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Biomedical subjects

J H Chang

Publications and source records attributed to J H Chang.

At least 109 records · Page 6Linked to original sources
PubMed1997

Thoracoscopic decortication in infants and children.

BACKGROUND: The treatment of pediatric empyemas remains controversial. While thoracentesis and tube thoracostomy appear adequate for relatively benign organisms, virulent bacteria cause thick fibrinous pleural peels entrapping the lung. Open thoracotomies have been effectively used for decortication but are painful. METHODS: We report the use of minimally invasive thoracoscopic decortication in 12 patients (mean age 5 years). All failed conventional management with persistent fever, increasing oxygen requirement, recurrent effusion, and pleural consolidation; 5- and 10-mm trocars were used and complete decortication was accomplished. RESULTS: Ten of 12 patients were afebrile by 72 h and discharged 4-12 days after surgery. Eleven of 12 patients had clear chest x-rays by 1 month. CONCLUSION: Thoracoscopic decortication is a safe and effective means of treating pediatric empyemas.

Adolescent↗
PubMed1997

Anterior exposure of spinal deformities and tumors: a 20-year experience.

Data from 505 patients (1976 through 1995) who underwent anterior spinal exposure were retrospectively analyzed. There were 222 boys and 283 girls with a mean age of 14.5 years; 166 had thoracic exposure (T), 300 thoracoabdominal (TA), 44 retroperitoneal (R), and 7 transperitoneal (TP); 17 had repeat exposure (5 had initial exposure elsewhere); 70% had scoliosis, 25% kyphosis, 27% a neuromuscular disorder (NMD) and 6.7% a tumor. Average intensive-care-unit stay was 2.5 days, 6.2 days for NMD (P < .05); average ileus was 3.4 days, 4.1 days for NMD (P < .05); and average length of stay was 15.4 days for all patients, 19.3 days for NMD (P < .05). Mechanical ventilation over 96 hours was required in 31 patients, 66% had an NMD (P < .05). The morbidity rate was 9.8%, 10.1% for NMD; the morbidity rate was zero for tumor and repeat exposures. Mortality was zero. Over half of the vessel injuries (57%) and the urinary tract infections (60%) occurred in NMD patients. Differences between the 1976 through 1985 period and the 1986 through 1995 period were a shorter length of stay and a majority of one-stage combined exposures in the latter period. The authors conclude that anterior exposure of spinal deformities is well tolerated by most pediatric patients, and that this technique is easily adaptable to the resection of retroperitoneal and thoracolumbar tumors.

Adolescent↗
PubMed1997

Laparoscopic pull-through procedures using the harmonic scalpel in infants and children with Hirschsprung's disease.

Hirschsprung's disease in infants has routinely been treated by a three- or four-stage process requiring a rectal biopsy, diverting colostomy, pull-through procedure, and then colostomy takedown. This algorithm requires multiple hospitalizations and surgeries over several months. The authors have adopted a laparoscopic approach that allows the surgery to be performed in one stage with a marked decrease in morbidity and hospital stay. From March 1995 to May 1996, 15 infants and children, ages 7 days to 8 years and weighing 2.3 kg to 40 kg, underwent laparoscopic pull-through procedures. Eleven underwent primary pull-through, while four underwent a previous diverting colostomy. The laparoscopic portion of the pull-through was performed using three or four ports, size 3.5 mm or 5 mm and an ultrasonic dissector. The final submucosal dissection was performed transrectally starting 1 cm above the pectinate line. The rectal anastomosis was hand sewn, and no patient was left with a diverting colostomy. Operative time averaged 2 hours and 50 minutes. Average time to feeds was 1.3 days and the average days to discharge was 3.4. There was one intraoperative pathology misdiagnosis and one patient with an anastomotic stricture. All patients are excreting stools spontaneously at least daily and there have been no episodes of colitis. This preliminary report shows that the one-stage laparoscopic pull-through is safe and effective.

Anastomosis, Surgical↗
PubMed1997

Short-term effects of flurbiprofen and diclofenac on refractive outcome and corneal haze after photorefractive keratectomy.

PURPOSE: To evaluate the short-term effects of topical nonsteroidal anti-inflammatory drugs (NSAIDs) on refractive outcome and corneal haze after excimer laser photorefractive keratectomy (PRK) according to the degree of myopia and to compare the results with those of topical steroids. SETTING: Seoul National University Hospital, Seoul, Korea. METHODS: Patients were divided into two groups: low to moderate myopia (-6.00 diopters [D] or less) and high myopia (greater than 6.00 D). Then, each patient was randomly assigned to one of three drug subgroups for initial management (4 months post-PRK): corticosteroids (fluorometholone 0.1%); flurbiprofen sodium 0.03% (Ocufen); diclofenac sodium 0.1% (Decrol). Follow-up was 6 months. RESULTS: In eyes with low to moderate myopia, the steroid and diclofenac subgroups had significantly different refractions 2 and 4 months postoperatively but no difference at 6 months; subjective haze grading was consistently lower in the steroid subgroup than in the NSAID subgroups (flurbiprofen, diclofenac) after 2 months. In eyes with high myopia, the steroid subgroup had significantly less myopic regression after 3 weeks and lower subjective haze after 2 months than the NSAID subgroups. The steroid subgroup had severe myopic regression or corneal haze less frequently than the NSAID subgroups. CONCLUSION: Topical NSAIDs were less effective than topical steroids in reducing myopic regression and haze after PRK, especially in highly myopic eyes.

Adult↗
PubMed1997

Abdominal fluid collection secondary to acute pancreatitis: treated with percutaneous catheter drainage.

BACKGROUND: Complicated pancreatic inflammatory diseases are often life-threatening, multifocal, and multibacterial disorders. Untreated, these lesions often prove fatal. The purpose of the study is to describe interventional radiologic techniques for diagnosis and treatment of complicated peripancreatic fluid collections. METHODS: Between January 1994 and December 1995, 17 patients with abdominal fluid collection from complicated acute pancreatitis underwent percutaneous drainage following initial diagnosis with computed tomography (CT). These patients required multiple CT examinations, multiple catheter insertions, multiple catheter manipulations, and long-term catheter drainage. RESULTS: Twenty-five infected fluid collections among these 17 patients were percutaneously drained. Sixteen (94%) patients were successfully treated with catheter drainage alone. Surgical treatment was necessary in one patient because of segmental stricture of transverse colon caused by inflammation and adhesion of transverse mesocolon. Catheter drainage duration averaged 31 days. Patients required an average of three catheter manipulations and four abdominal CT scans. Mean hospital stay was 42 days (range, 11-95 days), and mean ICU stay was 25 days (range, 1-70 days). CONCLUSIONS: The study confirms that complicated peripancreatic fluid collections can be safely and effectively treated in most patients with percutaneous catheter technique.

Abscess↗
PubMed1996

Tyrosine-phosphorylated Cbl binds to Crk after T cell activation.

Crk is a Src homology 2 (SH2)/Src homology 3 (SH3)-containing adapter protein that has been implicated in intracellular signaling in fibroblasts and PC12 pheochromocytoma cells. Crk has been shown to bind to a tyrosine-phosphorylated protein of 116 kDa after TCR-mediated T cell activation. Here we demonstrate that the Crk-associated p116 phosphoprotein is not the Crk-associated substrate (Cas) but, rather, is a protein product of the c-cbl proto-oncogene. Whereas Cas was not tyrosine-phosphorylated after T cell activation, Cbl became highly phosphorylated. Crk immunoprecipitates from activated T cell lysates contain tyrosine-phosphorylated Cbl. This association is mediated by the SH2 domain of Crk, as evidenced by the interaction between Cbl and the fusion protein product of a glutathione S-transferase (GST) expression construct encoding the Crk-SH2 domain in vitro. Furthermore, phosphopeptide-binding studies revealed that the GST-Crk SH2 domain binds to a tyrosine-phosphorylated peptide corresponding to amino acids 770-781 of Cbl with high affinity. Cbl is a protein tyrosine kinase (PTK) substrate that becomes phosphorylated after engagement of numerous cell surface receptors including the TCR. Data revealed by genetic studies in the nematode, Caenorhabditis elegans, implicates a Cbl-like molecule, Sli-1, as a negative regulator of the Let-23-signaling pathway. Because the signal from the Let-23 pathway affects the activation status of the Let-60 (Ras homologue in C. elegans) pathway, the activation-dependent association between Crk and Cbl may represent another TCR-generated signal leading to Ras-related pathways.

Amino Acid Sequence↗
PubMed1996

The safety and efficacy of thoracoscopic lung biopsy for diagnosis and treatment in infants and children.

Thoracoscopic techniques were used to perform lung biopsies and limited resections in 36 consecutively treated cases. Biopsies were performed for interstitial lung disease in 27 cases, presumed metastatic lesions in 5, and cavitary lesions in 4. Histological diagnosis was obtained in 35 of the 36 cases, and therapy was directly affected by the results in 30 of 36 cases. There were no postoperative complications, and the average hospital stay for patients admitted the morning of surgery was less than 2 days. Limited thoracoscopic resection provides a safe and effective means for diagnosing and treating parenchymal disease of the lung.

Adolescent↗
PubMed1996

In vitro T-lymphocyte response and house dust mite-induced bronchoconstriction.

BACKGROUND: There is considerable evidence that T cells may play an important role in asthma. The purpose of this study was to determine whether the responsiveness of T lymphocytes to mite allergen stimulation in vitro is a determinant of bronchial response to house dust mite (HDM) allergen challenge in subjects who are allergic to HDM. METHODS: Peripheral blood was taken from seven healthy nonatopic subjects and 23 subjects with positive skin test reactions to HDM. Of the subjects in the latter group, 16 had an asthmatic reaction on inhalation challenge with HDM extract (HDM-responders), whereas the remaining seven had a negative reaction (HDM allergic). The proportion of subsets of T lymphocytes and their activation and the amount of IL-2, IL-4, IL-5, and interferon-gamma released in the supernatants with and without stimulation with the HDM extract were determined. RESULTS: Without stimulation, the proportions of subsets of T lymphocytes and their activation were similar between groups. When stimulated with the HDM allergen, the proportion of CD4+CD25+ cells from HDM responders was significantly higher than those in the control group. Comparison within groups of cell cultures with and without stimulation with the mite allergen showed that the proportion of CD4+, CD4+CD25+, CD4+/CD8+, and CD3+HLADR+ cells were significantly increased in HDM responders with stimulation; there was a trend for CD4+CD25+ cells to be increased in the HDM-allergic subjects; no increase in any T-lymphocyte subsets was found in the control subjects. The release of IL-5 was significantly greater in HDM responsers than in the other two groups. The severity of the immediate asthmatic reaction was significantly associated with the degree of nonallergic bronchial hyperresponsiveness and the amount of IL-5 released but not with the level of specific IgE to the mite allergen or subsets of T lymphocytes with and without stimulation. CONCLUSION: The findings suggest that responsiveness of T lymphocytes to allergen challenge in vitro may play a role in determining the bronchial response to the allergen in vivo.

Animals↗
PubMed1996

Effect of application of benzyl benzoate on house dust mite allergen levels.

BACKGROUND: Several acaricides have become available for reducing house dust mite allergen levels. OBJECTIVE: The purpose of this study was to assess whether the use of benzyl benzoate (Acarosan) provides additional benefit to the usual mite control measures including encasement of mattress and pillows with vinyl covers. METHODS: A randomized controlled trial was carried out in 26 homes (14 control versus 12 treatment) of asthmatic patients in two cities (Vancouver and Winnipeg). The control group had the usual house dust mite control measures including the use of vinyl covers for mattresses and pillows while the treatment group had application of benzyl benzoate to mattresses and carpets in the bedroom and the most commonly used room, in addition to the above control measures. Mite allergen levels were measured 3 months and immediately before, 1 week, and 1 and 3 months after the application of house dust mite control measures. Patients kept diary cards on asthma symptoms and peak expiratory flow rates morning and evening one month before and three months after the onset of mite allergen control measures. RESULTS: A reduction of mite allergen level was found in mattress samples in both groups, statistically significant at all times in the treatment group and at one and three months in the control group. Mite allergen levels on floor carpets also showed progressive reduction in both groups, but were significantly different in the treatment group (compared with controls) at 1 week, and were lower compared with baseline in the treatment group up to 3 months. No significant changes in asthma symptoms, peak expiratory flow rates, spirometric measurements, or bronchial hyperresponsiveness were observed among treatment or control group subjects. CONCLUSION: The addition of benzyl benzoate to conventional house dust mite control measures resulted in a significant reduction in floor carpet dust mite levels that persisted for 3 months. The results of this study should be confirmed in a larger and longer study.

Adult↗
PubMed1996

Role of T cell subpopulations in mice infected with Angiostrongylus cantonensis.

When C57BL/6 mice were infected with Angiostrongylus cantonensis, the percentage of T helper (CD4+) cells and T supressor (CD8+) cells in peripheral blood increased weekly until the third and seventh week respectively, and then gradually decreased. C57BL/6 mice were depleted of CD4+ and CD8+ T cells by in vivo injection of anti-CD4 and anti-CD8 monoclonal antibodies, respectively, and then infected with A. cantonensis. There were significantly more and less worms recovered in the mice depleted of CD4+ and CD8+ T cells respectively than in undepleted mice. Discrete subpopulations of T cells from mice exposed to A. cantonensis for 3 weeks or 7 weeks were adoptively transferred to syngeneic recipients which were then given a challenge infection. Protection was mediated by a CD4+ T cell population present in mice after 3 weeks of infection but was not demonstrable with cells taken 7 weeks after infection. When CD4+ T cells obtained from 3-week infected mice were mixed with 5% CD8+ T cells obtained from mice infected for 7 weeks, no significant transfer of resistance was observed. Thus, immune responses to A. cantonensis in mice were regulated by discrete subpopulations of T lymphocytes.

Adoptive Transfer↗
PubMed1996

Changes in peak flow, symptom score, and the use of medications during acute exacerbations of asthma.

Changes in symptom score and peak expiratory flow (PEF) and the use of medications during the first acute exacerbation of asthma were studied in 41 patients and matched controls who took part in a panel study. An acute exacerbation was defined as the presence of at least one of the following: any unscheduled physician visit, visit to an emergency room, or hospitalization for treatment of asthma; a decrease in PEF by 30% from the patient's best reading; an increase in asthma symptoms during the day and night for over 48 h and not responding to usual medications; and the commencement or doubling of the dose of oral or inhaled steroids for any of the foregoing reasons. Data from -9 to -7 d before the onset of an acute exacerbation were taken as the baseline data, with which the values of the subsequent 14 d were compared. Significant increases in symptoms occurred before a significant reduction in PEF. None of the patients had a decrease of more than 30% in PEF before the onset of symptoms. Daily variation in PEF was not significantly increased from the baseline. Our results suggest that PEF monitoring is not as sensitive as a symptom diary for revealing acute exacerbations of asthma, and that a 30% decrease in PEF is too stringent a criterion for defining an acute exacerbation.

Acute Disease↗
PubMed1995

Two SH2 domains of p120 Ras GTPase-activating protein bind synergistically to tyrosine phosphorylated p190 Rho GTPase-activating protein.

p120 GTPase-activating protein (GAP) is a negative regulator of Ras that functions at a key relay point in signal transduction pathways that control cell proliferation. Among other proteins, p120 GAP associates with p190, a GAP for the Ras-related protein, Rho. To characterize the p120.p190 interaction further, we used bacterially expressed glutathione S-transferase fusion polypeptides to map the regions of p120 necessary for its interactions with p190. Our results show that both the N-terminal and the C-terminal SH2 domains of p120 are individually capable of binding p190 expressed in a baculovirus/insect cell system. Moreover, the two SH2 domains together on one polypeptide bind synergistically to p190, and this interaction is dependent on tyrosine phosphorylation of p190. In addition, mutation of the highly conserved Arg residues in the critical FLVR sequences of both SH2 domains of full-length p120 reduces binding to tyrosine-phosphorylated p190. The dependence on p190 phosphorylation for complex formation with p120 SH2 domains observed in vitro is consistent with analysis of the native p120.p190 complexes formed in vivo. These findings suggest that SH2-phosphotyrosine interaction is one mechanism by which the cell regulates p120.p190 association and thus may be a means for coordinating the Ras- and Rho-mediated signaling pathways.

Animals↗
PubMed1995

Crk interacts with tyrosine-phosphorylated p116 upon T cell activation.

Products of the crk oncogene are expressed in all tissues. Crk proteins are composed exclusively of Src homology 2 (SH2) and Src homology 3 (SH3) domains, and they have been implicated in intracellular signaling. For example, they participate as mediators of Ras activation during nerve growth factor stimulation of PC12 pheochromocytoma cells. We examined the role of Crk proteins during T cell receptor-mediated signaling and observed that Crk proteins specifically interact, via their SH2 domains, with a tyrosine-phosphorylated 116-kDa protein upon T cell activation. p116 may be related to the recently cloned fibroblast p130cas and/or p120-Cbl. In addition, we observed that GST-Crk fusion proteins and Crk-L bind, most likely via their SH3 domain, to C3G, a Ras guanine nucleotide exchange factor. Thus, the interaction of Crk with p116 and C3G strongly implicates Crk as a mediator of T cell receptor signaling, possibly involved in Ras activation.

Adrenal Gland Neoplasms↗
PubMed1995

Thoracoscopic closure of patent ductus arteriosus: a less traumatic and more cost-effective technique.

The authors have developed a technique of thoracoscopic closure of patent ductus arteriosus (PDA) that significantly reduces the surgical morbidity, recovery time, and hospital costs traditionally associated with the standard open procedure. Ten patients have undergone the procedure, with nine completed successfully. One patient required conversion to an open thoracotomy. There were no operative complications, and closure of the ductus was confirmed in all cases with a postoperative echocardiogram. Eight of ten patients were discharged in under 24 hours, and hospital charges were on the average 30% to 40% less.

Child, Preschool↗