Biomedical subjects

M Y Chen

Publications and source records attributed to M Y Chen.

At least 163 records · Page 9Linked to original sources

PubMed1994

[Prognostic evaluation of lymph node metastasis in thoracic esophageal cancer--an analysis of 212 cases].

The authors studied retrospectively lymph node metastatic status impacts on survival of the 212 patients with thoracic esophageal squamous cell carcinoma and lymph node metastasis after curative resection. 663 (19.4%) of the total 3419 lymph nodes examined (an average of 16.1 per patient) were proved to be positive. The overall 5-year survival rate was 19.3%. The results showed that no difference in survival was observed in relation to the site of the involved lymph node. Difference in survival based on the number of metastatic lymph nodes (1 or > or = 2) and the frequency of positive nodes (< or = 10% or > 10%). The results indicate that staging of esophageal cancer should be made according to the absolute number and the relative frequency of lymph nodes involved. The effectiveness and limitation of extended lymph node dissection in relation to prognosis was discussed.

Adult↗

PubMed1994

[41 cases of video-assisted thoracoscopy].

Video-assisted of thoracoscopic surgery (VATS) is the minimally invasive surgery. It has characteristic of mini-incision, less pain, less bleeding, less transfusing, less affecting cardio pulmonary function. So it is one of the development directions of thoracic surgery. The authors had finished 41 cases VATS. Operative indication was expatiated. The requirement of anesthesia is lower. The patients whose pulmonary function were too severe destructive to walk could be treated by VATS. The authors discussed some questions of VATS.

Adolescent↗

PubMed1994

Barrett esophagus and adenocarcinoma.

Barrett esophagus has become a common lesion in the esophagus; it is presumably caused by reflux esophagitis. Double-contrast barium esophagraphy improves radiographic evaluation of Barrett esophagus. The presence of midesophageal stricture, mucosal reticular pattern, and deep esophageal ulceration suggests the presence of Barrett esophagus. Other findings, such as hiatal hernia, thickened mucosal folds, and gastroesophageal reflux, are also frequently seen in Barrett esophagus but are not specific. Adenocarcinoma may complicate Barrett mucosa, usually with severe dysplasia. Adenocarcinoma has morphologic forms similar to squamous cell carcinoma in the esophagus. Barium esophagram, CT scans, and endoscopic sonography are used to evaluate and stage adenocarcinoma in the esophagus.

Adenocarcinoma↗

PubMed1994

Esophageal squamous carcinoma.

Squamous cell carcinoma of the esophagus is a tumor with poor prognosis; it is usually in an advanced state when first diagnosed. Because a multimodal treatment approach is currently used, proper tumor staging is essential to determine whether therapy should be directed toward cure or palliation. Important prognostic features of squamous cell carcinoma include the depth of tumor infiltration into or through the esophageal wall and the presence of distant metastases. Imaging strategies should not be limited to visualization of the tumor but also should be directed toward accurate pretreatment staging. In this article, the authors review the use of barium swallow, CT scans, and endoscopic ultrasonography both alone and in combination to visualize and stage esophageal carcinoma. The strengths and limitations of each modality are also discussed.

Barium↗

PubMed1994

Achalasia associated with esophageal diverticula. Prevalence and potential implications.

Although esophageal diverticula have been rarely reported in patients with achalasia, their prevalence and the potential implications of the relationship are not well known. We reviewed the medical records and the manometric and radiographic examinations in 120 patients with achalasia to determine the prevalence of esophageal diverticula and to evaluate their importance in this motility disorder. Esophageal diverticula were found in only 6 (5%) of 120 patients, and all were located in the lower half of the esophagus. Sex distribution and the prevalence of dysphagia and regurgitation, which affected all patients with diverticula and 88% of those with achalasia only, were not different significantly. Patients with esophageal diverticula were significantly older (72 vs. 52 years) than those without diverticula. In 5 of 6 patients with diverticula, mean lower esophageal sphincter (LES) pressure was 44.5 mm Hg compared to 39.1 mm Hg in 86 of 114 patients with achalasia only. Treatment by pneumatic dilatation was done in 4 patients with esophageal diverticula and in 105 patients without diverticula. Five esophageal perforations occurred, all in patients without esophageal diverticula.

Adolescent↗

PubMed1994

Specific acute colonic disorders.

This article reviews a variety of specific colonic disorders that may have been an acute clinical presentation. Less common causes of colonic obstruction include volvulus, intussusception, and hernias. Nonobstructive colonic dilatation is most often due to pseudo-obstructions and toxic megacolon. Several miscellaneous disorders discussed include colonic perforation, complications of leukemia that may affect the colon, and pseudomembranous colitis. The pathogenesis and clinical aspects of these disorders are reviewed, but the radiologic features are emphasized.

Acute Disease↗

PubMed1994

Skull-base foramina of the middle cranial fossa: reassessment of normal variation with high-resolution CT.

PURPOSE: To evaluate by means of high-resolution CT the anatomic variations of the middle cranial fossa foramen. METHODS: We examined 123 CT studies of the temporal bone in patients with no evidence of disease that might alter foraminal anatomy. A checklist of known variants and suspected structures was used as each case was systematically examined for the presence or absence of these foramina; variations in size, shape, and location; and relationship of structures to each other. Inclusion criteria were established to eliminate error. RESULTS: The foramen rotundum had a constant appearance. We identified the inferior rotundal canal in 16% of patients and the lateral rotundal canal in 8%. The foramen of Vesalius was present, at least unilaterally, in 80% of our cases. Asymmetry of the foramen of Vesalius did not indicate disease in our patient group. We did not find an inverse relationship between the size of the foramen of Vesalius and that of the ipsilateral foramen ovale. We found variations in the size and shape of the foramen ovale and its confluence with the foramen spinosum (n = 2) and the foramen of Vesalius (n = 8). We did not find an inverse relationship between the size of the foramen ovale and that of the foramen spinosum. The canaliculus innominatus for the lesser superficial petrosal nerve was identified in 16.3% of our patients. Variations of the foramen spinosum that we found include a medial bony defect (26.8%) and absence (3.2%). CONCLUSION: Although it is unlikely that well-formed foramen will be misinterpreted as diseased, it is nonetheless important to recognize foraminal variants and associated neurovascular anatomy.

Adolescent↗

PubMed1993

Mutational study of Streptomyces tyrosinase trans-activator MelC1. MelC1 is likely a chaperone for apotyrosinase.

The melanin operon (melC) of Streptomyces antibioticus contains two genes, melC1 and melC2 (apotyrosinase). Our previous studies indicated that MelC1 forms a transient binary complex with the downstream apotyrosinase MelC2 to facilitate the incorporation of copper ion and the secretion of tyrosinase. In this study, we investigated the role of histidine residues in the function of MelC1 by examining a series of substitution or deletion mutants. Of eight mutants only the substitution of His-117 with Asp in the mutant M-117D rendered the complete abolishment of the intracellular tyrosinase activity in both Streptomyces and Escherichia coli. Replacement of His-102 by Leu in the mutant M-102L also caused a 64-70% reduction of tyrosinase activity in Streptomyces and E. coli. These two mutations also affected the secretion of both MelC1 and MelC2 proteins. In vitro copper activation of the purified MelC1.MelC2 binary complex from these two mutants regained only 20-30% tyrosinase activity of the wild type. Biochemical characterization of the tyrosinases from these two mutants revealed that they were different in several aspects. The intracellular tyrosinase activity in M-117D, but not in M-102L, could be partially reactivated by copper ion or by the cell extract containing MelC1. The copper content and the specific activity of the tyrosinase purified from the culture supernatant from M-117D were only 40% of those in wild type and M-102L. Additionally, fast protein liquid chromatography analysis indicated that in these two mutants the copper activation process was defective, very likely due to the incompetent MelC1.MelC2 binary complex formed: reduced association in M-117D and elevated association in M-102L. Furthermore, the conformation of MelC2 in the binary complex or in the mature enzyme form in wild type could be differentiated by the proteinase K digestion pattern, and so did the conformation of MelC2 found in those of M-102L, but not in M-117D mutant. Taken together, our results demonstrate that MelC1 is indispensable in the incorporation of copper ion into MelC2 apotyrosinase via a transient, competent binary complex formation, during which a conformational transition of MelC2 has occurred. This strongly suggests that MelC1 is a chaperone for the apotyrosinase MelC2.

Amino Acid Sequence↗

PubMed1993

Toxic effects of linear alkylbenzene sulfonate on the tiger prawn, Penaeus monodon.

The toxic effects of linear alkybenzene sulfonate (LAS) on the larvae and juveniles of tiger prawn Penaeus monodon were tested. The 24-hr LC50 values of LAS were 0.06, 0.10, and 3.11 ppm for the zoea 2nd substage, mysis 2nd substage (M2), and postlarva 12th substage (PL12) of the tiger prawn, respectively. The 48-hr LC50 values of LAS were 0.07, 1.03, and 4.36 ppm for M2, PL12, and postlarva 15th substage of the tiger prawn, respectively. The hepatopancreatic glutathione (GSH) in juvenile tiger prawn was obviously depleted when LAS concentration was over 1.0 ppm. The hepatopancreatic GSH content of tiger prawn exposed to solutions of greater than 1.0 ppm LAS was difficult to raise to normal levels, even after the tiger prawns were switched to an LAS-free solution. The activity of malate dehydrogenase in the serum of juvenile tiger prawns exposed to 10.0 ppm LAS solution was significantly increased.

Alkanesulfonic Acids↗

PubMed1993

Achalasia associated with hiatal hernia: prevalence and potential implications.

Although hiatal hernia is reported with a 40-50% frequency in the general population, its occurrence and potential implications in achalasia are less well known. We reviewed the medical records and radiographic examinations of 120 patients with achalasia to assess the prevalence of hiatal hernia and its importance in evaluation and management of this motility disorder. Hiatal hernia was present in only 10 (8.3%) patients. Age, sex distribution, prevalence of dysphagia and regurgitation, and lower esophageal sphincter pressure measured manometrically were not significantly different in patients having hiatal hernia compared to those without hernia. Most patients (88%) underwent pneumatic dilatation and five esophageal perforations occurred, but all in patients without hiatal hernia. In conclusion, hiatal hernia is uncommon in patients with achalasia for reasons not known. Age, sex, symptoms, and results of esophageal manometry were not significantly different in those with hiatal hernia. Finally, the presence of hiatal hernia is not a contraindication to treatment of achalasia by pneumatic dilatation.

Adolescent↗

PubMed1993

Compression filming with high-density barium suspensions.

A method is described for use of high-density barium suspension (250% wt/vol) during compression filming performed in conjunction with the double-contrast examination of the stomach. The technique employs control of the distribution of barium within the stomach by table tilting and use of the vertebral column to stabilize the posterior wall of the stomach. The technique allows routine demonstration of the area gastricae and gastric erosions on compression films, as well as detection of anterior wall lesions that may be undetected by double-contrast films.

Barium Sulfate↗

PubMed1993

In vivo uptake of ethanol and release of acetate in rat liver and GI.

The concentration gradients of ethanol and acetate across liver and GI were determined in overnight starved rats infused with ethanol at a rate (15 mu mol/min/rat) below and a rate (30 mu mol/min/rat) exceeding the rate of ethanol disposal in the animals. Plasma concentrations of ethanol in the systemic circulation reached steady-state levels of approximately 0.6 mM between 30 and 60 min during low rate of infusion; increased steadily from 3.5 mM at 30 min to 6.4 mM at 2 h during high rate of infusion. GI metabolism was determined by concentration differences in aorta and portal vein; hepatic metabolism by differences in hepatic influx and hepatic veins. Hepatic influx was the sum of the concentrations in aorta and portal vein, each multiplied by their fractional contributions to hepatic blood supply. At low rate of infusion, hepatic extraction of ethanol was nearly complete and could be accounted for entirely by the acetate released from liver. The concentrations of ethanol in aorta were greater but not significantly than that in portal vein. At high rate of infusion, hepatic and GI gradients of ethanol remained constant despite changes in circulating concentrations of ethanol. The concentration gradients of ethanol and acetate across liver, though different in signs, were identical in magnitude. GI gradient indicating uptake of ethanol was statistically significant and was about 30% of hepatic gradient. Enzyme activity of alcohol dehydrogenase in stomach was found to be about 10% of that in liver. Our results thus show that acetate generated during ethanol oxidation is completely released from liver in rats, in either conscious or anesthetized state under submaximal or maximal condition of ethanol disposal, and that GI metabolism of circulating ethanol can be as high as one third of the metabolism in liver.

Acetates↗

PubMed1993

Infiltrating lymphocytes and accessory cells in nasopharyngeal carcinoma.

The infiltrating lymphocytes (LCs) and accessory cells (ACs) including dendritic cells (DCs) and monocytes/macrophages in nasopharyngeal biopsies taken from 4 groups of nasopharyngeal carcinoma (NPC) patients were observed by using an immunostaining technique and the correlation of the results to the clinical manifestations and follow-up data was examined. The findings were as follows. (1) NPCs without lymph node metastasis always had marked infiltrating LCs and DCs as compared with those with lymph node(s) metastasis. (2) Advanced NPCs with lymph node(s) involvement (T1-4N1-3M0) and a rapid development of distant metastasis followed by death within 1 year after radiotherapy always showed fewer infiltrating LCs and DCs as compared with those with lymph node(s) metastasis (T1-4N1-3M0) and having longer than 5-year survival after radiotherapy. The amount of both LCs and ACs, especially DCs, infiltrating in NPC tissues appears to be an indicator of the activity of host immune defence mechanisms against cancer and influences the progression of the neoplasm as well as the prognosis.

Antigen-Presenting Cells↗

PubMed1993

Human immunodeficiency virus type 1 Vpu protein induces degradation of CD4 in vitro: the cytoplasmic domain of CD4 contributes to Vpu sensitivity.

CD4 is an integral membrane glycoprotein which functions as the human immunodeficiency virus (HIV) receptor for infection of human host cells. We have recently demonstrated that Vpu, an HIV type 1 (HIV-1) encoded integral membrane phosphoprotein, induces rapid degradation of CD4 in the endoplasmic reticulum. In this report, we describe an in vitro model system that allowed us to define important parameters for Vpu-dependent CD4 degradation. The rate of CD4 decay in rabbit reticulocyte lysate was approximately one-third of that observed previously in tissue culture experiments in the presence of Vpu (40 versus 12 min) and required no other HIV-1 encoded proteins. Degradation was contingent on the presence of microsomal membranes in the assay and the coexpression of Vpu and CD4 in the same membrane compartment. By using the in vitro degradation assay, the effects of specific mutations in CD4, including C-terminal truncations and glycosylation mutants, were analyzed. The results of these experiments indicate that Vpu has the capacity to induce degradation of glycosylated as well as nonglycosylated membrane-associated CD4. Truncation of 13 C-terminal amino acids of CD4 did not affect the ability of Vpu to induce its degradation. However, the removal of 32 amino acids from the C-terminus of CD4 completely abolished sensitivity to Vpu. This suggests that Vpu targets specific sequences in the cytoplasmic domain of CD4 to induce its degradation. We also analyzed the effects of mutations in Vpu on its biological activity in the in vitro CD4 degradation assay. The results of these experiments suggest that sequences critical for this function of Vpu are located in its hydrophilic C-terminal domain.

Amino Acid Sequence↗

PubMed1993

Human immunodeficiency virus type 1 Vpu protein is an oligomeric type I integral membrane protein.

The human immunodeficiency virus type 1 Vpu protein is a 16-kDa phosphoprotein which enhances the efficiency of virion production and induces rapid degradation of CD4, the cellular receptor for human immunodeficiency virus. The topology of membrane-inserted Vpu was investigated by using in vitro-synthesized Vpu cotranslationally inserted into canine microsomal membranes. Proteolytic digestion and immunoprecipitation studies revealed that Vpu was a type I integral membrane protein, with the hydrophilic domain projecting from the cytoplasmic membrane face. In addition, several high-molecular-weight proteins containing Vpu were identified by chemical cross-linking. Such complexes also formed when wild-type Vpu and a Tat-Vpu fusion protein were coexpressed. Subsequent analysis by one- and two-dimensional electrophoresis revealed that these high-molecular-weight complexes consisted of homo-oligomers of Vpu. These findings indicate that Vpu is a type I integral membrane protein capable of multimerization.

Animals↗

PubMed1993

Successful treatment of Kaposi's sarcoma with interferon-alpha in a patient with acquired immunodeficiency syndrome.

Although combined therapy with interferon-alpha and zidovudine may be safely administered to some patients with the acquired immunodeficiency syndrome (AIDS) and Kaposi sarcoma, no ethnic Chinese patient has been successfully treated before in this area. This case report concerns a 47-year-old male with a history of bisexuality who had suffered from oral ulcers for half a year, Human immunodeficiency virus (HIV) serology was positive, and pathology of the oral ulcers disclosed Kaposi sarcoma. Combination therapy with zidovudine and interferon-alpha was initiated. The patient received a low-dose regimen of 5.0 million U interferon-alpha s.c. per day for 8 weeks and 5 million U twice a week for another 8 weeks. The oral ulcers faded away without recurrence. This report also reviews the literatures on treatment of AIDS-related Kaposi sarcoma with interferon.

Acquired Immunodeficiency Syndrome↗

PubMed1993

Measurement of anti-endothelial and anti-cardiolipin autoantibodies and intercellular adhesion molecules-1 in patients with systemic and cutaneous vasculitis.

Two types of autoantibodies and intercellular adhesion molecule-1 (ICAM-1) were measured in patients with vasculitis. There were 13 patients with systemic vasculitis, and 12 with cutaneous vasculitis. The measured antibodies included antiendothelial cell antibodies (AECA) and anti-cardiolipin (ACL) antibodies of three isotypes. Results showed that patients with systemic vasculitis had elevated levels of ICAM-1 and IgG isotype ACL antibodies. Higher levels of ICAM-1 and IgG isotype ACL antibody were found in patients with systemic vasculitis than in those with cutaneous vasculitis. Levels of ICAM-1 and IgG isotype ACL antibodies also decreased after disease activity subsided in patients with systemic vasculitis. Measurement of ICAM-1 and autoantibodies may be useful in evaluating the extent of involvement, and for following the disease course.

Adolescent↗

PubMed1993

Postoperative hysterosalpingography. Radiographic appearances and clinical results following tubal surgery.

Medical records and postoperative hysterosalpingograms on 23 women following tubal surgery who failed to become pregnant within 2-28 months were reviewed. A total of 39 tubes were analyzed. The surgical indications were reversal of tubal ligation in 24 tubes and correction of tubal or perifimbrial disease in 15 tubes. Tubal ligation had been performed by a variety of methods. At surgery, tubal patency, as shown by chromotubation, was seen in 37 (95%) of 39 tubes. On postoperative hysterosalpingography, tubal spillage was present in 32 (82%) of 39 tubes. Radiographically, the tubes that spilled appeared normal except for occasional shortening after reversal of tubal ligation. The eventual pregnancy rate was 8 (35%) of 23 patients, with 7 intrauterine. Pregnancy occurred only in women under 35 years and was more likely in the group having reversal of tubal ligation. We conclude that among patients who do not initially become pregnant following tubal surgery for infertility, tubal patency is restored in most. During hysterosalpingography, tubes operated on may appear normal or shortened. On long-term follow-up, younger patients and those requiring tubal anastomosis only had a higher pregnancy rate.

Adult↗