Biomedical subjects

R Chappell

Publications and source records attributed to R Chappell.

57 records · Page 4Linked to original sources

PubMedDate not supplied

Sonicated echocardiographic contrast agents: reproducibility studies.

This article describes the production, analysis, and reproducibility of forming microbubbles for contrast ultrasound imaging. The sonication method used to generate microbubbles was tested by four independent observers, and a subsequent laser particle counter analysis of microbubble size and concentration determined the reproducibility of the method. The results indicated that the mean bubble size was 3.3 +/- 1.2 microns for the entire group, based on three trials of each of the four participants. The characteristics of the bubble size of the microbubbles between observers were assessed with a Poisson distribution with the reproducibility based on the sample mean for each observer's trials. Standardization and calibration of the laser particle counter was accomplished with commercially available latex spheres, sonicated albumin microspheres, and a Coulter counter analysis. Our results indicate that the sonication technique generates small microbubbles with a reproducible uniform size distribution. The method of microbubble production is reproducible and can be widely applied for use in contrast echocardiographic perfusion imaging of tissue in a variety of research and clinical studies.

Air↗

PubMedDate not supplied

Botulinum toxin injection of spastic finger flexors in hemiplegic patients.

OBJECTIVE: To assess the outcomes of botulinum toxin injection of spastic finger flexors followed by intensive training of finger extensors. DESIGN: Fourteen subjects with chronic hemiplegia spasticity of the upper limb had electromyographic-guided botulinum toxin injection into the long finger flexors. All patients presented with minimal active finger extension with the wrist flexed, sustained clonus of the finger flexors, functional proximal arm function, and absence of fixed contracture. Cadaver dissections directed selection of two injection sites: the flexor digitorum sublimis and the flexor digitorum profundus. Fifty mouse units of botulinum toxin were injected into each muscle. After injection, the subjects were instructed in a home program of stretching the long finger flexors, upper limb weight bearing with a weight-bearing splint, and exercise to improve finger extension control. RESULTS: Compared with preinjection measures, assessment the first week after the initial injection showed significantly reduced tone, reduced clonus, and greater active finger extension with the wrist in the neutral position. Four months later, the Ashworth scale increased to preinjection levels in the six subjects with repeated injections but was again decreased postinjection. Active finger extension with the wrist in the neutral position and clonus showed a statistically nonsignificant trend toward cumulative improvement after the second injection. CONCLUSION: The greatest change in finger extension and spasticity reduction occurred after the first injection. Continued significant improvement in finger extension was not observed.

Adult↗

PubMedDate not supplied

Early testicular biopsy in males with acute lymphoblastic leukemia: lack of impact on subsequent event-free survival.

PURPOSE: Children with acute lymphoblastic leukemia (ALL) who had bulky disease (lymphomatous features) at diagnosis had the highest rate of testicular relapse (20%) of any ALL subgroup on previous Children's Cancer Group (CCG) studies in the late 1980s. To limit curative, but sterilizing, testicular irradiation to those with testicular disease, testicular biopsies were performed to detect occult testicular disease within the first 6 months of treatment. Testicular irradiation then was provided to those with occult disease to increase disease-free survival. Identification of those with occult disease was believed to be a factor that would influence ultimate survival in such patients in that era. PATIENTS AND METHODS: One hundred ninety-nine patients had bilateral testicular wedge biopsies performed during the first maintenance therapy phase of the four different chemotherapy regimens. Patients with positive biopsy results were treated with testicular irradiation and continued on therapy. RESULTS: Eleven of 199 biopsy results (5.5%) were judged positive. Patients with positive biopsy results given testicular radiation had a 45% subsequent adverse event rate, compared with 36% for those with a negative biopsy results (P = 0.4). The survival rates for the two groups were similar. The low rate of positive biopsy specimens resulted in discontinuation of the procedure before closure of the study. CONCLUSION: Positive testicular biopsy results early in remission identified patients at a slightly higher risk of subsequent adverse events but did not influence survival. However, because negative biopsy results (94.5%) did not alter the prescribed treatment, the small number of positive biopsy results did not warrant undertaking the procedure in most male patients with ALL, and this procedure was abandoned.

Adolescent↗