has increased globally in recent years, imposing great disease burden worldwide. Moreover, gout or hyperuricemia is clearly associated with a variety of comorbidities, including cardiovascular diseases, chronic kidney disease, urolithiasis, metabolic syndrome, diabetes mellitus, thyroid dysfunction, and psoriasis. To prevent acute arthritis attacks and complications, earlier use of pharmacotherapeutic treatment should be considered, and patients with hyperuricemia and previous episodes of acute gouty arthritis should receive long‐term urate‐lowering treatment. Urate‐lowering drugs should be used during the inter‐critical and chronic stages to prevent recurrent gout attacks, which may elicit gradual resolution of tophi. The goal of urate‐lowering therapy should aim to maintain serum uric acid (sUA) level <6.0 mg/dL. For patients with tophi, the initial goal can be set at lowering sUA to <5.0 mg/dL to promote tophi dissolution. The goal of this consensus paper was to improve gout and hyperuricemia management at a more comprehensive level. The content of this consensus paper was developed based on local epidemiology and current clinical practice, as well as consensuses from two multidisciplinary meetings and recommendations from Taiwan Guideline for the Management of Gout and Hyperuricemia.     

Purine metabolism in murine virus-induced erythroleukemic cells during differentiation in vitro.

Purine metabolism was studied in murine virus-induced erythroleukemia cells stimulated to differentiate in vitro in the presence of dimethylsulfoxide. The activities of the enzymes that catalyze the synthesis of the first intermediate of the de novo purine pathway, phosphoribosyl-1-amine, were decreased while the enzymes that catalyze the conversion of purine bases to purine ribonucleotides remained unchanged at the time the cells acquired the specialized function of hemoglobin synthesis. In addition, cytidine deaminase (cytidine aminohydrolase, EC 3.5.4.5) activity increased with erythropoietic maturation, as it does during murine erythropoiesis in vivo. Stimulation of cellular proliferation of stationary erythroleukemic cells resulted in a marked increase in the activities of purine biosynthetic enzymes. These data provide a convincing example of repression and derepression of the PRA synthesizing enzymes in mammalian cells in vitro, and further evidence that the regulatory mechanisms operative in the normal development of erythrocytes can be activated by exposure of erythroleukemic cells to dimethylsulfoxide.     

Overexpression of an unstably inherited gene in cultured mouse cells.

The specific activity of hypoxanthine-guanine phosphoribosyltransferase (IMP:pyrophosphate phosphoribosyltransferase, EC 2.4.2.8) is increased up to 58-fold in unstable gene transferents produced by the transfer of cell-free chromosomal material from one mouse L cell line to another; the specific activity of this enzyme returns to normal levels when the transferred gene becomes stabilized. This phenomenon, which is not observed in comparable heterospecific transfers, may be an effect of gene dosage (multiple copies of the transferred genetic fragment in the unstable gene transferents), or it may represent an escape of the unstably inherited gene from the normal regulatory mechanisms of the recipient cell.     

前言--重视老年高尿酸血症及痛风的防治(一)

原发性高尿酸血症和痛风是嘌呤代谢紊乱及(或)尿酸排泄减少所引起的一组代谢性疾病。其主要的临床特征为反复发作的关节炎、痛风石形成和痛风肾病等。痛风与高尿酸血症患者常伴有肥胖、高血压、糖代谢及脂代谢紊乱、凝血系统功能障碍等,这些疾病以胰岛素抵抗为其共同的病理生理     

The epidemiology of gout and hyperuricemia in a rural population of Java.

The prevalence of gout and hyperuricemia was investigated by a survey of a total population of 4683 rural adults. The successful response rate was 95.2%. Of the respondents 85.3% of the individuals were examined. The prevalence of gout and hyperuricemia in men was 1.7 and 24.3%, respectively. The male to female ratio was 34:1 for gout and 2:1 for hyperuricemia. The observed higher prevalence of gout and hyperuricemia in this male Malayo-Polynesian population compared with Caucasian data, in spite of a lower life expectancy and subsistence economy, suggests that genetic and racial predisposition are key causative factors.     

Difficult gout and new approaches for control of hyperuricemia in the allopurinol-allergic patient

A major obstacle to the treatment of hyperuricemia in patients allergic to allopurinol is the limited availability of suitable, equally effective, alternative, urate-lowering drugs. Conventional uricosuric drugs, including probenecid and sulfinpyrazone, are recommended for allopurinolintolerant patients with gout and “underexcretion” hyperuricemia who have normal renal function and no history of nephrolithiasis. Therapeutic options in those in whom traditional uricosuric drugs are contraindicated, ineffective, or poorly tolerated include slow oral desensitization to allopurinol and cautious administration of oxipurinol. Allopurinol desensitization is useful particularly in those who have failed other treatment modalities. If available (as in Europe, South Africa, and Japan), benzbromarone may be tried in patients with gout and mild-to-moderate renal insufficiency. Recombinant urate oxidase can be used in the short-term prophylaxis and treatment of chemotherapy-associated hyperuricemia in patients with lymphoproliferative and myeloproliferative disorders. Hyperuricemia and gout occur with increased frequency in cyclosporine-treated allograft transplant recipients. The management of gout in these patients is complicated by two main factors: cyclosporine-induced renal impairment, and interactions with medications used to preserve the allograft.     

Risk factors for gout developed from hyperuricemia in China: a five-year prospective cohort study

The aim of the study was to investigate the factors that promote the development of gout in Chinese patients with hyperuricemia. Chinese cohort with 659 patients with hyperuricemia who had no history of gout at base line had been followed up for 5 years. The baseline data of the general states (gender, age, occupation and education level), lifestyle and behavior (smoking, drinking, and diet), the major chronic diseases (diabetes and hypertension), family history and gout attacks, physical examination (height, weight and blood pressure), and blood parameters (creatinine, urea nitrogen, triglycerides, total cholesterol and high-density lipoprotein cholesterol) were recorded before the follow-up. Over the five-year period, 75 hyperuricemia patients developed gout. In the logistic regression model, shrimp intake and shell intake were the risk factors (P = 0.038 and P < 0.001, respectively) and, combined with diabetes, also served as risk factor for gout developed from hyperuricemia, with relative risk (RR) of 2.571 (95 % confidence interval (95 % CI), 1.110–5.953), and females served as protective factors of gout, with RR of 0.113 (95 % CI, 0.041–0.312, referred to male). We identified that shrimp intake and shell intake, combined with diabetes, were the independent risk factors, and females served as protective factors of gout in those suffering from hyperuricemia in coast regions of Shandong province, China.     

Intracellular activity of HPRTCape Town: Purine uptake and growth of cultured cells in selective media

The low activity of the human variant HPRT_{Cape Town} is associated with substrate inhibition by hypoxanthine and guaninein vitro. The intracellular activity of this variant was investigated by studying the relative uptake or radiolabelled purine nucleotide precursors and the growth in selective media of EBvirus-transformed lymphoblasts prepared from the proband (TK). These cells incorporated less than 10% of the [¹⁴C]hypoxanthine and [¹⁴C]guanine of the control cells; while their purinede novo synthesis was accelerated 8-fold. In selective media the HPRT_CapeTown cells grew in a similar manner to HPRT-ve cells. These results indicate that if substrate inhibition is responsible for the low intracellular activity of HPRT_{Cape Town}, the concentration of either hypoxanthine or guanine in the vicinity of the active site of the enzyme must be greater than theK _i(app) for these substrates, 118 and 28 µmol L^–1 respectively. Evidence is presented that the intracellular concentration of guanine, but not hypoxanthine, is well in excess of theK _i(app) in cultured lymphoblasts.     

Purine metabolism in cultured human fibroblasts derived from patients deficient in hypoxanthine phosphoribosyltransferase, purine nucleoside phosphorylase, or adenosine deaminase.

Rates of purine synthesis de novo, as measured by the incorporation of [14C]formate into newly synthesized purines, have been determined in cultured human fibroblasts derived from normal individuals and from patients deficient in adenosine deaminase, purine nucleoside phosphorylase, or hypoxanthine phosphoribosyltransferase, three consecutive enzymes of the purine salvage pathway. All four types of cell lines are capable of incorporating [14C]formate into purines at approximately the same rate when the assays are conducted in purine-free medium. The purine overproduction that is characteristic of a deficiency in either the transferase or the phosphorylase and that results from a block in purine reutilization can be demonstrated by the resistance of [14C]formate incorporation into purines to inhibition by hypoxanthine in the case of hypoxanthine phosphoribosyltransferase-deficient fibroblasts and by resistance to inhibition by inosine in the case of purine nucleoside phosphorylase-deficient fibroblasts.     

Induction of antitumour immunity using survivin peptide-pulsed dendritic cells in a murine lymphoma model

Survivin is overexpressed in several types of haematological malignancies making it an attractive target for therapeutic cytotoxic T-lymphocyte responses. Here, we identify two peptide epitopes derived from the murine survivin protein and demonstrate that Balb/c mice treated with syngeneic dendritic cells pulsed with the survivin epitopes were able to reject an otherwise lethal tumour inoculation of the A20 lymphoma. For the first time, these data provide evidence for the use of survivin peptide epitopes in T cell-based immunotherapeutic concepts against a B-cell lymphoma in vivo.     

中国高尿酸血症与痛风诊疗指南(2019)

近年来,中国高尿酸血症与痛风患病率急剧增加,亟需制订基于国人研究证据的临床循证指南。为此,中华医学会内分泌学分会遵循国际通用GRADE分级方法,采用临床循证指南制订流程,由方法学家在内的多学科专家参与制订了本指南。本指南包含3条推荐总则和针对10个临床问题的推荐意见,涵盖了高尿酸血症与痛风的诊断、治疗和管理;首次提出了亚临床痛风、难治性痛风的概念和诊治意见;首次对碱化尿液相关问题进行了推荐;首次对痛风常见合并症药物选择进行了推荐。本指南旨在为临床医生和相关从业者对高尿酸血症与痛风的诊疗决策提供最佳依据。     

Steroid receptors and steroid response in cultured L1210 murine leukemia cells.

Murine L1210 leukemia cells were cultured in the presence of various steroid hormones to determine their growth response. Cells maintained in medium containing glucocorticoids such as dexamethasone exhibit a 10--20% inhibition of growth, whereas progesterone of 17 beta estradiol produce a 40--50% inhibition of growth. The response is due to growth inhibition and not to any cytolytic effect of the steroids. L1210 cytoplasmic and nuclear extracts contain high affinity binding sites for [3H]dexamethasone, [3H]progesterone and [3H]17 beta-estradiol. Competition with various steroids indicate that estrogens bind to one class of cytoplasmic binding sites, while glucocorticoids and progestins bind to a second class of receptor sites. These receptors appear not be be completely responsible for growth inhibition since there is no correlation between the magnitude of growth inhibition and the intracellular concentration of receptor sites, and since the concentration of steroid required to cause significant growth inhibition exceeds those concentrations required to saturate the cytoplasmic receptors.     

Comorbidities of gout and hyperuricemia in the US general population: NHANES 2007-2008

PurposeThe objective of this study was to estimate the latest prevalence of major comorbidities associated with gout and hyperuricemia in the US based on a recent, nationally representative sample of US men and women.MethodsUsing data from 5707 participants aged 20 years and older in the National Health and Nutrition Examination Survey 2007-2008, we calculated the national prevalence and population estimates of major comorbidities according to gout status and various hyperuricemia levels, compared with those without these conditions. Case definitions of gout and comorbidities were based on an affirmative answer to a question that asked whether a physician or a health professional had diagnosed the corresponding condition.ResultsAmong these individuals with gout, 74% (6.1 million) had hypertension, 71% (5.5 million) had chronic kidney disease stage ≥2, 53% (4.3 million) were obese, 26% (2.1 million) had diabetes, 24% (2.0 million) had nephrolithiasis, 14% (1.2 million) had myocardial infarction, 11% (0.9 million) had heart failure, and 10% (0.9 million) had suffered a stroke. These proportions were substantially higher than those among individuals without gout (all P-values <.67). With increasing levels of hyperuricemia, there were graded increases in the prevalences of these comorbidities. In the top category (serum urate ≥10 mg/dL), 86% of subjects had chronic kidney disease stage ≥2, 66% had hypertension, 65% were obese, 33% had heart failure, 33% had diabetes, 23% had myocardial infarction, and 12% had stroke. These prevalences were 3-33 times higher than those in the lowest serum urate category (<4 mg/dL). Sex-specific odds ratios tended to be larger among women than men, and the overall comorbidity prevalence was highest among individuals with both gout and hyperuricemia.ConclusionsThese findings from the latest nationally representative data highlight remarkable prevalences and population estimates of comorbidities of gout and hyperuricemia in the US. Appropriate preventive and management measures of these comorbidities should be implemented in gout management, with a preference to strategies that can improve gout and comorbidities together.