Pathogenesis of hyperuricemia: recent advances

Pharmacological activities and mechanisms of action of hypophyllanthin: A review

Hypophyllanthin is a major lignan present in various Phyllanthus species and has been used as one of the bioactive chemical markers for quality control purposes as it contributes to their diverse pharmacological activities. The objective of this study is to compile up-to-date data on the pharmacological actions and mechanisms of hypophyllanthin. This review also includes the extracts of Phyllanthus species whose pharmacological actions have been partially attributed to hypophyllanthin. The scientific findings on the compound are critically analyzed and its potential as a lead molecule for the discovery of drug candidates for the development of therapeutics to treat diverse diseases is highlighted. Data collection was mainly through the exploration of Ovid-MEDLINE, Scopus, Science Direct, and Elsevier databases. Studies conducted in vitro and in vivo showed that hypophyllanthin had potent immunomodulating properties as well as a variety of other pharmacological properties, including anti-inflammatory, hepatoprotective, anti-tumor, anti-allergic, anti-hypertensive, and phytoestrogenic properties. Several mechanisms of action on the effects of hypophyllanthin on the immune system, in cancer and other disease states, were presented to provide some insights into its pharmacological effects. Before being submitted to clinical investigations, additional animal studies utilising different animal models are necessary to analyse its bioavailability, pharmacokinetics, and pharmacodynamic properties, as well as its toxicity, to determine its efficacy and safety. Understanding its potential as a lead molecule for the discovery of therapeutic candidates, particularly for the development of therapies for inflammatory and immune-related disorders, requires an understanding of its pharmacological activities and mechanisms of action. An insight into its pharmacological activities and mechanisms of action will provide an understanding of its potential as a lead compound for the discovery of drug candidates, especially for the development of therapies for inflammatory and immune related diseases.

Probiotics, bioactive compounds and dietary patterns for the effective management of hyperuricemia: a review

Hyperuricemia is closely linked with an increased risk of developing hypertension, diabetes, renal failure and other metabolic syndromes. Probiotics, bioactive compounds and dietary patterns are safe cost-efficient ways to control hyperuricemia, whereas comprehensive reviews of their anti-hyperuricemic mechanisms are limited. This review summarizes the roles of probiotics, bioactive compounds and dietary patterns in treating hyperuricemia and critically reviews the possible mechanisms by which these interventions exert their activities. The dietary patterns are closely related to the occurrence of hyperuricemia through the indirect action of gut microbiota or the direct effects of host purine metabolism. The Mediterranean and Dietary Approaches to Stop Hypertension diets help reduce serum uric acid concentrations and thus prevent hyperuricemia. Meanwhile, probiotics alleviate hyperuricemia by ways of absorbing purine, restoring gut microbiota dysbiosis and inhibiting xanthine oxidase (XO) activity. Bioactive compounds such as polyphenols, peptides and alkaloids exert various anti-hyperuricemic effects, by regulating urate transporters, blocking the active sites of XO and inhibiting the toll-like receptor 4/nuclear factor kappa B signaling pathway and NOD-, LRR- and pyrin domain-containing protein 3 signaling pathway. This review will assist people with hyperuricemia to adopt a healthy diet and contribute to the application of natural products with anti-hyperuricemic activity.

The chemistry, processing, and preclinical anti-hyperuricemia potential of tea: a comprehensive review

Hyperuricemia is an abnormal purine metabolic disease that occurs when there is an excess of uric acid in the blood, associated with cardiovascular diseases, hypertension, gout, and renal disease. Dietary intervention is one of the most promising strategies for preventing hyperuricemia and controlling uric acid concentrations. Tea (Camellia sinensis) is known as one of the most common beverages and the source of dietary polyphenols. However, the effect of tea on hyperuricemia is unclear. Recent evidence shows that a lower risk of hyperuricemia is associated with tea intake. To better understand the anti-hyperuricemia effect of tea, this review first briefly describes the pathogenesis of hyperuricemia and the processing techniques of different types of tea. Next, the epidemiological and experimental studies of tea and its bioactive compounds on hyperuricemia in recent years were reviewed. Particular attention was paid to the anti-hyperuricemia mechanisms targeting the hepatic uric acid synthase, renal uric acid transporters, and intestinal microbiota. Additionally, the desirable intake of tea for preventing hyperuricemia is provided. Understanding the anti-hyperuricemia effect and mechanisms of tea can better utilize it as a preventive dietary strategy.HighlightsHigh purine diet, excessive alcohol/fructose consumption, and less exercise/sleep are the induction factors of hyperuricemia.Tea and tea compounds showed alleviated effects for hyperuricemia, especially polyphenols.Tea (containing caffeine or not) is not associated with a higher risk of hyperuricemia.Xanthine oxidase inhibition (reduce uric acid production), Nrf2 activation, and urate transporters regulation (increase uric acid excretion) are the potential molecular targets of anti-hyperuricemic effect of tea.About 5 g tea intake per day may be beneficial for hyperuricemia prevention.

Prediction model of random forest for the risk of hyperuricemia in a Chinese basic health checkup test

Objectives: The present study aimed to develop a random forest (RF) based prediction model for hyperuricemia (HUA) and compare its performance with the conventional logistic regression (LR) model. Methods: This cross-sectional study recruited 91,690 participants (14,032 with HUA, 77,658 without HUA). We constructed a RF-based prediction model in the training sets and evaluated it in the validation sets. Performance of the RF model was compared with the LR model by receiver operating characteristic (ROC) curve analysis. Results: The sensitivity and specificity of the RF models were 0.702 and 0.650 in males, 0.767 and 0.721 in females. The positive predictive value (PPV) and negative predictive value (NPV) were 0.372 and 0.881 in males, 0.159 and 0.978 in females. AUC of the RF models was 0.739 (0.728–0.750) in males and 0.818 (0.799–0.837) in females. AUC of the LR models were 0.730 (0.718–0.741) for males and 0.815 (0.795–0.835) for females. The predictive power of RF was slightly higher than that of LR, but was not statistically significant in females (Delong tests, P=0.0015 for males, P=0.5415 for females). Conclusion: Compared with LR, the good performance in HUA status prediction and the tolerance of features associations or interactions showed great potential of RF in further application. A prospective cohort is necessary for HUA developing prediction. People with high risk factors should be encouraged to actively control to reduce the probability of developing HUA.

Geographical distribution of hyperuricemia in mainland China: a comprehensive systematic review and meta-analysis

BACKGROUND

Fructose plays an important role in the complex metabolism of uric acid in the human body. However, high blood uric acid concentration, known as hyperuricemia, is the main risk factor for development of gout. Therefore, we conducted an updated meta-analysis on the prevalence and geographical distribution of hyperuricemia among the general population in mainland China using systematic literature search.

METHODS

Five electronic databases were used to search for relevant articles published until 2019. All calculations were conducted using the Comprehensive Meta-Analysis (CMA) software. We included 108 eligible articles (172 studies by sex, 95 studies by regions, and 107 studies by study type) and an overall sample size of > 808,505 participants.

RESULTS

The pooled prevalence of hyperuricemia among the general population in mainland China was 17.4% (95% CI: 15.8-19.1%). Our subgroup analysis indicated that the pooled prevalence by regions ranged from 15.5 to 24.6%. Those living Northeast region and being males had the highest prevalence (P < 0.001). In addition, some provinces in South Central, East and Northeast regions reported a high prevalence (> 20%), particularly in males. An increasing prevalence was reported since 2005-2009 until 2015-2019. No publication of bias was observed as indicated by a symmetrical funnel plot and Begg and Mazumdar rank correlation (P = 0.392).

CONCLUSION

Prevalence of hyperuricemia is increasing in China, and future studies should investigate the association between the prevalence of hyperuricemia and its risk factors in order to tackle the issue, particularly among the vulnerable groups. Also, our study was the first comprehensive study to investigate the overall prevalence of hyperuricemia in mainland China covering the six different regions.

Therapeutic Efficacy of Urinile Against Gouty Arthritis

Gout is arthritis caused due to Monosodium urate (MSU) crystals deposition occurring particularly in patients with associated comorbidities limiting the use of conventional therapies. This study was planned to evaluate the therapeutic efficacy of urinile (a herbal drug) for the treatment of gouty arthritis. Allopurinol was used as standard drug (positive control). The study population of 250 volunteers (gouty arthritis patients) were divided into 2 groups as test and control group (n = 125 each). Gouty arthritis patients in test and control group were treated with 300 mg each of urinile and allopurinol, respectively. Clinical symptoms of all the study volunteers were recorded and serum uric acid was determined. Significant (p < 0.05) reduction in serum uric acid level toward normal was found in test group individuals. Clinical symptoms of gouty arthritis patients were also improved in test group compared to control group. Results showed that urinile has the potential to decrease serum uric acid level in gouty arthritis patients probably because of its antioxidant potential and xanthine oxidase inhibitory activity. It can be concluded that the tested herbal drug urinile is more potent in treating gouty arthritis patients and can be used as an effective alternative to the most commonly used allopathic drugs.

Effects of resveratrol on the inflammatory response and renal injury in hyperuricemic rats

BACKGROUND/OBJECTIVES

Hyperuricemic nephropathy is a common cause of acute kidney injury. Resveratrol can ameliorate kidney injury, but the explicit mechanism remains unclear. We investigated the effects of resveratrol on the inflammatory response and renal injury in hyperuricemic rats.

MATERIALS/METHODS

A rat model of hyperuricemic nephropathy was established by the oral administration of a mixture of adenine and potassium oxinate. Biochemical analysis and hematoxylin and eosin staining were performed to assess the rat kidney function. Enzyme-linked immunosorbent assays were performed to evaluate the immune and oxidative responses.

RESULTS

The expression levels of urine albumin and β2-microglobulin were significantly decreased after resveratrol treatment. In addition, the levels of serum creatinine and uric acid were significantly decreased in the resveratrol groups, compared with the control group. The levels of proinflammatory factors, such as interleukin-1β and tumor necrosis factor-α, in kidney tissue and serum were also increased in the hyperuricemic rats, and resveratrol treatment inhibited their expression. Moreover, the total antioxidant capacity in kidney tissue as well as the superoxide dismutase and xanthine oxidase levels in serum were all decreased by resveratrol treatment.

CONCLUSIONS

Resveratrol may protect against hyperuricemic nephropathy through regulating the inflammatory response.

Flavonoids and phenylethanoid glycosides from Lippia nodiflora as promising antihyperuricemic agents and elucidation of their mechanism of action

ETHNOPHARMACOLOGICAL RELEVANCE

Lippia nodiflora has been traditionally used in the Ayurvedic, Unani, and Sidha systems, as well as Traditional Chinese Medicine (TCM) for the treatment of knee joint pain, lithiasis, diuresis, urinary disorder and swelling.

AIM OF THE STUDY

The present study aims to investigate the antihyperuricemic effect of the L. nodiflora methanol extract, fractions, and chemical constituents and their mechanism of action in the rat model.

MATERIALS AND METHODS

The mechanisms were investigated by performing xanthine oxidase inhibitory, uricosuric, and liver xanthine oxidase/xanthine dehydrogenase (XOD/XDH) inhibitory studies in potassium oxonate- and hypoxanthine-induced hyperuricemic rats. The plant safety profile was determined using acute toxicity study. The molecular docking of the active compound to the xanthine oxidase was simulated using computer aided molecular modeling analysis.

RESULTS

Oral administration of methanol extract showed a dose-dependent reduction effect on the serum uric acid level of hyperuricemic rats. F3 was the most potent fraction in lowering the serum uric acid level of hyperuricemic rats. Bioactivity-guided purification of F3 afforded two phenylethanoid glycosides, arenarioside (1) and verbascoside (2) and three flavonoids, 6-hydroxyluteolin (3), 6-hydroxyluteolin-7-O-glycoside (4), and nodifloretin (5). The highest serum uric acid reduction effect was exhibited by 3 (66.94%) in hyperuricemic rats, followed by 5 (55.97%), 4 (49.16%), 2 (29.03%), and 1 (22.08%) at 0.2 mmol/kg. Dose-response investigation on 3 at doses of 0.05, 0.1, and 0.3 mmol/kg produced a significant dose-dependent reduction on the serum uric acid level of hyperuricemic rats. Repeated administration of F3 or 3 to the hyperuricemic rats for 10 continuous days resulted in a significant and progressive serum uric acid lowering effect in hyperuricemic rats. In contrast, methanol extract and F3 did not reduce serum uric acid level of normoruricemic rats. In addition, F4 significantly increased the uric acid excretion of hyperuricemic rats at 200mg/kg. No toxic effect was observed in rats administered with 5000 mg/kg of methanol extract or F3.

CONCLUSION

The potential application of L. nodiflora against hyperuricemia in the animal in accordance with its traditional uses has been demonstrated in the present study for the first time. The antihyperuricemic effect possessed by L. nodiflora was contributed mainly by liver XOD/XDH inhibitory activities and partially by uricosuric effect. Flavonoids mainly accountable for the uric acid lowering effect of L. nodiflora through the inhibition of XOD/XDH activities.

Prevalence of Hyperuricemia and Gout in Mainland China from 2000 to 2014: A Systematic Review and Meta-Analysis

We systematically identified the prevalence of hyperuricemia and gout in mainland China and provided informative data that can be used to create appropriate local public health policies. Relevant articles from 2000 to 2014 were identified by searching 5 electronic databases: PubMed, Google Scholar, Chinese Wanfang, CNKI, and Chongqing VIP. All of the calculations were performed using the Stata 11.0 and SPSS 20.0 software. The eligible articles (n = 36; 3 in English and 33 in Chinese) included 44 studies (38 regarding hyperuricemia and 6 regarding gout). The pooled prevalence of hyperuricemia and gout was 13.3% (95% CI: 11.9%, 14.6%) and 1.1% (95% CI: 0.7%, 1.5%), respectively. Although publication bias was observed, the results did not change after a trim and fill test, indicating that that impact of this bias was likely insignificant. The prevalence of hyperuricemia and gout was high in mainland China. The subgroup analysis suggested that the geographical region, whether the residents dwell in urban or rural and coastal or inland areas, the economic level, and sex may be associated with prevalence.

In vitro Xanthine Oxidase Inhibitory Studies of Lippia nodiflora and Isolated Flavonoids and Phenylethanoid Glycosides as Potential Uric Acid-lowering Agents

Lippia nodiflora has been traditionally used for treatment of knee joint pain. Hitherto, no studies have been reported on the effective use of L. nodiflora against hyperuricemia, gout or other metabolic disorders. In this present study, L. nodiflora was examined for its ability to lower uric acid levels using an in vitro xanthine oxidase inhibitory assay. The whole plant methanolic extract was subjected to bioactivity-guided fractionation to yield 4 fractions (F1–F4). F3 displayed the highest potency and was further purified by column chromatography to afford two phenylethanoid glycosides, arenarioside (1) and verbascoside (2), and three flavonoids, 6-hydroxyluteolin (3), 6-hydroxyluteolin-7- O-glycoside (4), and nodifloretin (5). These compounds inhibited xanthine oxidase activity, with IC50 values between 7.52 ± 0.01 and 130.00 ± 2.25 μM, of which 3 was the most potent. In contrast, allopurinol, serving as a positive control, was 0.22 ± 0.00 μM. Thus, L. nodiflora, and its chemical constituents are worthy of further studies as potential anti-hyperuricemic agents.

Uric acid in heart disease: a new C-reactive protein?

PURPOSE OF REVIEW

To review and interpret the recently published data on hyperuricemia and cardiovascular disease to present an opinion on the nature of link between serum uric acid concentration and the risk for cardiovascular outcomes, and to comment on its implications for clinical practice.

RECENT FINDINGS

Evidence has accumulated in prospective observational studies that link hyperuricemia among younger adults with the risk of subsequent hypertension. Such associations have been observed with respect to insulin resistance, diabetes, and other cardiovascular risk factors. Newer data confirm the link between hyperuricemia and cardiovascular mortality. The use of allopurinol has been shown to be associated with reduced mortality risk in longer term observational studies and with reduced blood pressure in short-term randomized controlled trials. None of these findings is confounded by traditional risk factors.

SUMMARY

The available evidence has established a link between hyperuricemia and cardiovascular disease and this may be causal. Without waiting for the resolution of causality arguments, one can start using serum uric acid concentration as an inexpensive cardiovascular risk marker.

The dual actions of Sanmiao wan as a hypouricemic agent: down-regulation of hepatic XOD and renal mURAT1 in hyperuricemic mice

ETHNOPHARMACOLOGICAL RELEVANCE

Sanmiao wan (SMW) is widely used for the treatment of gout and hyperuricemia in traditional Chinese medicine.

AIM OF THE STUDY

The aim of the present study was to investigate the hypouricemic effects of SMW and its possible mechanism in potassium oxonate-induced hyperuricemic mice.

MATERIALS AND METHODS

SMW at 489, 978 and 1956 mg/kg was orally administered to hyperuricemic and normal mice, and standard drug allopurinol (2.5mg/kg) was served as a positive control. The effects of SMW on serum, urine and liver levels of uric acid, serum levels of creatinine, and activity of hepatic xanthine oxidase (XOD) were measured in mice. Moreover, the effects of SMW on the mRNA and protein levels of hepatic XOD and renal urate transporter 1 (mURAT1) in mice were analyzed by semi-quantitative RT-PCR and Western blotting methods, respectively.

RESULTS

SMW significantly reduced uric acid levels in serum and liver, inhibited hepatic XOD activity, mRNA and protein levels in hyperuricemic mice. Furthermore, SMW could effectively down-regulate renal mURAT1 mRNA and protein levels of hyperuricemic mice. And it reversed oxonate-induced elevation in serum creatinine levels of mice. However, SMW did not show any effects in normal mice.

CONCLUSION

These findings suggested that SMW produced dual hypouricemic actions by suppressing hepatic XOD to reduce uric acid production and down-regulating renal mURAT1 to decrease urate reabsorption and enhance urate excretion in hyperuricemic mice.

Hyperuricemia and its related factors in an urban population, Izmir, Turkey

The aim of this study was to examine the prevalence of hyperuricemia and its associated factors in an urban area of Izmir, located in western Turkey. Our study group was selected by computerized sampling from the participants of a larger population-based study searching for the prevalence of rheumatoid arthritis in Balcova and Narlidere districts of Izmir. A total of 132 subjects (69 women and 63 men) were included in this study. Serum uric acid, glucose, creatinine and lipid levels were studied. Body composition along with body fat percentage was determined anthropometrically. A total of 16 subjects had hyperuricemia (4 women and 12 men). The overall prevalence of hyperuricemia was 12.1% and the mean uric acid level was 4.9 +/- 1.3 mg/dl. Males had significantly higher uric acid levels than females (P < 0.05; 5.5 +/- 1.3 vs. 4.3 +/- 1.1 mg/dl, respectively). The prevalence of hypertension, diabetes, obesity and metabolic syndrome was 24.4, 5.3, 28 and 26.5%, respectively. There was no gouty subject. Sum of skinfold thickness (SFT) measurements and creatinine levels were the independent predictors of hyperuricemia (beta = 0.45, 0.47, respectively). Uric acid measurement is important not only for inflammatory rheumatic disorders but also for predicting metabolic syndrome and related coronary artery disease. There is sex difference in uric acid levels in favor of women most probably explained by gonadal hormones. Hyperuricemia is significantly predicted by anthropometric measure of SFT which is a simple clinical screening method along with creatinine levels.

[Molecular basis of primary renal hyperuricemia : role of the human urate transporter hURAT1]

In highly industrialized countries hyperuricemia is one of the most common metabolic disorders. High uric acid blood levels may lead to the manifestation of gout owing to the precipitation of urate crystals in connective tissue, the skeletal system and kidneys. A primary reduction of renal uric acid excretion can be detected in more than 90% of all cases of hyperuricemia. Despite the identification of several uric acid transporting proteins their pathogenetic role for the induction of primary reduced renal uric acid excretion has not yet been verified. As a result of a case-control study on individuals with normal and reduced renal uric acid excretion, an association of polymorphisms in the human urate transporter 1 gene (hURAT1) with primary reduced urate excretion has been demonstrated for the first time. The hURAT1 gene is an organic anion transporter (SLC22A12), which is preferentially expressed in the apical membrane of proximal renal tubule cells. Functioning as an antiporter, hURAT1 mediates the uptake of urate from the lumen into proximal tubule cells in exchange for organic and inorganic anions. Loss-of-function mutations in the hURAT1 gene are a cause of hereditary renal hypouricemia. The precisely regulated hURAT1 is a candidate gene for hyperuricemia and an important target for the development and optimization of new diagnostic approaches and pharmacological interventions of primary reduced renal uric acid excretion.

Change in serum uric acid between baseline and 1-year follow-up and its associated factors in male subjects

A number of cross-sectional analysis studies have been conducted to determine the relationships between serum uric acid and related variables or clinical manifestations. However, few data related to changes in serum uric acid within the same cohort population at two separate periods of time have been reported. In this study, we investigated the changes in serum uric acid in a population from baseline to 1-year follow-up and examined the associations with related parameters and medical conditions. A total of 1,437 eligible male subjects who underwent 2 medical examinations at a health promotion center at an interval of approximately 12 months were enrolled in this study. Data were obtained from routine physical assessments such as blood pressure, height, waist circumference, blood analyses for liver function, renal function, lipid profile, and electrolytes, along with standardized questionnaires including self-reported data. In this population, serum uric acid was significantly increased at 1-year follow-up compared with the baseline level (5.94 +/- 1.20 vs 5.99 +/- 1.22, p = 0.003). Changes of some confounders such as total bilirubin, creatinine, BUN, phosphorus, total cholesterol, and triglyceride were significantly associated with changes in serum uric acid. Among them, serum creatinine may be the most influential in determining the serum uric acid level (odds ratio = 21.691, 95%CI = 5.110-92.086). A change of serum uric acid over 1 year did not seem to affect changes in the clinical status for some medical conditions including hypertension, diabetes mellitus, cardiovascular disease, and metabolic syndrome. This analysis showed that a change in serum creatinine level between baseline and 1-year follow-up might be the most potent factor affecting a change in serum uric acid in healthy, male subjects. Changes of serum uric acid did not show any meaningful impact on the development of hypertension, heart failure, diabetes mellitus, and metabolic syndrome in this 1-year follow-up study.

Effect of fenofibrate in combination with urate lowering agents in patients with gout

BACKGROUND

To assess the efficacy of fenofibrate treatment in combination with urate lowering agents in patients with gout.

METHODS

Fourteen male patients with chronic tophaceous or recurrent acute attacks of gout were evaluated in an open-label pilot study of the hypolipidemic agent, fenofibrate (Lipidil Supra 160 mg/d). Patients were stable on urate lowering agents (allopurinol or benzbromarone) for > or = three months without acute attack for the most recent one month before participating. All patients were being treated with established doses of urate lowering agents without modification throughout the study. Clinical and biochemical assessments including serum uric acid, creatinine, liver function test and fasting serum lipid were measured at (1) baseline (2) after two months of fenofibrate treatment and (3) two months after fenofibrate was withdrawn.

RESULTS

Serum uric acid was lowered by 23% after two months of fenofibrate treatment (6.93 +/- 2.16 vs. 5.22 +/- 1.16 mg/dL; p = 0.016). Triglyceride levels were also reduced after fenofibrate treatment (p = 0.001). However, this effect was reversed after the withdrawal (p = 0.002) of the drug. Alkaline phosphatase was reduced after fenofibrate treatment (p = 0.006), but increased 21% after the withdrawal of the drug (p = 0.002). By contrast, serum levels of high density lipoprotein and creatinine were increased 9% (p = 0.018) and 12% (p = 0.006), respectively; however, both levels were significantly decreased to the baseline levels upon withdrawal of fenofibrate.

CONCLUSIONS

Fenofibrate can effectively reduce uric acid levels in addition to its known hypolipidemic effect. Fenofibrate may be used as a potential urate lowering agent in patients with gout, especially in those with coexisting hyperlipidemia.

Development of a new reporter gene system--dsRed/xanthine phosphoribosyltransferase-xanthine for molecular imaging of processes behind the intact blood-brain barrier

We report the development of a novel dual-modality fusion reporter gene system consisting of Escherichia coli xanthine phosphoribosyltransferase (XPRT) for nuclear imaging with radiolabeled xanthine and Discosoma red fluorescent protein for optical fluorescent imaging applications. The dsRed/XPRT fusion gene was successfully created and stably transduced into RG2 glioma cells, and both reporters were shown to be functional. The level of dsRed fluorescence directly correlated with XPRT enzymatic activity as measured by ribophosphorylation of [14C]-xanthine was in vitro (Ki = 0.124 +/- 0.008 vs. 0.00031 +/- 0.00005 mL/min/g in parental cell line), and [*]-xanthine octanol/water partition coefficient was 0.20 at pH = 7.4 (logP = -0.69), meeting requirements for the blood-brain barrier (BBB) penetrating tracer. In the in vivo experiment, the concentration of [14C]-xanthine in the normal brain varied from 0.20 to 0.16 + 0.05% dose/g under 0.87 + 0.24% dose/g plasma radiotracer concentration. The accumulation in vivo in the transfected flank tumor was to 2.4 +/- 0.3% dose/g, compared to 0.78 +/- 0.02% dose/g and 0.64 +/- 0.05% dose/g in the control flank tumors and intact muscle, respectively. [14C]-Xanthine appeared to be capable of specific accumulation in the transfected infiltrative brain tumor (RG2-dsRed/XPRT), which corresponded to the 585 nm fluorescent signal obtained from the adjacent cryosections. The images of endogenous gene expression with the "sensory system" have to be normalized for the transfection efficiency based on the "beacon system" image data. Such an approach requires two different "reporter genes" and two different "reporter substrates." Therefore, the novel dsRed/XPRT fusion gene can be used as a multimodality reporter system in the biological applications requiring two independent reporter genes, including the cells located behind the BBB.