"Sweet space" strategy for solvent system selection in countercurrent chromatography: A case study on separation of polyunsaturated fatty acids from borage oil.

This study presents a comprehensive strategy for the selection and optimization of solvent systems in countercurrent chromatography (CCC) for the effective separation of compounds. With a focus on traditional organic solvent systems, the research introduces a "sweet space" strategy that merges intuitive understanding with mathematical accuracy, addressing the significant challenges in solvent system selection, a critical bottleneck in the widespread application of CCC. By employing a combination of volume ratios and graphical representations, including both regular and trirectangular tetrahedron models, the proposed approach facilitates a more inclusive and user-friendly strategy for solvent system selection. This study demonstrates the potential of the proposed strategy through the successful separation of gamma-linolenic acid, oleic acid, and linoleic acid from borage oil, highlighting the strategy's effectiveness and practical applicability in CCC separations.

A comparison of ultrasound volume navigation, O-arm navigation, and X-ray guidance for screw placement in minimally invasive transforaminal lumbar interbody fusion: a randomized controlled trial.

OBJECTIVE: To compare the differences between Ultrasound Volume Navigation (UVN), O-arm Navigation, and conventional X-ray fluoroscopy-guided screw placement in Minimally Invasive Transforaminal Lumbar Interbody Fusion (MIS-TLIF) surgeries. METHODS: A total of 90 patients who underwent MIS-TLIF due to lumbar disc herniation from January 2022 to January 2023 were randomly assigned to the UVN group, O-arm group, and X-ray group. UVN, O-arm navigation, and X-ray guidance were used for screw placement in the respective groups, while the remaining surgical procedures followed routine MIS-TLIF protocols. Intraoperative data including average single screw placement time, total radiation dose, and average effective radiation dose per screw were recorded and calculated. On the 10th day after surgery, postoperative X-ray and CT examinations were conducted to assess screw placement accuracy and facet joint violation. RESULTS: There were no significant differences in general characteristics among the three groups, ensuring comparability. Firstly, the average single screw placement time in the O-arm group was significantly shorter than that in the UVN group and X-ray group (P<0.05). Secondly, in terms of total radiation dose during surgery, for single-level MIS-TLIF, the O-arm group had a significantly higher radiation dose compared to the UVN group and X-ray group (P<0.05). However, for multi-level MIS-TLIF, the X-ray group had a significantly higher radiation dose than the O-arm group and UVN group (P<0.05). In terms of average single screw radiation dose, the O-arm group and X-ray group were similar (P>0.05), while the UVN group was significantly lower than the other two groups (P<0.05). Furthermore, no significant differences were found in screw placement assessment grades among the three groups (P>0.05). However, in terms of facet joint violation rate, the UVN group (10.3%) and O-arm group (10.7%) showed no significant difference (P>0.05), while the X-ray group (26.7%) was significantly higher than both groups (P<0.05). Moreover, in the UVN group, there were significant correlations between average single screw placement time and placement grade with BMI index (r = 0.637, P<0.05; r = 0.504, P<0.05), while no similar significant correlations were found in the O-arm and X-ray groups. CONCLUSION: UVN-guided screw placement in MIS-TLIF surgeries demonstrates comparable efficiency, visualization, and accuracy to O-arm navigation, while significantly reducing radiation exposure compared to both O-arm navigation and X-ray guidance. However, UVN may be influenced by factors like obesity, limiting its application.

Development of a general separation strategy by countercurrent chromatography using sanshools from Zanthoxylum bungeanum oleoresin as a case study.

Three kinds of sanshools were separated from Zanthoxylum bungeanum oleoresin by high-speed countercurrent chromatography. Sanshools are a series of amide compounds extracted from the Zanthoxylum bungeanum. Due to similar structures, polarities, and dissociation constants, it was challenging to select an appropriate solvent system for their complete separation by countercurrent chromatography. To address this challenge, a solvent-system-selection strategy was proposed to identify a relatively suitable solvent system. Additionally, a separation procedure incorporating multi-elution modes selection was established to separate similar compounds in a logical order. Ultimately, a solvent system comprising n-hexane:ethyl acetate:methanol:water in a ratio of 19:1:1:5.67 was selected. Three amide compounds with high purity were obtained through the use of recycling elution mode to improve separation resolution: hydroxy-ε-sanshool (8.4 mg; purity: 90.64%), hydroxy-α-sanshool (326.4 mg; purity: 98.96%), and hydroxy-ß-sanshool (71.8 mg; purity: 98.26%) were obtained from 600 mg sanshool crude extract. The summarized solvent-system-selection strategy and separation procedure incorporating multi-elution modes may instruct countercurrent chromatography users, particularly novices, seeking to separate compounds with highly similar chemical properties.

Using Drosophila Two-Choice Assay to Study Optogenetics in Hands-On Neurobiology Laboratory Activities.

Optogenetics has made a significant impact on neuroscience, allowing activation and inhibition of neural activity with exquisite spatiotemporal precision in response to light. In this lab session, we use fruit flies to help students understand the fundamentals of optogenetics through hands-on activities. The CsChrimson channelrhodopsin, a light-activated cation channel, is expressed in sweet and bitter sensory neurons. Sweet sensory neurons guide animals to identify nutrient-rich food and drive appetitive behaviors, while bitter sensory neurons direct animals to avoid potentially toxic substances and guide aversive behavior. Students use two-choice assays to explore the causality between the stimulation activation of these neurons and the appetitive and avoidance behaviors of the fruit flies. To quantify their observations, students calculate preference indices and use the Student's t-test to analyze their data. After this lab session, students are expected to have a basic understanding of optogenetics, fly genetics, sensory perception, and how these relate to sensory-guided behaviors. They will also learn to conduct, quantify, and analyze two-choice behavioral assays.

Evaluating the effect of methotrexate on the rate of renal fibrosis by elastography and fibrosis-related gene expression.

Methotrexate is mainly used to treat diseases such as rheumatoid arthritis (RA), but its potential for nephrotoxicity has always been a significant concern on the use of this medication. This study aimed to determine the rate of renal fibrosis using transient elastography and its relationship with cumulative dose and duration of drug use in patients with rheumatoid arthritis treated with methotrexate. TGFß gene expression was also assessed for further evaluation. Patients with rheumatoid arthritis who received methotrexate for more than six months were included. Renal fibrosis was determined by measuring the stiffness of the kidney by elastography (FiberScan Device). RA patients were divided into two groups based on kidney stiffness measurement with and without renal fibrosis, and demographic, clinical, and biochemical parameters were compared to investigate the relationship between cumulative dose and duration of methotrexate treatment and renal fibrosis. Also, in this study, 50 controls (healthy people) and 50 cases (RA patients) were used to evaluate the expression of the TGFß gene by real-time PCR method. The existence of kidney fibrosis was observed in 10 patients. There was no significant relationship between renal fibrosis and the cumulative dose (P = 0.21) and duration of methotrexate (P = 0.30). Multivariate regression analysis showed that the chances of developing renal fibrosis in patients increase with increasing serum ALT levels (P = 0.01). The results of the TGFß gene expression showed that the expression of this gene in the group of RA patients with fibrosis was higher than the control group (healthy people) and the group of RA patients without fibrosis (P <0.01). These results showed that evaluation of renal fibrosis by elastography method is recommended for scanning RA patients while they are being treated with methotrexate, which is also confirmed by the results of the fibrosis-related-gene expression.

Effects of enteral nutrition semi-curing feeding on nutritional diarrhoea improvement in the patients with severe stroke.

OBJECTIVE: The present study aims to explore the effects of enteral nutrition (EN) semi-curing feeding on nutritional diarrhoea in the patients with stroke. METHODS: The patients admitted to the neurological intensive care unit of a tertiary care hospital with stroke- and EN-related diarrhoea between May 2019 and October 2020 were included in the study. The 60 patients, who met the inclusion criteria were divided into the two groups (30 patients each), the experimental group (EN solution+probiotics+90 ml of pectin) and the control group (EN solution+probiotics), in accordance with the random number table method. The stool number, total stool amount, perineal skin score, and time required to achieve the nutritional target of each patient were recorded at admission and on days 1, 3, and 7 of pectin intervention. The lymphocyte count and the haemoglobin, serum pre-albumin (PA), and total cholesterol (TC) levels were measured in order to assess the patients' nutritional statuses. RESULTS: The stool number and total stool amount on days 1 and 3 of pectin intervention in the experimental group were better than in the control group; the differences were statistically significant (p <0.05). On day 7 of the intervention, the stool number, total stool amount, and perineal skin score had decreased in the experimental group; the differences were statistically significant, when compared to the control group (p <0.05). Furthermore, the PA levels increased, and TC levels decreased in the experimental group; the differences were statistically significant, when compared to the control group (p <0.05). On day 3 of the intervention, the PA levels in the experimental group were increased compared to the control group; the difference was statistically significant (p <0.05). CONCLUSION: EN semi-curing feeding could improve EN-related diarrhoea and nutritional status levels in patients with stroke (Tab. 3, Ref. 9).

Efficacy and safety of omalizumab in children with moderate-to-severe asthma: a meta-analysis.

OBJECTIVE: To assess the efficacy and safety of omalizumab in children with moderate-to-severe asthma. DATA SOURCES: We systematically searched MEDLINE, EMBASE, and Cochrane for randomized controlled trials (RCTs ) (inception to January 2020). STUDY SELECTIONS: All RCTs which were conducted in childhood and adolescence with asthma and compared the efficacy or safety of omalizumab were adopted. RESULTS: Three studies with four publications including 1380 pediatric patients met our criteria. For children with moderate-to-severe asthma, omalizumab decreased asthma exacerbations rate (OR 0.51, 95% CI: 0.44-0.58, p < 0.001) compared with placebo with no evidence of heterogeneity. Omalizumab reduced the rate of asthma exacerbations 0.58) with treatment period ≥30 weeks (p for heterogeneity = 0.03). Omalizumab treated patients had an excellent or good response rate of treatment effectiveness assessed by physicians (2.75, 2.45-3.09) and a bigger reduction in the dosage of inhaled corticosteroid (ICS) at the end of follow-up. For children with severe asthma, omalizumab also reduced the likelihood of asthma exacerbations and increased the odd of treatment effectiveness rated as excellent or good. Patients receiving omalizumab had a lower incidence of severe adverse events (0.36, 0.22-0.57). CONCLUSIONS: These findings suggested that omalizumab had beneficial effects on moderate-to-severe asthma in children. Patients may benefit more from long-term use of omalizumab. In addition, omalizumab reduces the rate of serious adverse events requiring hospitalizations.

Stabilizing a laser frequency by the Pound-Drever-Hall technique with an acousto-optic modulator.

We develop and demonstrate a method of optical phase modulation in the Pound-Drever-Hall (PDH) technique. The phase modulation in this paper is realized by an acousto-optic modulator (AOM) operating in the Bragg diffraction regime. In this process, a light beam separated from a laser (780 nm) is sent through the AOM twice and coupled to a high finesse Fabry-Perot cavity. Then, the light power coupling into the cavity is stabilized by modulating the optical amplitude with this AOM. The coupling light power is stabilized to a level of 10-3. In the meantime, the PDH error signal is obtained by modulating the optical phase with the same AOM. After the error signal is fed back to the laser current, the laser linewidth is suppressed to approximately 907.91 Hz. This method of phase modulation is simple and convenient, and we believe it can be widely used in modulation transfer spectroscopy and frequency-modulation sideband spectroscopy.

Ginsenoside Rg3 inhibits pulmonary fibrosis by preventing HIF-1α nuclear localisation.

BACKGROUND: Excessive fibroblast proliferation during pulmonary fibrosis leads to structural abnormalities in lung tissue and causes hypoxia and cell injury. However, the mechanisms and effective treatment are still limited. METHODS: In vivo, we used bleomycin to induce pulmonary fibrosis in mice. IHC and Masson staining were used to evaluate the inhibitory effect of ginsenoside Rg3 in pulmonary fibrosis. In vitro, scanning electron microscopy, transwell and wound healing were used to evaluate the cell phenotype of LL 29 cells. In addition, biacore was used to detect the binding between ginsenoside Rg3 and HIF-1α. RESULTS: Here, we found that bleomycin induces the activation of the HIF-1α/TGFß1 signalling pathway and further enhances the migration and proliferation of fibroblasts through the epithelial mesenchymal transition (EMT). In addition, molecular docking and biacore results indicated that ginsenoside Rg3 can bind HIF-1α. Therefore, Ginsenoside Rg3 can slow down the progression of pulmonary fibrosis by inhibiting the nuclear localisation of HIF-1α. CONCLUSIONS: This finding suggests that early targeted treatment of hypoxia may have potential value in the treatment of pulmonary fibrosis.

Elevated high mobility group A2 expression in liver cancer predicts poor patient survival.

BACKGROUND: liver cancer is a malignant tumor with a high morbidity and mortality that endangers human health. High mobility group A2 (HMGA2) is a chromosome associated protein that participates in embryogenesis, tissue development, tumorigenesis and development. OBJECTIVE: to explore the relationship between HMGA2 expression and the clinicopathological parameters and survival of liver cancer patients using The Cancer Genome Atlas Liver Hepatocellular Carcinoma (HCC) data. METHODS: RNA-sequencing data and the corresponding clinical characteristics of the patients were downloaded from the Atlas database. The Chi-squared test was used to assess the relationship between HMGA2 expression and clinical variables. Cox regression analysis was used to compare survival rates between the high- and low-expressing groups; the p-values and Kaplan-Meier survival curves were compared using the log-rank test. RESULTS: RNA-seq data from 373 cases of liver cancer cases were analyzed. HMGA2 was overexpressed in liver cancer and significantly associated with gender (p = 0.0357), T classification (p = 0.0063), clinical classification (p = 0.0026) and overall survival (p = 0.0386). According to the multivariate analysis, HMGA2 could independently predict overall survival in liver cancer. CONCLUSIONS: HMGA2 independently predicts poor prognosis in liver cancer and serves as a molecular marker to determine disease prognosis.

[Blepharoptosis and dysarthria in a boy aged 2 years].

A boy, aged 2 years and 4 months, had a sudden onset of blepharoptosis of the right eyelid, accompanied by the mouth deviated to the right side, drinking cough, nystagmus, and developmental regression. Cranial MRI showed softening lesions formed after infarction of the right dorsolateral medulla oblongata, while head CT angiography showed no imaging of the proximal part of the V4 segment of the right vertebral artery. The child was diagnosed with dorsolateral medulla oblongata syndrome and was treated with gamma globulin to regulate immune function, with mannitol to reduce neuronal edema, with low-molecular-weight heparin sodium to improve local hypercoagulation of occluded blood vessels, with hyperbaric oxygen to improve local ischemia and hypoxia and promote the recovery of brain function, and with neuromuscular electrical stimulation to promote the recovery of neuromuscular function. Before discharge, only mild right ataxia and Horner syndrome remained. This article reports the first case of infantile dorsolateral medulla oblongata syndrome and provides experience for the diagnosis and treatment of the disease.

Value of Ultrasound-Guided Closed Reduction and Minimally Invasive Fixation in the Treatment of Metacarpal Fractures.

OBJECTIVES: To investigate the value of ultrasound-guided closed reduction and minimally invasive fixation in the treatment of metacarpal fractures. METHODS: Twenty-four patients with acute metacarpal fractures were randomly divided into experimental and control groups, with 12 patients in each group. Ultrasound-guided closed reduction and fixation were performed in the experimental group, whereas C-arm fluoroscopy-assisted fixation was performed in the control group. Patients in both groups were followed to compare the treatment efficacy. RESULTS: The success rates of ultrasound-guided closed reduction of fractures were 75.00% (9 of 12) in the experimental group and 83.33% (10 of 12) in the control group, and the difference was not statistically significant (χ2 = 0.253; P = .615) between the groups. The mean numbers of C-arm fluoroscopy-assisted procedures ± SD were 1.50 ± 0.67 times in the experimental group and 2.50 ± 0.80 in the control group, and the difference was statistically significant (t = -3.317; P = .003). The mean healing times of fractures were 5.47 ± 0.67 weeks in the experimental group and 5.73 ± 0.81 weeks in the control group; the excellence rates of total active motion were 83.33% (10 of 12) in the experimental group and 91.67% (11 of 12) in the control group; the mean grip strength values were 31.78 ± 3.13 kg in the experimental group and 33.43 ± 3.30 kg in the control group. There were no significant differences in those 3 parameters between the groups (P > .05 in each comparison). CONCLUSIONS: Ultrasound-guided closed reduction and minimally invasive fixation is an effective treatment of metacarpal fractures and can reduce exposure to x-ray radiation.

A triple signal amplification method for chemiluminescent detection of the cancer marker microRNA-21.

Mesoporous silica nanospheres (MSNs) are used in a triple signal amplification chemiluminescent (CL) assay for microRNA-21. It is based on (a) the synergistic amplification via loading and controlled-release of signal reagents by MSNs, (b) target recycling amplification, and (c) the enhancement effect of graphene oxide quantum dots (GOQD). CL is generated by the bis(2,4,6-trichlorophenyl) oxalate (TCPO) and H2O2 reaction in the presence of the fluorophore rhodamine B (RB). RB is firstly loaded into the pores of MSNs modified with amino groupsand coupled with ssDNA. Then, the pores are capped by GOQD. Upon the addition of microRNA-21 into the system, the designed ssDNA assumes a double stranded structure. With the aid of duplex-specific nuclease, the double strand structure is cleaved and the free microRNA-21 enters into the next cycling process to combine with other ssDNA forming double strand structures. After several cycling process, amounts of GOQDs departing from the surface of MSNs cause the opening of the pores of MSNs and the release of RB causes the CL of TCPO-H2O2 reaction system. Free GOQDs can lead to a further CL enhancement. By this method, even a low amount of microRNA-21 leads to a large number of released RB molecules and triggers high-intensity CL. The method was applied in an assay where the CL signal increases linearly with the logarithm of the microRNA-21 concentration in the range of 0.005-50 pmol L-1 and the detection limit is 1.7 fmol L-1 (at 3σ). Graphical abstract Schematic presentation of a triple signal amplification chemiluminescence (CL) analysis platform based on rodamine B (RB) loading and controlled release, target recycling amplification and graphene oxide quantum dots (GOQD) as the enhancer for analysis of microRNA-21 in human serum.

Long noncoding RNA H19 mediates LCoR to impact the osteogenic and adipogenic differentiation of mBMSCs in mice through sponging miR-188.

The research aimed to examine the expression of lncRNA H19, miR-188, and LCoR in mouse bone marrow stromal stem cells (mBMSCs), and to investigate the regulatory mechanism of lncRNA H19/miR-188/LCoR in osteogenic and adipogenic differentiation of mBMSCs. The expression of miR-188 in mBMSCs and osteogenesis induced mBMSCs was detected by stem-loop RT-PCR, while the expression of H19 and LCoR in mBMSCs and adipogenesis induced mBMSCs was examined by qRT-PCR. Luciferase reporter assay verified the targeted relationship between miR-188 and H19 or LCoR. Cell proliferation ability was determined by MTT assay, while cell surface markers of mBMSCs were analyzed via flow cytometry. Alkaline phosphatase staining and Alizarin red staining was utilized to detect the osteogenic differentiation capability of mBMSCs, whereas Oil red O staining was applied to examine the ability of adipogenic differentiation of mBMSCs. The expression of miR-188 was lower in osteogenesis induced mBMSCs compared with normal mBMSCs, while H19 and LCoR were downregulated in adipogenic induced mBMSCs. Si-H19 could significantly increase the mRNA level of miR-188. Meanwhile, miR-188 directly regulated LCoR in mBMSCs. Overexpression of miR-188 and knockdown of LCoR suppressed osteogenic differentiation and induced adipogenic differentiation in mBMSCs. Long noncoding RNA H19 mediates LCoR to regulate the balance between osteogenic and adipogenic differentiation of mBMSCs in mice through sponging miR-188.

Long-term high-fat diet induces hippocampal microvascular insulin resistance and cognitive dysfunction.

Insulin action on hippocampus improves cognitive function, and obesity and type 2 diabetes are associated with decreased cognitive function. Cerebral microvasculature plays a critical role in maintaining cerebral vitality and function by supplying nutrients, oxygen, and hormones such as insulin to cerebral parenchyma, including hippocampus. In skeletal muscle, insulin actively regulates microvascular opening and closure, and this action is impaired in the insulin-resistant states. To examine insulin's action on hippocampal microvasculature and parenchyma and the impact of diet-induced obesity, we determined cognitive function and microvascular insulin responses, parenchyma insulin responses, and capillary density in the hippocampus in 2- and 8-mo-old rats on chow diet and 8-mo-old rats on a long-term high-fat diet (6 mo). Insulin infusion increased hippocampal microvascular perfusion in rats on chow diet by ~80-90%. High-fat diet feeding completely abolished insulin-mediated microvascular responses and protein kinase B phosphorylation but did not alter the capillary density in the hippocampus. This was associated with a significantly decreased cognitive function assessed using both the two-trial spontaneous alternation behavior test and the novel object recognition test. As the microvasculature provides the needed endothelial surface area for delivery of nutrients, oxygen, and insulin to hippocampal parenchyma, we conclude that hippocampal microvascular insulin resistance may play a critical role in the development of cognitive impairment seen in obesity and diabetes. Our results suggest that improvement in hippocampal microvascular insulin sensitivity might help improve or reverse cognitive function in the insulin-resistant states.

[Immune regulation effect of Chinese medicine of invigorating spleen and kidney detoxification on simian immunodeficiency virus-infected rhesus macaque].

To evaluate the effect of Chinese medicine of invigorating spleen and kidney detoxification on simian immunodeficiency virus-infected rhesus macaque. Eight SIV rhesus macaques of the same age were randomly divided into Chinese medicine of invigorating spleen and kidney detoxification group(hereinafter referred to as Chinese medicine group) and anti-virus drug(HAART) group. The traditional Chinese medicine and antiviral therapy were given for 8 weeks, and peripheral blood was collected for detection in every 4 weeks. The results showed that Chinese medicine of invigorating spleen and kidney detoxification could not obviously decrease plasma viral load as HAART, but it can increase CD4 number in peripheral blood, especially the CD4 naive cells, and increase the number of CD4 and CD8 cells, enhance the immune response to pathogens. Therefore, it delayed the occurrence and development of spleen deficiency to a certain extent, indicating that the medicine had immune regulation effect, with considerable clinical value and application prospects.

Liraglutide prevents microvascular insulin resistance and preserves muscle capillary density in high-fat diet-fed rats.

Muscle microvasculature critically regulates endothelial exchange surface area to facilitate transendothelial delivery of insulin, nutrients, and oxygen to myocytes. Insulin resistance blunts insulin-mediated microvascular recruitment and decreases muscle capillary density; both contribute to lower microvascular blood volume. Glucagon-like peptide 1 (GLP-1) and its analogs are able to dilate blood vessels and stimulate endothelial cell proliferation. In this study, we aim to determine the effects of sustained stimulation of the GLP-1 receptors on insulin-mediated capillary recruitment and metabolic insulin responses, small arterial endothelial function, and muscle capillary density. Rats were fed a high-fat diet (HFD) for 4 wk with or without simultaneous administration of liraglutide and subjected to a euglycemic hyperinsulinemic clamp for 120 min after an overnight fast. Insulin-mediated muscle microvascular recruitment and muscle oxygenation were determined before and during insulin infusion. Muscle capillary density was determined and distal saphenous artery used for determination of endothelial function and insulin-mediated vasodilation. HFD induced muscle microvascular insulin resistance and small arterial vessel endothelial dysfunction and decreased muscle capillary density. Simultaneous treatment of HFD-fed rats with liraglutide prevented all of these changes and improved insulin-stimulated glucose disposal. These were associated with a significantly increased AMPK phosphorylation and the expressions of VEGF and its receptors. We conclude that GLP-1 receptor agonists may exert their salutary glycemic effect via improving microvascular insulin sensitivity and muscle capillary density during the development of insulin resistance, and early use of GLP-1 receptor agonists may attenuate metabolic insulin resistance as well as prevent cardiovascular complications of diabetes.

Globular adiponectin ameliorates metabolic insulin resistance via AMPK-mediated restoration of microvascular insulin responses.

Adiponectin is an adipokine with anti-inflammatory and anti-diabetic properties. Hypoadiponectinaemia is closely associated with endothelial dysfunction and insulin resistance in obesity and diabetes. Insulin resistance is present in muscle microvasculature and this may contribute to decreased insulin delivery to, and action in, muscle. In this study we examined whether adiponectin ameliorates metabolic insulin resistance by affecting muscle microvascular recruitment. We demonstrated that a high-fat diet induces vascular adiponectin and insulin resistance but globular adiponectin administration can restore vascular insulin responses and improve insulin's metabolic action via an AMPK- and nitric oxide-dependent mechanism. This suggests that globular adiponectin might have a therapeutic potential for improving insulin resistance and preventing cardiovascular complications in patients with diabetes via modulation of microvascular insulin responses. Hypoadiponectinaemia is closely associated with endothelial dysfunction and insulin resistance, and microvasculature plays a critical role in the regulation of insulin action in muscle. Here we tested whether adiponectin replenishment could improve metabolic insulin sensitivity in male rats fed a high-fat diet (HFD) via the modulation of microvascular insulin responses. Male Sprague-Dawley rats were fed either a HFD or low-fat diet (LFD) for 4 weeks. Small resistance artery myograph changes in tension, muscle microvascular recruitment and metabolic response to insulin were determined. Compared with rats fed a LFD, HFD feeding abolished the vasodilatory actions of globular adiponectin (gAd) and insulin on pre-constricted distal saphenous arteries. Pretreatment with gAd improved insulin responses in arterioles isolated from HFD rats, which was blocked by AMP-activated protein kinase (AMPK) inhibition. Similarly, HFD abolished microvascular responses to either gAd or insulin and decreased insulin-stimulated glucose disposal by ∼60%. However, supplementing gAd fully rescued insulin's microvascular action and significantly improved the metabolic responses to insulin in HFD male rats and these actions were abolished by inhibition of either AMPK or nitric oxide production. We conclude that HFD induces vascular adiponectin and insulin resistance but gAd administration can restore vascular insulin responses and improve insulin's metabolic action via an AMPK- and nitric oxide-dependent mechanism in male rats.

Inflammation-induced microvascular insulin resistance is an early event in diet-induced obesity.

Endothelial dysfunction and vascular insulin resistance usually coexist and chronic inflammation engenders both. In the present study, we investigate the temporal relationship between vascular insulin resistance and metabolic insulin resistance. We assessed insulin responses in all arterial segments, including aorta, distal saphenous artery and the microvasculature, as well as the metabolic insulin responses in muscle in rats fed on a high-fat diet (HFD) for various durations ranging from 3 days to 4 weeks with or without sodium salicylate treatment. Compared with controls, HFD feeding significantly blunted insulin-mediated Akt (protein kinase B) and eNOS [endothelial nitric oxide (NO) synthase] phosphorylation in aorta in 1 week, blunted vasodilatory response in small resistance vessel in 4 weeks and microvascular recruitment in as early as 3 days. Insulin-stimulated whole body glucose disposal did not begin to progressively decrease until after 1 week. Salicylate treatment fully inhibited vascular inflammation, prevented microvascular insulin resistance and significantly improved muscle metabolic responses to insulin. We conclude that microvascular insulin resistance is an early event in diet-induced obesity and insulin resistance and inflammation plays an essential role in this process. Our data suggest microvascular insulin resistance contributes to the development of metabolic insulin resistance in muscle and muscle microvasculature is a potential therapeutic target in the prevention and treatment of diabetes and its related complications.

Globular adiponectin enhances muscle insulin action via microvascular recruitment and increased insulin delivery.

RATIONALE: Adiponectin enhances insulin action and induces nitric oxide-dependent vasodilatation. Insulin delivery to muscle microcirculation and transendothelial transport are 2 discrete steps that limit insulin's action. We have shown that expansion of muscle microvascular surface area increases muscle insulin delivery and action. OBJECTIVE: To examine whether adiponectin modulates muscle microvascular recruitment thus insulin delivery and action in vivo. METHODS AND RESULTS: Overnight fasted adult male rats were studied. We determined the effects of adiponectin on muscle microvascular recruitment, using contrast-enhanced ultrasound, on insulin-mediated microvascular recruitment and whole-body glucose disposal, using contrast-enhanced ultrasound and insulin clamp, and on muscle insulin clearance and uptake with (125)I-insulin. Globular adiponectin potently increased muscle microvascular blood volume without altering microvascular blood flow velocity, leading to a significantly increased microvascular blood flow. This was paralleled by a ≈30% to 40% increase in muscle insulin uptake and clearance, and ≈30% increase in insulin-stimulated whole-body glucose disposal. Inhibition of endothelial nitric oxide synthase abolished globular adiponectin-mediated muscle microvascular recruitment and insulin uptake. In cultured endothelial cells, globular adiponectin dose-dependently increased endothelial nitric oxide synthase phosphorylation but had no effect on endothelial cell internalization of insulin. CONCLUSIONS: Globular adiponectin increases muscle insulin uptake by recruiting muscle microvasculature, which contributes to its insulin-sensitizing action.