[Research progress on signaling pathways related to drug research in proliferative vitreoretinopathy].

Proliferative vitreoretinopathy (PVR) is an avascular fibroproliferative disease that occurs in the retina. The main pathological changes are the proliferation and traction of retinal pigment epithelial cells (RPE) and glial cells on the vitreous and retina. Basic research has confirmed that the formation of PVR is related to multiple signaling pathways, including NK-κB signaling pathway, MAPK and its downstream signaling pathways, JAK/STAT signaling pathway, PI3K/Akt signaling pathway, thrombin and its receptor pathway, TGF-ß and downstream signaling pathway, North signaling pathway and Wnt/ß-catenin signaling pathway, etc. This review summarizes the research progress of the main signaling pathways in the formation mechanism of PVR, and provides the basis and support for the research of PVR drug therapy.

[Observational study on peripapillary hyper-reflective ovoid mass-like structures in children and adolescents with myopia].

Objective: To investigate the correlation of peripapillary hyper-reflective ovoid mass-like structures (PHOMS) in children and adolescents with myopia and its correlation factors. Methods: It was a cross-sectional study. From September 2021 to January 2022, myopic children and adolescents aged 6-16 years treated in Wuhan Central Hospital and Renmin Hospital of Wuhan University with a myopic spherical equivalent (SE) ≥0.5 D were consecutively included. All patients underwent best corrected visual acuity, refraction, intraocular pressure, slit lamp microscope, axial length, fundus photography and enhanced depth imaging optical coherence tomography (EDI-OCT) examination. EDI-OCT optic disc parameter measurements included diameter, degree of tilt and shift and PHOMS height. The patients were divided into PHOMS group and non-PHOMS group according to the presence or absence of PHOMS. According to the height of PHOMS, the patients were further divided into 3 subgroups: large (>400 µm), medium (200-400 µm) and small (<200 µm). The optic disc characteristics of the PHOMS group and the non-PHOMS group and each subgroup were observed, and the correlation factors of PHOMS were analyzed. Mann-Whitney U test, Kruskal-Wallis test, chi-square test, Logistic regression analysis and Kendall's tau-b correlation coefficient were used. Results: A total of 108 patients (108 eyes) were included, including 46 males (46 eyes) and 62 females (62 eyes). There were 70 eyes (64.8%) in the PHOMS group and 38 eyes (35.2%) in the non-PHOMS group. Small PHOMS can only be detected by EDI-OCT, while medium to large PHOMS showed blurred optic disc boundaries on fundoscopy images. Univariate Logistic regression analysis showed that PHOMS was associated with age (OR=1.36, 95%CI: 1.13-1.65, P=0.001) and myopic SE (OR=4.57, 95%CI: 2.51-8.32, P<0.001), axial length (OR=2.28, 95%CI: 1.37-3.82, P=0.002), optic disc tilt (OR=3.44, 95%CI: 2.09-5.66, P<0.001), optic disc shift (OR=0.95, 95%CI: 0.93-0.98, P<0.001) and optic disc diameter (OR=0.75, 95%CI: 0.58-0.95, P=0.019). Multivariate Logistic regression analysis showed that the higher the myopic SE (OR=3.01, 95%CI: 1.27-7.17, P=0.013) and the greater the tilt of the optic disc (OR=4.06,95%CI:1.99-8.29,P<0.001), the higher the risk of PHOMS. Kendall's tau-b correlation coefficient analysis showed that the height of PHOMS was negatively correlated with optic disc shift (r=-0.31, P<0.001). Conclusions: PHOMS can be found in a subset of myopic children. The fundus manifestations of PHOMS of different heights are slightly different. The large myopic SE and great optic disc tilt are risk factors of PHOMS, and their magnitudes correlate with the border tissue angle.

[The association between blood homocysteine level and Chinese Healthy Eating Index in a suburb population of Shanghai].

Objective: To explore the relationship between the level of blood homocysteine (Hcy) and the total score of Chinese Healthy Eating Index (CHEI) and its item score. Methods: The subjects were recruited from the East China Natural Population Cohort Study, led by the School of Public Health in Fudan University, which was conducted in Zhongshan Community, Songjiang District of Shanghai from April to September 2017. By using the cluster random sampling method, 8 neighborhood committees were randomly selected from 18 neighborhood committees in Zhongshan community (Beimen, Baiyun, Dongwai, Huaqiao, Lantian village 1, Lantian village 2, Lantian village 4, and Lantian village 5). All the residents who met the standard and had lived in Shanghai for more than half a year were selected as research subjects. 4 995 subjects with complete survey information were finally included in this study. General information (age, sex, disease history, etc.), lifestyle (smoking, drinking, tea drinking, physical activity, etc.), food frequency and blood Hcy concentration were collected through questionnaire survey, physical examination and biological sample detection. The multivariate linear regression model was used to analyze the correlation between blood Hcy concentration and the total score of CHEI and its item score, and the multivariate logistics regression model was used to analyze the correlation between hyperhomocysteinemia (hHcy) and the total score of CHEI and its item score. Results: The age of the subjects was (56.72±9.72) years. The proportion of females, people with middle and high school education and high physical activity was 64.90% (3 241), 50.80% (2 539) and 63.20% (3 157), respectively. The blood Hcy concentration was (11.25±4.90) µmol/L, and the total prevalence of hHcy was 9.3% (467 cases). The results of multivariate linear regression showed that after adjusting for the relevant confounding factors, the blood Hcy concentration of subjects decreased with the increase of the total score of CHEI and the item score of fruit, milk, seafood, poultry and egg, but increased with the increase of the item score of total grain and tuber. In males, blood Hcy levels decreased with the increase of the item score of seafood and poultry [ß (95%CI) values were -0.343 (-0.582, -0.102) and -0.225 (-0.402, -0.046), respectively]. In females, the blood Hcy level decreased with the increase of the total score of CHEI and its item score of milk, egg, seafood and poultry [ß (95%CI) values were -0.130 (-0.207, -0.052), -0.091 (-0.148, -0.034), -0.016 (-0.026, -0.007), -0.069 (-0.122, -0.016), and -0.087 (-0.157, -0.017), respectively]. The results of multivariate logistic regression showed that the higher the total score of CHEI and its item score of milk and seafood, the lower the risk of hHcy [OR (95%CI) value were 0.986 (0.978, 0.995), 0.915 (0.864, 0.969), and 0.862 (0.806, 0.922), respectively]. In females, the higher the total score of CHEI and its item score of milk and seafood, the lower the risk of hHcy [OR (95%CI) values were 0.984 (0.970, 0.999), 0.877 (0.802, 0.958), and 0.845 (0.760, 0.941), respectively]. In males, the higher the total score of CHEI and its item score of seafood, the lower the risk of hHcy [OR (95%CI) values were 0.988 (0.977, 0.998) and 0.858 (0.791, 0.930), respectively]. Conclusion: The dietary pattern of residents in Zhongshan Community, Songjiang District, Shanghai can affect their own blood Hcy concentration and the risk of hHcy. The total score of CHEI and the item score of fruit, milk, seafood, poultry and eggs play an important role in reducing the level of blood Hcy. The higher the total score of CHEI and the item score of milk and seafood, the lower the risk of hHcy.

Neuroprotective effect of ketamine on acute spinal cord injury in rats.

The aim of this study was to investigate the neuroprotective effects of ketamine during acute spinal cord injury in rats. Sprague Dawley (SD) rats (N = 70) were randomly divided into three groups: sham-operated (N = 10), control (N = 30), and treatment (N = 30) groups. The moderate spinal cord injury model was established. After injury, the sham-operated group received no drug, the treatment group received intraperitoneal ketamine injections, and the control group received intraperitoneal normal saline injections. Serum levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and spinal cord malondialdehyde (MDA) were assessed, and nerve cell apoptosis was evaluated in each group at varying time points. After spinal cord injury, TNF-α, IL-6, and MDA levels, and the number of TUNEL-positive cells among 2500 cells significantly increased (P < 0.05). Further, compared with the control group, the treatment group showed significantly lower TNF-α, IL-6, and MDA levels, and fewer TUNEL-positive cells among 2500 cells at each time point (P < 0.05). Our data indicate that ketamine exerts a neuroprotective effect on injured spinal cord.

Mechanisms of human insulin resistance and thiazolidinedione-mediated insulin sensitization.

Cellular and tissue defects associated with insulin resistance are coincident with transcriptional abnormalities and are improved after insulin sensitization with thiazolidinedione (TZD) PPARgamma ligands. We characterized 72 human subjects by relating their clinical phenotypes with functional pathway alterations. We transcriptionally profiled 364 biopsies harvested before and after hyperinsulinemic-euglycemic clamp studies, at baseline and after 3-month TZD treatment. We have identified molecular and functional characteristics of insulin resistant subjects and distinctions between TZD treatment responder and nonresponder subjects. Insulin resistant subjects exhibited alterations in skeletal muscle (e.g., glycolytic flux and intramuscular adipocytes) and adipose tissue (e.g., mitochondrial metabolism and inflammation) that improved relative to TZD-induced insulin sensitization. Pre-TZD treatment expression of MLXIP in muscle and HLA-DRB1 in adipose tissue from insulin resistant subjects was linearly predictive of post-TZD insulin sensitization. We have uniquely characterized coordinated cellular and tissue functional pathways that are characteristic of insulin resistance, TZD-induced insulin sensitization, and potential TZD responsiveness.

Genetic association of UBE2B variants with susceptibility to male infertility in a Northeast Chinese population.

The ubiquitin-conjugating enzyme 2B gene (UBE2B) is involved in the regular and symmetric organization of the fibrous sheath of sperm flagella. This study aimed to examine the relationship between single nucleotide polymorphisms (SNPs) in UBE2B and infertility in Northeast Chinese men. We carried out a polymerase chain reaction-restriction fragment length polymorphism analysis for SNPs in 312 fertile males and 388 infertile males in Northeast China. Taking advantage of the high degree of linkage disequilibrium among SNPs surrounding UBE2B (r(2) > 0.90), we selected 2 haplotype-tagging SNPs with a minor allele frequency of 5% or greater (rs17167484: g.-293T>G and rs3777373: g.20016A>G) that captured the majority of the genetic variations in a 40-kbp region of this gene. No significant differences between cases and controls were found in the allelic and genotype distribution of the 2 SNPs. However, the haplotype analysis for the 2 SNPs showed that the GA haplotype was significantly associated with a greater than 3-fold decreased risk of male infertility (P = 0.003). Because the frequency of the GA haplotype (1.1%) is relatively low in Chinese men, such a significant finding may occur by chance, but the results are still significant after multiple comparison adjustments (P = 0.012 after Bonferroni's correction). We conclude that the UBE2B polymorphisms g.-293T>G, g.20016A>G and g.9157A>G are not associated with male infertility, and the GA haplotype is likely a protective factor for male fertility in Northeast Chinese men.

Mechanical stimulation activates Galphaq signaling pathways and 5-hydroxytryptamine release from human carcinoid BON cells.

5-Hydroxytryptamine (5-HT) released from enterochromaffin cells activates secretory and peristaltic reflexes necessary for lubrication and propulsion of intestinal luminal contents. The aim of this study was to identify mechanosensitive intracellular signaling pathways that regulate 5-HT release. Human carcinoid BON cells displayed 5-HT immunoreactivity associated with granules dispersed throughout the cells or at the borders. Mechanical stimulation by rotational shaking released 5-HT from BON cells or from guinea pig jejunum during neural blockade with tetrodotoxin. In streptolysin O-permeabilized cells, guanosine 5'-O- (2-thiodiphosphate) (GDP-beta-S) and a synthetic peptide derived from the COOH terminus of Galphaq abolished mechanically evoked 5-HT release, while the NH(2)-terminal peptide did not. An antisense phosphorothioated oligonucleotide targeted to a unique sequence of Galphaq abolished mechanically evoked 5-HT release and reduced Galphaq protein levels without affecting the expression of Galpha(11). Depletion and chelation of extracellular calcium did not alter mechanically evoked 5-HT release, whereas depletion of intracellular calcium stores by thapsigargin and chelation of intracellular calcium by 1,2-bis (o-Aminophenoxy) ethane-N,N,N',N'-tetraacetic acid tetra (acetoxymethyl) ester (BAPTA-AM) reduced 5-HT release. Mechanically evoked 5-HT release was inhibited by somatostatin-14 in a concentration-dependent manner. The results suggest that mechanical stimulation of enterochromaffin-derived BON cells directly or indirectly stimulates a G protein-coupled receptor that activates Galphaq, mobilizes intracellular calcium, and causes 5-HT release.

Structure of pp32, an acidic nuclear protein which inhibits oncogene-induced formation of transformed foci.

pp32 is a nuclear protein found highly expressed in normal tissues in those cells capable of self-renewal and in neoplastic cells. We report the cloning of cDNAs encoding human and murine pp32. The clones encode a 28.6-kDa protein; approximately two-thirds of the N-terminal predicts an amphipathic alpha helix containing two possible nuclear localization signals and a potential leucine zipper motif. The C-terminal third is exceptionally acidic, comprised of approximately 70% aspartic and glutamic acid residues; the predicted pI of human pp32 is 3.81. Human and murine pp32 cDNAs are 88% identical; the predicted proteins are 89% identical and 95% similar. Although the structure of pp32 is suggestive of a transcription factor, pp32 did not significantly modulate transcription of a reporter construct when fused to the Gal4 DNA-binding domain. In contrast, in cotransfection experiments, pp32 inhibited the ability of a broad assortment of oncogene pairs to transform rat embryo fibroblasts, including ras + myc, ras + jun, ras + E1a, ras + mutant p53, and E6 + E7. In related experiments, pp32 inhibited the ability of Rat 1a-myc cells to grow in soft agar, whereas it failed to affect ras-induced focus formation in NIH3T3 cells. These results suggest that pp32 may play a key role in self-renewing cell populations where it may act in the nucleus to limit their sensitivity to transformation.

The structure and functions of paxillin and its roles in neovascularization.

Identifying and studying the molecular mechanisms of neovascularization biomarkers are critical for conquering many diseases, such as corneal diseases and cancer. Paxillin is an important cell scaffold and cellular signaling protein, especially a key molecule of the Integrin-mediated downstream signaling transduction. This review summarizes the structure and functions of paxillin, and the research progress of its roles in neovascularization. Although there are still some problems to be solved, paxillin may become an important target of anti-neovascularization therapies.

Long intergenic non-coding RNA APOC1P1-3 inhibits apoptosis by decreasing α-tubulin acetylation in breast cancer.

Increasing evidence indicates that long non-coding RNAs (lncRNAs) act as important regulatory factors in tumor progression. However, their roles in breast cancer remain largely unknown. In present studies, we identified aberrantly expressed long intergenic non-coding RNA APOC1P1-3 (lincRNA-APOC1P1-3) in breast cancer by microarray, verified it by quantitative real-time PCR, and assessed methylation status in the promoter region by pyrosequencing. We also investigated the biological functions with plasmid transfection and siRNA silencing experiments, and further explored their mechanisms by RNA pull-down and RNA immunoprecipitation to identify binding proteins. We found that 224 lncRNAs were upregulated in breast cancer, whereas 324 were downregulated. The lincRNA-APOC1P1-3 was overexpressed in breast cancer, which was related to tumor size and hypomethylation in its promoter region. We also found that APOC1P1-3 could directly bind to tubulin to decrease α-tubulin acetylation, to inactivate caspase-3, and to inhibit apoptosis. This study demonstrates that overexpression of APOC1P1-3 can inhibit breast cancer apoptosis.

Effects of troglitazone on blood concentrations of plasminogen activator inhibitor 1 in patients with type 2 diabetes and in lean and obese normal subjects.

Low plasma fibrinolytic activity in association with increased plasma plasminogen activator inhibitor 1 (PAI-1) levels has been linked to an increased risk of atherosclerosis in obesity and type 2 diabetes. We tested the hypothesis that troglitazone, which improves insulin sensitivity and lowers plasma insulin levels in insulin-resistant obese subjects and patients with type 2 diabetes, would also lower circulating PAI-1 antigen concentrations and activity. We assessed insulin sensitivity (5-h, 80 mU x m(-2) x min(-1) hyperinsulinemic-euglycemic clamp) and measured plasma PAI-1 antigen and activities and tissue plasminogen activator (tPA) in 14 patients with type 2 diabetes and 20 normal control subjects (10 lean, 10 obese) before and after 3 months of treatment with troglitazone (600 mg/day). At baseline, plasma PAI-1 antigen levels after an overnight fast were significantly higher in the obese (33.5 +/- 4.7 microg/l) and type 2 diabetic subjects (54.9 +/- 6.3 microg/l) than in the lean control subjects (16.3 +/- 3.2 microg/l; P < 0.01 and P < 0.001, respectively). Troglitazone decreased plasma PAI-1 antigen concentrations in the diabetic patients (36.8 +/- 5.0 microg/l; P < 0.001 vs. baseline), but the reduction in the obese subjects did not reach statistical significance (baseline, 33.5 +/- 4.7; after troglitazone, 25.6 +/- 5.2 microg/l). Changes in plasma PAI-1 activity paralleled those of PAI-1 antigen. The extent of the reduction in plasma PAI-1 antigen concentrations in the diabetic patients after troglitazone correlated with the reductions in fasting plasma insulin (r = 0.60, P < 0.05), nonesterified fatty acid (r = 0.63, P < 0.02), and glucose concentrations (r = 0.64, P < 0.02) but not with the improvement in glucose disposal rates during the glucose clamps. Three nonresponders to troglitazone with respect to effects on insulin sensitivity and fasting glucose and insulin levels also had no reduction in circulating PAI-1. In conclusion, troglitazone enhances fibrinolytic system activity in insulin-resistant type 2 diabetic patients. This effect appears to be intimately linked to its potential to lower plasma insulin levels and improve glycemic control through its peripheral tissue insulin-sensitizing effects.

A comparison of troglitazone and metformin on insulin requirements in euglycemic intensively insulin-treated type 2 diabetic patients.

Troglitazone and metformin lower glucose levels in diabetic patients without increasing plasma insulin levels. We compared the insulin sparing actions of these two agents and their effects on insulin sensitivity and insulin secretion in 20 type 2 diabetic patients. To avoid the confounding effect of improved glycemic control on insulin action and secretion, patients were first rendered euglycemic with 4 weeks of continuous subcutaneous insulin infusion (CSII) before randomization to CSII plus troglitazone (n = 10) or CSII plus metformin (n = 10); euglycemia was maintained for another 6-7 weeks. Insulin sensitivity was assessed by a hyperinsulinemic-euglycemic clamp 1) at baseline, 2) after 4 weeks of CSII, and 3) after CSII plus either troglitazone or metformin. The 24-h glucose, insulin, and C-peptide profiles were performed on the day before the second and third glucose clamps. Good glycemic control was achieved with CSII alone and was maintained with CSII plus an oral agent (mean 24-h glucose: troglitazone, 6.2+/-0.6 mmol/l; metformin, 6.2 +/-0.3 mmol/l). Insulin requirements decreased 53% with troglitazone compared with CSII alone (48+/-4 vs. 102+/-13 U/day, P < 0.001), but only 31% with metformin (76+/-13 vs. 110+/-18 U/day, P < 0.005). The 24-h C-peptide profiles were similar. Normal fasting hepatic glucose output was maintained with both agents despite lower insulin levels than on CSII alone. Insulin sensitivity did not change significantly with CSII alone or with CSII plus metformin, but improved 29% with CSII plus troglitazone (P < 0.005 vs. CSII alone) and was then 45% higher than in the CSII plus metformin patients (P < 0.005). In conclusion, metformin has no effect on insulin-stimulated glucose disposal independent of glycemic control in type 2 diabetes. Troglitazone (600 mg/day) has greater insulin-sparing effects than metformin (1,700 mg/day) in CSII-treated euglycemic patients. This is probably explained by the peripheral tissue insulin-sensitizing effects of troglitazone.

Effects of nonesterified fatty acids on glucose metabolism after glucose ingestion.

Impaired suppression of plasma nonesterified fatty acids (NEFAs) after glucose ingestion may contribute to glucose intolerance, but the mechanisms are unclear. Evidence that insulin inhibits hepatic glucose output (HGO), in part by suppressing plasma NEFA levels, suggests that impaired suppression of plasma NEFA after glucose ingestion would impair HGO suppression and increase the systemic delivery of glucose. To test this hypothesis, we studied glucose kinetics (constant intravenous [3-3H]glucose [0.4 microCi/min], oral [1-14C]glucose [100 microCi]), whole-body substrate oxidation, and leg glucose uptake in eight normal subjects (age, 39 +/- 9 years [mean +/- SD]; BMI, 24 +/- 2 kg/m2) in response to 75 g oral glucose on two occasions. In one study, plasma NEFAs were prevented from falling by infusion of 20% Liposyn (45 ml/h) and heparin (750 U/h). Plasma glucose rose more rapidly during lipid infusion (P < 0.05), and mean levels tended to be higher after 120 min (6.45 +/- 0.41 vs. 5.81 +/- 0.25 SE, 0.1 < P < 0.05, NS); peak glucose levels were similar. Total glucose appearance (Ra) was higher during lipid infusion due to a higher HGO (28.4 +/- 1.0 vs. 21.2 +/- 1.5 g over 4 h, P < 0.005). Total glucose disposal (Rd) was also higher (88 +/- 2 vs. 81 +/- 3 g in 4 h, P < 0.05). Plasma insulin rose more rapidly after glucose ingestion with lipid infusion, and leg glucose uptake was 33% higher (P < 0.05) during the 1st hour. During lipid infusion, subjects oxidized less glucose (47 +/- 3 vs. 55 +/- 2 g, P < 0.05) and more fat (7.1 +/- 0.8 vs. 3.9 +/- 0.9 g, P < 0.02). In summary, 1) impaired suppression of NEFAs after oral glucose impairs insulin's ability to suppress HGO, and 2) in normal subjects the greater insulin response compensates for the increased systemic glucose delivery by increasing peripheral glucose Rd.

Regulation of skeletal muscle hexokinase II by insulin in nondiabetic and NIDDM subjects.

Impaired muscle glucose phosphorylation to glucose-6-phosphate by hexokinases (HKs)-I and -II may contribute to insulin resistance in NIDDM and obesity. HK-II expression is regulated by insulin. We tested the hypothesis that basal and insulin-stimulated expression of HK-II is decreased in NIDDM and obese subjects. Skeletal muscle HK-I and HK-II activities were measured in seven lean and six obese normal subjects and eight patients with NIDDM before and at 3 and 5 h of a hyperinsulinemic (80 mU x m(-2) x min(-1)) euglycemic clamp. To assess whether changes in HK-II expression seen during a glucose clamp are likely to be physiologically relevant, we also measured HK-I and HK-II activity in 10 lean normal subjects before and after a high-carbohydrate meal. After an overnight fast, total HK, HK-I, and HK-II activities were similar in lean and obese control subjects; but HK-II was lower in NIDDM patients than in lean subjects (1.42 +/- 0.16 [SE] vs. 2.33 +/- 0.24 nmol x min(-1) x mg(-1) molecular weight, P < 0.05) and accounted for a lower proportion of total HK (33 +/- 3 vs. 47 +/- 3%, P < 0.025). HK-II (but not HK-I) activity increased during the clamp in lean and obese subjects by 34 and 36% after 3 h and by 14 and 22% after 5 h of hyperinsulinemia; no increase was found in the NIDDM patients. In the lean subjects, muscle HK-II activity also increased by 15% 4 h after the meal, from 2.47 +/- 0.19 basally to 2.86 +/- 0.28 nmol x min(-1) x mg(-1) protein (P < 0.05). During the clamps, muscle HK-II activity correlated with muscle citrate synthase activity in the normal subjects (r = 0.58, P < 0.05) but not in the NIDDM patients. A weak relationship was noted between muscle HK-II activity and glucose disposal rate at the end of the clamp when all three groups were combined (r = 0.49, P < 0.05). In summary, NIDDM patients have lower muscle HK-II activity basally and do not increase the activity of this enzyme in response to a 5-h insulin stimulus. This defect may contribute to their insulin resistance. In nondiabetic obese subjects, muscle HK-II expression and its regulation by insulin are normal.

Decreased susceptibility to fatty acid-induced peripheral tissue insulin resistance in women.

Elevation of plasma nonesterified fatty acid (NEFA) levels has been shown in various studies to induce peripheral tissue insulin resistance and impair the suppression of endogenous glucose production (EGP). These studies have been conducted predominantly in men. We compared the effects of elevated plasma NEFA levels on basal and insulin-stimulated glucose metabolism in 8 normal women (age 42 +/- 8 years [mean +/- SD], BMI 25 +/- 3 kg/m(2)) and 10 normal men (35 +/- 6 years, 24 +/- 3 kg/m(2)). Each subject underwent two 5-h 80 mU. m(-2). min(-1) hyperinsulinemic-euglycemic clamps with measurement of glucose kinetics (intravenous [3-(3)H]glucose) and substrate oxidation. Plasma NEFA levels were elevated in one study for 3 h before and during the clamp ( approximately 1 mmol/l in both groups) by infusion of 20% Intralipid (60 ml/h) and heparin (900 U/h). In the control studies, the men and women had similar insulin-stimulated glucose disposal rates (R(d)) and substrate oxidation rates. In the men, elevated NEFA levels decreased insulin-stimulated glucose R(d) during the final 40 min of the clamp by 23% (P < 0.001). By contrast, no significant change in glucose R(d) was found in the women (control 10.4 +/- 1.1, lipid study 9.9 +/- 1.3 mg. kg(-1). min(-1)). Glucose R(d) was also unchanged in six women studied at a lower insulin dose (40 mU. m(-2). min(-1)). During the last 40 min of the high-insulin dose clamps with elevated NEFA, glucose oxidation was decreased by 33% in the men (P < 0.001) and by 23% in the women (P < 0.02). Nonoxidative glucose R(d) at this time was decreased by 15% in the men (P = 0.02) but was not significantly affected in women. Basal EGP was unaffected by elevation of plasma NEFA levels in both groups. Suppression of EGP during the glucose clamps, however, was impaired. At the insulin infusion rate used, the magnitude of this defect was comparable in men and women. In summary, our findings suggest that although the effects on EGP appear comparable, the inhibitory effects of NEFA on peripheral tissue insulin sensitivity are observed in men but cannot be demonstrated in women.

Metabolic effects of troglitazone therapy in type 2 diabetic, obese, and lean normal subjects.

OBJECTIVE: To characterize metabolic effects of troglitazone in type 2 diabetic, obese, and lean subjects, and examine the effects of troglitazone 2-3 weeks after discontinuation. RESEARCH DESIGN AND METHODS: Nine type 2 diabetic, nine obese, and nine lean subjects underwent baseline metabolic studies including an 8-h meal-tolerance test (MTT) and a 5-h glucose clamp. Subjects then received troglitazone (600 mg/day) for 12 weeks and subsequently had repeat metabolic studies. Diabetic subjects remained off hypoglycemic agents for 2-3 weeks and then underwent a 5-h glucose clamp. RESULTS: In diabetic subjects, fasting plasma glucose was reduced (P<0.05) and insulin-stimulated glucose disposal (Rd) was enhanced by treatment (P<0.02). The area under the MTT 8-h plasma glucose curve declined with therapy (P<0.001), and its change was positively correlated with the improvement in Rd (r = 0.75, P<0.05). There was also a positive correlation between the change in fasting hepatic glucose output (HGO) and the change in fasting plasma glucose with treatment (r = 0.92, P<0.001). Discontinuation of therapy for 2-3 weeks did not significantly affect fasting plasma glucose or insulin-stimulated glucose Rd. In obese subjects, insulin-stimulated glucose Rd improved with therapy (P<0.001), allowing for maintenance of euglycemia by lower plasma insulin concentrations (P<0.05). In lean subjects, an increase in fasting HGO (P<0.001) and glucose clearance (P<0.01) was observed. CONCLUSIONS: Troglitazone lowers fasting and postprandial plasma glucose in type 2 diabetes by affecting both fasting HGO and peripheral insulin sensitivity. Its effects are evident 2-3 weeks after discontinuation. In obese subjects, its insulin sensitizing effects suggest a role for its use in the primary prevention of type 2 diabetes.

Betulin inhibits pro-inflammatory cytokines expression through activation STAT3 signaling pathway in human cardiac cells.

OBJECTIVE: Signal transducer and activator of transcription 3 (STAT3) is an important regulator of cardiac survival pathways. Decreased expression or activity of STAT3 in patients with end-stage heart failure demonstrated a clinical relevance of STAT3 in cardiac diseases. Betulin, a pentacyclic triterpene, has drawn extensive attention towards its beneficial effects. However, little is known about its roles in cardiac cells. MATERIALS AND METHODS: We investigated the effects of betulin on the pro-inflammatory processes in human cardiac AC16 cells. Genes expression of pro-inflammatory cytokines and activation of NF-κB signaling were analyzed. Besides, levels of phosphorylated STAT3 and its down-stream target genes were measured to evaluate the activation of STAT3. Finally, STAT3 inhibitor and small interfering RNA (siRNA) oligos were used to determine the roles of STAT3 in AC16 cells treated with betulin. RESULTS: Our results revealed that betulin inhibited pro-inflammatory cytokines expression and NF-κB signaling activation through STAT3 signaling. Besides, betulin treatment also induced the expression of Bcl-xL, an anti-apoptotic downstream effector of STAT3. CONCLUSIONS: Our results, for the first time, uncovered the cardioprotective roles of betulin, which may be useful to reduce the occurrence of adverse cardiovascular events.

Morphologic evidence for L-citrulline conversion to L-arginine via the argininosuccinate pathway in porcine cerebral perivascular nerves.

Results from biochemical and pharmacologic studies suggest that Lcitrulline is taken up by cerebral perivascular nerves and is converted to Larginine for synthesizing nitric oxide (NO). The current study was designed using morphologic techniques to determine whether Lcitrulline is taken up into axoplasm of perivascular nerves and to explore the possibility that conversion of Lcitrulline to Larginine in these nerves is through the argininosuccinate pathway in porcine cerebral arteries. Results from light and electron microscopic autoradiographic studies indicated that dense silver grains representing L-[3H] citrulline uptake were found in cytoplasm of perivascular nerves, smooth muscle cells, and endothelial cells. The neuronal silver grains were significantly decreased in arteries pretreated with glutamine, which has been shown biochemically to block neuronal uptake of Lcitrulline. Results from light and electron microscopic immunohistochemical and histochemical studies indicate that dense nitric oxide synthase-immunoreactive (NOS-I), argininosuccinate synthetase-immunoreactive (ASS-I), and argininosuccinate lyase-immunoreactive (ASL-I) fibers were found in the adventitia of cerebral arteries. NOS-, ASS-, and ASL-immunoreactivities fibers were found in the axoplasm and in the endothelium. In whole-mount preparations, the NOS-I, ASS-I, and ASL-I fibers were completely coincident with NADPH diaphorase fibers, suggesting that axoplasmic ASS, ASL, and NOS were co-localized in the same neurons. These studies provide the first morphologic evidence indicating that Lcitrulline is taken up into cytoplasm of cerebral perivascular nerves and that the axoplasmic enzymes catalyzing the conversion of Lcitrulline to Larginine (for synthesizing NO) by argininosuccinate pathway always are co-localized in same neurons. These results support the hypothesis that Lcitrulline, the by-product of NO synthesis, is recycled to form Larginine for synthesizing NO in perivascular nerves to mediate cerebral neurogenic vasodilation. Results of the current morphologic studies also support the presence of Lcitrulline-Larginine cycle in cerebral vascular endothelium.

Differential gene expression of adenosine A1, A2a, A2b, and A3 receptors in the human enteric nervous system.

Adenosine receptors (ADORs) in the enteric nervous system may be of importance in the control of motor and secretomotor functions. Gene expression and distribution of neural adenosine A1, A2a, A2b, or A3 receptors (Rs) in the human intestine was investigated using immunochemical, Western blotting, RT-PCR, and short-circuit current (I(sc)) studies. Adenosine A1R, A2aR, A2bR, or A3R mRNAs were differentially expressed in neural and nonneural layers of the jejunum, ileum, colon, and cecum and in HT-29, T-84, T98G, and Bon cell lines. A1R, A2aR, A2bR, and A3R immunoreactivities (IRs) were differentially expressed in PGP 9.5-immunoreactive neurons. A2bR IR occurs exclusively in 50% of submucosal vasoactive intestinal peptide (VIP) neurons (interneurons, secretomotor or motor neurons) in jejunum, but not colon; A2aR is also found in other neurons. A3R IR occurs in 57% of substance P-positive jejunal submucosal neurons (putative intrinsic primary afferent neurons) and less than 10% of VIP neurons. Western blots revealed bands for A3R at 44 kDa, 52 kDa, and 66 kDa. A2aR and A2bR are coexpressed in enteric neurons and epithelial cells. 5'-N-methylcarboxamidoadenosine or carbachol evoked an increase in I(sc). A2bR IR is more prominent than A2aR IR in myenteric neurons, nerve fibers, or glia. A1R is expressed in jejunal myenteric neurons and colonic submucosal neurons. Regional differences also exist in smooth muscle expression of ADOR IR(s). It is concluded that neural and nonneural A1, A2a, A2b, and A3Rs may participate in the regulation of neural reflexes in the human gut. Clear cell and regional differences exist in ADOR gene expression, distribution, localization, and coexpression.

Melanocortin-1 receptor gene variants in four Chinese ethnic populations.

There is strong relationship between melanocortin-1 receptor (MC1R) gene variants and human hair color and skin type. Based on a sequencing study of MC1R gene in 50 individuals from the Uygur, Tibetan, Wa and Dai ethnic populations, we discuss the occurrence of 7 mc1r variants consisting of 5 nonsynonymous sites (Val60Leu, Arg67Gln, Val92Met, Arg163Gln and Ala299Val) and 2 synonymous sites (C414T and A942G), among which C414T and Ala299Val were reported for the first time. Confirmation and analysis were also made of 122 individuals at three common point mutations (Val92Met, Arg163Gln, A942G) using PCR-SSCP. The frequency of Arg163Gln variant varies in the four ethnic populations, with percentage of 40%, 85.0%, 66.2% and 72.7%, respectively, while those of Val92Met and A942G are roughly similar in these four populations. The different environments, migration and admixture of various ethnic groups in China might have impact on the observed frequency of Arg163Gln.