Bull frogs posterior semicircular canals (psc) were used to simulate the condition of benign paroxysmal positional vertigo (BPPV). The psc was isolated in frog Ringer's solution, and the saccular otoconia were used as a responsible material to stimulate the cupula. When the otoconia were placed on the cupular surface to mimic the condition of cupulolithiasis, the psc ampullary nerve action potentials instantaneously changed according to the direction of the gravity produced by otoconia. When the otoconia were dropped into the canal to mimic the condition of moving otoconia in the canal, the action potentials changed together with the otoconial flow after a latent period. Both cupulolithiasis and moving otoconia are possibly valid mechanisms of BPPV, since they effectively stimulate the cupula. However, moving otoconia with a latent period would better explain clinical features of BPPV.
Isolated posterior semicircular canals (psc) of bull frogs were used for a model of positional vertigo. Induced ampullary nerve action potentials were recorded. When the cupula was removed and the saccular otoconia were dropped onto the cilia, excitatory, and inhibitory potentials were evoked by changing the psc positions into canal-down and canal-up, respectively. When the otoconia were allowed to stay on the cupular surface, canal-down and canal-up positions also evoked excitatory and inhibitory responses, respectively. When the otoconia were inserted in the canal and were allowed to move, changing the psc positions likewise evoked responses. However, when one end of the canal was closed, these responses disappeared, indicating the efficacy of canal plugging.
D Abstract -Effect of thermal stimulus on the vestibular receptor was studied using the isolated frog semicircular canal. The posterior (PSC) and lateral semicircular canals (LSC) were placed in the horizontal plane in frog Ringer's solution. The ampullary nerve was sucked into a glass suction electrode to record compound potentials. The steel thermal probe was positioned next to the ampul· lary surface to give thermal stimuli. When the PSC ampulla was cooled, the spontaneous dis· charge markedly increased. When the PSC am· pulla was warmed, the discharge decreased. When the LSC ampulla was cooled, the discharge in· creased in the same manner as in the PSC. Also, warming of the LSC decreased the discharge in the same manner as in the PSC. The cupula was removed from the crista in order to eliminate the effect of volume change of the endolymph. The reo suits were comparable to those with intact cupula in both the PSC and LSC. Cooling increased, while warming decreased the discharge. These reo sponses are possibly due to a mechanism other than mechanical volume change, because the PSC and LSC yielded the same type of responses. Di· rect temperature reaction of the vestibular hair cell was suggested.
The action of streptomycin sulfate (SM) on the regenerative process of the vestibular nerve and posture recovery was studied, using bull frogs. The vestibular nerve was sectioned in various conditions with intact endorgan or with SM intoxication. When the nerve was sectioned with the hair cells left intact, the nerve regenerated well and body balance recovered to normal. However, when neural regeneration was blocked, recovery was incomplete. SM intoxication resulted in various degrees of hair cell damage. Degree of posture recovery correlated well with the number of hair cells. When the nerve was sectioned after damaging the hair cell, the nerve failed to regenerate and posture recovery was incomplete. These results suggest that the degree of posture recovery depends on hair cell function and neural regeneration. Furthermore, neural regeneration is strongly influenced by hair cell function.
Hand surgery in Malaysia began modestly with the correction of claw deformity in leprosy patients early in the last century, and began to evolve over the years into the treatment of injuries in plantation and industrial workers, at home and then in road crashes. With training of some of our surgeons in various overseas centres, particularly in the UK and then in USA and Singapore, hand and microsurgery began to be developed in General Hospital Kuala Lumpur and University Malaya Hospital, when they returned home. An international three-day conference on hand surgery in Kuala Lumpur in the mid-1980's created greater awareness on the topic and helped to bring hand surgery to the forefront , with setting up hand clinics, training in micro-surgery, and so on, in the major hospitals in Kuala Lumpur initially. Today, there are dedicated hand surgeons, technicians and hand therapists in the major government and private hospitals throughout the country, providing excellent services in this specialised and demanding area of trauma and reconstructive surgery.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.