Characterization of four new cycloartane triterpenoids from Swietenia macrophylla and their angiotensin-I-converting enzyme inhibitory activity.

Angiotensin I-converting enzyme (ACE) inhibition is currently a common method for the treatment and control of hypertension. In this study, four new (1-4) and one known (5) cycloartane triterpenoids were isolated from the leaves of Swietenia macrophylla by chromatographic techniques and identified by their spectroscopic data and a comprehensive comparison of published data. The triterpenoids were evaluated for their ACE inhibitory potential using in vitro inhibition assays and in silico methods. The inhibition assay and enzyme kinetics results showed that the most active triterpenoid, compound 4, inhibited ACE in a mixed-type manner with an IC50 value of 57.7 ± 6.07 µM. Computer simulations revealed that compound 4 reduces the catalytic efficiency of ACE by competitive insertion into the active pocket blocking the substrate, and the binding activity occurs mainly through hydrogen bonds and hydrophobic interactions. The study showed that S. macrophylla can be a source of bioactive material and the ACE inhibitory triterpenoid could be a potential antihypertensive agent.

The Beneficial Role of Photobiomodulation in Neurodegenerative Diseases.

Photobiomodulation (PBM), also known as Low-level Laser Therapy (LLLT), involves the use of light from a laser or light-emitting diode (LED) in the treatment of various disorders and it has recently gained increasing interest. Progressive neuronal loss with attendant consequences such as cognitive and/or motor decline characterize neurodegenerative diseases. The available therapeutic drugs have only been able to provide symptomatic relief and may also present with some side effects, thus precluding their use in treatment. Recently, there has been an exponential increase in interest and attention in the use of PBM as a therapy in various neurodegenerative diseases in animal studies. Because of the financial and social burden of neurodegenerative diseases on the sufferers and the need for the discovery of potential therapeutic inventions in their management, it is pertinent to examine the beneficial effects of PBM and the various cellular mechanisms by which it modulates neural activity. Here, we highlight the various ways by which PBM may possess beneficial effects on neural activity and has been reported in various neurodegenerative conditions (Alzheimer's disease, Parkinson's disease, epilepsy, TBI, stroke) with the hope that it may serve as an alternative therapy in the management of neurodegenerative diseases because of the biological side effects associated with drugs currently used in the treatment of neurodegenerative diseases.

Experience from a Singapore tertiary hospital with restructuring of a vascular surgery practice in response to national and institutional policies during the COVID-19 pandemic.

Singapore was one of the first countries to be affected by COVID-19, with the index patient diagnosed on January 23, 2020. For 2 weeks in February, we had the highest number of COVID-19 cases behind China. In this article, we summarize the key national and institutional policies that were implemented in response to COVID-19. We also describe in detail, with relevant data, how our vascular surgery practice has changed because of these policies and COVID-19. We show that with a segregated team model, the vascular surgery unit can still function while reducing risk of cross-contamination. We explain the various strategies adopted to reduce outpatient and inpatient volume. We provide a detailed breakdown of the type of vascular surgical cases that were performed during the COVID-19 pandemic and compare it with preceding months. We discuss our operating room and personal protective equipment protocols in managing a COVID-19 patient and share how we continue surgical training amid the pandemic. We also discuss the challenges we might face in the future as COVID-19 regresses.

Broadening horizons: the case for capturing function and the role of health informatics in its use.

BACKGROUND: Human activity and the interaction between health conditions and activity is a critical part of understanding the overall function of individuals. The World Health Organization's International Classification of Functioning, Disability and Health (ICF) models function as all aspects of an individual's interaction with the world, including organismal concepts such as individual body structures, functions, and pathologies, as well as the outcomes of the individual's interaction with their environment, referred to as activity and participation. Function, particularly activity and participation outcomes, is an important indicator of health at both the level of an individual and the population level, as it is highly correlated with quality of life and a critical component of identifying resource needs. Since it reflects the cumulative impact of health conditions on individuals and is not disease specific, its use as a health indicator helps to address major barriers to holistic, patient-centered care that result from multiple, and often competing, disease specific interventions. While the need for better information on function has been widely endorsed, this has not translated into its routine incorporation into modern health systems. PURPOSE: We present the importance of capturing information on activity as a core component of modern health systems and identify specific steps and analytic methods that can be used to make it more available to utilize in improving patient care. We identify challenges in the use of activity and participation information, such as a lack of consistent documentation and diversity of data specificity and representation across providers, health systems, and national surveys. We describe how activity and participation information can be more effectively captured, and how health informatics methodologies, including natural language processing (NLP), can enable automatically locating, extracting, and organizing this information on a large scale, supporting standardization and utilization with minimal additional provider burden. We examine the analytic requirements and potential challenges of capturing this information with informatics, and describe how data-driven techniques can combine with common standards and documentation practices to make activity and participation information standardized and accessible for improving patient care. RECOMMENDATIONS: We recommend four specific actions to improve the capture and analysis of activity and participation information throughout the continuum of care: (1) make activity and participation annotation standards and datasets available to the broader research community; (2) define common research problems in automatically processing activity and participation information; (3) develop robust, machine-readable ontologies for function that describe the components of activity and participation information and their relationships; and (4) establish standards for how and when to document activity and participation status during clinical encounters. We further provide specific short-term goals to make significant progress in each of these areas within a reasonable time frame.

Increased brain entropy of resting-state fMRI mediates the relationship between depression severity and mental health-related quality of life in late-life depressed elderly.

BACKGROUND: Entropy analysis is a computational method used to quantify the complexity in a system, and loss of brain complexity is hypothesized to be related to mental disorders. Here, we applied entropy analysis to the resting-state functional magnetic resonance imaging (rs-fMRI) signal in subjects with late-life depression (LLD), an illness combined with emotion dysregulation and aging effect. METHODS: A total of 35 unremitted depressed elderly and 22 control subjects were recruited. Multiscale entropy (MSE) analysis was performed in the entire brain, 90 automated anatomical labeling-parcellated ROIs, and five resting networks in each study participant. LIMITATIONS: Due to ethical concerns, all the participants were under medication during the study. RESULTS: Regionally, subjects with LLD showed decreased entropy only in the right posterior cingulate gyrus but had universally increased entropy in affective processing (putamen and thalamus), sensory, motor, and temporal nodes across different time scales. We also found higher entropy in the left frontoparietal network (FPN), which partially mediated the negative correlation between depression severity and mental components of the quality of life, reflecting the possible neural compensation during depression treatment. CONCLUSION: MSE provides a novel and complementary approach in rs-fMRI analysis. The temporal-spatial complexity in the resting brain may provide the adaptive variability beneficial for the elderly with depression.

A new C-glycosyl flavone and a new neolignan glycoside from Passiflora edulis Sims peel.

A new C-glycosyl flavone, Chrysin-8-C-(2″-O-ß-6-deoxy-glucopyranosyl)-ß-D-glucopyranoside (1), a new neolignan glycoside, citrusin G (2), as well as 15 known compounds (3-17) were isolated from the peel of Passiflora edulis Sims. The structure determinations were primarily based on comprehensive spectroscopic analyses, and the absolute configuration of 2 were unequivocally determined by the CD experiment and chemical transformation. Compound 1 represents the rare examples of the flavonoid featuring a deoxy glucose sugar moiety. Compounds 5, 7 and 9 exhibited moderate inhibitory effects on nitric oxide (NO) production stimulated by lipopolysaccharide (LPS) in RAW 264.7 cells, with IC50 values of 34.92, 16.12 and 26.67 µM, respectively.

Modelling High-temperature EBPR by Incorporating Glycogen and GAOs: Challenges from a Preliminary Study.

Recently reported kinetic and stoichiometric parameters of the Activated Sludge Model no. 2d (ASM2d) for high-temperature EBPR processes suggested that the absence of glycogen in the model contributed to underestimation of PHA accumulation at 32 °C. Here, two modified ASM2d models were used to further explore the contribution of glycogen in the process. The ASM2d-1G model incorporated glycogen metabolism by PAOs (polyphosphate-accumulating organisms), while the ASM2d-2G model further included processes by GAOs (glycogen-accumulating organisms). These models were calibrated and validated using experimental data at 32 °C. The ASM2d-1G model supported the hypothesis that the excess PHA was attributed to glycogen, but remained inadequate to capture the dynamics of glycogen without considering GAOs activities. The ASM2d-2G model performed better, but it was challenging to calibrate as it often led to wash-out of either PAOs or GAOs. Associated hurdles are highlighted and additional efforts in calibrating ASM2d-2G more effectively are proposed.

Disproportionate Reduction of Serotonin Transporter May Predict the Response and Adherence to Antidepressants in Patients with Major Depressive Disorder: A Positron Emission Tomography Study with 4-[18F]-ADAM.

BACKGROUND: Many lines of evidence suggest the role of serotonin transporter (SERT)-mediated reuptake of serotonin in the pathophysiology and treatment of major depressive disorder (MDD). This study aimed to examine whether the pretreatment of SERT binding potential or SERT binding ratio between terminal projection regions relative to the midbrain raphe nuclei was associated with treatment outcomes to SERT-targeted antidepressants. METHODS: We recruited 39 antidepressant-naïve patients with MDD and 39 heathy controls. Positron emission tomography with N,N-dimethyl-2-(2-amino-4-[(18)F]fluorophenylthio)benzylamine (4-[(18)F]-ADAM) was used to measure in vivo SERT availability prior to antidepressant treatment. The 21-item Hamilton Depression Rating Scale (HDRS) was use to assess the severity of depression from baseline to week 6. All the patients with MDD had HDRS scores of 18 or more. RESULTS: Pretreatment SERT binding in the thalamus and striatum positively correlated with an early reduction in HDRS scores at week 3. Nonresponders and dropout patients showed a proportionate reduction in SERT binding in the terminal projection regions and midbrain compared to healthy controls. In contrast, a disproportionate reduction in SERT binding in the terminal projection regions relative to midbrain was observed in responders. CONCLUSIONS: The results of this study suggested that a disproportionate reduction in SERT binding between terminal projection regions and midbrain may predict better treatment outcomes in patients with MDD.

Kinetic and stoichiometric characterization for efficient enhanced biological phosphorus removal (EBPR) process at high temperatures.

A recently reported stable and efficient EBPR system at high temperatures around 30 °C has led to characterization of kinetic and stoichiometric parameters of the Activated Sludge Model no. 2d (ASM2d). Firstly, suitable model parameters were selected by identifiability analysis. Next, the model was calibrated and validated. ASM2d was found to represent the processes well at 28 and 32 °C except in polyhyroxyalkanoate (PHA) accumulation of the latter. The values of the kinetic parameters for PHA storage (q PHA), polyphosphate storage (q PP) and growth (µ PAO) of polyphosphate-accumulating organisms (PAOs) at 28 and 32 °C were found to be much higher than those reported by previous studies. Besides, the value of the stoichiometric parameter for the requirement of polyphosphate for PHA storage (Y PO4) was found to decrease as temperature rose from 28 to 32 °C. Values of two other stoichiometric parameters, i.e. the growth yield of heterotrophic organisms (Y H) and PAOs (Y PAO), were high at both temperatures. These calibrated parameters imply that the extremely active PAOs of the study were able to store PHA, store polyphosphate and even utilize PHA for cell growth. Besides, the parameters do not follow the Arrhenius correlation due to the previously reported unique microbial clade at 28 and 32 °C, which actively performs EBPR at high temperatures.

Reporter enzyme inhibitor study to aid assembly of orthogonal reporter gene assays.

Reporter gene assays (RGAs) are commonly used to measure biological pathway modulation by small molecules. Understanding how such compounds interact with the reporter enzyme is critical to accurately interpret RGA results. To improve our understanding of reporter enzymes and to develop optimal RGA systems, we investigated eight reporter enzymes differing in brightness, emission spectrum, stability, and substrate requirements. These included common reporter enzymes such as firefly luciferase (Photinus pyralis), Renilla reniformis luciferase, and ß-lactamase, as well as mutated forms of R. reniformis luciferase emitting either blue- or green-shifted luminescence, a red-light emitting form of Luciola cruciata firefly luciferase, a mutated form of Gaussia princeps luciferase, and a proprietary luciferase termed "NanoLuc" derived from the luminescent sea shrimp Oplophorus gracilirostris. To determine hit rates and structure-activity relationships, we screened a collection of 42,460 PubChem compounds at 10 µM using purified enzyme preparations. We then compared hit rates and chemotypes of actives for each enzyme. The hit rates ranged from <0.1% for ß-lactamase to as high as 10% for mutated forms of Renilla luciferase. Related luciferases such as Renilla luciferase mutants showed high degrees of inhibitor overlap (40-70%), while unrelated luciferases such as firefly luciferases, Gaussia luciferase, and NanoLuc showed <10% overlap. Examination of representative inhibitors in cell-based assays revealed that inhibitor-based enzyme stabilization can lead to increases in bioluminescent signal for firefly luciferase, Renilla luciferase, and NanoLuc, with shorter half-life reporters showing increased activation responses. From this study we suggest strategies to improve the construction and interpretation of assays employing these reporter enzymes.

The antiapoptotic effects of different doses of ß-carotene in chronic ethanol-fed rats.

BACKGROUND: Ethanol consumption might induce hepatic apoptosis and cause liver damage. The study was to investigate the effects of different doses of ß-carotene supplementation on the antioxidant capacity and hepatic apoptosis in chronic ethanol-fed rats. METHODS: Rats were divided into 6 groups: C (control liquid diet), CLB [control liquid diet with ß-carotene supplementation at 0.52 mg/kg body weight (BW)/day], CHB (control liquid diet with ß-carotene supplementation at 2.6 mg/kg BW/day), E (ethanol liquid diet), ELB (ethanol liquid diet with ß-carotene supplementation at 0.52 mg/kg BW/day), and EHB (ethanol liquid diet with ß-carotene supplementation at 2.6 mg/kg BW/day). After 12 weeks, rats were sacrificed and blood and liver samples were collected for analysis. RESULTS: Lipid peroxidation and hepatic cytochrome P450 2E1 (CYP2E1) expression had increased, and hepatic Fas ligand, caspase-8, cytochrome c, caspase-9, and -3 expressions had significantly increased in the E group. However, lipid peroxidation and CYP2E1, caspase-9, and -3 expressions were significantly lower and Bcl-xL expression was higher in the ELB group. The hepatic tumor necrosis factor (TNF)-α level, lipid peroxidation, and cytochrome c expression were significantly lower and Bcl-2 expression was significantly higher in the EHB group. CONCLUSIONS: The results suggest that ethanol treatment causes oxidative stress and hepatic apoptosis leading to liver injury, and ß-carotene supplementation (0.52 mg/kg BW/day) can prevent ethanol-induced liver damage by decreasing ethanol-induced oxidative stress and inhibiting apoptosis in the liver.

Chlorella pyrenoidosa ameliorated L-NAME-induced hypertension and cardiorenal remodeling in rats.

PURPOSE: Hypertension is one of the main factors causing cardiovascular diseases. The aim of the study is to investigate the effects of Chlorella pyrenoidosa on blood pressure and cardiorenal remodeling in rats with N (ω)-nitro-L-arginine methyl ester hydrochloride (L-NAME)-induced endothelial dysfunction. METHODS: Rats were fed a diet containing L-NAME (40 mg/kg) with or without chlorella (4 or 8 %) for 5 weeks. We found that chlorella retarded the development of hypertension and cardiorenal remodeling during the 5-week experimental period. RESULTS: Although there was no difference in NO( x ) levels or plasma arginine concentrations, plasma and tissues ACE activities were significantly lower in the chlorella groups than in the L-NAME group. Moreover, tissue tumor necrosis factor-α concentrations and renal CYP4A expression were also lower in the chlorella group. CONCLUSION: These results suggest that chlorella might ameliorate the elevation of blood pressure and show cardiorenal-protective effects in nitric oxide-deficient rats, and one possible mechanism might be mediated by its ACE inhibitory activity.

Chronic urotensin II receptor antagonist treatment does not alter hypertrophy or fibrosis in a rat model of pressure-overload hypertrophy.

Urotensin II (UII) is a potential mediator in the pathogenesis of cardiovascular disease, and inhibition of its actions at the urotensin receptor (UT) has been shown to improve cardiac function and structural changes of the myocardium in a model of myocardial infarction. In this study we utilized a model of pressure-overload hypertrophy induced by abdominal aortic constriction (AAC) which resulted in hypertrophy, increased fibrosis and impaired diastolic and systolic function. These changes were associated with a 4-fold increase in UII protein expression in the myocardium. Treatment of animals with a selective UT (SB-657510) antagonist for 20 weeks at a dose of 1500 ppm did not improve cardiac function as assessed by echocardiography and pressure-volume loop analysis, nor did it inhibit left ventricular hypertrophy or fibrosis. We hypothesize that other neurohumoral pathways may have a greater involvement in the pathogenesis of this model. Targeting the UII system appears to be insufficient to observe a beneficial outcome.

Assay development and screening of human DGAT1 inhibitors with an LC/MS-based assay: application of mass spectrometry for large-scale primary screening.

Many attractive targets for therapeutic intervention are enzymes that catalyze biological reactions involving small molecules such as lipids, fatty acids, amino acid derivatives, nucleic acid derivatives, and cofactors. Some of the reactions are difficult to detect by methods commonly used in high-throughput screening (HTS) without specific radioactive or fluorescent labeling of substrates. In addition, there are instances when labeling has a detrimental effect on the biological response. Generally, applicable assay methodologies for detection of such reactions are thus required. Mass spectrometry (MS), being a label-free detection tool, has been actively pursued for assay detection in HTS in the past several years. The authors have explored the use of multiparallel liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) for high-throughput detection of biochemical reactions. In this report, we describe in detail the assay development and screening with a LC/MS-based system for inhibitors of human diacylglycerol acyltransferase (DGAT1) with a chemical library of approximately 800,000 compounds. Several strategies and process improvements have been investigated to overcome technical challenges such as data variation and throughput. Results indicated that, through these innovative approaches, the LC/MS-based screening method is both feasible and suitable for high-throughput primary screening.

Up-regulation of inflammatory signalings by areca nut extract and role of cyclooxygenase-2 -1195G>a polymorphism reveal risk of oral cancer.

Because the mRNA expression of cyclooxygenase-2 (COX-2) is up-regulated by arecoline in human gingival fibroblasts, as shown in our previous study, we further investigated the mRNA expression level of COX-2 and its upstream effectors in three oral epithelial carcinoma cell lines (KB, SAS, and Ca9-22) by using areca nut extract (ANE) and saliva-reacted ANE (sANE). A case-control study of 377 oral squamous cell carcinoma (OSCC) patients and 442 controls was conducted to evaluate the gene-environment interaction between COX-2 promoter polymorphisms and substance use of alcohol, betel quid, and cigarettes (ABC) in risk of OSCC. The heterogeneous characteristics of the oral site and the COX-2 -1195G>A polymorphism in these cell lines showed diverse inflammatory response (KB>>Ca9-22>SAS) after 24-hour ANE/sANE treatments, and the COX-2 up-regulation might be mostly elicited from alternative nuclear factor-kappaB activation. In the case-control study, betel chewing [adjusted odds ratios (aOR), 42.2] posed a much higher risk of OSCC than alcohol drinking and cigarette smoking (aORs, 2.4 and 1.8, respectively), whereas the COX-2 -1195A/A homozygote presented a potential genetic risk (OR, 1.55). The strongest joint effect for OSCC was seen in betel chewers with -1195A/A homozygote (aOR, 79.44). In the non-betel chewing group, the -1195A/G and A/A genotypes together with the combined use of alcohol and cigarettes increased risk to 15.1-fold and 32.1-fold, respectively, compared with the G/G genotype without substance use. Taken together, these findings illustrate a valuable insight into the potential role of the COX-2 promoter region in contributing to the development of betel-related OSCC, including ANE/sANE-induced transcriptional effects and enhanced joint effects of COX-2 -1195A allele with substance use of ABC.

Comparing factors affecting commencement and cessation of betel quid chewing behavior in Taiwanese adults.

BACKGROUND: Betel quid is the fourth most common used substance in the world after tobacco, alcohol and caffeine. Although factors related to betel quid chewing or cessation of behaviors were reported previously, few studies simultaneously compared both behaviors in the same population. In addition, it is essential to consider time-to-event concept, since the chance of developing or stopping habit may vary over time. The purpose of this study was to compare the risk factors for commencement and cessation of betel quid chewing behaviors in a time-to-event setting. METHODS: A stratified multi-stage cluster sampling with selection probabilities proportional to size (PPS) was designed for Taiwanese adults with aged 18 years old and above. Kaplan-Meier estimates and Cox proportional hazard regression models were used to compare and calculate the hazard rate ratios for related factors to commencement or cessation of chewing habits. RESULTS: In Taiwan, men had a higher betel quid chewing rate (M: 20.9%, W: 1.2%), but woman chewers had a lower cessation rate (M: 27.5%, W: 12.7%). The hazard rate ratio (HRR) of having chewing habit changed from 4.22 (men vs women) univariately to 1.38 multivariablely, which indicated gender differences were confounded by other factors. In multivariable analysis, the risk factors of gender, education and ethnicity were significantly associated with both starting and cessation of betel quid chewing behavior. The factors of occupation, cigarette smoking and alcohol drinking were only associated with starting habit. CONCLUSION: Commencement or cessation of chewing behavior involves a scenario of time, hence it is preferable to use a time-to-event approach for the comparison. The cessation rates of betel quid chewing were decreasingly associated with the daily consumption of betel quid. Hence, reducing of daily amount in betel quid cessation program may be associated with future stopping habit.

Mass spectrometric techniques for label-free high-throughput screening in drug discovery.

High-throughput screening (HTS) is an important tool for finding active compounds to initiate medicinal chemistry programs in pharmaceutical discovery research. Traditional HTS methods rely on fluorescent or radiolabeled reagents and/or coupling assays to permit quantitation of enzymatic target inhibition or activation. Mass spectrometry-based high-throughput screening (MS-HTS) is an alternative that is not susceptible to the limitations imposed by labeling and coupling enzymes. MS-HTS offers a selective and sensitive analytical method for unlabeled substrates and products. Furthermore, method development times are reduced without the need to incorporate labels or coupling assays. MS-HTS also permits screening of targets that are difficult or impossible to screen by other techniques. For example, enzymes that are challenging to purify can lead to the nonspecific detection of structurally similar components of the impure enzyme or matrix of membraneous enzymes. The high selectivity of tandem mass spectrometry (MS/MS) enables these screens to proceed with low levels of background noise to sensitively discover interesting hits even with relatively weak activity. In this article, we describe three techniques that we have adapted for large-scale (approximately 175,000 sample) compound library screening, including four-way parallel multiplexed electrospray liquid chromatography tandem mass spectrometry (MUX-LC/MS/MS), four-way parallel staggered gradient liquid chromatography tandem mass spectrometry (LC/MS/MS), and eight-way staggered flow injection MS/MS following 384-well plate solid-phase extraction (SPE). These methods are capable of analyzing a 384-well plate in 37 min, with typical analysis times of less than 2 h. The quality of the MS-HTS approach is demonstrated herein with screening data from two large-scale screens.

Ingredients contribute to variation in production of reactive oxygen species by areca quid.

Areca quid (AQ) chewing has been implicated an independent risk factor for the development of oral cancer. Taiwanese areca quid (AQ) refers to a combination of areca nut (AN), lime, and inflorescence of Piper betle Linn. (IPB) or Piper betle leaf (PBL). Studies of AQ in other countries reported that AN extract combined with lime generates reactive oxygen species (ROS), such as hydroxyl radical (HO.), known to be a contributing factor in oral mucosa damage. To determine whether HO. is formed in the oral cavity during AQ chewing, the formation of meta-tyrosine (m-Tyr) and ortho-tyrosine (o-Tyr) from l-phenylalanine (Phe) was confirmed. It was demonstrated that combined aqueous extracts of AN, lime, metal ions (such as Cu2+ and Fe2+), and IPB or PBL produced HO.. Thus, the yield of HO. significantly increases when higher amounts of IPB or lime are added and also when Cu2+ and Fe2+ are increased. Further, the omission of any one of these ingredients significantly reduces the formation of HO.. Our results found that chewing AQ with IPB generated significantly higher HO. than chewing AQ with PBL, and may result in greater oxidative damage to the surrounding oral mucosa.

Green tea supplementation ameliorates insulin resistance and increases glucose transporter IV content in a fructose-fed rat model.

BACKGROUND: Sprague-Dawley rats fed a fructose-rich diet exhibit insulin resistance and hypertension, a pathologic status resembling human type II diabetes mellitus, and are an excellent laboratory animal model for research on insulin action and the development of hypertension. Since green tea has numerous beneficial effects, we tested its effect on fructose-fed rats. AIM: The present study was therefore designed to further evaluate the effects of green tea supplementation on insulin resistance, hypertension, and the glucose transporters I and IV contents in adipose tissue in the fructose-fed rat model. METHODS: The animals were divided into three groups and fed for 12 weeks with standard chow and water (control group), a high fructose diet and water (fructose group), or the same high fructose diet, but with green tea (0.5 g of lyophilized green tea powder dissolved in 100 mL of deionized distilled water) instead of water (fructose/green tea group). During the 12 weeks study period, fresh water or green tea was provided daily at 6:00 PM. Blood pressure was measured twice a week, and an oral glucose tolerance test performed after 12 weeks of diet supplementation. At the end of the experiment, plasma triglyceride (TG), free fatty acid (FFA), glucose, and insulin were assayed. The epididymal fat pads from all rats in the same group were pooled and adipocytes isolated and tested for insulin binding, glucose uptake, and their content of glucose transporters I (GLUT I) and IV (GLUT IV). RESULT: Compared to the control group, the fructose group developed fasting hyperglycemia, hyperinsulinemia, and elevated blood pressure. Insulin-stimulated glucose uptake and insulin binding of adipocytes were significantly reduced, and the glucose transporter IV content of adipocytes also decreased. The fructose/green tea group showed improvement in all of these metabolic defects and in insulin resistance and blood pressure. CONCLUSION: Based on these results, we suggest that the amelioration of insulin resistance by green tea is associated with the increased expression of GLUT IV.

Folate deprivation induces neurodegeneration: roles of oxidative stress and increased homocysteine.

Clinical studies suggest a relationship between folate deficiency and neurological and disorders including Alzheimer's disease (AD). To investigate mechanisms underlying this association, we examined the consequences of folate deprivation on neuronal cultures. Culturing embryonic cortical neurons and differentiated SH-SY-5Y human neuroblastoma cells in folate-free medium induced neurodegenerative changes characteristic of those observed in AD, including increased cytosolic calcium, reactive oxygen species (ROS), phospho-tau and apoptosis. In accord with clinical studies, generation of the neurotoxic amino acid homocysteine (HC) was likely to contribute to these phenomena, since (1) a significant increase in HC was detected following folate deprivation, (2) addition of the inhibitor of HC formation, 3-deazaadenosine, both prevented HC formation and eliminated the increase in ROS that normally accompanied folate deprivation, (3) direct addition of HC in the presence of folate induced the neurotoxic effects that accompanied folate deprivation, and (4) an antagonist of NMDA channels that blocks HC-induced calcium influx also blocked calcium influx following folate deprivation. Folate deprivation decreased the reduced form of glutathione, indicating a depletion of oxidative buffering capacity. This line of reasoning was supported by an increase in glutathione and reduction in ROS following supplementation of folate-deprived cultures with the cell-permeant glutathione precursor, N-acetyl-L-cysteine, or vitamin E. Folate deprivation potentiated ROS and apoptosis induced by amyloid-beta, while folate supplementation at higher concentrations prevented generation of ROS by amyloid-beta, suggesting that folate levels modulate the extent of amyloid-beta neurotoxicity. These findings underscore the importance of folate metabolism in neuronal homeostasis and suggest that folate deficiency may augment AD neuropathology by increasing ROS and excitotoxicity via HC generation.