RESUMEN
Ascidian sperm bind to vitelline coat N-acetylglucosamine groups of the egg via sperm surface N-acetylglucosaminidase. This sperm surface egg receptor remains anchored throughout penetration. Localization to the sperm surface was verified by biotinylation of intact sperm followed by solubilization in Triton X-100 and binding to streptavidin agarose. The enzyme was determined to be an integral membrane protein as judged by resistance to release by Kl and high pH. Linkage of the enzyme to the sperm surface was probed through differential solubilization followed by measuring released enzymatic activity with a fluorogenic substrate. Nonionic detergents released 90% of the activity. Proteases released about 40%. No activity was released by a phosphatidylinositol specific phospholipase C. This finding, combined with the similarity of release level by all the detergents, including Triton X-100 and octylglucoside, argues against a phosphatidyl-inositol linkage. The release form enters the hydrophilic phase of a Triton X-114 phase separation experiment. This observation, coupled with the findings of release by nonionic detergents, suggests that the protein is hydrophilic once released from the membrane. Thus, although clearly an integral membrane protein, the enzyme has limited hydrophobicity such as would be present in a single transmembrane sequence or extensive glycosylation.
Asunto(s)
Acetilglucosaminidasa/metabolismo , Membrana Celular/metabolismo , Glicoproteínas de Membrana/metabolismo , Receptores de Superficie Celular/metabolismo , Interacciones Espermatozoide-Óvulo , Espermatozoides/enzimología , Urocordados/metabolismo , Membrana Vitelina/metabolismo , Animales , Fenómenos Químicos , Química Física , Detergentes/farmacología , Endopeptidasas/farmacología , Femenino , Glicosilación , Masculino , Espermatozoides/efectos de los fármacos , Fosfolipasas de Tipo C/farmacologíaRESUMEN
One of the disabilities in patients with cerebral palsy (CP) is dysphagia. To establish the prevalence of dysphagia in a population of children with CP, and to determine if any factors are related to dysphagia, we studied 56 CP patients, 5-21 years, enrolled in a primary school for the disabled. Fifteen patients (27%) had either radiographic or clinical evidence of dysphagia. These 15 patients were compared to the remaining 41 patients without dysphagia. Using data obtained from chart review and interviews with speech pathologists, several factors that contributed to dysphagia were found. These included: bite reflexes, slowness of oral intake, poor trunk control, inability to feed independently, anticonvulsant medication, coughing with meals, choking, and pneumonia. We also noted trends in the following factors: presence of tongue thrusting, presence of drooling, severity of CP, poor head control, severity of mental retardation, seizures, and speech disorders. Factors not related to the presence of dysphagia include: subject age, cause of CP, and type of CP. Early, aggressive work-up and identification in CP patients with the risk factors outlined above can reduce the associated pulmonary complications.