PubMed · 9085475
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C J Mathias. 1996. Gastrointestinal dysfunction in multiple system atrophy.. https://doi.org/10.1055/s-2008-1040982
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Endosonography has evolved into an effective tool for the accurate preoperative assessment of anorectal pathology, from idiopathic anal pain to malignancy. The published data suggest that endosonography is currently the best method for assessing the structural integrity of the anal sphincter and for staging rectal cancer. The development of new treatment modalities for rectal cancer, including local excision, preoperative radiotherapy, and total mesorectal excision, has increased the importance of accurate preoperative staging to allow the optimum treatment planning. However, there is little information about the impact of endosonographic findings on clinical decision making. Education, training, and quality control in the use of endosonography also require further work. This article aims to evaluate the usefulness and limitations of this technique in clinical practice.
Recent investigations have suggested carbon monoxide (CO) as a putative messenger molecule. Although several studies have implicated the heme oxygenase (HO) pathway, responsible for the endogenous production of CO, in the neuromodulatory control of the internal anal sphincter (IAS), its exact role is not known. Nitric oxide, produced by neuronal nitric oxide synthase (nNOS) of myenteric neurons, is an important inhibitory neural messenger molecule mediating nonadrenergic noncholinergic (NANC) relaxation of the IAS. The present studies were undertaken to investigate in detail the presence and coexistence of heme oxygenase-2 (HO-2) with nNOS in the opossum anorectum. In perfusion-fixed, frozen-sectioned tissue, HO-2 immunoreactive (IR) and nNOS IR nerves were identified using immunocytochemistry. Ganglia containing HO-2 IR neuronal cell bodies were present in the myenteric and submucosal plexuses throughout the entire anorectum. Colocalization of HO-2 IR and nNOS IR was nearly 100% in the IAS and decreased proximally from the anal verge. In the rectum, colocalization of HO-2 IR and nNOS IR was approximately 70%. Additional confocal microscopy studies using c-Kit staining demonstrated the localization of HO-2 IR and nNOS IR in interstitial cells of Cajal (ICC) of the anorectum. From the high rate of colocalization of HO-2 IR and nNOS IR in the IAS as well as the localization of HO-2 IR and nNOS IR in ICC in conjunction with earlier studies of the HO pathway, we speculate an interaction between HO and NOS pathways in the NANC inhibitory neurotransmission of the IAS and rectum.