Hemostatic efficacy of chitosan-based bandage for closure of percutaneous arterial access sites: An experimental study in heparinized sheep model

Background

Most of the presently used percutaneous arterial closure devices (PACD) for hemostasis after interventional vascular procedures are effective, but carry risk of complications by deposition of a foreign body. A new promising externally applied PACD – chitosan-based HemCon Bandage (HCB) was explored in sheep. The HCB hemostatic efficacy and complications occurring with its use were compared to those with the standard manual compression (SMC).

Material and methods

Both superficial femoral arteries (SFA) of 9 heparinized sheep were catheterized with an 8F sheath for 5 minutes. After the sheath withdrawal, hemostasis with the HCB was compared with hemostasis achieved with SMC in the contralateral SFA. Iliac angiograms performed by carotid artery approach determined the hemostasis time.

Results

The HCB use shortened time to hemostasis with a mean time of 6.9 ± 3.9 minutes versus 10.8 ± 2.8 minutes for the SMC (P-value 0.019). Seven SFAs in the HCB group and only 1 SFA in the SMC group exhibited hemostasis in 5 minutes. All nine SFAs using the HCB showed femoral artery patency and demonstrated less hematoma (2/9) than in the SMC group (8/9). No complications developed in the HCB group, one SFA occlusion was seen in the SMC group.

Conclusions

The externally applied HCB in heparinized sheep was safe and effective. It significantly shortened time to hemostasis at the SFA access sites following 8F sheath removal. Proper application of the HCB was necessary to shorten hemostasis and prevent hematoma formation. The HCB should be tested in a clinically controlled study to evaluate its efficacy in humans.     

Testing Percutaneous Arterial Closure Devices: An Animal Model

The ovine superficial femoral artery was used for testing the efficacy of percutaneous arterial closure devices (PACDs) in their developmental stage. Two topical devices containing chitostan, one staple-mediated PACD and a porcine small intestinal submucosa plug, were tested by follow-up angiography in 37 sheep. Absence or presence of bleeding and time to bleeding cessation were the main criteria for evaluation of PAVD efficacy. The results of these tests directed modification of individual PACDs and improved their efficacy.     

Electrospun cellulose acetate doped with astaxanthin derivatives from Haematococcus pluvialis for in vivo anti-aging activity

This research aims to study the release, in vivo anti-aging activity against Caenorhabditis elegans and stability of astaxanthins in a crude acetone extract of Haematococcus pluvialis from electrospun cellulose acetate (CA) nanofibers. The content and 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging activity of astaxanthins in the crude extract were also determined. The content of astaxanthins was reported in terms of total carotenoid content (TCC) and found to be 10.75 ± 0.16 mg gcE⁻¹. IC₅₀ of DPPH radical scavenging activity for astaxanthins was 233.33 ± 4.18 μg mL⁻¹. It has been well known that astaxanthins are very unstable under environmental conditions, so the electrospinning technique was used to enhance their stability. In order to fabricate CA nanofibers containing a crude acetone extract of H. pluvialis, various solvent systems and percent loading of the crude acetone extract were studied. The optimal solvent system for fabrication of CA nanofibers was the acetone/dimethylformamide (DMF) system (2 : 1 v/v) with incorporation of 0.25% v/v Tween80, resulting in good morphology of CA nanofibers with av. 420 nm diameter. The loading efficiency (%) of the crude astaxanthins extract was 5% w/w of CA. With regard to the results of the in vivo oxidative stress assay, C. elegans pre-treated with 200 μg mL⁻¹ of the crude extract had a survival percent of 56 after administration of 250 mM of paraquat for 8 h. Under phosphate-buffered saline (pH 7.4) containing 10% v/v acetone, the release of astaxanthins from the CA nanofibers loaded with the crude extract exhibited a prolonged profile. The stability of astaxanthins in electrospun CA nanofibers was examined using the freeze–thaw cycle testing through a DPPH radical scavenging assay. It was found that their stability was significantly different (P < 0.05) after the 12^th freeze–thaw cycle compared with the crude extract.

The astaxanthin derivatives loaded CA fibers enhanced the percentage survival of C. elegans upto 56.17% after adding paraquat and it stability increased with 1.7 times by using DPPH scavenging assay.     

Holothuria scabra extracts exhibit anti-Parkinson potential in C. elegans: A model for anti-Parkinson testing

Objectives: Parkinson's disease (PD) is associated with aggregation of α-synuclein and selective death of dopaminergic (DA) neurons in the substantia nigra, thereby leading to cognitive and motor impairments. Nowadays, the drugs commonly used for PD treatment, such as levodopa, provide only symptomatic relief. Therefore, seeking new drugs against PD, especially from plants and marine organisms, is one of the major research areas to be explored. This study aimed to investigate the anti-Parkinson activity of the extracts from the sea cucumber, Holothuria scabra, by using Caenorhabditis elegans as a model.

Methods: H. scabra was solvent-extracted and subdivided into six fractions including whole body-ethyl acetate (WBEA), body wall-ethyl acetate (BWEA), viscera-ethyl acetate (VIEA), whole body-butanol (WBBU), body wall-butanol (BWBU), and viscera-butanol (VIBU). The extracts were tested in C. elegans BZ555 strain expressing the green fluorescent protein (GFP) specifically in the DA neurons and NL5901 strain expressing human α-synuclein in the muscle cells.

Results: WBEA, BWEA, and WBBU fractions of H. scabra extracts at 500?µg/ml significantly attenuated DA neuron-degeneration induced by selective cathecholamine neurotoxin 6-hydroxydopamine (6-OHDA) in the BZ555 strain. Moreover, the extracts also reduced α-synuclein aggregation and restored lipid content in NL5901, as well as improved food-sensing behavior and prolonged lifespan in the 6-OHDA-treated wild-type strain.

Discussion: The study indicated that the H. scabra extracts have anti-Parkinson potential in the C. elegans model. These findings encourage further investigations on using the H. scabra extract, as well as its active constituent compounds, as a possible preventive and/or therapeutic intervention against PD.     

Prevalence of ocular demodicosis among patients at Tertiary Care Center, Bangkok, Thailand

AIM: To determine the prevalence of ocular demodicosis by both microscopic examination and molecular detection among patients at King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok. METHODS: One hundred individuals were enrolled in the study and were divided into five age groups. The meibomian gland dysfunction (MGD) score and qualities of cylindrical dandruff (CD) were also determined. Demodex mite infestations of eyelash samples were screened by both microscopic examination and semi-nested polymerase chain reaction (PCR). RESULTS: The prevalence of ocular demodicosis as determined by microscopic examination was 42% [Demodex folliculorum (D. folliculorum) 41% and Demodex brevis (D. brevis) 1%]. Among patients who had ocular Demodex infestation, 69% have CD and had an average MGD score of 4; in patients without demodicosis, 15.5% had CD and had an average MGD score of 4.12. Prevalence of ocular demodicosis as determined by semi-nested PCR was 79% (D. folliculorum 78% and D. brevis 1%). CONCLUSION: This is the first report on the prevalence of ocular demodicosis in Thailand. Patients with CD also had Demodex mites present. Semi-nested PCR is better than microscopy for Demodex infestation detection. An extensive survey with more representative samples is required to determine the prevalence in the country.