Biomedical subjects

Jafar Hamzavi

Publications and source records attributed to Jafar Hamzavi.

5 recordsLinked to original sources

PubMed2003

Smad7 prevents activation of hepatic stellate cells and liver fibrosis in rats.

BACKGROUND & AIMS: Numerous studies implicate transforming growth factor (TGF)-beta signaling in liver fibrogenesis. To perturb the TGF-beta pathway during this process, we overexpressed Smad7, an intracellular antagonist of TGF-beta signaling, in vivo and in primary-cultured hepatic stellate cells (HSCs). METHODS: Ligation of the common bile duct (BDL) was used to induce liver fibrosis in rats. Animals received injections of an adenovirus carrying Smad7 cDNA into the portal vein during surgery and via the tail vein at later stages. The effect of Smad7 on TGF-beta signaling and activation of HSC was further analyzed in primary-cultured cells. RESULTS: Smad7-overexpressing BDL rats displayed reduced collagen and alpha-SMA expression and reduced hydroxyproline content in the liver, when compared with animals administered AdLacZ. Such a beneficial effect was also observed when Smad7 was expressed in animals with established fibrosis. Accordingly, Smad7 arrested transdifferentiation of primary-cultured HSCs. AdSmad7 infected cells remained in a quiescent stage and retained storage of vitamin A droplets. Smad7 expression totally blocked TGF-beta signal transduction, shown by inhibiting Smad2/3 phosphorylation, nuclear translocation of activated Smad complexes, and activation of (CAGA)(9)-MLP-Luc, resulting in decreased collagen I expression. Smad7 also abrogated TGF-beta-dependent proliferation inhibition of HSC. Smad7 did not decrease expression of alpha-SMA, but immunofluorescent staining with anti alpha-SMA antibodies displayed destruction of the fibrillar organization of the actin cytoskeleton. CONCLUSIONS: In summary, gene transfer of Smad7 inhibits experimental fibrogenesis in vivo. Studies with isolated HSC suggest that the underlying mechanisms involve inhibition of TGF-beta signaling and HSC transdifferentiation.

Actins↗

PubMed2003

Variables affecting speech perception in postlingually deaf adults following cochlear implantation.

OBJECTIVE: To evaluate the time span over which there is greatest improvement in postlingually deaf adults undergoing cochlear implantation. Additionally, to quantify potential patient and device factors that may predict the postoperative results. MATERIAL AND METHODS: A longitudinal study was conducted. Numbers, monosyllables and sentence test results were collected for 66 cochlear implant subjects [Combi 40/40 +, n = 60; Clarion HF2, n = 2; Nucleus 24m/k, n = 4] at regular intervals for up to 6 years following cochlear implantation. RESULTS: All patients showed a steady improvement over time on all tests. Progress during the first 12 months was statistically significant, with further improvements being recorded after the 12-month testing period. The duration of deafness and the number of electrodes (8 for the Combi 40, 12 for the Combi 40 + ) appeared to be weakly correlated with postoperative performance. Re-implantation after device failure had no negative effect on speech reception. Subjects who were "upgraded" from an analogue to a digital cochlear implant improved their test results almost twofold. CONCLUSION: All the patients in our study gained substantial benefit from their cochlear implants. It is encouraging to note that the factors examined were not deemed to be relevant predictors of performance. Even long-term deaf subjects and re-implantees are able to achieve an excellent level of speech perception.

Cochlear Implantation↗

PubMed2002

The role of age in pediatric cochlear implantation.

OBJECTIVE: To document progress, benefit and importance of age in paediatric cochlear implantation. DESIGN: The EARS (Evaluation of Auditory Responses to Speech) test battery was performed on 33 prelingually deaf children at regular intervals up to 36 months following implantation. All children participated in individually tailored intensive audiological rehabilitation programs after receiving their implants. In this respect, it was attempted to evaluate speech perception scores in children implanted before and after the age of 3 in a homogenous group. RESULTS: All children demonstrated encouraging improvements over time in their speech recognition abilities. Furthermore, it was observed that the children who were implanted under the age of 3 achieved higher levels of speech perception performance. CONCLUSION: In order to shorten the process of central maturation of the auditory system, it is desirable to implant the children as young as possible. Early intervention seems to be the ideal strategy in enabling prelingually deaf children to derive maximum benefit from cochlear implantation.

Age Factors↗

PubMed2002

Vestibular symptoms as a complication of sildenafil: a case report.

Potential vasodilator side effects of sildenafil such as headache, flushing, dyspepsia, heartburn, nasal congestion, dizziness and visual changes have been frequently observed. We report a 79-year-old man who developed severe vestibular neuritis-like symptoms (horizontal nystagmus with rotatory components and vomiting) two hours after taking 50 mg sildenafil. Additionally, the patient complained of tinnitus in both ears. Internal and neurological examination revealed no pathological findings and the patient had no history of cardiovascular disease. The symptoms lasted for 24 hours and then resolved completely. All of the patient's complaints indicated a drug-related phenomenon. This drug related adverse reaction should be included in the long list of potential side effects of sildenafil.

Adverse Drug Reaction Reporting Systems↗

PubMed2002

Does cochlear reimplantation affect speech recognition?

Although cochlear implantation has been proven to be a very effective method of rehabilitation for post-lingually deaf adults and pre-lingually deaf children, as electronic devices, cochlear implants are occasionally subject to damage or breakdowns. In these cases, reimplantation would be necessary. The aim of this study was to find out whether or not there are any negative effects on speech abilities after reimplantation with the same type of multichannel digital implant in the same ear. Seven patients were provided with a digital multi-channel cochlear implant. One subject suffered manipulative damage to the implant, and in six subjects an implant failure was observed. All reimplantations were performed on the same ear as the initial implantation. with the same implant type. Parameters such as insertion depth and number of active channels were the same in all subjects before and after reimplantation. Immediately following the revision surgery, three patients attained the same level of hearing that they had with their original implants. Three months following reimplantation, five subjects achieved almost the same scores that they had before reimplantation. The results showed that cochlear implant patients undergoing re-implantation can anticipate achieving nearly the same level of speech recognition as they had with their original implant. Nevertheless, patients need to be aware of potential problems before undergoing reimplantation so that expectations are not too high.

Aged↗