Biomedical subjects

C Chung

Publications and source records attributed to C Chung.

At least 37 records · Page 2Linked to original sources

PubMed2001

Traumatic stress and ways of coping of community residents exposed to a train disaster.

OBJECTIVES: The aims of this study were to examine the degree of traumatic stress and the coping strategies employed by community residents who lived on both sides of a rail track where a train collision occurred in 1996 in Stafford, UK. The hypothesis was that there would be a high level of traumatic stress and that emotion-focused coping would be the predictor to distress. METHOD: This was a cross-sectional survey with a retrospective design in which 66 community residents, who lived between 30 and 100 feet away from the crash site, were interviewed. The study began approximately 7 months after the disaster. The Impact of Event Scale (IES), the General Health Questionnaire (GHQ-28) and the Ways of Coping Checklists (WOC) were administered to the residents. RESULTS: On the whole, the results did not entirely support the hypothesis. The residents were found to have experienced some intrusive thoughts and avoidance behaviour but their mean scores were significantly lower than those of standardized samples. Thirty-five per cent scored at 4 or above on the GHQ-28. Traumatic stress was predicted by both emotion-focused and problem-focused coping strategies. CONCLUSION: Although community residents were not on the train or related to the dead or injured in any way, they could, after being exposed to a train disaster, manifest traumatic stress symptoms which had long-lasting effects. Such traumatic stress was found to be associated with coping strategies of community residents characterized by their efforts to manage or alter the source of stress, and by their efforts to regulate stressful emotions.

Adaptation, Psychological↗

PubMed2001

Indomethacin prevents the development of experimental ammonia-induced brain edema in rats after portacaval anastomosis.

Patients with fulminant hepatic failure (FHF) die with brain edema, exhibiting an increased cerebral blood flow (CBF) at the time of cerebral swelling. Mild hypothermia prevents brain edema in experimental models and in humans with FHF, an effect associated with normalization of CBF. To study the effects of alterations of CBF on the development of brain edema, we administered intravenous (IV) indomethacin to rats receiving an ammonia infusion after portacaval anastomosis. This model predictably develops brain edema and a marked increase in CBF at 3 hours of infusion. Brain water was measured with the gravimetry technique; CBF was monitored with both laser Doppler flowmetry and radioactive microspheres, whereas intracranial pressure (ICP) was monitored with a cisterna magna catheter. Coadministration of indomethacin prevented the increase in CBF seen with ammonia alone (110 +/- 19% vs. -2 +/- 9%) as well as the increase in brain water (80.86 +/- 0.12% vs. 80.18 +/- 0.06%) and the increase in ICP. Plasma ammonia and brain glutamine levels were markedly elevated in the ammonia-infused group and unaffected by indomethacin. However, ammonia uptake by the brain was significantly reduced by indomethacin. Levels of 6-keto-PGF(1alpha), a stable metabolite of prostacyclin, were reduced in the cerebrospinal fluid (CSF) of indomethacin-treated animals. As with mild hypothermia, avoiding cerebral vasodilatation with indomethacin will prevent the development of brain edema in this hyperammonemic model. Cerebral vasoconstriction reduces cerebral ammonia uptake and, if selective to the brain, may be of benefit in FHF.

6-Ketoprostaglandin F1 alpha↗

PubMed2001

Population pharmacokinetic analysis of pegylated interferon alfa-2b and interferon alfa-2b in patients with chronic hepatitis C.

BACKGROUND: This study quantified pharmacokinetic changes in pegylated and nonpegylated interferon alfa-2b during 48 weeks of treatment and the influences of covariates on the basis of sparsely sampled serum concentrations and activity values. Possible relationships between pharmacokinetic and pharmacodynamic variables were investigated. METHODS: Patients with chronic hepatitis C were enrolled in a clinical trial that compared the efficacy of pegylated interferon alfa-2b with interferon alfa-2b. Single blood samples were obtained from each patient at weeks 4, 12, 24, 36, and 48. Three pharmacostatistical models were developed for 2 immunoassays and 1 bioassay. RESULTS: Apparent clearance values of pegylated interferon alfa-2b and interferon alfa-2b at the end of treatment declined 33.7% and 80.0%, respectively, from their week 4 values. Bioactivity increased 41% to 58% at week 48 for different treatment groups. Changes were greatest in the first weeks of administration and diminished during the subsequent months. Body weight had a modest positive effect on clearance values and activity. Within each dose level, no significant associations were observed between pharmacokinetic variables and any pharmacodynamic variables (hepatitis C virus--RNA responses or changes in neutrophils and platelets). CONCLUSIONS: This analysis confirms earlier observations of progressive pharmacokinetic changes in the patients with hepatitis C during 48 weeks of treatment. The absence of a relationship between toxicity or efficacy variables and interferon concentration or activity (within a dose level) suggests that clinical management of patients (eg, for efficacy or to manage toxicity) should be based on clinically derived dosing guidelines rather than on serum concentration or activity criteria.

Adolescent↗

PubMed2001

In vivo changes after mechanical injury.

Chondrocytes undergo apoptosis in response to mechanical injury in vitro. The current clinical study correlates arthroscopic and magnetic resonance imaging results with biopsy specimens of cartilage from patients with knee injury. Twenty patients were evaluated at a mean 2.7 months after acute knee injury. The mean age of the patients was 32 years and the mean weight was 83 kg. Cartilage lesions were graded separately on magnetic resonance images and arthroscopy in a blinded manner. During arthroscopy, a 1.8 mm diameter biopsy specimen was obtained from the edge of cartilage lesion. The biopsy specimen underwent histologic examination by safranin O staining and detection of chondrocyte apoptosis by the presence of deoxyribonucleic acid fragmentation. There was a positive correlation in 50% (10 of 20) when the presence or absence of cartilage lesions by magnetic resonance imaging was correlated with arthroscopy. All cases of partial thickness or full-thickness cartilage loss that were seen by arthroscopy also were detected by magnetic resonance images. Apoptotic cells were significantly more numerous in biopsy specimens from lesions compared with control biopsy specimens. The findings of reduced cell viability attributable to apoptosis may have profound implications for cartilage repair. This opens potential therapeutic avenues for the treatment of posttraumatic cartilage lesions through apoptosis prevention.

Adult↗

PubMed2001

Social cognitive factors predicting the health of elders.

The social cognitive model of health is primarily concerned with influences on a person's decisions to perform health behaviors. In this study, the relationships among social cognitive factors reflecting enabling skills (learned resourcefulness), internal motivation for health (health self-determinism), and help responses (coping responses) and a measure of physical and psychosocial health were examined in 137 chronically ill elders. Gender, race, and number of chronic conditions were predictors of learned resourcefulness. Learned resourcefulness was associated with the use of informal help, whereas health self-determinism was related to self-help and formal help. None of the help responses were significant predictors of health. Model testing revealed that greater resourcefulness or skill in coping with stressful situations was the most important predictor of health. Strategies are recommended to help elders achieve optimal health.

Adaptation, Psychological↗

PubMed2000

Use of simultaneous high-resolution endoluminal sonography (HRES) and manometry to characterize high pressure zone of distal esophagus.

The purpose of this investigation was to separate the high pressure zone (HPZ) of the distal esophagus into its two components, the intrinsic lower esophageal sphincter (LES) and the extrinsic crural diaphragm (CD), using simultaneous esophageal manometry and high-resolution endoluminal sonography. Five normal subjects were studied during end inspiration using a dual manometry/ultrasound catheter. The HPZ in the distal esophagus was characterized ultrasonographically as the CD distally and as an overlap of CD and LES proximally. In four of five volunteers, the initial distal rise in pressure at the HPZ corresponded to imaging of CD rather than imaging of the LES. In all subjects, peak pressure corresponded to an overlap of CD and LES. In conclusion, it is possible to divide the HPZ into its two components, the LES and CD using simultaneous high-resolution endoluminal sonography and esophageal manometry. During end inspiration, the CD contributes to the initial distal rise in pressure at the HPZ. Peak pressure of the HPZ corresponds to an overlap of the LES with the CD.

Adult↗

PubMed2000

Prehospital delay with myocardial infarction: the interactive effect of clinical symptoms and race.

This study examined prehospital delays and clinical symptoms of myocardial infarction (MI) in blacks and whites and the relationship between longer delays and types of clinical symptoms. The convenience sample included 128 patients, admitted consecutively, with acute MI. Data on types of clinical symptoms of MI and treatment-seeking behavior were collected on day 2 or 3 after admission, using face-to-face semistructured interviews. The total mean delay time differed significantly between blacks and whites (16 hours vs. 8.8 hours, p < .05). Although the frequency of chest pain was similar in both blacks and whites (78% vs. 77%), more than twice as many blacks as whites presented with symptoms of dyspnea (56% vs. 24%, p < .01) and fatigue (32% vs. 17%, p < .05). There was an interactive effect of race-ethnicity and types of symptoms on delay (p < .05) was present. Delay times for whites with chest pain were shorter than for whites without chest pain. Delay times for blacks with dyspnea were significantly shorter than for blacks without dyspnea, although delay times did not differ between whites with and without dyspnea.

Black or African American↗

PubMed2000

Traumatic stress and death anxiety among community residents exposed to an aircraft crash.

This article examined the relationship between traumatic stress and death anxiety among community residents who lived near woodlands in which an aircraft had crashed in Coventry, England. The hypothesis was that there would be a high level of impact of the crash experienced by residents and that the residents would experience psychological distress. It was also hypothesized that the impact of the crash and distress were associated with death anxiety. Eighty-two residents were interviewed for the study. They were asked to complete the Impact of Event Scale, the General Health Questionnaire (GHQ), and the Death Anxiety Scale. The results showed that Coventry residents were found to experience intrusive thoughts and display avoidance behavior. The residents' intrusive thoughts and avoidance behavior were significantly more severe than one group of Horowitz's standardized samples (i.e., the medical students), but not significantly different from another group (i.e., the stress clinic samples). Fifty-seven percent scored at or above the GHQ cutoff point, which meant that they were considered to be psychiatric cases. Community residents scored significantly lower in death anxiety than the standardized high-death anxiety patients but no differently from the standardized control patients. Correlations were found between the impact of the event, psychological distress, and death anxiety.

Accidents, Aviation↗

PubMed2000

Genetic characterization of rebounding HIV-1 after cessation of highly active antiretroviral therapy.

Despite prolonged treatment with highly active antiretroviral therapy (HAART), infectious HIV-1 continues to replicate and to reside latently in resting memory CD4(+) T lymphocytes, creating a major obstacle to HIV-1 eradication. It is therefore not surprising to observe a prompt viral rebound after discontinuation of HAART. The nature of the rebounding virus, however, remains undefined. We now report on the genetic characterization of rebounding viruses in eight patients in whom plasma viremia was undetectable throughout about 3 years of HAART. Taking advantage of the extensive length polymorphism in HIV-1 env, we found that in five patients who did not show HIV-1 replication during treatment, the rebound virus was identical to those isolated from the latent reservoir. In three other patients, two of whom had been free of plasma viremia but had showed some residual viral replication, the rebound virus was genetically different from the latent reservoir virus, corresponding instead to minor viral variants detected during the course of treatment in lymphoid tissues. We conclude that in cases with apparent complete HIV-1 suppression by HAART, viral rebound after cessation of therapy could have originated from the activation of virus from the latent reservoir. In patients with incomplete suppression by chemotherapy, however, the viral rebound is likely triggered by ongoing, low-level replication of HIV-1, perhaps occurring in lymphoid tissues.

Adult↗

PubMed2000

Spinal epidural abscess in a young child.

This is a case report of a spinal epidural abscess, caused by Staphylococcus aureus, in a 3-year-old girl. The child presented with fever and hip pain, but without any neurologic deficit. After normal plain films and a normal bone scan were obtained, the diagnosis was made via magnetic resonance imaging (MRI). The neurosurgery and pediatric infectious disease teams evaluated the patient, and the decision was made to forego surgical drainage and to treat medically with appropriate intravenous and then oral antibiotics. Several months later, the child was doing well without any signs of neurologic sequelae. Because of the rarity of this disease in children, the treatment guidelines are controversial. Many suggest that a spinal epidural abscess must be drained surgically. Our experience adds to the literature a case of a child successfully treated with antibiotics alone. We believe that this success is related to the fact that the child was diagnosed by MRI early in the course of the disease and that she never displayed any neurologic deficits.

Anti-Bacterial Agents↗

PubMed2000

Effectiveness of propofol pretreatment on the extent of deranged cerebral mitochondrial oxidative enzyme system after incomplete forebrain ischemia/reperfusion in rats.

It has been suggested that propofol has the protective effect on cerebral ischemia-reperfusion injury. The aim of this study is to evaluate the effect of propofol pretreatment on incomplete forebrain ischemia-reperfusion injury in rats. Thirty Sprague-Dawley rats were anesthetized with isoflurane in oxygen and randomly allocated into propofol group (n=13) and saline group (n=17). In propofol group, propofol was pretreated in a step-down scheme before inducing forebrain ischemia by occlusion of both common carotid arteries and arterial hypotension. After ischemia (20 min) and reperfusion (30 min), rats were decapitated. Brain was sliced to obtain coronal slices of 4-12 mm from frontal pole, which were reacted with 2% 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) for 10 min to differentiate the damaged tissues from normal tissues. Median (interquartile range) values of the average percent infarct area were 0.0 (8.6)% and 20.1 (41.2)% in propofol and saline groups, respectively. There was significant difference between the groups. In conclusion, propofol may have a protective effect on incomplete forebrain ischemia-reperfusion injury.

Animals↗

PubMed1999

Phosphorylation and activation of phospholipase D1 by protein kinase C in vivo: determination of multiple phosphorylation sites.

Protein kinase C (PKC) is an important regulator of phospholipase D1 (PLD1). Currently there is some controversy about a phosphorylation-dependent or -independent mechanism of the activation of PLD1 by PKC. To solve this problem, we examined whether PLD1 is phosphorylated by PKC in vivo. For the first time, we have now identified multiple basal phophopeptides and multiple phorbol myristate acetate (PMA) induced phosphopeptides of endogenous PLD1 in 3Y1 cells as well as of transiently expressed PLD1 in COS-7 cells. Down regulation or inhibition of PKC greatly attenuated the PMA-induced phosphorylation as well as the activation of PLD1. In the presence of PMA, purified PLD1 from rat brain was also found to be phosphorylated by PKCalpha in vitro at multiple sites generating seven distinct tryptic phosphopeptides. Four phosphopeptides generated in vivo and in vitro correlated well with each other, suggesting direct phosphorylation of PLD1 by PKCalpha in the cells. Serine 2, threonine 147, and serine 561 were identified as phosphorylation sites, and by mutation of these residues to alanine these residues were proven to be specific phosphorylation sites in vivo. Interestingly, threonine 147 is located in the PX domain and serine 561 is in the negative regulatory "loop" region of PLD1. Mutation of serine 2, threonine 147, or serine 561 significantly reduced PMA-induced PLD1 activity. These results strongly suggest that phosphorylation plays a pivotal role in PLD1 regulation in vivo.

Amino Acid Sequence↗

PubMed1999

The relationship between trauma and personality in victims of the Boeing 737-2D6C crash in Coventry.

The aims of this paper were to (a) ascertain the extent of psychological distress and (b) identify the association between personality variables and psychological distress among individuals who had been exposed to an aircraft disaster in Coventry, U.K. Hundreds of people escaped death but were exposed to the impact of the disaster when a Boeing 737-2D6C 7T-VEE crashed into a woodland area on the edge of a large housing estate in Coventry, U.K. in 1994. Eighty-two residents were randomly chosen for interviews in which they were assessed using the Impact of Event Scale, the General Health Questionnaire, and the Eysenck Personality Questionnaire-R Short Scale (EPQ-R). The results showed that the Coventry residents' scores reached similar levels of intrusion and avoidance compared with standardized samples and the Lockerbie samples. Fifty-two percent reached the GHQ case level score, which was again similar to the Lockerbie residents. The Coventry residents were significantly less extroverted and neurotic than standardized samples. Stepwise multiple regression showed that there were associations between intrusion and neuroticism and intrusion and extroversion, as well as between avoidance and neuroticism.

Adult↗

PubMed1999

Stress fractures of the lateral metatarsal bones in metatarsus adductus foot deformity: a previously unrecognized association.

OBJECTIVE: To document a distinctive pattern of stress fractures in the lateral metatarsal bones of patients with metatarsus adductus foot deformity. DESIGN AND PATIENTS: Conventional radiographs and available medical records were reviewed in 11 patients (6 women, 5 men; ages 25-61 years) with stress fractures of the lateral (fourth or fifth) metatarsal bones and metatarsus adductus. Evaluation included the number and location of fracture(s), forefoot adduction angle, and qualitative assessment of bone mineral density. Conditions that might predispose patients to metatarsal fractures, including direct trauma, osteoporosis, and neuropathic osteoarthropathy were also recorded. RESULTS: A total of 22 stress fractures were demonstrated, 17 of which involved the lateral metatarsals. A solitary fracture was present in six patients, while multiple fractures were evident in five patients. The sites of involvement were the fifth metatarsal (n=10), fourth metatarsal (n=7), third metatarsal (n=3), second metatarsal (n=1), and first metatarsal (n=1) bones. The locations of the stress fractures were in the proximal one-third of the metatarsal bones in 19 instances (86%) and in the middle one-third in three instances (14%). Forefoot adduction angle measured between 21 degrees and 37 degrees (normal range 8 degrees -14 degrees). CONCLUSION: Patients with metatarsus adductus may be at increased risk for stress fractures involving the lateral metatarsal bones, likely owing to the presence of altered biomechanics that place greater loads across the lateral aspect of the foot.

Adult↗

PubMed1999

Surface hydrophobicity is increased in the ileum and proximal colon of cystic fibrosis mice.

Patients with cystic fibrosis (CF) have abnormal concentrations and composition of electrolytes and macromolecules in gastrointestinal secretions. Such alterations could change intestinal surface properties, such as surface hydrophobicity, and may influence the adhesion of macromolecules, bacteria, or microbial toxins to the intestinal surface. The objective of this study was to compare the surface hydrophobicity of the gastrointestinal tract in wild type and CF mice. We used axisymmetric drop shape analysis-contact diameter to determine surface hydrophobicity by measuring contact angles of sessile water droplets placed onto epithelial surfaces. In wild type mice, there were no differences in contact angles between the duodenum, upper jejunum, lower jejunum, and ileum. The contact angle of the gastric mucosa was lower than the rest of the gastrointestinal tract. Contact angles of the proximal colon and distal colon were both higher than that of the gastric mucosa and those of the small intestinal sections. In CF mice, contact angles along the gastrointestinal tract followed the same pattern as in wild type mice. However, contact angles in the ileum and proximal colon of CF mice were greater than those from wild type mice. This study of the murine intestine showed regional differences in surface hydrophobicity comparable to those observed in other mammalian species. In addition, we showed that the ileum and proximal colon of CF mice were more hydrophobic than the corresponding segments in wild type mice. These observations are of potential clinical relevance because patients with CF exhibit clinical manifestations of gastrointestinal disease primarily in the ileum and proximal colon.

Animals↗

PubMed1998

Two novel presenilin-1 mutations (Ser169Leu and Pro436Gln) associated with very early onset Alzheimer's disease.

Mutations in the presenilin-1 (PS-1) gene account for the majority of early onset autosomal-dominant familial Alzheimer's disease (FAD) cases. We identified three missense mutations in the coding sequence of the PS-1 gene in three early onset (EO), FAD pedigrees. Alzheimer's disease was confirmed in one pedigree by autopsy. Mutation analysis of PCR products amplified from genomic DNA templates of affected individuals showed two novel mutations resulting in Ser169Leu and Pro436Gln and one known mutation resulting in Glu318Gly. The two new mutations are located within predicted transmembrane domains three (TM-3) and seven (TM-7), and are associated with a very early age of onset which is consistent with a marked loss of function of the protein. The age of onset in the pedigree with Glu318Gly mutation was similar to that reported previously in a separate pedigree with this mutation.

Adult↗

PubMed1998

The effects of sample selection bias on racial differences in child abuse reporting.

OBJECTIVE: The aim was to examine whether design features of Wave 1, 1980 National Incidence Study (NIS) data resulted in sample selection bias when certain victims of maltreatment were excluded. METHOD: Logistic regression models for the probability of child abuse reports to the child protective services (CPS) were estimated using maximum likelihood methods for Black (n = 511) and White (n = 2499) child abuse cases. The models were estimated with and without correction for selection bias using a two-step procedure proposed by Heckman. RESULTS: Substantial differences were found in the characteristics of Black and White victims by source of report and by type of maltreatment. Also found were sizeable differences within each racial group between sampled agencies and nonsampled agencies. Sample selection bias affected the estimation of both White and Black child abuse reporting rates. In the Black sample, however, the effect of sample selection bias was to reduce the statistical significance of the impacts of reporting agency and physical and sexual abuse on report rates. In the White sample, most significant factors in the basic model remained statistically significant with correction for selection bias. CONCLUSIONS: Selection bias was found to be caused by the exclusion of family, friends, and neighbors in the NIS sample design. Such exclusion has the effect of altering the interpretation of the determinants of child abuse reporting among Blacks, but not among Whites. Thus, conclusions about racial differences in child maltreatment must be reached cautiously, given the NIS study design.

Child↗

PubMed1998

Leg ulceration in the sickle cell patient.

BACKGROUND: The purpose of this study was to determine cost of care for leg ulcers in sickle cell patients and suggest an improved modality in ulcer care. STUDY DESIGN: We performed a retrospective study of a group of sickle cell disease patients with leg ulcers. RESULTS: Eighteen patients with a leg ulcer (duration: mean, 53.7 months), sickle cell disease, and a mean of 20.7 years of age had various modalities of treatment with the only consistency in healing being a commercial moist-wound dressing. CONCLUSIONS: There is no consistency in the treatment of the sickle cell patient with a leg ulcer. Treatment with a moist dressing had the best results.

Adolescent↗