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Biomedical subjects

K T Chen

Publications and source records attributed to K T Chen.

At least 55 records · Page 3Linked to original sources
PubMed1998

Identification of neutral and acidic sphingomyelinases in Helicobacter pylori.

We demonstrated for the first time the presence of sphingomyelinase (SMase) in Helicobacter pylori. Activation of SMase has been implicated as the cause of elevation of cellular ceramide levels and consequently of apoptosis. The data indicate that there are two classes of SMase, defined by their optimal pHs and cellular locations, existing in H. pylori. One is an Mg(2+)-dependent membrane-bound enzyme with an optimal activity at pH 7, and the other is an Mg(2+)-independent cytosolic enzyme with an optimal activity at pH 5. Bisalumin, a bismuth salt, was found to inhibit the activities of both forms of SMase regardless of the presence of Mg2+. By Western blot analysis, the membrane-bound SMases of H. pylori and Bacillus cereus were shown to be antigenically related and to have a similar denatured molecular mass of 28 kDa.

Bismuth↗
PubMed1998

Unusual dental injuries following facial fractures: report of three cases.

We report 3 cases of unusual dental injuries following facial fractures. The first patient sustained intrusion of a maxillary incisor into the nasal cavity following a mandibular fracture. The tooth dislocated into the pharynx and was found lodged in the piriform fossa during surgery. The second patient sustained intrusion of molars into the maxillary sinus following maxillary and mandibular fractures. His treatment was delayed due to life-threatening hemorrhage. The third case involved ingestion of multiple avulsed teeth into the alimentary tract following severe maxillofacial fractures. Although the diagnosis was made more than a week after the injury, the patient did not suffer any complications as a result of the dental avulsion. The aim of this report is to emphasize the possibility of associated dental injuries in patients with facial fractures. The trauma surgeon should be cognizant of the importance of carrying out a thorough intraoral examination during the initial evaluation. Any missing tooth should be considered as possibly displaced into other tissue compartments, and must be routinely searched for with x-rays of the skull, cervical spine, chest, and abdomen. If full intrusion injury is suspected, further diagnostic investigation with facial computed tomography scanning may be worth while.

Adolescent↗
PubMed1997

Massive intratumor hemorrhage in facial plexiform neurofibroma.

BACKGROUND: Plexiform neurofibromatosis is a feature of von Recklinghausen's disease. Head and neck lesions may produce varying degrees of cosmetic and functional deformity. However, life-threatening hemorrhage into facial plexiform neurofibromas has not been previously reported. METHOD: We report two patients with von Recklinghausen's disease who experienced massive hemorrhage into facial neurofibromas, one following a blunt injury and the other without a known initiating event. RESULTS: Conservative management did not stop the hemorrhage into facial neurofibromas in either instance. Surgical exploration was mandated for hemorrhage control and evacuation of blood clots. Hemostasis was attained by a combination of hypotensive anesthesia and chromic catgut suture ligatures. CONCLUSIONS: These case reports demonstrate a potentially lethal complication in patients with facial plexiform neurofibroma. Where a competent and experienced interventional neuroradiologist is not available, surgical exploration should be undertaken to control bleeding.

Adolescent↗
PubMed1997

[Seroepidemiology of Japanese encephalitis viral infection among 3-6 years old children from mountainous and plains townships located in the northern, central, southern and eastern Taiwan].

In order to evaluate the Japanese encephalitis virus (JEV) vaccination program in rural Taiwan, we conducted a seroepidemiological survey of JEV among rural children 3 to 6 years of age in Taiwan. The children were selected through a systemic sampling following stratification by age of children in 4 selected aboriginal villages and 4 adjacent nonaboriginal villages. The overall vaccine coverage rate for the primary (2 doses) dose was 81.2% (1853/2281) with higher rates (87.7%-87.9%) found among the more recent birth cohort of 3 to 4 years of age. The neutralizing antibody (NT) against JEV was measured with plaque reduction neutralization test (PRNT) using Nakayama strain as the virus. With a positive NT antibody defined as > or = 1:10 dilution of serum yielding more than 50% plaque reduction, the overall JEV NT antibody positive rate among children receiving 3 doses of vaccine was 67%. However, the age-specific positive rates varied significantly with varying ages; the lowest of 47% being among children 4 years of age which was lower than the rates of 68%, 76% and 87% among children of 3, 5 and 6 years of age, respectively. This trend of rising seropositive rates of JEV antibody with increasing age among 4 and 6 years of age was also noted among children who had received no vaccine, suggesting the importance of natural infection among rural Taiwanese children. Despite the high frequency of natural infection, the seropositive rates of JEV antibody still correlated well with the dose of vaccine received, i.e., 67% (1122/1664), 66% (65/97), 33% (4/12) and 40% (19/47) for children receiving 3, 2, 1, and 0 dose of JE vaccines, respectively (P < 0.0001 Chi-square for trend test). When stratified analysis by dose and by type of vaccines was conducted, a significantly higher seropositive rate of JEV NT antibody was noted among children receiving JE vaccine of Beijing type (87%) than children receiving Nakayama type (39%) (p < 0.0001, Chi-square test). Our data indicated that the JEV vaccination, in conjunction with JEV natural infection, has maintained high JEV NT antibody level among rural children of Taiwan.

Age Factors↗
PubMed1996

Vacuolating toxin from Helicobacter pylori activates cellular signaling and pepsinogen secretion in human gastric adenocarcinoma cells.

We investigated cellular signaling and pepsinogen secretion in the human gastric adenocarcinoma cell line AGS which was pretreated with the purified vacuolating cytotoxin from Helicobacter pylori. Results indicated that vacuolating toxin increased the levels of inositol phosphates, cytosolic free calcium concentration, adenosine 3',5'-cyclic monophosphate, and phosphorylation of 31 kDa and 22 kDa proteins in the host cells. Moreover, pepsinogen secretion from AGS cells was stimulated with increasing concentrations of cytotoxin. We conclude that besides the H. pylori cytotoxin-induced cellular vacuoles, cytotoxin-stimulated signaling mediators and pepsinogen release are important factors involved in the etiology of chronic active gastritis and peptic ulcer disease.

Adenocarcinoma↗
PubMed1996

Genomic structure of carp mitogen-activated protein kinase kinase 1 gene.

Carp mitogen-activated protein kinase kinase 1 (cMKK1) gene was isolated from a liver genomic library. The sequence around the exon-intron boundaries and 2 kb of the promoter region were determined. Our data indicate that this gene is composed of 11 exons and 10 introns spanning about 9 kb. Multiple potential transcription initiation sites were located by primer extension analysis. Examination of 2 kb of 5'-flanking sequence revealed potential binding sites for a variety of transcription factors such as E2F, Ets-1, GATA-1, Myb, NF-IL6, Sp1, and NF-kB.

Amino Acid Sequence↗
PubMed1996

Exfoliative cytology of tracheobronchial adenoid cystic carcinoma.

The cytologic findings in the bronchial brushing and washing specimens of three cases of tracheobronchial adenoid cystic carcinoma are reported and compared with those reported in the literature. The cytodiagnostic features including cribriform epithelial clusters, epithelial balls, branching epithelial cylinders, cellular hyaline mucous globules, and a heretofore unemphasized diagnostic clue in exfoliative cytology--naked hyaline globules in washing smears, are illustrated and discussed.

Bone Neoplasms↗
PubMed1996

Protective effects of Gynostemma pentaphyllum in gamma-irradiated mice.

Radiation protective effects of Gynostemma Pentaphyllum (Gp) were investigated in gamma-irradiated mice. Animals were sacrificed on days 5, 15, 25 and 35 after gamma-irradiation. GOT, GPT, serum IgG and leukocyte counts were measured. Proliferation of splenocytes stimulated by mitogens, such as PHA, Con A, and LPS were detected and compared. The results showed that all parameters measured in this study were decreased and proliferation of splenocytes stimulated by mitogens were repressed in gamma-irradiated mice. Gp helped to recover the decreased leukocyte counts, GOT, GPT and IgG in serum and the proliferation of splenocytes stimulated by PHA, LPS and Con A in the gamma-ray irradiated mice.

Animals↗
PubMed1996

Recurrence rate and risk factors for urinary calculi after extracorporeal shock wave lithotripsy.

PURPOSE: We determined the recurrence rate after extracorporeal shock wave lithotripsy (ESWL*) and evaluated its associated risk factors, such as patient sex and age, volume of daily water intake, related diseases, family history of urinary calculi, number, burden and location of stones, residual stones after ESWL, serum uric acid level before ESWL and so forth. MATERIALS AND METHODS: We conducted a retrospective study of 841 patients who underwent ESWL for primary treatment of urinary calculi between 1985 and 1987. Charts were reviewed for stone characteristics, outcomes and associated laboratory data. Followup 6 to 9 years later was done by mail and telephone interviews. RESULTS: Followup data were available for 436 patients (52%). Overall, stones recurred in 51% of the 436 patients at a mean followup of 7.1 years. Late recurrences were common, and were noted in as many as 70% of the patients after 9 years. This rate is greater than what has been previously reported after other treatments. Cox regression analysis indicated that the major risk factors associated with recurrence were male gender (relative risk 1.406, p < 0.05) and multiple stones (relative risk 1.777, p < 0.05). CONCLUSIONS: The frequent late recurrences support the speculation that ESWL might lead to greater recurrence rates. Therefore, the cost-effectiveness of ESWL versus other modalities for stone removal warrants more long-term evaluation.

Adolescent↗
PubMed1996

Effects of low dose gamma-ray irradiation on peripheral leukocyte counts and spleen of mice.

OBJECTIVE: To study the effects of low dose gamma-ray irradiation on peripheral leukocyte counts and spleen weight of mice. MATERIALS AND METHODS: Two hundred male mice of ICR strain were divided into four groups. Group A served as normal control. Groups B, C and D, the experimental groups were treated with 5, 50 and 100 cGy (exposure dose in air) of whole body gamma-ray irradiation respectively. The leukocyte counts and its differential counts, body weight and the spleen weight of mice were measured on days 1, 5, 12, 19, 26 and 33 after irradiation. The relative spleen weight derived from the data of body weight and spleen weight was also calculated in tested animals. RESULTS: The leukocytes and its differential counts and relative spleen weight in mice decreased after 100 cGy gamma-ray irradiation. Fifty cGy gamma-ray irradiation could inhibit the leukocyte and its differential counts. The lowest dose, 5 cGy had no considerable damage. CONCLUSIONS: One hundred cGy of 137Cs gamma-ray irradiation had an inhibitory effect on counts of total leukocyte, lymphocyte, neutrophil, monocyte, spleen weight and body weight, while 50 cGy gamma-ray irradiation had an evident inhibition on peripheral leukocytes and its differential counts in mice. However, 5 cGy gamma-ray irradiation had no obvious inhibition in the tested mice in the period of the investigation.

Animals↗
PubMed1996

Effects of glycyrrhizae and glycyrrhizic acid on cellular immunocompetence of gamma-ray-irradiated mice.

OBJECTIVE: To investigate the effects of glycyrrhizae (GL) and glycyrrhizic acid (GA) on cellular immunocompetence in the gamma-ray-irradiated mice. MATERIALS AND METHODS: Tested mice of ICR strain were treated with GL and GA for 10 days continuously after 4 Gy gamma-irradiation. The counts of total leukocytes, lymphocytes, neutrophils and monocytes in peripheral blood of mice were measured. The blastogenic responses of splenocytes to mitogens, such as PHA, PWM, Con A and LPS were also detected. The cellular immunocompetence was measured by 3H-thymidine incorporation in each tested mouse. RESULTS: The leukocytes and their differential counts decreased in gamma-irradiated mice. The blastogenic responses of splenocytes to mitogens were inhibited by gamma-ray irradiation. GL and GA were effective in enhancing the recovery of leukocyte count and the blastogenic responses of splenocytes to mitogens, such as PHA, PWM, Con A and LPS from the inhibition of 4 Gy gamma-irradiation. CONCLUSIONS: Four Gy gamma-ray irradiation can decrease leukocytes and their differential counts, and the blastogenic responses of splenocytes of mice. GL and GA can help the recovery of the cellular immunocompetence in the gamma-irradiated mice.

Animals↗
PubMed1996

Effects of gypenosides on cellular immunity of gamma-ray-irradiated mice.

OBJECTIVE: To investigate the effects of gypenosides (Gs) on cellular immunocompetence in the gamma-ray-irradiated mice. MATERIALS AND METHODS: Tested mice of ICR strain were treated continuously with Gs for 10 days before or after 4 Gy gamma-irradiation. Body weight and splenic weight of mice were measured. The blastogenic response of splenocytes to mitogens, such as PHA, Con A and LPS were also detected. The cellular immunocompetence was measured by 3H-thymidine incorporation in each tested mouse. RESULTS: Body weight as well as splenic weight decreased in gamma-ray-irradiated mice. The blastogenic responses of splenocytes to mitogens were inhibited after gamma-ray irradiation. To treat with Gs was effective to enhance the recovery of body weight, splenic weight and immunocompetence in gamma-ray-irradiated mice from radiation damage. CONCLUSIONS: Four Gy gamma-ray irradiation could decrease splenic weight and cellular immunocompetence of mice. Gs could help the recovery of the splenic weight and cellular immunocompetence in gamma-ray-irradiated mice.

Animals↗
PubMed1996

[Post-obstructive pulmonary edema following extubation--report of two cases].

Pulmonary edema may develop in healthy patients after anesthesia. It usually results from upper airway obstruction which may be caused by laryngospasm or aspiration. Increased inspiratory effort following airway obstruction significantly produces negative intrathoracic pressure that may lead to pulmonary edema. We reported two cases of post-obstructive pulmonary edema following extubation. They were essentially healthy young males, one of whom received urethroplasty and the other received pulmonary blebectomy. Their hemodynamic and ventilatory conditions had been kept stable during surgery. Upper airway obstruction followed by pulmonary edema developed immediately after extubation, which was successfully treated without any sequelae.

Adult↗