Comparison of silicon-coated nylon suture to plain nylon suture in the rat middle cerebral artery occlusion model

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Abstract

A variety of intraluminal sutures have been used in the middle cerebral artery occlusion model (MCAO) of focal ischemia. In the present study we tested commercially available silicon-coated nylon suture in the MCAO model and compared the results to traditional monofilament nylon suture occlusion. Twelve Sprague-Dawley male rats were randomly divided two groups, MCAO with 4-0 nylon suture (Group N, n = 6) and MCAO with silicone-coated 4-0 nylon suture (Group S, n = 6). Rats were sacrificed 24 h after reperfusion. Assessment included mortality rates, neurological evaluation, and infarct volume. One rat died in each group from subarachanoid hemorrhage. Neurological evaluation demonstrated that Group S tended to have worse neurological outcomes than Group N, although this difference was not statistically significant. On TTC stain Group S had significantly larger infarct volumes than Group N. We conclude that the commercially available silicone-coated occlusion suture provides better occlusion of the middle cerebral artery than the traditional uncoated nylon suture. Classification: Disease-related neuroscience (Section 6).

Introduction

In 1986, Koizumi et al. first described the middle cerebral artery occlusion model (MCAO) of focal ischemia in rats Koizumi et al., 1986. The MCAO protocol requires occlusion of the middle cerebral artery with an intraluminal suture. Multiple studies since then have employed this model, frequently with different types of intraluminal sutures. Monofilament nylon sutures Bhardwaj et al., 2001, Chen et al., 2001, Kuge et al., 1995, Li et al., 1998, Longa et al., 1989, Palmer et al., 2001 as well as silicon-coated nylon sutures Barber et al., 2004, Dittmar et al., 2003, Wegener et al., 2005 have been used in this model. Although both types of sutures are accepted in this model, there has been an informal trend toward use of silicone-coated sutures in published literature. Presently there is little published data to support the use of silicone-coated sutures to the exclusion of traditional nylon monofilament. In this study, we tested the commercially available silicone-coated 4-0 nylon suture in the MCAO model, and compared the results to the traditional 4-0 nylon monofilament occlusion suture.

Section snippets

Materials and methods

All experiments were approved by the Loma Linda University Animal Care Committee and performed in accordance with the guidelines provided by the American Academy of Accreditation of Laboratory Animal Care.

Twelve male Sprague-Dawley rats (290–310 g) were housed under identical conditions. Rats were fasted overnight with free access to the water before the experiment. Rats were anesthetized with a-chloralose (Fisher Scientific, Fair Lawn, NJ. 60 mg/kg ip) and urethane (Acros Organics, Morris

Mortality

One rat died in each group from subarachanoid hemorrhage, for an overall mortality of 16.7% in each group.

Neurological evaluation

Using a modified Garcia's neurological evaluation (Table 1, and Garcia et al., 1995, the neurological Score of Group N was 9.2 ± 1.5 (n = 5) and of Group S was 5.6 ± 1.4 (n = 5). There was not a statistically significant difference between the two groups due to relatively high variability.

Correlation of neurological score with infarct volume

The neurological scores correlated well with the size of infarct on a case-by-case basis, as shown in Fig. 3B.

Discussion

Although both flame-rounded nylon occlusion sutures and silicone-coated occlusion sutures are used in the MCAO model, there has been an informal trend toward use of silicone-coated suture in the literature. Presently, there is limited published data to support the use of one type of occlusion suture to the exclusion of the other. In this study, we demonstrated that commercially available silicone-coated occlusion sutures produce better occlusion in the MCAO model.

One of the weaknesses of the

Acknowledgments

This study was partially supported by grants from NIH HD43120,NS43338, and NS45694 to JHZ.

References (14)

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