Biomedical subjects

B C Lin

Publications and source records attributed to B C Lin.

At least 37 records · Page 2Linked to original sources

PubMed1999

Retroperitoneal laparostomy: an effective treatment of extensive intractable retroperitoneal abscess after blunt duodenal trauma.

BACKGROUND: Delay in surgical treatment and duodenal wound dehiscence are two major causes of extensive retroperitoneal abscess formation after blunt duodenal injury. This complication is traditionally treated with primary repair of the duodenal wound and drainage of the abscess through anterior laparotomy. Pyloric exclusion is sometimes added as an adjunctive procedure. The anterior approach, however, may result in inadequate drainage, and repeat surgery is sometimes needed. We reviewed our experiences and evaluated the effectiveness of retroperitoneal laparostomy for the treatment of retroperitoneal abscess with continuous soiling. METHODS: There were 52 blunt duodenal injuries during a 7-year period. Eleven patients developed extensive retroperitoneal abscesses. RESULTS: All 11 patients were treated with anterior laparotomy initially. Five patients recovered after this procedure. Six patients continued to have retroperitoneal abscesses and were under septic status. Two patients received another anterior drainage, and had recurrent abscesses later. Retroperitoneal laparostomy was performed for these six patients. After retroperitoneal laparostomy, daily wound care, and antibiotic treatment, all six patients recovered. Only two patients developed incisional hernia. CONCLUSION: Retroperitoneal laparostomy is effective in treating extensive intractable retroperitoneal abscess after blunt duodenal injury. Patients with the complications of duodenal leak and extensive retroperitoneal abscess should be treated with pyloric exclusion and drainage through anterior laparotomy first. If the duodenal wound does not heal after pyloric exclusion and retroperitoneal abscess persists, retroperitoneal laparostomy should be performed without further attempt to repair the wound.

Abdominal Abscess↗

PubMed1999

Small bowel perforation: is urgent surgery necessary?

BACKGROUND: Controversies regarding how urgent bowel perforation should be diagnosed and treated exist in recent reports. The approach for early diagnosis is also debatable. The purposes of this study were to evaluate the relationship between treatment delay and outcome of small bowel perforation after blunt abdominal trauma and to determine the best assessment plan for the diagnosis of this injury. METHODS: One hundred eleven consecutive patients with small bowel perforations caused by blunt abdominal trauma were retrospectively reviewed. The patients were divided into four groups according to the time interval between injury and surgery. Hospital stay, time to resume oral intake, and mortality and morbidity rates were compared between groups. Physical signs, laboratory and computed tomographic findings, and the results of diagnostic peritoneal lavage were analyzed to find the most sensitive and specific test for early diagnosis of small bowel perforation. RESULTS: Delay in surgery for more than 24 hours did not significantly increase the mortality with modern method of treatment; however, complications increased dramatically. Hospital stay and time to resume oral intake increased significantly when surgery was delayed for more than 24 hours. Abdominal tenderness was a common finding, but it was not specific for bowel perforation. Only 40% of the computed tomographic scans were diagnostic for bowel perforations: 50% of them showed suggestive signs, and 10% were considered as negative. Persistence of abdominal signs indicated peritoneal lavage. By using cell count ratio in diagnostic peritoneal lavage and/or increased lavage amylase activity, presence of particulate matter and/or bacteria in the lavage fluid, all patients with intraperitoneal bowel perforation were diagnosed accurately before operation. CONCLUSION: Small bowel perforation has low mortality and complication rates if it is treated earlier than 24 hours after injury. The principle of "rushing to the operation suite" for a stable blunt abdominal trauma patients without detailed systemic examination is not justified. The priority of treatment for the small bowel perforation should be lower than the limb-threatening injuries. Diagnostic peritoneal lavage provides high sensitivity and specificity rates for the diagnosis of small bowel perforation if a specially designed positive criterion is applied.

Abdominal Injuries↗

PubMed1999

Prognosis in presumptive hypoxic-ischemic coma in nonneurologic trauma.

BACKGROUND: The neurologic outcome of comatose patients has a wide variation from complete reawakening to death. Methods of predicting the outcome of coma caused by either head injury or cardiac arrest have been the subject of much discussion in the literature. However, prediction of neurologic prognosis in comatose trauma patients without head injury has rarely been discussed. We reviewed our experience in treating patients with presumptive hypoxic-ischemic coma after trauma and tried to identify factors relating to their neurologic outcomes. METHODS: Thirty-six patients with normal brain computed tomographic scans, who remained comatose 10 minutes after stabilization of their hemodynamic status, were studied. Serial motor response, verbal response, pupillary light reflex, presence of spontaneous breathing and seizure, and blood glucose level were recorded to evaluate their roles in predicting neurologic outcomes. RESULTS: There were five deaths (mortality rate, 14%) and 11 patients (31%) with neurologic deficits. An absence of spontaneous breathing, a blood glucose level greater than 300 mg/dL during resuscitation, and a presence of seizure signified a poor prognosis. Initial neurologic evaluation at 10 minutes after stabilization of hemodynamic status was not accurate in predicting outcome. A motor response worse than withdrawal from painful stimuli at 24 hours after injury and an absence of pupillary light reflex at 48 hours after injury predicted a poor neurologic outcome, with a 100% accuracy rate. CONCLUSION: Hypoxic-ischemic coma in patients sustaining major trauma yielded a significantly better survival and neurologic outcome than that induced by cardiac arrest or head injury. Decision-making in the first 24 hours after injury should not be affected by the patient's neurologic status at that time. A motor response worse than withdrawal at 24 hours after injury and an absence of pupillary light reflex at 48 hours after injury predicted a poor neurologic outcome.

Adolescent↗

PubMed1999

Anesthesia for ankylosing spondylitis patients undergoing transpedicle vertebrectomy.

BACKGROUND: Ankylosing Spondylitis (AS) patients present specific challenges to the anesthesiologists. Airway management, central venous access, positioning, neuraxial monitoring and protection as well as management of massive blood loss may prove to be difficult. We retrospectively reviewed the anesthetic management of consecutive AS patients who underwent transpedicle vertebrectomy (TPV). METHODS: To secure airway and administer anesthesia, we used awake fiberoptic endotracheal intubation. The central venous access was attempted through the infraclavicular approach. The positioning was made possible with modification of the operation table and padding. The neuraxial monitoring was done with both somatosensory evoked potentials (SSEPs) and the modified transcranial magnetic evoked potential (tcMMEP). The spinal cord protection was attempted with deliberate hypothermia. To prevent massive blood loss we did controlled hypotension, and autotransfusion. RESULTS: Fiberoptic endotracheal intubation was done smoothly in all cases except two. In one of these two cases, endotracheal intubation was successful only after cricothyroidectomy and retrograde intubation. In the other case antegrade stiff catheter guided intubation was attempted to overcome the acute angulation cause by fixed cervical flexion. Central venous access through infraclavicular approach was agreeable except one case of pneumothorax. Massive rapid blood loss during vertebral osteotomy, occurred in one patient with fall of the mean blood pressure to 20 mmHg and ventricular tachycardia for 10 min, during which all the SSEPs and tcMMEP activities disappeared. The patient recovered without sequelae. CONCLUSIONS: Although it is extremely challenging, with proper planning, anticipation of difficulties and meticulous work in airway management, central venous catheterization and positioning as well as prevention of neurological injury and massive bleeding, we successfully accomplished fine job of anesthesia for the AS patients presented for correction of severe kyphosis.

Adult↗

PubMed1999

Postoperative myocardial infarction in a patient with perioperative ST-depression--a case report.

Often we ignore electrocardiogram (EKG) evidence of ischemia and no adverse events occur. However, once in a while these ischemic episodes will turn into a full-blown myocardial infarction. Therefore, studying perioperative events which tilt the balance over to postoperative myocardial infarction (PMI) can enlighten our knowledge in postoperative myocardial infarction (MI) prevention. We present a case of ST depression in perioperative EKG evolving into postoperative MI. In this paper we attempt to explore various possibilities which could have altered this patient from her ischemic state into an infracted event.

Aged↗

PubMed1998

Pooling of contrast material on computed tomography mandates aggressive management of blunt hepatic injury.

BACKGROUND: Nonoperative management of blunt hepatic injury is currently a widely accepted treatment modality. Computed tomography (CT) is an important imaging study both for diagnosis and follow-up of these patients. There is, however, no reliable predictor of failure of nonoperative treatment other than the ultimate development of hemodynamic instability. Previous reports mostly were based on the data obtained from low-speed dynamic incremental scanners. The purpose of this study is to evaluate the value of a high-speed helical scanner in predicting the outcome of patients managed nonoperatively. METHODS: During a 30-month period, 194 patients with blunt hepatic injury were treated, 150 of them were hemodynamically stable after initial resuscitation and underwent abdominal CT examination. All CT scans were performed with the High Speed Advantage Scanner. The CT scans and medical records were reviewed. RESULTS: Nonoperative management was successfully applied to all patients with grade I and II, 93% of grade III, 87% of grade IV, and 67% of grade V liver injuries. Twelve patients required liver-related celiotomy. Pooling of contrast material was detected on the CT scans of 8 patients. Six (75%) of these patients developed hemodynamic instability and required liver-related celiotomy later. Pooling of contrast material can be detected in 50% of the patients receiving liver-related celiotomy. CONCLUSION: The presence of pooling of contrast material within the hepatic parenchyma indicates free extravasation of blood as a result of active bleeding. In patients with blunt hepatic injury, if this sign is detected, nonoperative treatment should be terminated and angiography or celiotomy undertaken promptly. With the increasing use of high-speed spiral CT scanner and improvement in scanning technique, pooling of contrast material may become a sensitive sign for active bleeding and may be used as a guide for the selection of treatment modality.

Adolescent↗

PubMed1998

Selective application of laparoscopy and fibrin glue in the failure of nonoperative management of blunt hepatic trauma.

BACKGROUND: Most blunt hepatic trauma patients can be managed nonoperatively. The current failure rate in adult blunt hepatic trauma is reportedly 0 to 19%. We wished to evaluate the applicability of laparoscopy and fibrin glue as a minimally invasive alternative to laparotomy in these unsuccessfully nonoperative cases. METHODS: All adult patients with blunt hepatic trauma managed nonoperatively at Linkou, Chang Gung Memorial Hospital Medical Center, Taipei, Taiwan, over a 2-year period from July 1, 1994, to June 30, 1996, were eligible for the study. A laparoscopic examination was performed on those who failed conservative care before undertaking an exploratory laparotomy. Fibrin glue was sprayed over the wound surface if ongoing hemorrhage was evident from any liver laceration. The clinical data, operative and laparoscopic findings, operative methods, and outcomes of these patients were studied. RESULTS: Of the 61 patients, 55 patients were successfully treated without operation. Of the six failures (10%) all were liver related. After the introduction of laparoscopy, the nontherapeutic laparotomy rate would have decreased from 100% (6 of 6) to 50% (3 of 6), and with the adjunctive use of fibrin glue, the laparotomy rate went down to 0% (0 of 6). There were no deaths among the six patients receiving laparoscopy and fibrin glues; and only one developed a liver abscess, for a morbidity rate of 17% (1 of 6). CONCLUSIONS: The selective use of laparoscopy and fibrin glue can effectively reduce the nontherapeutic laparotomy rate among blunt hepatic trauma patients who fail nonoperative management.

Adolescent↗

PubMed1998

Cell count ratio: new criterion of diagnostic peritoneal lavage for detection of hollow organ perforation.

OBJECTIVES: Diagnostic peritoneal lavage (DPL) had been widely used in evaluating patients with suspected intraperitoneal injuries due to its high sensitivity. If the positive criteria are strictly followed, however, the incidence of nontherapeutic laparotomies will be unacceptably high. This realization has become more important recently with the popularization of nonoperative treatment for blunt solid organ injuries. For these patients, the early diagnosis of an associated hollow organ perforation is mandatory. METHODS: Three hundred and twenty patients undergoing DPL over an 18-month period were retrospectively reviewed to evaluate the usefulness of "cell count ratio" in diagnosing hollow organ perforation. The cell count ratio was defined as the ratio between white blood cell count and red blood cell count in the lavage fluid divided by the ratio of the same parameters in the peripheral blood. RESULTS: Two hundred twelve patients were diagnosed as having a positive DPL according to the classic criteria. Forty-four patients (21%) had a cell count ratio of greater than or equal to 1. The diagnosis at laparotomy was small bowel perforation in 31 patients, colon perforation in eight patients, diaphragmatic hernia in one patient, pancreatic transection in two patients, and liver laceration in two patients. None of the patients with a cell count ratio of less than I sustained hollow organ perforation. The average interval from injury to DPL was 5 hours, with the shortest being 1.5 hours. CONCLUSION: A cell count ratio of greater than or equal to 1 predicted hollow organ perforation with a specificity of 97% and a sensitivity of 100%. The selective use of the cell count ratio has improved the probability of early diagnosis of bowel perforation without increasing the cost of care. Nonoperative management can be applied more confidently to those patients sustaining a blunt solid viscus injury of the abdomen if the cell count ratio is low. We conclude that the cell count ratio of DPL effluent is a very sensitive and specific indicator of hollow organ perforation. In the treatment of blunt abdominal injuries, if the cell count ratio is positive, nonoperative treatment should be abandoned and a laparotomy undertaken.

Abdominal Injuries↗

PubMed1998

Controlled reopen suture technique for pyloric exclusion.

BACKGROUND: Pyloric exclusion had been widely used in the management of complicated duodenal injuries. The original concept of pyloric exclusion was that this technique would temporarily exclude the pylorus during the healing phase, but would subsequently allow resumption of normal gastrointestinal tract transit through the duodenum. The best method for pyloric exclusion has not been well established. Controversies exist regarding the need for a gastrojejunostomy and vagotomy as part of the procedure. None of these combinations can fulfill the original concept of pyloric exclusion and avoid late complications. METHODS: We developed a controlled reopen suture technique for pyloric exclusion. This technique was applied to nine patients (group II) with a complicated blunt duodenal injury over the past 5 years. The clinical courses and outcomes of these patients were compared with an eight-patient comparison group treated by pyloric exclusion and gastrojejunostomy (group I) over the same time period. RESULTS: All 17 patients survived. There were one early (duodenal wound leakage) and two late complications (marginal ulcers) in the group I patients. No delayed complications were found in the group II patients. The average hospital stay was about the same in both groups. CONCLUSION: The controlled reopen suture technique is a quick and simple procedure. In the treatment of a complicated blunt duodenal injury, if repair of the duodenal wound will not compromise the lumen, gastrojejunostomy and vagotomy can be omitted when using this technique. This technique offers the best combination of limited surgery in the severely injured patient, effective exclusion of the duodenum until after the healing has occurred, and allowance for the resumption of normal gastrointestinal tract transit through the duodenum. The late complications of gastrojejunostomy can also be avoided.

Adolescent↗

PubMed1998

Method for reduction of inhibition in a Mycobacterium tuberculosis-specific ligase chain reaction DNA amplification assay.

The present study describes the identification of inhibitors of a Mycobacterium tuberculosis-specific gap ligase chain reaction (LCR) DNA amplification assay as well as a method for their removal. A major contributor to inhibition was deduced to be a calcium phosphate precipitate, CaHPO4. The precipitate forms during N-acetyl-L-cysteine-sodium hydroxide (NALC-NaOH) decontamination, digestion, and concentration of respiratory specimens. The solubility product of CaHPO4 precipitate at pH 7.8, the pH at which gap LCR is optimized, indicates that the precipitate releases an amount of phosphate ions sufficient to inhibit amplification. A method for removal of the precipitate was identified. The precipitate is dissociated by exposing it to a mildly acidic (pH 4.1) buffer during the first of two centrifugation steps; the inhibitory phosphate ions are removed by the centrifugation steps. When 100 NALC-NaOH respiratory sediments were tested by gap LCR, none of the sediments were inhibitory when the acidic buffer was used while 24 samples were inhibitory when TE buffer, pH 7.8, was used. In another study, when the acidic buffer wash was applied to 1,440 NALC-NaOH respiratory sediments, only 10 sediments were found to be inhibitory. None of the inhibited sediments were culture positive for M. tuberculosis. This work demonstrates that when inhibition mechanisms are identified, relatively simple protocols can be used to obtain low inhibition rates and to allow the use of larger volume equivalents in amplification reactions.

Acetylcysteine↗

PubMed1998

Periaortic hematoma on helical CT of the chest: a criterion for predicting blunt traumatic aortic rupture.

OBJECTIVE: The purpose of this study was to evaluate the accuracy of helical CT of the chest for predicting blunt traumatic aortic ruptures when periaortic hematoma is used as a positive criterion. CONCLUSION: We recommend the use of periaortic hematoma as a criterion for predicting traumatic aortic ruptures on CT because this criterion is sensitive and can reduce the false-positive rate of CT interpretations.

Adult↗

PubMed1998

Modified transcranial electromagnetic motor evoked potential obtained with train-of-four monitor for scoliosis surgery.

BACKGROUND: To monitor the spinal cord with somatosensory evoked potential (SSEP) is an accepted adjunct in the surgical correction of spinal deformities, but it does not directly assess the motor function. The use of motor evoked potential (MEP) has thus been introduced in an effort to meet this important need. METHODS: This preliminary report concerned 30 cases of scoliosis who underwent surgical correction under the surveillance of modified transcranial electromagnetic motor evoked potential (tcMMEP). Train-of four (TOF) stimulator output was connected to an electromagnetic stimulator. The rate of repetition and interval of stimulation were controlled by TOF stimulator. Electromyographic (EMG) signals were obtained from the abductor hallucis muscle of both feet and interpreted as MEP activity. Anesthesia was made possible by propofol as a basic agent and isoflurane as supplement. Analgesia was obtained with sufentanil and fentanyl and amnesia enhanced by midazolam. Atracurium mixed with vecuronium in a ratio of 4:1 by weight in possible lowest dose was given to provide adequate muscle relaxation yet without the molestation of rapid reversal upon the request of wake-up test by the surgeon. Deliberate hypothermia and controlled hypotension were also applied since they did not interfere with the tcMMEP signals. RESULTS: Although no attempt was made to control the level of muscle relaxation at T1 more than 30%, tcMMEP signals could be obtainable during induction, at the time of surgical correction and at the end of the operation. TcMMEP onset latency was 27.32 +/- 0.45 msec on the left side and 27.27 +/- 0.54 msec on the right side. The amplitude was 3.52 +/- 1.97 mV on the left side and 4.05 +/- 1.22 mV on the right side. CONCLUSIONS: The modified tcMMEP is so stable and convincing that research for similar modification is now undergoing with the other brand of TOF monitor by our team.

Adolescent↗

PubMed1998

Malakoplakia of the mesocolon with gastric serosa invasion: a case report and review of the literature.

Malakoplakia is a rare, granulomatous, inflammatory disease. The clinical presentation and radiological appearance of the malakoplakia mimics a malignant tumor. In this article we describe a case of the malakoplakia of the mesocolon with invasion into the serosa of the stomach. The frozen section report considered the lesion to be a malignancy. The definitive diagnosis depended on microscopic detection of Michaelis-Gutmann bodies by electronic microscope. We review the current literature about the malakoplakia of gastrointestinal tract, and focus on the pathogenesis, clinical manifestation, diagnosis and treatment.

Adult↗

PubMed1998

Traumatic thoracic aortic injury caused by a sharp edge of left fractured rib on body position change: case report.

Aortic injury caused by penetration of a fractured rib is very rare. We present a patient with aortic injury demonstrated using serial imaging studies. A 66-year-old woman fell from a ladder and sustained multiple left-side rib fractures. There was a small left hemothorax and widened mediastinum on the initial chest roentgenogram in the emergency department. Chest computed tomography (CT) revealed a posterior segmental fracture of the sixth rib on the left side with a sharp edge penetrating into the posterior aspect of the thoracic aorta. It was initially missed. More than 1000 cc of fresh blood suddenly gushed out of the chest tube 7 hours after the traumatic event. After resuscitation, an aortogram was performed which showed blood extravasation from the thoracic aorta at the rib fracture site. Unfortunately, surgical intervention was delayed and she died. Early detection and early surgical intervention are necessary in patients with a widened mediastinum and positive results on imaging studies.

Aged↗

PubMed1998

The maternal and fetal effects of the addition of sufentanil to 0.5% spinal bupivacaine for cesarean delivery.

BACKGROUND: Opioid added to local anesthetic for spinal anesthesia was first introduced into clinical practice in 1979 with intrathecal morphine as a forerunner. As morphine is water soluble and has prolonged action, late respiratory depression following spinal anesthesia is not infrequent and is the most serious complication that causes our concern. Sufentanil which is more hydrophobic than morphine also with shorter duration of action and quicker onset when injected into the subarchnoid space could be more effective and a safer drug as an adjuvant to local anesthetic in spinal anesthesia. METHODS: Forty-one parturients who had given consent to spinal anesthesia for Cesarean delivery, were anesthetized with 12.5 mg of 0.5% bupivacaine alone or in combination with 10 micrograms sufentanil in a randomized double blind manner. They were assigned either to C group (Control group) in which nothing is added to the local anesthetic and S group (Study group) in which sufentanil was added to the local anesthetic. RESULTS: Perioperatively, hypotension occurred more in S group (17 against 11) but chest discomfort was less (3 against 7). Within 3 h after anesthesia 3 out of 19 parturients in S group requested analgesics but almost all parturients in C group did so. CONCLUSIONS: The addition of intrathecal sufentanil to 0.5% bupivacaine for spinal anesthesia improved perioperative discomfort and significantly reduced the demand of post-operative analgesia but on the other hands, it tended to increase perioperative hypotension and cause mild pruritus.

Adult↗

PubMed1997

Plasticity of tetramer formation by retinoid X receptors. An alternative paradigm for DNA recognition.

Retinoid X receptors (RXRs) are transcription factors that traditionally have been thought to bind DNA as protein dimers. Recently, however, it has been recognized that RXRs can also bind to DNA as protein tetramers. Receptor tetramers form cooperatively on response elements containing suitably reiterated half-sites, and play an important role in determining the specificity of DNA recognition by different nuclear receptors. We report here that RXR tetramers exhibit significant functional plasticity, and form on response elements possessing diverse half-site orientations and spacings. This ability of RXRs to form tetramers and related oligomers appears to contribute to the synergistic transcriptional activation observed when multiple, spatially separated response elements are introduced into a single promoter. Oligomerization may therefore be a common paradigm for DNA recognition and combinatorial regulation by several different classes of transcription factors.

Animals↗

PubMed1997

Hepatitis B infection and changes in interferon-alpha and -gamma production in patients with systemic lupus erythematosus in Taiwan.

According to previous reports, the prevalence of hepatitis B virus (HBV) infection in patients with systemic lupus erythematosus (SLE) is varied. There has been no report on Taiwan, a hyperendemic area for HBV infection. Furthermore, impaired production of interferon (IFN) in peripheral blood mononuclear cells (PBMC) has been reported to be potentially pathogenic to both chronic HBV infection and SLE. However, the production of IFN in patients with both diseases coexisting is unknown. The aims of this study were to evaluate the prevalence of HBV infection in lupus patients in Taiwan and to measure the production of IFN in patients with both diseases coexisting. One hundred and seventy-three consecutive lupus patients and a control group of 692 age- and sex-matched healthy subjects were included for evaluation of the prevalence of HBsAg. Four groups of subjects (patients with SLE and HbsAg, SLE, chronic hepatitis B and normal controls) were selected for evaluation of the in vitro production of IFN-alpha and -gamma. Six (3.5%) of the 173 SLE patients were positive for HBsAg, which was significantly lower than that of controls (14.7%; P < 0.0001). Patients with coexistent SLE and chronic HBV infection had less lupus activity, including less proteinuria (P = 0.02) and a lower serum titre of anti-double stranded DNA antibodies (anti-dsDNA; P = 0.04), than HBsAg-negative lupus patients. The in vitro production of IFN-alpha in patients with chronic hepatitis B was significantly lower than in those patients with SLE or in the normal control group (P < 0.01). The yields of IFN-alpha and -gamma in patients with coexistent SLE and chronic HBV infection were significantly different from those patients with SLE alone (P < 0.05), but close to those of patients with chronic HBV infection. In conclusion, the prevalence of HBsAg carriers is significantly lower in lupus patients in Taiwan. Patients with coexistent SLE and chronic HBV infection had less lupus activity. Interferon-alpha and -gamma may play a role in the above phenomenon.

Adult↗

PubMed1997

A conformational switch in nuclear hormone receptors is involved in coupling hormone binding to corepressor release.

Nuclear hormone receptors are ligand-regulated transcription factors that modulate gene expression in response to small, hydrophobic hormones, such as retinoic acid and thyroid hormone. The thyroid hormone and retinoic acid receptors typically repress transcription in the absence of hormone and activate it in the presence of hormone. Transcriptional repression is mediated, in part, through the ability of these receptors to physically associate with ancillary polypeptides called corepressors. We wished to understand the mechanism by which corepressors are recruited to unliganded nuclear hormone receptors and are released on the binding of hormone. We report here that an alpha-helical domain located at the thyroid hormone receptor C terminus appears to undergo a hormone-induced conformational change required for release of corepressor and that amino acid substitutions that abrogate this conformational change can impair or prevent corepressor release. In contrast, retinoid X receptors appear neither to undergo an equivalent conformational alteration in their C termini nor to release corepressor in response to cognate hormone, consistent with the distinct transcriptional regulatory properties displayed by this class of receptors.

Amino Acid Sequence↗