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Biomedical subjects

S Hassanzadeh

Publications and source records attributed to S Hassanzadeh.

7 recordsLinked to original sources
PubMed2006

Cochlear implantation in prelingually deaf persons with additional disability.

OBJECTIVES: We aimed to identify the frequency with which the following conditions were present as a second disability in cochlear-implanted, prelingually deaf persons: mild and moderate mental retardation; learning disability; attention deficit/hyperactivity disorder; cerebral palsy; congenital blindness; and autism. We also aimed to document the development of auditory perception in patients having one of these additional disabilities. STUDY DESIGN: A retrospective study was designed to pursue the above aims. METHODS: We examined the records of 398 cochlear-implanted, prelingually deaf patients who had received a cochlear implant at least one year previously. Patients were selected who showed a delay in motor, cognitive or emotional development. The selected cases were referred for psychological evaluation in order to identify patients with additional disabilities. We then compared these patients' auditory perception prior to and one year following cochlear implantation. RESULTS: A total of 60 (15 per cent) cochlear-implanted, prelingually deaf patients were diagnosed with additional disabilities. These were classified as: mild mental retardation in eight cases (13.33 per cent); moderate mental retardation in five (8.33 per cent); learning disability in 20 (33.33 per cent); attention deficit/hyperactivity disorder in 15 (25 per cent); cerebral palsy in five (8.33); congenital blindness in three (5 per cent); and autism in four (6.66 per cent). All patients showed significant development in speech perception, except for autistic and congenitally deaf-blind patients. CONCLUSION: Although cochlear implantation is not contraindicated in prelingually deaf persons with additional disabilities, congenitally deaf-blind and autistic patients showed limited development in auditory perception as a main outcome of cochlear implantation. These patients require unique rehabilitation in order to achieve more auditory development.

Adolescent↗
PubMed2005

Cochlear implantation in children with Waardenburg syndrome.

Waardenburg syndrome is an autosomal-dominant trait resulting from mutations occurring in different genes. It is often characterized by varying degrees of: congenital hearing loss; dystopia canthorum; synophrys; broad nasal root; depigmentation of hair (white forelock), skin or both; and heterochromic or hypochromic irides. A retrospective case study was done to assess speech perception, speech production, general intelligence and educational setting in six profoundly hearing-impaired children with Waardenburg syndrome (four with type I, one with type II and one with type III) ranging in age from two years to 14 years, seven months (mean = six years, six months). None of the patients had malformation of the cochlea and were implanted using Nucleus 22/24 and Med-el combi40+. Five out of the six cases were of average intelligence and one had a borderline intelligence quotient. The follow-up period ranged from one year, 10 months to six years, six months (mean = three years, six months) after implantation. The evaluation of auditory perception in patients was accomplished using the Persian Auditory Perception Test for the Hearing-Impaired, a Persian Spondee words test and the Categories of Auditory Performance Index. The Speech Intelligibility Rating test was used to evaluate speech production ability. All the patients' speech perception and speech intelligibility capabilities improved considerably after receiving the implants, and they were able to be placed in regular educational settings. Patients used their cochlear-implant devices whenever awake, implying that they benefitted from the devices. We suggest that any further expansion of cochlear-implantation criteria in children include those with Waardenburg syndrome.

Adolescent↗
PubMed2001

The overall pattern of cardiac contraction depends on a spatial gradient of myosin regulatory light chain phosphorylation.

Evolution of the human heart has incorporated a variety of successful strategies for motion used throughout the animal kingdom. One such strategy is to add the efficiency of torsion to compression so that blood is wrung, as well as pumped, out of the heart. Models of cardiac torsion have assumed uniform contractile properties of muscle fibers throughout the heart. Here, we show how a spatial gradient of myosin light chain phosphorylation across the heart facilitates torsion by inversely altering tension production and the stretch activation response. To demonstrate the importance of cardiac light chain phosphorylation, we cloned a myosin light chain kinase from a human heart and have identified a gain-in-function mutation in two individuals with cardiac hypertrophy.

Animals↗
PubMed1999

The stretch-activation response may be critical to the proper functioning of the mammalian heart.

The "stretch-activation" response is essential to the generation of the oscillatory power required for the beating of insect wings. It has been conjectured but not previously shown that a stretch-activation response contributes to the performance of a beating heart. Here, we generated transgenic mice that express a human mutant myosin essential light chain derived from a family with an inherited cardiac hypertrophy. These mice faithfully replicate the cardiac disease of the patients with this mutant allele. They provide the opportunity to study the stretch-activation response before the hearts are distorted by the hypertrophic process. Studies disclose a mismatch between the physiologic heart rate and resonant frequency of the cardiac papillary muscles expressing the mutant essential light chain. This discordance reduces oscillatory power at frequencies that correspond to physiologic heart-rates and is followed by subsequent hypertrophy. It appears, therefore, that the stretch-activation response, first described in insect flight muscle, may play a role in the mammalian heart, and its further study may suggest a new way to modulate human cardiac function.

Animals↗
PubMed1996

Mutations in either the essential or regulatory light chains of myosin are associated with a rare myopathy in human heart and skeletal muscle.

The muscle myosins and hexomeric proteins consisting of two heavy chains and two pairs of light chains, the latter called essential (ELC) and regulatory (RLC). The light chains stabilize the long alpha helical neck of the myosin head. Their function in striated muscle, however, is only partially understood. We report here the identification of distinct missense mutations in a skeletal/ventricular ELC and RLC, each of which are associated with a rare variant of cardiac hypertrophy as well as abnormal skeletal muscle. We show that myosin containing the mutant ELC has abnormal function, map the mutant residues on the three-dimensional structure of myosin and suggest that the mutations disrupt the stretch activation response of the cardiac papillary muscles.

Amino Acid Sequence↗