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A Lina

Publications and source records attributed to A Lina.

6 recordsLinked to original sources
PubMed1995

Regulation of the Nur77 orphan steroid receptor in activation-induced apoptosis.

T-cell receptor (TCR)-mediated apoptosis in immature thymocytes and T-cell hybridomas is calcium dependent and can be inhibited by cyclosporin A (CsA). Induction of the orphan steroid receptor Nur77 (NGFI-B) is required for activation-induced apoptosis. Here, we examined the regulation of Nur77 expression, in response to apoptotic TCR signals, which consists of kinase C and calcium pathways. We show that the major control of Nur77 induction is mediated by the calcium signaling pathway. In contrast, protein kinase C signals induce only a low level of Nur77 activity. Nur77 promoter activity parallels its protein levels. CsA decreases both Nur77 protein levels and promoter activity, and the kinetics of CsA inhibition of apoptosis correlates with a decrease in Nur77 protein levels. TCR signals and kinase C signals result in a similar level of Nur77 protein phosphorylation but mediate differential transactivation activity of Nur77. In addition, Nur77 promoter deletion analysis revealed two RSRF (related to serum-responsive factor) binding sites, which can confer calcium and CsA sensitivity on a heterologous promoter. Taken together, our data suggest that the levels of transcriptional induction of Nur77 play an important role during activation-induced apoptosis and that calcium signals regulate a novel CsA-sensitive nuclear factor required for Nur77 transcription in T cells.

Animals↗
PubMed1982

Evoked potential changes produced by positioning for retromastoid craniectomy.

Reversible changes in brain stem auditory evoked potentials (BAEPs) occurred in a patient with hemifacial spasm when she was positioned for retromastoid craniectomy. The peak latencies increased and the amplitudes decreased. These alterations persisted for 3 hours, but returned immediately toward normal when the head was removed from pin fixation and the neck was returned to a neutral position. Similar BAEP changes were documented during a second procedure. Audiograms were normal pre- and postoperatively, although minimal BAEP changes were seen after operation. Our observation sheds light on possible mechanisms of intraoperative BAEP alteration and provides new information about the degree and duration of intraoperative BAEP distortion that can be tolerated in at least some cases without permanent neurological sequelae.

Brain Stem↗
PubMed1982

Monitoring of cortical somatosensory evoked potentials to determine the safety of sacrificing the anterior cerebral artery.

Cortical somatosensory evoked potentials (SSEPs) reflect the functional integrity of somatosensory pathways from the site of stimulation to the primary somatosensory cortex. We used intraoperative monitoring of cortical SSEPs to determine whether the right anterior cerebral artery (RACA), the major feeding vessel of a large arteriovenous malformation (AVM), could be sacrificed without compromising sensorimotor function in the left lower extremity. The SSEPs recorded after test occlusion of the RACA showed preservation of the initial cortical positivity, and the RACA was divided. The AVM was excised completely, and the patient suffered no neurological deficit.

Adult↗
PubMed1982

Intraoperative monitoring of brain-stem auditory evoked potentials.

Brain-stem auditory evoked potentials (BAEP) were monitored during 545 neurosurgical operations in the cerebellopontine angle. The BAEP were irreversibly obliterated in five patients who required deliberate section of the auditory nerve. Technical difficulties interfered with monitoring in three cases, and three patients had deafness and absent BAEP preoperatively. Reversible alterations in BAEP were seen during 32 operations, with recovery after as long as 177 minutes of virtually complete obliteration. Changes in BAEP were associated with surgical retraction, operative manipulation, positioning of the head and neck for retromastoid craniectomy, and the combination of hypocarbia and moderate hypotension. In 19 cases, waveforms improved after specific interventions made by the surgeon or anesthesiologist because of deteriorating BAEP. In 13 other cases, BAEP recovered after maneuvers not specifically related to the electrophysiological monitoring, most often completion of operative manipulation. Whenever BAEP returned toward normal by the end of anesthesia, even after transient obliteration, hearing was preserved. Irreversible loss of BAEP occurred only when the auditory nerve was deliberately sacrificed. The authors conclude that monitoring of BAEP may help prevent injury to the auditory nerve and brain stem during operations in the cerebellopontine angle.

Adult↗