Rat Jugular Vein Research Articles

Disturbed flow in the juxta-anastomotic area of an arteriovenous fistula correlates with endothelial loss, acute thrombus formation, and neointimal hyperplasia.

Clinical failure of arteriovenous neointimal hyperplasia (NIH) fistulae (AVF) is frequently due to juxta-anastomotic NIH (JANIH). Although the mouse AVF model recapitulates human AVF maturation, previous studies focused on the outflow vein distal to the anastomosis. We hypothesized that the juxta-anastomotic area (JAA) has increased NIH compared with the outflow vein. AVF was created in C57BL/6 mice without or with chronic kidney disease (CKD). Temporal and spatial changes of the JAA were examined using histology and immunofluorescence. Computational techniques were used to model the AVF. RNA-seq and bioinformatic analyses were performed to compare the JAA with the outflow vein. The jugular vein to carotid artery AVF model was created in Wistar rats. The neointima in the JAA shows increased volume compared with the outflow vein. Computational modeling shows an increased volume of disturbed flow at the JAA compared with the outflow vein. Endothelial cells are immediately lost from the wall contralateral to the fistula exit, followed by thrombus formation and JANIH. Gene Ontology (GO) enrichment analysis of the 1,862 differentially expressed genes (DEG) between the JANIH and the outflow vein identified 525 overexpressed genes. The rat jugular vein to carotid artery AVF showed changes similar to the mouse AVF. Disturbed flow through the JAA correlates with rapid endothelial cell loss, thrombus formation, and JANIH; late endothelialization of the JAA channel correlates with late AVF patency. Early thrombus formation in the JAA may influence the later development of JANIH.NEW & NOTEWORTHY Disturbed flow and focal endothelial cell loss in the juxta-anastomotic area of the mouse AVF colocalizes with acute thrombus formation followed by late neointimal hyperplasia. Differential flow patterns between the juxta-anastomotic area and the outflow vein correlate with differential expression of genes regulating coagulation, proliferation, collagen metabolism, and the immune response. The rat jugular vein to carotid artery AVF model shows changes similar to the mouse AVF model.

Defective autophagy triggered by arterial cyclic stretch promotes neointimal hyperplasia in vein grafts via the p62/nrf2/slc7a11 signaling pathway

Autophagy is an adaptation mechanism to keep cellular homeostasis, and its deregulation is implicated in various cardiovascular diseases. After vein grafting, hemodynamic factors play crucial roles in neointimal hyperplasia, but the mechanisms are poorly understood. Here, we investigated the impacts of arterial cyclic stretch on autophagy of venous smooth muscle cells (SMCs) and its role in neointima formation after vein grafting. Rat jugular vein graft were generated via the ‘cuff’ technique. Autophagic flux in venous SMCs is impaired in 3-day, 1-week and 2-week grafted veins. 10%-1.25 Hz cyclic stretch (arterial stretch) loaded with FX5000 stretch system on venous SMCs blocks cellular autophagic flux in vitro and shows no significant impact on activity of mTORC1 and AMPK. Microtubule depolymerization but not lysosome dysfunction nor autophagosome/amphisome-lysosomal membrane fusion blockade is involved in the impairment of autophagic flux. Microtubule stabilization, induced by paclitaxel treatment and external stents intervention respectively, restores venous SMC autophagy and ameliorates neointimal hyperplasia in vivo. Moreover, autophagy impairment causes accumulation of the cargo receptor p62, which sequesters keap1 to p62 aggregates and results in the stabilization and nuclear translocation of nrf2 to modulate its target antioxidative gene SLC7A11. p62 silencing abrogates the increases of nrf2 and slc7a11 protein expression, glutathione level and venous SMC proliferation triggered by arterial cyclic stretch in vitro, and further hinders nrf2 nuclear translocation, reduces neointimal thickness after vein grafting in vivo. p62 (T349A) mutation also inhibited venous SMC proliferation and alleviated neointimal formation in vivo. These findings suggest that stabilization of microtubules to rescue autophagic flux or direct silencing of p62 are potential therapeutic strategies for neointimal hyperplasia.

Dynamic Continuous Blood Extraction from Rat Heart via Noninvasive Microdialysis Technique.

Dynamic analysis of blood components is of great importance in understanding cardiovascular diseases and their related diseases, such as myocardial infarction, arrhythmia, atherosclerosis, cardiogenic pulmonary edema, pulmonary embolism, and cerebral embolism. At the same time, it is urgent to break through the continuous heart blood sampling technique in live rats to evaluate the effectiveness of distinctive ethnic medicine therapy. In this study, a blood microdialysis probe was implanted in the right jugular vein of rats in a precise and noninvasive surgical procedure. Cardiac blood samples were then collected at a rate of 2.87 nL/min to 2.98 mL/min by connecting to an online microdialysis sample collection system. Even more momentously, the acquired blood samples can temporarily be stored in microdialysis containers at 4 °C. The microdialysis-based online continuous blood collection program from rat heart has greatly guaranteed the quality of blood samples, advancing and invigorating the scientific rationality of the research on systemic cardiovascular diseases and evaluating ethnomedicine therapy from the perspective of hematology.

The optimized jugular vein catheterization reinforced cocaine self-administration addictive model for adult male Sprague–Dawley rats

The self-administration (SA) model represents one of the most important and classic methods for drug addiction, and jugular vein catheterization is one of the most critical techniques in this animal model. We aimed to explore an optimized scheme to improve the success rate of rat jugular vein catheterization and SA model. Our experiment provided an optimized scheme which including numerous details, materials, approaches, updated techniques and protocols. Our experimental group consisted of 120 adult male Sprague–Dawley rats, which were divided into the Traditional Operation group (TO group) and the Optimized Operation group (OO group) by the random number table method and then further individually divided into the Saline Training group and the Cocaine Training group for the following SA training. Our results showed that the success rate of the jugular vein catheterization in the OO group was significantly greater than that in the TO group (93.33% vs 46.67%, χ2 = 31.11, P < 0.001). The optimized jugular vein catheterization could make the SA model more stable, reliable and efficient than the traditional operation. Compared with traditional methods, our optimized scheme made numerous improvements in materials and techniques including uniformity, individualized variability of the S-type positioning nail, the length and connection matching, the shape of the end and low cost. Our optimized scheme could provide a more stable and efficient tool for basic research on drug addiction. Several subtle improvements under our personal experience are usually important for augmenting operational efficiency.

Hydrogel-coated needles prevent puncture site bleeding

IntroductionIncomplete hemostasis after vascular cannulation can cause a hematoma or pseudoaneurysm. We hypothesized that a hydrogel-coated needle would effectively and rapidly stop bleeding after vascular cannulation.Methods: A hydrogel composed of sodium alginate, hyaluronic acid, and calcium carbonate was coated onto the surface of suture needles. Needles were observed using scanning electronic microscopy (SEM) and immunofluorescence. Cannulation was performed in both mouse and rat models; the liver, kidney, jugular vein, inferior vena cava and aorta were punctured using uncoated and hydrogel-coated needles. Needles coated with a hydrogel with and without CD34 antibody were used to puncture the rat jugular vein and aorta. Tissues were examined by histology and immunofluorescence.Results: The hydrogel was successfully coated onto the surface of 22G and 30G needles and confirmed by SEM. Hydrogel-coated needles rapidly stopped bleeding after cannulation of the liver, kidney, jugular vein, inferior vena cava and aorta. Hydrogel-coated needles that contained CD34 antibody attracted vascular progenitor cells near the puncture site; there were fewer M1-type macrophages and more M2-type macrophages.Conclusion: Hydrogel-coated needles can effectively and rapidly stop puncture-site bleeding. The hydrogel that contains CD34 antibody attracted vascular progenitor cells, potentially promoting healing of the site after cannulation. Statement of significanceIncomplete hemostasis after vascular cannulation can cause a hematoma or pseudoaneurysm and remains a significant clinical problem. We developed a hydrogel composed of sodium alginate, hyaluronic acid, and calcium carbonate; hydrogel-coated needles effectively and rapidly stopped bleeding after vascular cannulation. Interestingly, the hydrogel can also serve as a carrier for drugs that are delivered to the puncture site during the short time of cannulation that could additionally promote puncture site healing. Hydrogel-coated needles may be a new method for rapid hemostasis with application to patients especially at risk for bleeding.

A rat arteriovenous graft model using decellularized vein.

The high rate of clinical failure of prosthetic arteriovenous grafts continues to suggest the need for novel tissue-engineered vascular grafts. We tested the hypothesis that the decellularized rat jugular vein could be successfully used as a conduit and that it would support reendothelialization as well as adaptation to the arterial environment. Autologous (control) or heterologous decellularized jugular vein (1 cm length, 1 mm diameter) was sewn between the inferior vena cava and aorta as an arteriovenous graft in Wistar rats. Rats were sacrificed on postoperative day 21 for examination. All rats survived, and grafts had 100% patency in both the control and decellularized groups. Both control and decellularized jugular vein grafts showed similar rates of reendothelialization, smooth muscle cell deposition, macrophage infiltration, and cell turnover. The outflow veins distal to the grafts showed similar adaptation to the arteriovenous flow. Both CD34, CD90 and nestin positive cells, as well as M1-type and M2-type macrophages accumulated around the graft. This model shows that decellularized vein can be successfully used as an arteriovenous graft between the rat aorta and the inferior vena cava. Several types of cells, including progenitor cells and macrophages, are present in the host response to these grafts in this model. This model can be used to test the application of arteriovenous grafts before conducting large animal experiments.

Lack of toxicological influences by microsampling (50 µL) from jugular vein of rats in a collaborative 28-day study.

Due to finalization of the ICH S3A Q&A focusing on microsampling, application of microsampling technique to regular non-clinical animal studies is expected for non-clinical safety assessment of pharmaceuticals. In Europe, microsampling from the tail vein or saphenous vein has often been used, whereas sampling from the jugular vein is thought to be more common for non-clinical studies in Japan. Therefore, we assessed the toxicological effects of serial microsampling from the jugular vein of SD rats in a common 28-day study at 4 independent organizations. Fifty microliter sampling was performed at 6 timepoints on day 1 to 2 and 7 timepoints on day 27 to 28 and its toxicological influences on body weight, food consumption, hematological and clinical chemistry parameters, and organ weights (on day 29 for 3 and day 28 for 1 organizations) were evaluated. The serial microsampling was shown to have no or minimal influences on the assessed parameters. The observed statistical differences for the 18 parameters were sporadic and did not appear to be systemically associated with microsampling. However, the sporadic changes were more often observed in females (14/18 parameters) than in males (6/18), suggesting the possibility that female rats were more susceptible to treatment-based influences. The current results indicate that serial 50 μL sampling from the jugular vein of SD rats had no or very slight toxicological effects, suggesting that this microsampling condition is applicable for toxicokinetic evaluation of non-clinical rat toxicity studies.

Carthamin Yellow Protects the Heart Against Ischemia/Reperfusion Injury With Reduced Reactive Oxygen Species Release and Inflammatory Response.

Carthamin yellow (CY) is a flavonoid compound isolated from safflower, which is widely used clinically in China. It has various pharmacological effects including promoting blood circulation to remove blood stasis and alleviating pain. Ischemic heart disease is one of the main culprits of illness and death. Here, in this study, ex vivo and in vivo models were used to investigate whether CY reduces ischemia/reperfusion injury. In vitro experiments further verify and explain the potential mechanisms of CY cardioprotective function. Isolated hearts from male rats with or without CY pretreatment before ischemia which underwent 30-minute ischemia followed by 60-minute reperfusion showed that CY pretreatment significantly reduced the infarct size and lactate dehydrogenase release. The in vivo experiments also indicated CY preadministration (i.v.) reduced infarct size and improved the heart function, which was impaired by myocardial ischemia/reperfusion injury. The in vitro model on myocardial cell also showed that CY reduced ischemia/reperfusion injury by reducing the lactate dehydrogenase and reactive oxygen species (ROS) releasing. Eliminating ROS with N-acetylcysteine or preinject CY into rat jugular vein reduces the expression of IL-6, TNF-a, and, especially, IL-1b in an in vivo I/R model. Also, CY pretreatment strongly reduces ischemia/reperfusion-induced NLRP3 up-expression and caspase-1 activation. Our results indicated CY reduced ischemia-reperfusion injury when administered before reperfusion. The reduction in injury is accompanied by a reduced ROS release and decreased inflammatory response.

The BD2 domain of BRD4 is a determinant in EndoMT and vein graft neointima formation

BackgroundVein-graft bypass is commonly performed to overcome atherosclerosis but is limited by high failure rates, principally due to neointimal wall thickening. Recent studies reveal that endothelial-mesenchymal transition (EndoMT) is critical for vein-graft neointima formation. BETs are a family of Bromo/ExtraTerminal domains-containing epigenetic reader proteins (BRD2, BRD3, BRD4). They bind acetylated histones through their unique tandem bromodomains (BD1, BD2), facilitating transcriptional complex formation and cell-state transitions. The role for BETs, including individual BRDs and their unique BDs, is not well understood in EndoMT and neointimal formation. Methods and resultsRepression of BRD4 expression abrogated TGFβ1-induced EndoMT, with greater effects than BRD2 or BRD3 knockdown. An inhibitor selective for BD2 in all BETs, but not that for BD1, blocked EndoMT. Moreover, expression of a dominant-negative BRD4-specific BD2 fully abolished EndoMT. Concordantly, BRD4 knockdown repressed TGFβ1-stimulated increase of ZEB1 protein – a transcription factor integral in EndoMT. In vivo, lentiviral gene transfer of either BRD4 shRNA or dominant negative BRD4-specific BD2 mitigated neointimal development in rat jugular veins grafted to carotid arteries. ConclusionsOur data reveal the BD2 domain of BRD4 as a determinant driving EndoMT in vitro and neointimal formation in vivo. These findings provide new insight into BET biology, while offering prospects of specific BET domain targeting as an approach to limiting neointima and extending vein graft patency.

Activation of Interleukin-1 Beta in Arterialized Vein Grafts and the Influence of the -511C/T IL-1β Gene Polymorphism.

The interleukin-1 family is associated with innate immunity and inflammation. The latter has been linked to the genesis of cardiovascular diseases. We, therefore, investigated whether interleukin-1 beta (IL-1β) is activated during arterialization of vein grafts. First, we examined the activation of IL-1β using the rat arterialized jugular vein serially sampled for up to 90 days. IL-1β expression increased 18 times on day 1 in the arterialized rat jugular vein and remained five times above nonarterialized vein levels for up to 90 days. Similarly, IL-1β expression increased early (1–5 days) in human vein graft autopsy samples compared with late phases (1–4 years). Activation was also detected in ex vivo arterialized human saphenous veins. Upon stratification of the results, we uncovered a T allele promoter attenuating effect in IL-1β activation in response to hemodynamic stress. Altogether, the results show that IL-1β is activated during arterialization of vein grafts in rats and humans, and this response is modulated by -511C/T IL-1β gene polymorphism. It is tempting to speculate that the activation of IL-1β, and consequently local inflammation, modulates early vascular remodeling and that the gene polymorphism may be useful in predicting outcomes or assisting in interventions.

Temporal Change of Extracellular Matrix during Vein Arterialization Remodeling in Rats.

The global expression profile of the arterialized rat jugular vein was established to identify candidate genes and cellular pathways underlying the remodeling process. The arterialized jugular vein was analyzed on days 3 and 28 post-surgery and compared with the normal jugular vein and carotid artery. A gene array platform detected 9846 genes in all samples. A heatmap analysis uncovered patterns of gene expression showing that the arterialized vein underwent a partial transition from vein to artery from day 3 to 28 post-surgery. The same pattern was verified for 1845 key differentially expressed genes by performing a pairwise comparison of the jugular vein with the other groups. Interestingly, hierarchical clustering of 60 genes with altered expression on day 3 and day 28 displayed an expression pattern similar to that of the carotid artery. Enrichment analysis results and the network relationship among genes modulated during vein arterialization showed that collagen might play a role in the early remodeling process. Indeed, the total collagen content was increased, with the augmented expression of collagen I, collagen IV, and collagen V in arterialized veins. Additionally, there was an increase in the expression of versican and Thy-1 and a decrease in the expression of biglycan and β1-integrin. Overall, we provide evidence that vein arterialization remodeling is accompanied by consistent patterns of gene expression and that collagen may be an essential element underlying extracellular matrix changes that support the increased vascular wall stress of the new hemodynamic environment.

In vivo protective effect of geraniol on colonization of Staphylococcus epidermidis in rat jugular vein catheter model.

Staphylococcal infections associated with indwelling medical devices are difficult to eradicate owing to its recalcitrant nature of biofilms to conventional antibiotics. In our earlier study, we reported the efficacy of geraniol (GE) in inhibiting the in vitro biofilm formation of Staphylococcus epidermidis and adaptive resistant development. To examine the in vivo potential of GE in eradicating the in vivo colonization of S. epidermidis, an implanted rat jugular vein catheter model was developed. Oral supplementation of GE (GE at 200 mg/kg bw for three days) in rats infected with S. epidermidis exhibited a significant reduction of the bacterial burden in catheter, blood, heart and kidney, when compared to the untreated infection control. In addition, GE supplemented animals showed significantly reduced level of inflammatory markers such as nitric oxide and malondialdehyde in heart and kidney tissues. Furthermore, in contrast to the infection control, histopathology analysis of the heart and kidney tissues of the GE-treated group showed a normal histoarchitecture similar to animal control. Thus, the outcome of the present study exhibits the potential of GE as antibiofilm and anti-inflammatory agent against S. epidermidis infections. Furthermore, elucidating the molecular mechanism of GE is important to exploit the therapeutic efficacy of GE.

Cyclic stretch-induced Crp3 sensitizes vascular smooth muscle cells to apoptosis during vein arterialization remodeling.

Vein graft failure limits the long-term patency of the saphenous vein used as a conduit for coronary artery bypass graft. Early graft adaptation involves some degree of intima hyperplasia to sustain the hemodynamic stress, but the progress to occlusion in some veins remains unclear. We have demonstrated that stretch-induced up-regulation of cysteine and glycine-rich protein 3 (Crp3) in rat jugular vein and human saphenous vein in response to arterialization. Here, we developed a Crp3-KO rat to investigate the role of Crp3 in vascular remodeling. After 28 days jugular vein arterialization, the intima layer was 3-fold thicker in the Crp3-KO that showed comparable smooth muscle cells (SMC) proliferation but an absence of early apoptosis observed in the wild-type rat (WT). We then investigated the role of Crp3 in early integrin-mediated signaling apoptosis in isolated jugular SMC. Interestingly, under basal conditions, ceramide treatment failed to induce apoptosis in both WT and Crp3-KO SMC. Under stretch, Crp3 expression increased in WT SMC and ceramide induced apoptosis. Immunoblotting analysis indicated that ceramide stretch-induced apoptosis in SMC is accompanied by a decrease in the phosphorylation status of both Fak and Akt, leading to an increase in Bax expression and caspase-3 cleavage. In contrast, ceramide failed to decrease Fak and Akt phosphorylation in Crp3-KO SMC and, therefore, there was no downstream induction of Bax expression and effector caspase-3 cleavage. Taken together, we provide evidence that stretch-induced Crp3 modulates vein remodeling in response to arterialization by sensitizing SMC to apoptosis.

Abstract 111: A Kidney Targeted Epoxyeicosatrienoic Acid Analog, EET-F01, Reduces Cisplatin-induced Nephrotoxicity

Epoxyeicosatrienoic acid (EET) analogs have exceptional therapeutic potential to combat cardiovascular and kidney diseases. EET analogs combat damage in acute and chronic kidney disease models. Biological actions attributed to EET analogs such as vasodilation, anti-inflammation, anti-apoptosis, and anti-fibrosis are ideally suited to treat kidney diseases. Although EET analogs have performed well in several in vivo models, targeted delivery of EET analogs to the kidney can be reasonably expected to reduce the level of drug needed to achieve a therapeutic effect in the kidney and obviate possible side effects. For EET analog kidney-targeted delivery, we conjugated an EET analog to folic acid because there is a high concentration of folate receptors in renal tissue. The EET analog was conjugated to folic acid via a PEG-diamine linker. Next, we compared the kidney targeted EET analog, EET-F01, to a well-studied EET analog, EET-A. EET-A or EET-F01 was infused i.v. (10mg/kg/hr) for 6 hours via the rat jugular vein. Plasma and kidney tissue were collected and EET-A or EET-F01 measured by LC-MS-MS. EET-A plasma level was 1.6 ng/mL, but EET-A was undetectable in the kidney. On the other hand, EET-F01 was 6.5 ng/mL in plasma and 26.7 ng/mL in kidney tissue. These data demonstrate that EET-F01 targets the kidney. Experiments were conducted to compare EET-F01 and EET-A to decrease cisplatin-induced nephrotoxicity. A single injection of cisplatin (7 mg/kg ip) was administered to WKY rats treated with vehicle, EET-A (10 mg/kg ip) or EET-F01 (20 mg/kg or 2 mg/kg ip) for five days. Cisplatin increased BUN (125 ± 11 mg/dL) and NAG (12 ± 4 IU/L) compared to control (36 ± 9 mg/dL and 4 ± 1 IU/L). EET-F01 was as effective as EET-A in decreasing BUN, NAG, and renal histological injury five days following cisplatin administration. Despite it almost 2x-greater molecular weight compared with EET-A, EET-F01 was effective in lowering BUN and NAG at 20 mg/kg/d and at a 10-fold lower dose of 2 mg/kg/d. These data clearly demonstrate that EET-F01 targets the kidney and allows for a lower effective dose. In conclusion, we have developed a kidney targeted EET analog, EET-F01, that demonstrates excellent potential as a therapeutic for kidney diseases.

Targeted metabolome profiling by dual-probe microdialysis sampling and treatment using Gardenia jasminoides for rats with type 2 diabetes

Diabetes causes a variety of end-stage organ complications, including diabetic nephropathy. Metabolomics offers an approach for characterizing biofluid metabolic changes, but studies focusing on diabetic nephropathy are limited due to the loss of tissue-specific metabolic information. A microdialysis application for the sampling of intact endogenous metabolites has been developed, utilizing two probes simultaneously inserted into the kidney tissues and jugular vein of rats with type 2 diabetes. The comprehensive and quantitative analysis of 20 diagnostic biomarkers closely realated to type 2 diabetes and its complications were performed. Results indicated that amino acid and nucleotide levels were lower in diabetic rats, revealing that the metabolic pathways of amino acid, as well as purine and pyrimidine, were disturbed. Targeted metabolomics using mass spectrometry was performed to find potential therapeutic biomarkers and related metabolic pathways of Gardenia jasminoides (G. jasminoides) for treating diabetes. Results suggested that seven biomarkers in the kidney and five biomarkers in the blood were related to G. jasminoides. In addition, the marked perturbations of pathways were regulated after treatment with G. jasminoides, including amino acid metabolism and purine metabolism. These biomarkers and metabolic pathways provided new understanding for molecular mechanisms of G. jasminoides for treating diabetes and its complications.

Enhanced neuroprotective efficacy of bone marrow mesenchymal stem cells co-overexpressing BDNF and VEGF in a rat model of cardiac arrest-induced global cerebral ischemia

Cardiac arrest-induced global cerebral ischemia injury (CA-GCII) usually leads to a poor neurological outcome without an effective treatment. Bone marrow-derived mesenchymal stem cells (BMMSCs) may provide a potential cell-based therapy against neurologic disorders through induction of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF). To optimize the neuroprotective efficacy of BMMSCs further, in this study we have derived BMMSCs, which co-overexpress both BDNF and VEGF, and tested them for the treatment of CA-GCII in a rat model. Lentiviruses that express rat BDNF exon IV or VEGF-A were created using the bicistronic shuttle vectors of pLVX-IRES-ZsGreen1 and pLVX-IRES-tdTomato, respectively. BMMSCs that were co-transduced with the engineered lentiviruses with co-overexpression of both BDNF and VEGF along with corresponding fluorescent protein reporters were injected via jugular vein of rats that just recovered from a cardiac arrest. Animals were then scored for neurofunctional deficits and examined for brain pathology and gene expression relevant to the engraftment seven days after the treatments. We demonstrate that anchorage of lentiviral vector-transduced BMMSCs, which co-overexpressed both BDNF and VEGF in the hippocampus and temporal cortex along with significantly ameliorated brain pathology and improved neurofunctional performance in CA-GCII rats after transplantation. These findings provide a proof of concept for the further validation of engineered BMMSCs for the treatment of CA-GCII patients in clinical practice in the future.

Modulation of Oral Bioavailability and Metabolism for Closely Related Cyclic Hexapeptides

Recently, a variety of studies concerned with the permeability and oral bioavailability of cyclic peptides have been reported. In particular, strategies aiming at modifying peptides to maintain or to enhance solubility while enabling permeability constitute a significant challenge, but are of high interest to ensure a smooth drug discovery process. Current methodologies include N-methylation, matching of hydrogen bonding acceptors and donors across the macrocycle, and additional masking of polarity. In this study, we investigate further the pivotal effects of shielding on permeability and studied the metabolism of the corresponding peptides in more detail by comparing peptide concentrations in the portal versus the jugular vein in rats. Interestingly, minor changes in one particular side chain impacts both permeability and liver metabolism.Graphical

Inhibitory effect of sustained perivascular delivery of paclitaxel on neointimal hyperplasia in the jugular vein after open cutdown central venous catheter placement in rats.

PurposeInhibitory effect of paclitaxel on neointimal hyperplasia after open cutdown has not been elucidated.MethodsFor the control group (n = 16), silicone 2.7-Fr catheters were placed via the right external jugular vein with the cutdown method. For the treatment group (n = 16), a mixture of 0.65 mg of paclitaxel and 1 mL of fibrin glue was infiltrated around the exposed vein after cutdown. After scheduled intervals (1, 2, 4, and 8 weeks), the vein segment was harvested and morphometric analysis was performed on cross-sections.ResultsProliferation of smooth muscle cell (SMC) was strongly suppressed in the treatment group, and the ratio of neointima to vein wall was significantly reduced in the treatment group (8 weeks; 0.63 ± 0.08 vs. 0.2 ± 0.08, P < 0.05). Luminal patency was significantly more preserved in the treatment group, and the luminal area was significantly wider in the paclitaxel-treated group compared to the control group (8 weeks; 1.91 ± 0.43 mm2 vs. 5.1 ± 0.43 mm2, P < 0.05). Mean SMC counts measured at 1 and 2 weeks after cutdown were significantly lower in the treatment group (2 weeks; 115 ± 22 vs. 62 ± 22). Paclitaxel was undetectable in systemic circulation (<10 ng/mL).ConclusionSustained perivascular delivery of paclitaxel with fibrin glue was effective in inhibiting neointimal hyperplasia in rat jugular vein after open cutdown.

In Vitro and In Vivo Effectiveness of an Innovative Silver-Copper Nanoparticle Coating of Catheters To Prevent Methicillin-Resistant Staphylococcus aureus Infection

In this study, silver/copper (Ag/Cu)-coated catheters were investigated for their efficacy in preventing methicillin-resistant Staphylococcus aureus (MRSA) infection in vitro and in vivo Ag and Cu were sputtered (67/33% atomic ratio) on polyurethane catheters by direct-current magnetron sputtering. In vitro, Ag/Cu-coated and uncoated catheters were immersed in phosphate-buffered saline (PBS) or rat plasma and exposed to MRSA ATCC 43300 at 10(4) to 10(8) CFU/ml. In vivo, Ag/Cu-coated and uncoated catheters were placed in the jugular vein of rats. Directly after, MRSA (10(7) CFU/ml) was inoculated in the tail vein. Catheters were removed 48 h later and cultured. In vitro, Ag/Cu-coated catheters preincubated in PBS and exposed to 10(4) to 10(7) CFU/ml prevented the adherence of MRSA (0 to 12% colonization) compared to uncoated catheters (50 to 100% colonization; P < 0.005) and Ag/Cu-coated catheters retained their activity (0 to 20% colonization) when preincubated in rat plasma, whereas colonization of uncoated catheters increased (83 to 100%; P < 0.005). Ag/Cu-coating protection diminished with 10(8) CFU/ml in both PBS and plasma (50 to 100% colonization). In vivo, Ag/Cu-coated catheters reduced the incidence of catheter infection compared to uncoated catheters (57% versus 79%, respectively; P = 0.16) and bacteremia (31% versus 68%, respectively; P < 0.05). Scanning electron microscopy of explanted catheters suggests that the suboptimal activity of Ag/Cu catheters in vivo was due to the formation of a dense fibrin sheath over their surface. Ag/Cu-coated catheters thus may be able to prevent MRSA infections. Their activity might be improved by limiting plasma protein adsorption on their surfaces.

Optimization of the process variables of tilianin-loaded composite phospholipid liposomes based on response surface-central composite design and pharmacokinetic study

Tilianin is attracting considerable attention because of its antihypertensive, anti-atherogenic and anticonvulsive efficacy. However, tilianin has poor oral bioavailability. Thus, to improve the oral bioavailability of tilianin, composite phospholipid liposomes were adopted in this work as a novel nanoformulation. The aim was to develop and formulate tilianin composite phospholipid liposomes (TCPLs) through ethanol injection and to apply the response surface-central composite design to optimize the tilianin composite phospholipid liposome formulation. The independent variables were the amount of phospholipids (X1), amount of cholesterol (X2) and weight ratio of phospholipid to drug (X3); the depended variables were particle size (Y1) and encapsulation efficiency (EE) (Y2) of TCPLs. Results indicated that the optimum preparation conditions were as follows: phospholipid amount, 500mg, cholesterol amount, 50mg and phospholipid/drug ratio, 25. These variables were also the major contributing variables for particle size (101.4±6.1nm), higher EE (90.28%±1.36%), zeta potential (−18.3±2.6mV) and PDI (0.122±0.027). Subsequently, differential scanning calorimetry techniques were used to investigate the molecular interaction in TCPLs, and the in vitro drug release of tilianin and TCPLs was investigated by the second method of dissolution in the Chinese Pharmacopoeia (Edition 2015). Furthermore, pharmacokinetics in Sprague Dawley rats was evaluated using a rat jugular vein intubation tube. Results demonstrated that the Cmax of TCPLs became 5.7 times higher than that of tilianin solution and that the area under the curve of TCPLs became about 4.6-fold higher than that of tilianin solution. Overall, our results suggested that the prepared tilianin composite phospholipid liposome formulations could be used to improve the bioavailability of tilianin after oral administration.