Free radical attenuation prevents thrombosis and enables photochemical inhibition of vein graft intimal hyperplasia

Antioxidative role of palm grass rhizome ameliorates anxiety and depression in experimental rodents and computer-aided model

Palm grass (Curculigo recurvata) is an ethnomedicinally important herb reported to have significant medicinal values. The present study aimed to evaluate the antidepressant and anxiolytic activities of a methanol extract of C. recurvata rhizome (Me-RCR) through different approaches. The antidepressant and anxiolytic properties of Me-RCR were assessed by using elevated plus maze (EPM), hole-board (HBT), tail suspension (TST), and forced swimming (FST) tests in Swiss Albino mice. The in-depth antioxidative potential of Me-RCR was also evaluated through DPPH radical scavenging activity, ferric-reducing power capacity, total phenolic, flavonoid, flavonol, and antioxidant content analysis. Computational investigations were performed using computer-aided methods for screening the anxiolytic, antidepressant, and antioxidative activities of the selected lead molecules. Treatment with Me-RCR (200 and 400 mg/kg, b.w.) notably increased the number of open arm entries and the time spent in the EPM test. In the HBT, Me-RCR exhibited significant anxiolytic activity at a dose of 200 mg/kg, whereas similar activity was observed at 400 mg/kg in the EPM test. Me-RCR significantly decreased the immobility time in a dose-dependent manner in both TST and FST. The IC₅₀ for DPPH and reducing power capacity assay were found to be 18.56 and 193 μg/mL, respectively. Promising outcomes were noted for the determination of total phenolics, flavonoids, flavonols, and antioxidant capacity. In the case of computer-aided studies, nyasicoside showed promising binding energy for antidepressant and anxiolytic activities, whereas isocurculigine demonstrated promising effects as an antioxidant. Overall, these findings suggest that Me-RCR could be a favourable therapeutic candidate for the treatment of mental and psychiatric disorders, as well as a good source of antioxidants.

Photodynamic therapy of balloon-injured rat carotid arteries using indocyanine green

Photodynamic therapy (PDT) has been used to inhibit intimal hyperplasia in injured arteries. Because of the limited tissue penetration of visible light, an endovascular light source with a guided wire is often required for effective treatment. Indocyanine green (ICG), a near-infrared (NIR) photosensitizer, has been used in PDT for cancers. An extracorporeal light source may be used for shallow tissue because of the better tissue penetration of NIR light. The aim of this study was to evaluate the effect of ICG-PDT using extracorporeal NIR light on the inhibition of intimal hyperplasia in balloon-injured carotid arteries. A balloon injury (BI) model was used to induce intimal hyperplasia of carotid artery. Sprague-Dawley rats were divided into control, BI, BI + 1 × PDT, and BI + 2 × PDT groups. The control group underwent a sham procedure. PDT was performed 7 days after BI. In the BI + 1 × PDT group, ICG was administered 1 h before light irradiation. External illumination with 780-nm light-emitting diode light at a fluence of 4 J/cm² was applied. For the BI + 2 × PDT group, PDT was performed again at day 7, following the first PDT. Hematoxylin and eosin (H & E) staining was performed to assess vessel morphology. Arterial wall thickness was significantly larger in the BI group compared with the control group. ICG-PDT significantly reduced arterial wall thickness compared with the BI group. Repeated PDT further decreased arterial wall thickness to the level of the control group. These findings indicate a promising approach for the treatment of restenosis of carotid arteries.

In Vitro and In Vivo Biological Activities of Cissus adnata (Roxb.)

This study was conducted to evaluate the in vitro polyphenol content, antioxidant, cytotoxic, antibacterial, anthelmintic properties, and in vivo antinociceptive activity of the ethanol extract of Cissus adnata leaves (EECA) in different experimental models. Polyphenol contents were investigated using spectrophotometric techniques. Antioxidant activity was determined by 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) radical-scavenging, ferric reducing power, and total antioxidant capacity assays. Cytotoxicity was determined by brine shrimp lethality bioassay and disc diffusion method was used for the antibacterial activity. Anthelmintic activity was studied using aquarium worm (Tubifex tubifex) whereas antinociceptive activity was evaluated in mice by acetic acid and formalin test. Phytochemical screening of EECA revealed the presence of alkaloids, carbohydrates, flavonoids, phenols, terpenoids, saponins, and tannins. EECA showed strong antioxidant activity with high polyphenol contents. It was observed that EECA possessed significant antibacterial activity with a low toxicity profile. EECA also demonstrated dose-dependent and statistically significant anthelmintic and antinociceptive activities. Our study shows that ethanol extract of C. adnata leaves possess strong antioxidant, antibacterial, anthelmintic and antinociceptive activities with lower toxicity. Further studies are needed to identify bioactive phytomolecules and to understand the mechanism of such actions better.

DHDMIQK(KAP): a novel nano-delivery system of dihydroxyl-tetrahydro-isoquinoline-3-carboxylic acid and KPAK towards the thrombus

Vascular thrombosis is a major risk of the onset of stroke and so novel therapeutic candidates have been attracting interest. In this context, here docking based computer assisted screening and mesoscale simulation were used to design N-[(S)-6,7-dihydroxy-1,1-dimethyl-1,2,3,4-tetrahydroisoquinoline-3-carbonyl]-Lys(Pro-Ala-Lys), DHDMIQK(KAP), for inhibiting P-selectin expression. In vitro, 1 nM of DHDMIQK(KAP) effectively down-regulated P-selectin expression. In water, in rat plasma and in the solid state DHDMIQK(KAP) formed nanoparticles of a size capable of suitable delivery in the blood circulation. FT-MS and NOESY 2D NMR spectra showed DHDMIQK(KAP) formed hexamers, identified the intermolecular interactions of the hexamer, and assigned the hexamer a butterfly like conformation. Transmission electron microscopy, scanning electron microscopy and atomic force microscopy (AFM) imaged DHDMIQK(KAP) forming size-suitable nanoparticles for safe delivery in the blood circulation. In particular, AFM images showed that the nanoparticles effectively adhered onto the surfaces of the platelets. In vivo DHDMIQK(KAP) lysed the thrombus and inhibited thrombosis with a minimal effective dose of 0.01 nmol kg^-1. FT-MS spectrum analyses defined a specific distribution of DHDMIQK(KAP) in the thrombus, but not in the blood and vital organs. Therefore, DHDMIQK(KAP) should be a novel nano-delivery system of 6,7-dihydroxyl-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid and KPAK to target the thrombus.

In vitro membrane stabilizing, thrombolytic and antioxidant potentials of Drynaria quercifolia L., a remedial plant of the Garo tribal people of Bangladesh

Background

Drynaria quercifolia L. (Family- Polypodiaceae) is a fern grows in Bangladesh used in traditional healing by the Garo tribe of Mymensingh district. In the current study, rhizomes and fertile foliage fronds of this plant have been investigated comprehensively to assess their in vitro membrane stabilizing, thrombolytic and antioxidant properties.

Methods

Rhizomes and fertile foliage fronds of D. quercifolia were collected, dried, powdered and extracted with methanol. Later on, crude methanol extracts of the plant parts were fractionated into petroleum ether, carbon tetrachloride, chloroform and aqueous soluble fractions. The extractives were then subjected to membrane stabilizing, thrombolytic and antioxidant assays.

Results

In membrane stabilizing assay, crude methanol extracts of rhizomes and fertile foliage fronds and their petroleum ether fractions were found to be very effective for stabilizing erythrocyte membrane in hypotonic solution. In case of thrombolytic study, crude methanol extract of rhizomes and its aqueous fraction exhibited noticeable clot lysis. However, in antioxidant assays, crude methanol extracts of the tested plant parts and their aqueous fractions exhibited potent 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydrogen peroxide and 2, 2’-azinobis (3-ethylbenzothiazoline sulphonic acid) (ABTS) radical scavenging activity. Besides, these extractives also displayed substantial ferric reducing potential in ferric reducing antioxidant power (FRAP) assay. Crude methanol extracts of the plant parts and their aqueous fractions were also found rich in phenolics.

Conclusion

This study demonstrates the medicinal potentials of D. quercifolia and justifies the local uses of it by the Garo tribal people of Bangladesh for multiple disease management.

Oral intake of hydrogen-rich water inhibits intimal hyperplasia in arterialized vein grafts in rats

AIMS

Arterialized vein grafts often fail due to intimal hyperplasia. Hydrogen potently protects organs and cells from many insults via its anti-inflammatory and antioxidant properties. We investigated the efficacy of oral administration of hydrogen-rich water (HW) for prevention of intimal hyperplasia.

METHODS AND RESULTS

The inferior vena cava was excised, stored in cold Ringer solution for 2 h, and placed as an interposition graft in the abdominal aorta of syngeneic Lewis rats. HW was generated by immersing a magnesium stick in tap water (Mg + 2H(2)O → Mg (OH)(2) + H(2)). Beginning on the day of graft implantation, recipients were given tap water [regular water (RW)], HW or HW that had been subsequently degassed water (DW). Six weeks after grafting, the grafts in the rats given RW or DW had developed intimal hyperplasia, accompanied by increased oxidative injury. HW significantly suppressed intimal hyperplasia. One week after grafting, the grafts in HW-treated rats exhibited improved endothelial integrity with less platelet and white blood cell aggregation. Up-regulation of the mRNAs for intracellular adhesion molecules was attenuated in the vein grafts of the rats receiving HW. Activation of p38 mitogen-activated protein kinase, matrix metalloproteinase (MMP)-2, and MMP-9 was also significantly inhibited in grafts receiving HW. In rat smooth muscle cell (A7r5) cultures, hydrogen treatment for 24 h reduced smooth muscle cell migration.

CONCLUSION

Drinking HW significantly reduced neointima formation after vein grafting in rats. Drinking HW may have therapeutic value as a novel therapy for intimal hyperplasia and could easily be incorporated into daily life.

Photodynamic Therapy Reduces Intimal Hyperplasia in Prosthetic Vascular Bypass Grafts in a Pig Model

BACKGROUND

Bypass surgery has a failing frequency of 30% during the first year, mainly due to intimal hyperplasia (IH). This negative effect is most pronounced in artificial grafts. Photodynamic therapy (PDT) is a technique in which light activates photosensitizer dyes to produce free-radicals resulting in an eradication of cells in the vascular wall. The aim of this study was to determine the effectiveness of PDT to reduce IH in a preclinical porcine PTFE bypass model.

MATERIAL AND METHODS

Ten pigs were used. After a pilot PDT dosimetry study (n=3) PTFE grafts were bilaterally placed into the circulation as bypasses from the common to the external iliac arteries (n=7). The right sides served as controls (C). Before implantation of the left grafts, the arterial connecting sites of the left distal anastomoses were PDT-treated. The arteries were pressurized at 180 mmHg for 5 minutes with the photosensitizer Methylene Blue (330 microg/ml), and thereafter endoluminally irradiated with laser light (lambda = 660 nm, 100 mW/cm(2), 150 J/cm(2)). After 4 weeks the specimens were retrieved and formalin fixed. Cross sections through the midportions of the distal anastomoses and the grafts were used for histology, immunohistochemistry to identify inflammatory cells and morphometric evaluation (n=7).

RESULTS

No systemic side effects and no graft occlusions were noted. PDT-treated anastomoses showed reduced IH in the mid-portions of the anastomoses (Area of IH: microm(2)/microm graft: C: 6970+/-1536, PDT: 2734+/-2560; P<0.005) as well as in the grafts (C: 5391+/-4031, PDT: 777+/-1331; P<0.02). The number of inflammatory cells per microscopic field was increased after PDT (C: 24+/-16, PDT: 37+/-15; P<0.009).

CONCLUSIONS

Adjuvant PDT, performed in an endovascular fashion, was a safe method to reduce prosthetic graftstenosis in a preclinical setting. This study underscores the clinical potential of PDT to inhibit the development of clinical bypass graftstenosis.

Radiation therapy induced modulation of wound healing at experimental vein graft anastomoses

OBJECTIVES

The aim of this study was to investigate if radiation therapy (RT) favorably modulates wound healing at vein graft anastomoses.

MATERIALS AND METHODS

Jugular vein grafts were sewn into carotid arteries in 32 rats which were randomly divided into two groups: RT (gamma source, 14 Gray, n=16) and control (C, sham irradiation, n=16). Grafts and adjacent arteries were analyzed at 2 (n=8) and 8 weeks (n=8) by histology, immunohistochemistry, and morphometry.

RESULTS

Although, RT did not reduce the overall occurrence of intimal hyperplasia, the distribution differed. RT led to a reduction of intimal hyperplasia in arterial segments (median: C: 41.873 microm2; RT: 6.452 microm2, p < 0.0007). In contrast, RT augmented intimal hyperplasia in vein grafts (median: C: 30.287 microm2; RT: 90.455 microm2, p < 0.014). Vein graft diameters after RT were enlarged (median: C: 2.098 microm; RT: 3.381, p < 0.031). Over 80% of the cells were of mesenchymal origin in both groups.

CONCLUSIONS

RT reduced intimal hyperplasia in arterial segments. However, RT led to graft dilatation and increased intimal hyperplasia in vein grafts. RT did not favorably modulate the vascular wound healing response in this model.