Biomedical subjects

Richard Chung

Publications and source records attributed to Richard Chung.

6 recordsLinked to original sources

PubMed2006

Effects of bupivacaine and tetrodotoxin on carrageenan-induced hind paw inflammation in rats (Part 1): hyperalgesia, edema, and systemic cytokines.

BACKGROUND: Local anesthetics exert antiinflammatory actions. To elucidate potential mechanisms, the authors examined effects of bupivacaine or tetrodotoxin, administered to rats by ipsilateral or contralateral sciatic blockade or systemically, on carrageenan-induced hind paw hyperalgesia, edema, and stimulated cytokine production in circulating blood cells. METHODS: Twelve groups of rats (n = 9-12) received injections in three sites: (1) right or left hind paw (carrageenan or saline), (2) left sciatic block, and (3) systemically (subcutaneously in the upper back). Sciatic and systemic injections were performed with epinephrine plus bupivacaine, tetrodotoxin, or saline; injections were repeated 6 h later. Fifteen hours later, hyperalgesia and/or sensory and motor block were assessed behaviorally, and paw edema was quantified by magnetic resonance imaging. Stimulated production of tumor necrosis factor alpha, interleukin 10, and interleukin 1beta in whole blood cultures was measured by enzyme-linked immunosorbent assay. RESULTS: Either ipsilateral or contralateral sciatic blocks using either bupivacaine or tetrodotoxin reduced carrageenan-induced edema and hyperalgesia. Systemic bupivacaine and tetrodotoxin were ineffective in preventing edema and hyperalgesia. Bupivacaine was effective in suppressing systemic tumor necrosis factor alpha and interleukin 1beta by all three routes, whereas tetrodotoxin was ineffective by all three routes. CONCLUSION: Bupivacaine and tetrodotoxin, via a contralateral or ipsilateral sciatic block, attenuate local inflammatory edema and hyperalgesia induced by hind paw injection of carrageenan in rats. Mechanisms underlying contralateral effects of sciatic blockade remain unexplained. Bupivacaine inhibits carrageenan-evoked systemic cytokine production by a mechanism not shared by tetrodotoxin; this action may involve tetrodotoxin-resistant sodium channels or a variety of non-sodium-channel targets.

Animals↗

PubMed2005

Magnetic resonance imaging is not needed to clear cervical spines in blunt trauma patients with normal computed tomographic results and no motor deficits.

HYPOTHESIS: Trauma patients with normal motor examination results and normal cervical spine helical computed tomographic (CT) scans with sagittal reconstructions do not have significant cervical spine injury. DESIGN: Prospectively collected registry data. SETTING: Level II community-based trauma center. PATIENTS: All patients admitted to the trauma service from January 1, 1999, to December 31, 2003. MAIN OUTCOME MEASURES: Injury detected by CT and/or magnetic resonance imaging (MRI) of the cervical spine. Neurologic examination and need for surgery were secondary outcomes. RESULTS: During the study period, 2854 trauma patients were admitted, of whom 91.2% had blunt trauma. Of these patients, 56.2% had a closed head injury. One hundred patients had cervical spine and/or spinal cord injuries. Eighty-five patients had a cervical spine injury diagnosed by CT. Fifteen patients had admission neurologic deficits not seen on CT, and 7 of these patients had non-bony abnormalities on MRI. Ninety-three patients had a normal admission motor examination result, a CT result negative for trauma, and persistent cervical spine pain, and were examined with MRI. All MRI examination results were negative for clinically significant injury. Seventeen patients had MRIs that showed degenerative disc disease, and 6 had spinal canal stenosis secondary to ossification. Twelve comatose patients (Glasgow Coma Scale score, <9), moving all 4 extremities on arrival, with normal CT results of the cervical spine, were examined with MRI. All of these MRI examination results were negative for injury. None of the patients experienced neurologic deterioration. No patient required operative management of spinal injury. CONCLUSION: Blunt trauma patients with normal motor examination results and normal CT results of the cervical spine do not require further radiologic examination before clearing the cervical spine.

Adult↗

PubMed2005

Cervical spine clearance in blunt trauma: evaluation of a computed tomography-based protocol.

BACKGROUND: Prompt identification of cervical spine injuries has been a critical issue in trauma management. In 1998, the authors developed a new protocol to evaluate cervical spines in blunt trauma. This protocol relies on clinical clearance for appropriate patients and helical computed tomography instead of plain radiographs for patients who cannot be clinically cleared. The authors then prospectively collected data on all cervical spine evaluations to assess the sensitivity and specificity of their approach. METHODS: Any patient without clinical evidence of neurologic injury, alcohol or drug intoxication, or distracting injury underwent cervical spine evaluation by clinical examination. Patients who did not meet these criteria underwent helical computed tomographic scanning of the entire cervical spine. For patients who had neurologic deficits, a magnetic resonance image was obtained. If the patient was not evaluable secondary to coma, the computed tomographic scan was without abnormality, and the patient was moving all four extremities at arrival in the emergency department, the cervical spine was cleared, and spinal precautions were removed. Data were collected for all patients admitted to Santa Barbara Cottage Hospital trauma service between 1999 and 2002. The authors selected for analysis patients with blunt trauma and further identified those with closed head injuries (Glasgow Coma Scale score < 15 and loss of consciousness). In addition, all blunt cervical spine injuries were reviewed. RESULTS: During the period of study, 2,854 trauma patients were admitted, of whom 2,603 (91%) had blunt trauma. Of these, 1,462 (56%) had closed head injuries. One hundred patients (7% of patients admitted for blunt trauma) had cervical spine or spinal cord injuries, of which 99 were identified by the authors' protocol. Only one injury was not appreciated in a patient with syringomyelia. Fifteen percent of patients with spinal cord injury had no radiographic abnormality; all of these patients presented with neurologic deficits. The sensitivity for detecting cervical spine injury was thus 99%, and the specificity was 100%. The risk of missing a cervical spine injury in these blunt trauma patients was 0.04%. The authors missed no spine injuries in patients with head injuries. CONCLUSION: The use of the authors' protocol resulted in excellent sensitivity and specificity in detecting cervical spine injuries. In addition, it allowed early removal of spinal precautions.

Adolescent↗

PubMed2004

Protein family comparison using statistical models and predicted structural information.

BACKGROUND: This paper presents a simple method to increase the sensitivity of protein family comparisons by incorporating secondary structure (SS) information. We build upon the effective information theory approach towards profile-profile comparison described in [Yona & Levitt 2002]. Our method augments profile columns using PSIPRED secondary structure predictions and assesses statistical similarity using information theoretical principles. RESULTS: Our tests show that this tool detects more similarities between protein families of distant homology than the previous primary sequence-based method. A very significant improvement in performance is observed when the real secondary structure is used. CONCLUSIONS: Integration of primary and secondary structure information can substantially improve detection of relationships between remotely related protein families.

Amino Acid Sequence↗

PubMed2004

Positive and negative network correlations in temporal lobe epilepsy.

Temporal lobe seizures are accompanied by complex behavioral phenomena including loss of consciousness, dystonic movements and neuroendocrine changes. These phenomena may arise from extended neural networks beyond the temporal lobe. To investigate this, we imaged cerebral blood flow (CBF) changes during human temporal lobe seizures with single photon emission computed tomography (SPECT) while performing continuous video/EEG monitoring. We found that temporal lobe seizures associated with loss of consciousness produced CBF increases in the temporal lobe, followed by increases in bilateral midline subcortical structures. These changes were accompanied by marked bilateral CBF decreases in the frontal and parietal association cortex. In contrast, temporal lobe seizures in which consciousness was spared were not accompanied by these widespread CBF changes. The CBF decreases in frontal and parietal association cortex were strongly correlated with increases in midline structures such as the mediodorsal thalamus. These results suggest that impaired consciousness in temporal lobe seizures may result from focal abnormal activity in temporal and subcortical networks linked to widespread impaired function of the association cortex.

Adolescent↗

PubMed2004

Patient characteristics, health status, and health-related behaviors associated with obesity.

The objective of this study was to identify factors associated with obesity and to examine the health habits of the obese and non-obese. In this study of over 44,000 insured individuals, obesity rates increased with age until age 65 and were highest among members of Samoan ancestry. Because the causes of obesity are multi-faceted, treatment approaches may need to address diet, exercise, pharmacotherapy and management of comorbid conditions.

Adolescent↗