Biomedical subjects
T Y Lin
Publications and source records attributed to T Y Lin.
G33D mutant thioredoxin primarily affects the kinetics of reaction with thioredoxin reductase. Probing the structure of the mutant protein.
Escherichia coli thioredoxin is a redox-active protein. A mutant protein with an aspartic acid substitution for the largely conserved glycine at position 33 (G33D) in the active site of thioredoxin has been generated to study the effects of a negatively charged residue in the active site of the protein. Despite the close proximity of the negative-charged Asp to the redox active cysteines, the effective concentration of the cysteines does not deviate significantly from that of the wild-type protein. The redox potential (E(o)') measured by the equilibrium between NADPH and the mutant thioredoxin is also close to that of the wild-type. Kinetic measurements of the reaction between thioredoxin and thioredoxin reductase show that G33D mutant and the wild-type proteins have identical kcat values. However, the Km for G33D mutant is approximately 10-fold higher than that for the wild-type protein. In vivo assay of the growth of E. coli strain carrying wild-type or G33D mutant thioredoxin on methionine sulfoxide indicates that the G33D mutant protein is a slower electron donor for methionine sulfoxide reductase. Structural stability of the oxidized protein is not altered by the G33D substitution, as illustrated by the same unfolding free energies studied by urea. The substitution does not show significant change of the near UV and far-UV circular dichroic (CD) and the fluorescence spectra for either the reduced or the oxidized protein. Therefore, the global structure of the G33D protein is not changed. However, the surface of the active site has been altered locally by G33D substitution, which accounts for the above kinetically poor behaviors. A model of G33D structure is constructed based on these studies.
Clinical features and risk factors of pulmonary oedema after enterovirus-71-related hand, foot, and mouth disease.
BACKGROUND: In Taiwan, from April to July, 1998, an epidemic of hand, foot, and mouth disease associated with enterovirus 71 (EV71) occurred with fatal complications. We did a clinical study of EV71-related diseases in Taiwan. METHODS: We studied 154 children with virus-culture confirmed EV71 infection. Children were divided into three groups: 11 patients with pulmonary oedema; 38 patients with central nervous system (CNS) involvement and no pulmonary oedema; and 105 children without complications. We compared the clinical features, laboratory findings, risk factors, and outcome among these three groups. FINDINGS: Nine children with pulmonary oedema had hand, foot, and mouth disease, one had herpangina, and one had febrile illness with eight children with limb weakness and one with limb hypesthesia. All children had had sudden onset of tachycardia, tachypnoea, and cyanosis 1-3 days after onset of the disease. Nine of 11 children died within 12 h of intubation; one child was braindead within 15 h and died 17 days after intubation; one child was in deep coma and died 3 months later. In children with CNS complication and no pulmonary oedema, one child died of pneumonia after 4 months of ventilator support and four children had sequelae. All 105 children without complications recovered. There was a significant association between CNS involvement and pulmonary oedema (odds ratio 12.4 [95% CI 2.6-60.1], p=0.001). Risk factors for pulmonary oedema after CNS involvement were hyperglycaemia, leucocytosis, and limb weakness. Hyperglycaemia was the most significant prognostic factor for pulmonary oedema (odds ratio 21.5 [3-159], p=0.003). INTERPRETATION: EV71 can cause hand, foot, and mouth disease, CNS involvement with severe sequelae, and fatal pulmonary oedema. Hyperglycaemia is the most important prognostic factor.
Toxicity of tunicamycin to cultured brain neurons: ultrastructure of the degenerating neurons.
Our previous study has shown that tunicamycin irreversibly downregulates the expression of GABA(A)R and causes cell death in cultured brain neurons by biochemical and light microscopic methods. In this study, we examined mechanisms underlying the degeneration of the neurons mainly employing electron microscopic analysis. Cultured neurons derived from embryonic chicken brains were incubated with 5 microg/ml of tunicamycin (TM) for 24 h, followed by continual incubation or removal of TM for additional 3 h or 24 h. Neurons treated with TM for 24 h showed dilated rough endoplasmic reticulum (rER), nuclear envelope and components of Golgi apparatus, in addition to the degranulation of rER and disaggregation of ribosomal rosettes. In neurons subjected to the prolonged incubation, some ribosomes reattached to the membranes of rER; the polyribosomes reappeared, and the swelling of Golgi apparatus subsided. However, the distention of rER persisted, and an uncommon spindle-like structure appeared in the perikarya. This structure is implicated to involve the neuronal degeneration. Moreover, extracellular cell debris was increased with time of incubation. The ratio of the light neurons, defined as containing lower cytoplasmic matrix density than the untreated control, decreased from 28% at 3 h to 3% at 24 h after the removal of TM, and 45% at further 3 h to 6% at further 24 h incubation of TM, whereas dense neurons only appeared in the two 24 h groups, as 44% and 34%. The light neurons resemble necrotic cells, but the dense neurons exhibit distinct morphological features from necrosis and apoptosis. The gel electrophoresis assay revealed the absence of DNA fragmentation in all cultures. In addition, whole cell recordings exhibited a 40% decrease of the GABA-elicited current in the neurons exposed to TM for 24 h. The results indicate irreversible toxicity of chronic TM treatment to the neurons and suggest differential mechanisms for the neuronal death among various populations of cells. It is evident that the N-glycosylation plays a critical role for neuronal survival.
Expression of Fas ligand in Langerhans' cell histiocytosis: A case report of a boy with multisystem involvement.
Previous reports of patients with Langerhans' cell histiocytosis have shown characteristics of osteolytic lesion, visceral involvement and organ dysfunction. We report a 2-year-old boy who was diagnosed as Langerhans' cell histiocytosis with a prominent hepatomegaly. X-Radiogram, computed tomography and magnetic resonance imaging revealed the osteolysis of the right iliac bone, the absence of the left eighth rib as well as the right mandible, and an enhancing mass in the left cerebellum. The data of radiography were highly suggestive of Langerhans' cell lineage. The presence of large CD1a-positive mononuclear cells associated with inflammatory cells in peripheral blood smear and bone marrow aspirate further confirmed the diagnosis. In addition, expressions of S100, CD25, CD68, CD80, CD86, and Fas ligand were identified on these cells by immunocytochemical staining. The results indicate that although these cells are activated Langerhans' cells, progression of the disease and the bone destruction could be mediated by the overt FasL expression of the cells.
Pregnancy with primary tubal placental site trophoblastic tumor--A case report and literature review.
Placental site trophoblastic tumor (PSTT) is a rare trophoblastic neoplasm with malignant potential. The diagnosis and prognosis of this rare disease remain difficult. A case of tubal PSTT with the primary manifestation of internal bleeding at 30 weeks' gestation is presented. Emergency exploratory laparotomy and right partial salpingectomy were performed initially. Total abdominal hysterectomy, bilateral salpingo-oophorectomy, and omentectomy were done immediately after cesarean section at 34 weeks' gestation. No further adjuvant therapy was given after surgery. No evidence of tumor recurrence or signs of metastasis were noted during 12 months of follow-up. Heterotopic pregnancy, one with intrauterine normal pregnancy and the other with implanting in the right fallopian tube and placental site trophoblastic tumor transformation, was proposed. To our knowledge, this is the first such case in the English literature.
Diagnosis of respiratory tract viruses in 24 h by immunofluorescent staining of shell vial cultures containing Madin-Darby Canine Kidney (MDCK) cells.
Nine hundred and seventy-eight clinical specimens were examined taken from patients with respiratory tract viruses (RV)-like syndrome between November 1996 and July 1998. The study was undertaken to evaluate the effectiveness of centrifuge-enhanced shell vial cultures (SVC) containing Madin-Darby Canine Kidney (MDCK) cells, combined with immunofluorescent (IF) staining in 24 h. This technique rapidly detects and identifies respiratory tract viruses. The conventional tube culture system with multiple cell lines would ordinarily detect RV within 3-30 days. The SVC/IF method using single cell line (MDCK cells) allowed detection of 81.5% of influenza A virus, 72% of parainfluenza virus, 82.6% of respiratory syncytial virus (RSV) and 79.6% of adenovirus in 24 h.
Laser hair removal affects sebaceous glands and sebum excretion: a pilot study.
BACKGROUND: During laser-assisted hair removal, sebaceous glands closely associated with hair follicles might also be affected. OBJECTIVE: We investigated the effect of the long-pulsed ruby laser on sebaceous glands. METHODS: Sebum excretion rates (SERs) of 16 subjects were measured quantitatively by means of sebum-absorbent tape and analyzed by means of image analysis techniques on laser-treated sites, compared with adjacent untreated areas. Evaluation was done at an average of 9 months (range, 4.5 to 12 months) after the last treatment. Histologic examinations were performed on 3 representative subjects before treatment, immediately after treatment, and 9 months after the last treatment. RESULTS: Significant increases in SERs were observed in 11 of 16 subjects (68.75%). Three subjects (18.75%) showed lower SERs, whereas 2 subjects (12.5%) demonstrated no difference in SERs between treated and untreated areas. Biopsy specimens showed an apparent reduction in sebaceous gland size. Specimens taken immediately after laser irradiation revealed sporadic damage to sebaceous glands. CONCLUSION: In some patients a variable but statistically significant increase in sebum excretion occurs 4 to 12 months after ruby-laser hair removal treatment at high fluences. A reduction in sebaceous gland sizes on laser-treated areas was observed. We hypothesize that decreased resistance to sebum outflow may explain this result, following miniaturization or absence of hair shaft after ruby laser treatment. Further study is needed to assess mechanisms for this interesting response.
In vitro evaluation of intracellular activity of antibiotics against non-typhoid Salmonella.
Non-typhoid salmonellae are the most common causative organisms of bacterial enteritis in children. Clinical studies have failed to show any influence of various antibiotics on the natural course of acute salmonella enteritis. Poor penetration of antibiotics into phagocytic cells that contain intracellular Salmonella spp., and possible intracellular antibiotic inactivation have been considered as possible reasons for this. In this study, we used an in vitro model to assess the intracellular activity of antibiotics against non-typhoid salmonellae. The survival of intracellular Salmonella spp. in P388D1 cells, a mouse macrophage cell line was measured in the presence of various antibiotics. Except for gentamicin, which entered phagocytes poorly, ofloxacin, azithromycin, chloramphenicol and three beta-lactam antibiotics, ampicillin, cefixime and ceftriaxone, exhibited bacteriostatic activity against susceptible intracellular Salmonella spp. at an extracellular concentration equal to the minimal inhibitory concentration (MIC). At a concentration of 10 x MIC, neither chloramphenicol nor the three beta-lactam antibiotics produced a bactericidal response; however, both ofloxacin and azithromycin were bactericidal after 8-24 h of incubation. The results showed that fluoroquinolones and new macrolides were more efficient than the other antibiotics in eradicating intracellular salmonella and might be useful agents for the treatment of non-typhoid salmonella enteritis in children. Clinical trials should be considered.
A clinical trial comparing oral azithromycin, cefixime and no antibiotics in the treatment of acute uncomplicated Salmonella enteritis in children.
OBJECTIVE: The objective of this study was to perform a prospective, randomized, controlled study to evaluate the role of azithromycin and cefixime in the treatment of uncomplicated non-typhoid Salmonella enteritis in children. METHODOLOGY: Patients with Salmonella enteritis were randomized to receive oral azithromycin (10 mg/kg/day once daily), cefixime (10 mg/kg/day divided twice daily) or no antibiotics for 5 days. The patients were followed up for the duration of their symptoms. Stool samples were sent for culture weekly following the therapy until two consecutive negative results were obtained. Susceptibility of the isolates to antibiotics was tested by the disk diffusion method. RESULTS: Forty-two patients with acute, uncomplicated, culture-confirmed Salmonella enteritis were studied. Duration of diarrhoea and time to defervescence after the therapy were not significantly different for patients treated with azithromycin, cefixime, or no antibiotics; there also were no significant differences with respect to the rate of clearance of Salmonella from stools among the three groups. Salmonella typhimurium was the most common serotype isolated. All 42 isolates were sensitive to cefixime, while two strains (5%) were resistant to azithromycin. CONCLUSION: Azithromycin or cefixime provides no benefit to paediatric patient with uncomplicated Salmonella enteritis.
Tumor seeding of the jejunostomy site after transhiatal esophagectomy for esophageal carcinoma.
A 65-year-old male patient with squamous cell carcinoma of the esophagus had a transhiatal esophagectomy after a prophylactic tube jejunostomy. The tube was removed 3 weeks after surgery. Ten months later, a painless 2-cm abdominal mass was noted at the previous jejunostomy site. Subsequent segmental resection of the jejunum disclosed metastatic squamous cell carcinoma of the esophagus. It is possible that tumor seeding may develop at the jejunostomy site after transhiatal esophagectomy for esophageal carcinoma.
Gossypiboma: migration of retained surgical gauze and spontaneous transurethral protrusion.
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Infected cephalohematoma associated with sepsis and skull osteomyelitis: report of one case.
Osteomyelitis is rarely complicated by an infected cephalohematoma. We report a case of an infected cephalohematoma associated with Escherichia coli sepsis and osteomyelitis of the skull. This 37-day-old boy had E. coli sepsis, which had a poor response to antibiotic treatment. An infected cephalohematoma was found when he was 43 days old. Cranial computed tomography (CT) scanning showed cephalohematoma with abscess formation and underlying bony destruction over the left parietal region. Antibiotics alone could not eradicate the infection. Extensive incision, drainage, and debridement of the necrotic bone resulted in prompt improvement. Three weeks of ceftizoxime administered intravenously, followed by 3 weeks of cefixime given orally completed the treatment course.
Bacteremic pneumonia caused by penicillin-resistant Streptococcus pneumoniae in siblings.
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Comparison of enterovirus 71 and coxsackie-virus A16 clinical illnesses during the Taiwan enterovirus epidemic, 1998.
OBJECTIVES: To compare enterovirus 71 (EV 71) with coxsackievirus A16 (Cox A16) clinical illness in patients at Chang Gung Children's Hospital during Taiwan's enterovirus epidemic of 1998. METHODS: With the use of the immunofluorescence assay and neutralization test, 177 cases of EV 71 and 64 cases of Cox A16 illness were confirmed from April to September, 1998. The clinical signs and symptoms, complications and case fatality rates were compared. RESULTS: Three-fourths of the cases were younger than 3 years of age, and the ratio of males to females was 1.3 in the EV 71 group and 1.2 in the Cox A16 group. In the EV 71 group 120 (68%) cases were uncomplicated, including 94 cases of hand, foot and mouth disease and 15 cases of herpangina, and 57 (32%) cases had complications, including 13 (7.3%) cases of aseptic meningitis, 18 (10%) cases of encephalitis, 4 (2.3%) cases of polio-like syndrome, 8 (4.5%) cases of encephalomyelitis and 12 (6.8%) cases of fatal pulmonary edema. Fourteen (7.9%) patients died, including 12 cases of pulmonary edema and 2 cases of encephalitis; seven (4%) patients had sequelae. By contrast, 60 (94%) of the 64 cases of Cox A16 infection were uncomplicated and only 4 (6.3%) cases were complicated by aseptic meningitis; no fatalities or sequelae were observed. By multivariate analysis vomiting (P = 0.01) and fever higher than 39 degrees C plus lasting longer than 3 days (P = 0.02) were significantly more frequent in the EV 71 group. CONCLUSION: EV 71 illness is more severe with significantly greater frequency of serious complications and fatality than is illness caused by Cox A16.
Prevalence of the virulence plasmids of nontyphoid Salmonella in the serovars isolated from humans and their association with bacteremia.
To determine if the virulence plasmid is one of the elements contributing to Salmonella bacteremia in humans, 436 clinical Salmonella isolates of different serovars were examined by a specific multiplex polymerase chain reaction assay for the presence of a virulence plasmid. These serovars showed differences in their ability to produce particular disease syndrome in humans. In the serovars usually causing bacteremia without concomitant gastroenteritis (primary bacteremia), i.e., S. choleraesuis, S. dublin, and S. enteritidis in this study, the rate of virulence plasmid carriage was 100%, while among those occasionally generating bacteremia following an episode of gastroenteritis (secondary bacteremia), the majority were plasmidless. Only a portion of S. typhimurium strains harbored a virulence plasmid; however, the rates of virulence plasmid carriage in S. typhimurium were not statistically different between non-fecal and fecal isolates (90% vs. 85%, 0.1 < P < 0.9). These results indicate that the virulence plasmids may be important for primary bacteremia, but not secondary bacteremia, to occur.
Color Doppler ultrasonographic evaluation of osteomyelitis in children.
We investigated the capability of color Doppler sonography in evaluating acute osteomyelitis in children. Twelve children suspected of having osteomyelitis were evaluated with color Doppler ultrasonography at admission and at regular intervals to observe the inflammatory process of osteomyelitis, determine the response of antibiotic therapy, and predict the need of surgery in these patients. At admission, color Doppler flow within or around the infected periosteum was found in patients with symptoms for 4 days or longer, whereas those with symptoms for less than 4 days showed no color Doppler flow within and around the periosteum. During sonographic follow-up, six cases were found to have increased color Doppler vascular flow within and around the affected periosteum, and two of them had periosteal abscess. They eventually required surgical treatment. Persistent or increased color Doppler flow during follow-up examination correlated with elevated serum levels of C-reactive protein as well. Our study indicated that color Doppler vascular flow within or around the infected periosteum correlated with advanced acute osteomyelitis, and surgery usually was required in these patients. Those with early stage acute osteomyelitis usually showed no vascular flow within or around the infected periosteum. Thus, color Doppler sonography allowed detection of advanced osteomyelitis and revealed the progression of inflammation during antibiotic therapy. Color Doppler ultrasonography might be valuable in determining the efficacy of antibiotic therapy and justifying the need for operation.
Diagnosis of necrotizing fasciitis in children.
Necrotizing fasciitis is a rare but progressive soft tissue infection. This condition is difficult to recognize in the early phase, when it is often confused with cellulitis. We report the cases of four children with necrotizing fasciitis. The initial presentation in these cases was cellulitis. Fever and soft tissue swelling occurred within 24 h and spreading erythema within 4 to 12 h. Radiologic studies of the lesions showed soft tissue thickening. Ultrasonography of the lesions demonstrated distorted, thickened fascia with fluid accumulation. Well-defined, loculated abscesses were demonstrated in two cases. Although typical dusky skin and purplish patches were not found in our cases, necrotizing fasciitis was strongly suspected on the basis of the clinical course and sonographic findings. Ultrasonography also was used as a guide for aspiration of pus. Gram-stained smears and bacterial cultures yielded the pathogens. The choice of antibiotic therapy was made on the results of smears and culture. All patients survived after immediate surgical debridement, intensive antibiotic therapy, and aggressive wound care. In conclusion, ultrasonography provides a rapid and valuable diagnostic modality for necrotizing fasciitis. The pus obtained through sonographically guided aspiration for bacterial culture can allow identification of the pathogenic organisms.