Biomedical subjects

M Y Chen

Publications and source records attributed to M Y Chen.

At least 127 records · Page 7Linked to original sources

PubMed1997

Cost-effective poster and print production with digital camera and computer technology.

OBJECTIVE: The purpose of this report is to describe a cost-effective method for producing black-and-white prints and color posters within a radiology department. CONCLUSION: Using a high-resolution digital camera, personal computer, and color printer, the average cost of a 5 x 7 inch (12.5 x 17.5 cm) black-and-white print may be reduced from $8.50 to $1 each in our institution. The average cost for a color print (8.5 x 14 inch [21.3 x 35 cm]) varies from $2 to $3 per sheet depending on the selection of ribbons for a color-capable laser printer and the paper used. For a 30-panel, 4 x 8 foot (1.2 x 2.4 m) standard-sized poster, the cost for materials and construction is approximately $100.

Copying Processes↗

PubMed1997

Strategies for diagnosing HIV-1 infection in atypical Western blots.

The Western blot (WB) has long been used to confirm positive ELISAs for diagnosing HIV-1 infections. However, some WB patterns may result in "indeterminate" or controversial reports thus impeding early diagnoses or accurate diagnoses. The interpretation of HIV-1 WB has no "gold standard" criterion. Incomplete antibody profiles on WB strips can be interpreted as positive or indeterminate according to different criteria. The possibility of HIV-2 infection was further checked in these serum samples. However, no reactivity to synthetic peptide of HIV-2 gp36 had been found. Serial WB analyses are important for attaining early diagnoses of HIV-1 infections as well as for evaluating clinical stages. Temporal changes on WB patterns of serial serum samples provide the evidence of seroconversion in individuals with risk behaviours and indeterminate WB. In late stage of HIV-1 infection, the reactivity to gag, pol and env antigen groups may decrease and result in indeterminate WB. We propose to diagnose HIV-1 infection and to differentiate the infection of HIV-1 from HIV-2 in these cases by using nested polymerase chain reaction (PCR) to demonstrate the presence of HIV-1 specific vpu gene.

Acquired Immunodeficiency Syndrome↗

PubMed1997

Microbiologic and histologic diagnosis of histoplasmosis in Taiwan.

Histoplasmosis is one of the most common opportunistic fungal infections in immunocompromised patients in endemic areas. We report the first two microbiologically documented cases of histoplasmosis in Taiwan. The first patient, with acquired immunodeficiency syndrome and a depleted CD4+ lymphocyte count, presented with a history of prolonged fever, papular skin rashes, pancytopenia and elevation of liver enzymes. He was diagnosed and treated initially for systemic toxoplasmosis, but the microbiologic and pathologic findings of the autopsied specimens disclosed disseminated infection caused by Histoplasma capsulatum. The second patient, an elderly man receiving corticosteroids for adrenal insufficiency, manifested with laryngeal histoplasmosis and was successfully treated with ketoconazole.

AIDS-Related Opportunistic Infections↗

PubMed1997

Bacteremia caused by Helicobacter cinaedi in an AIDS patients.

Helicobacter cinaedi bacteremia has been infrequently described in homosexual patients with HIV infection. It may recur despite appropriate antimicrobial therapy. We report a bisexual patient with AIDS in whom H. cinaedi bacteremia developed and presented with prolonged fever and chronic diarrhea. The symptoms resolved without relapse after intravenous immunoglobulin therapy, which was administered for the treatment of concurrent parvovirus B19-associated anemia, and subsequent treatment with clarithromycin for 14 days.

AIDS-Related Opportunistic Infections↗

PubMed1997

Heartburn correlated to 24-hour pH monitoring and radiographic examination of the esophagus.

OBJECTIVES: Study relationship of gastroesophageal reflux disease to findings on radiographic examination of the esophagus. METHODS: We correlated heartburn (HB) in 360 patients (174 women; 186 men; mean age, 53 yr) to results of pH monitoring (pHM) and radiographic examination of the esophagus. Radiographic findings were categorized as normal (n = 129), hiatal hernia (HH) only (n = 173), reflux esophagitis (n = 50), or peptic stricture (n = 8) (ES; 58). Abnormal pHM was defined as total percentage of esophageal acid exposure time (pH < 4) of 6% or greater. RESULTS: pHM was abnormal in 41 (31%) of 132 patients with HB versus 54 (24%) of 228 without the symptom (p > 0.05). Radiographic correlation showed abnormal pHM in only 21 (16%) of 129 patients with a normal esophagus, 52 (30%) of 173 with HH, and 22 (38%) of 58 with ES, which was significantly lower for those with a normal esophagus. In 132 patients with HB, those with normal esophagus had lower abnormal pHM (2 of 38; 5%) compared with patients with HH (24 of 64; 38%) or with ES (15 of 30; 50%) (p < 0.05). In the 228 patients without HB, abnormal pHM was found in 19 (21%) of 91 with a normal esophagus, 28 (26%) of 109 with HH, and 7 (25%) of 28 with ES (p > 0.05). CONCLUSIONS: (1) pHM findings did not correlate with presence or absence of HB; (2) pHM is usually normal in patients with normal esophagus on RE; (3) pHM is also usually normal in patients with HB and normal esophagus on RE; and (4) pHM is often normal in patients with radiographic findings of reflux esophagitis or peptic stricture.

Esophageal Stenosis↗

PubMed1996

Modified barium swallow: clinical and radiographic correlation and relation to feeding recommendations.

Clinical and videofluoroscopic evaluation of swallowing were correlated to determine their agreement and relationship to feeding recommendations. We reviewed a total of 148 patients with swallowing difficulties, of which 93 (45 women, 48 men; mean age 62 years) were evaluated by both clinical and radiographic examinations. A variety of materials were used for clinical bedside evaluation of oral and pharyngeal function. Radiographic examination was done with variable viscosity materials and videotape recording of the oral cavity and pharynx. The severity of oral and pharyngeal abnormalities was graded and findings of the examinations were compared. The combined results of both evaluations generated an index of swallowing difficulty which was correlated to the type of diet used if oral feeding was recommended or to a nonoral route of nutrition. In the assessment of oral and pharyngeal dysfunction, clinical evaluation and radiographic examination correlated closely in 94% of patients; however, the status of pharyngeal function was not determined in 61 (66%) of the 93 patients by clinical examination alone. The combined swallowing index was calculated in 89 patients and its severity correlated significantly with the type of feeding recommended; 64 patients were placed on one of three types of diets and 25 had enteral feedings. In conclusion, combined clinical and radiographic examinations correlated well, but clinical evaluation alone was limited by failure to evaluate the pharynx in many patients. The swallowing severity correlated well with final feeding recommendations.

Barium↗

PubMed1996

Videofluoroscopic evaluation of patients with Guillain-Barré syndrome.

We reviewed 14 patients with clinically confirmed Guillain-Barré syndrome for swallowing dysfunction. All had swallowing dysfunction varying from mild to severe. Six patients (43%) had equivalent impairment during oral and pharyngeal phases. Seven patients (50%) had more severe functional abnormalities during the pharyngeal phase than during the oral phase. One patient (7%) had moderate disorder during the oral phase and mild disorder during the pharyngeal phase. Thirty-six percent of the patients had moderate-to-severe dysfunction during the oral phase, and 71% had moderate-to-severe dysfunction during the pharyngeal phase. In 5 patients who had multiple sequential examinations, moderate or severe swallowing disorders improved to mild-to-moderate disorders within 4-8 weeks after the onset of the symptoms. Residual swallowing disorders may be seen in those who had severe swallowing dysfunction during the later phases of their disease. Further investigations are needed to determine if swallowing abnormalities persist after complete recovery from Guillain-Barré syndrome.

Adult↗

PubMed1996

A novel secondary metabolite relative to the degradation of PR toxin by Penicillium roqueforti.

A secondary metabolite different from PR-imine and PR-amide was produced in the liquid (YESC) and solid (buckwheat) culture medium of Penicillium roqueforti. We isolated and purified the compound in pure and colorless crystalline form. On the basis of elemental analysis, mass, 1H and 13C nuclear magnetic resonance, infrared, and UV spectroscopy, the compound was identified as PR-acid (C17H20O7). The structures of PR-acid and PR toxin (C17H20O6) are closely related. Moreover, we discovered that PR-acid disappeared concurrently with the PR toxin in the culture medium. Thus, we postulate that PR toxin is degraded to PR-acid in the culture of P. roqueforti.

Hydrogen-Ion Concentration↗

PubMed1996

Signaling through chemoattractant receptors in Dictyostelium.

Dictyostelium discoideum displays chemoattractant-directed cell migration typical of many higher cell types. Signaling through chemoattractant receptors involves a standard G-protein-linked pathway. Genetic analysis has distinguished essential and dispensable components and demonstrated that some signaling events are independent of G proteins. Genetic analysis has also led to the identification of additional genes involved in chemosensory transduction. Further studies on the newly discovered components and pathways should help in elucidating the molecular mechanisms of eukaryotic chemotaxis.

Animals↗

PubMed1996

Radiation exposure during ERCP: effect of a protective shield.

OBJECTIVES: To measure the radiation exposure to endoscopists, patients, and assistants during diagnostic and therapeutic ERCP and to assess the effect of a protective lead shield. Radiation dose with and without the protective lead shield was mapped in our standard fluoroscopy room. MATERIALS AND METHODS: Twenty patients undergoing ERCP were selected for this study. Radiation exposure of endoscopists with and without a protective shield was monitored by digital dosimeter. Radiation exposure for diagnostic procedures was correlated with that of therapeutic procedures. RESULTS: Endoscopists were exposed to 2.5 mR without the protective shield, but exposure was reduced to an average of 0.27 mR per procedure with the shield. Endoscopists received an average of 1.5 mR per diagnostic ERCP and 3.17 mR per therapeutic ERCP without the shield. When using the protective shield, however, those numbers were reduced to an average of 0.25 mR per diagnostic procedure and 0.28 mR per therapeutic procedure. Radiation exposure to endoscopic assistants, who were not shielded, averaged 0.56 mR per procedure. CONCLUSION: Amount of radiation exposure to occupational personnel during ERCP was related to duration of fluoroscopy and type of procedure. Radiation exposure to endoscopists can be significantly reduced by the use of a protective shield. Medical assistants received less radiation than did endoscopists because the assistant's position was more distant from x-ray sources.

Adult↗

PubMed1996

Incidence of post-transfusion hepatitis in Taiwan before and after introduction of anti-HCV testing.

The effectiveness of second-generation anti-hepatitis C virus antibody (anti-HCV) screening of blood donations for the prevention of non-A, non-B post-transfusion hepatitis (NANB PTH) was assessed. A prospective study of 192 transfusion recipients was performed to compare the incidence of NANB PTH after the introduction of the second-generation anti-HCV test with the incidence before its introduction. We used a polymerase chain reaction to detect HCV-RNA and HBV-DNA in the sera of patients with NANB PTH. The incidence of acute post-transfusion hepatitis C was 11% (8 of 71) before the screening for anti-HCV as compared with 2.5% (3 of 121) after the screening (p < 0.05). Viremia was detected within the first five weeks of infection in 10 patients with acute post-transfusion hepatitis C. However, there was no significant difference in the incidence of non-A, non-B, non-C (NANBNC) PTH before screening (3 of 71, 4.2%) compared with after screening (3 of 121, 2.5%). Usually, NANBNC PTH was not clinically important. Anti-HCV screening of blood donors significantly reduces the incidence of post-transfusion hepatitis C, but not the incidence of NANBNC PTH.

Adolescent↗

PubMed1996

The perirenal space: relationship of pathologic processes to normal retroperitoneal anatomy.

The perirenal space may be involved by disease processes that arise within or outside the perirenal space. Key anatomic details that dictate the features of perirenal processes include the renal capsule, the perirenal septa, the renal fascia, and the conic shape and inferomedial orientation of the perirenal space. Superiorly, the perirenal space is open to the bare area of the liver. The perirenal spaces communicate with one another at the level of the lower lumbar vertebrae. The hallmark of perirenal infection is localized or diffuse gas. Chronic urinoma appears as an encapsulated cystic mass, often aligned parallel with the perirenal space. Fat within an apparent spontaneous hematoma of the perirenal space suggests angiomyolipoma. Renal cell carcinoma, lymphoma, and melanoma are the most common causes of discrete solid masses in the perirenal space; metastases occur due to the characteristic lymphatic and vascular supply of the space. Amyloidosis and fibrosis create a nonspecific rind of soft tissue around the kidneys. Diaphragmatic pseudotumor produces a linear "lesion" in the perirenal space.

Amyloidosis↗

PubMed1996

Functional abnormalities of the pharynx: a prospective analysis of radiographic abnormalities relative to age and symptoms.

PURPOSE: To determine the prevalence and severity of functional abnormalities of the pharynx relative to patient age and symptoms. MATERIALS AND METHODS: Radiographic evaluation of the pharynx was performed in 110 consecutive outpatients aged 19-84 years old who had no previous surgery of the larynx, pharynx, or esophagus. Each patient completed a symptom data sheet, and we reviewed medical records to determine the main indication for each examination. Videofluoroscopy and static filming in frontal and lateral positions were done with 20-ml barium boluses. We then evaluated functional abnormalities and classified abnormal findings by type and severity. RESULTS: We categorized patients by age into three groups: less than 40 years old (n=31), between 40 and 60 years old (n =42), and greater than 60 years old (n=37). We found a significant increase in the prevalence (23%, 36%, 57%, respectively) and severity of functional abnormalities of the pharynx in older patients (p < .05). Laryngeal penetration, aspiration, pharyngeal stasis, and cricopharyngeal bar were the main abnormalities found in the two older groups. However, we found no correlation between functional abnormalities of the pharynx and symptoms and indications (p > .05). CONCLUSION: Functional abnormalities of the pharynx increased in prevalence and severity with age. Often these findings were not related to specific pharyngeal symptoms and must be interpreted cautiously in older patients.

Adult↗

PubMed1996

Functional abnormalities of the esophagus: a prospective analysis of radiographic findings relative to age and symptoms.

OBJECTIVE: The prevalence and severity of functional abnormalities of the esophagus seen on fluoroscopic examination were compared with the age and symptoms of the patients. SUBJECTS AND METHODS: The esophagus was examined radiographically in 139 consecutive outpatients 19-84 years old. All patients completed a data sheet about their symptoms, and medical records were reviewed to determine the main indication for the examination. Videofluoroscopy was used to evaluate primary peristalsis, proximal escape, and tertiary activity in the esophagus. The severity of proximal escape and activity was classified. RESULTS: Patients were categorized into three age groups: 39 years old or younger (n = 33); from 40 to 60 years old (n = 55); and 61 years old or older (n = 51). Abnormal esophageal motility, defined as disruption of peristalsis on two or more of five swallows, was found in 24% of patients 39 years old or younger, 36% of patients from 40 to 60 years old, and in 49% of patients 61 years old or older (p > .05). However, evaluation of the number of disrupted peristaltic swallows by age revealed 18% abnormal swallows in patients 39 years old or older, 27% in patients from 40 to 60 years old, and 37% in patients 61 years old or older (p < .01). Proximal escape and tertiary contractions increased significantly with the age of the patient. Regardless of age, proximal escape was seen in 79% of swallows and tertiary contractions were seen in 48% of swallows with disrupted peristalsis. The prevalence and severity of proximal escape and tertiary contractions increased in the older patients. Symptoms had no correlation with status of esophageal motility (p > .05). In 22 patients with secondary diseases, including rheumatoid arthritis and diabetes mellitus, those diseases showed no correlation with the status of esophageal motility. CONCLUSION: The prevalence of functional abnormalities of the esophagus increased with age. Most patients with abnormal swallows showed proximal escape with or without tertiary activity. Patients' symptoms and other diseases did not correlate with the status of their esophageal motility.

Adult↗

PubMed1996

Correlation of lower esophageal mucosal ring and 24-h pH monitoring of the esophagus.

OBJECTIVE: To study the relationship of LEMR and gastroesophageal reflux. The pathogenesis of the lower esophageal mucosal ring (LEMR) is not known. The most likely theory is that the ring results from reflux esophagitis as part of the morphological spectrum of peptic stricture. METHODS: We correlated barium esophagrams and 24-h pH monitoring (pHM) in 343 patients (173 women, 170 men; mean age 52 yr). Patients were categorized into three groups by radiographic findings: 1) normal esophagus (n = 121), 2) hiatal hernia (HH) only (n = 174), and 3) LEMR (n =48). Abnormal pHM was defined as a total percentage of the esophageal acid exposure time of 6% or more; abnormal pHM was also analyzed relative to patient position (supine vs. upright). RESULTS: Findings showed that 21 (17%) of 121 normal patients had abnormal pHM compared with 58 (33%) of 174 patients with HH and 15 (31%) of 48 patients with LEMR. Normal patients had a significantly lower frequency of abnormal pHM (p < 0.01) vs. the other two groups; however, no significant difference in results of pHM was found in the groups with HH and LEMR. No significant relationships of abnormal supine versus upright pHM was observed comparing the three groups. CONCLUSIONS: 1) Most patients in this study had normal pHM, regardless of the anatomic status of the esophagogastric region; 2) patients with HH and LEMR had a higher frequency of abnormal pHM, although the two groups were not significantly different; and 3) an etiological relationship of LEMR and gastroesophageal reflux was not supported, other than its association with HH.

Esophagogastric Junction↗

PubMed1996

The cutRS signal transduction system of Streptomyces lividans represses the biosynthesis of the polyketide antibiotic actinorhodin.

The nucleotide sequence of a two-component signal transduction operon (cutRS) of Streptomyces lividans TK64 was elucidated. Transcription of the operon was detected during the transition and stationary phases of growth, initiating at a single site upstream of cutR. This promoter region also possessed promoter activity directed away from cutRS, which appears to be responsible for the previously observed suppression of the translational deficiency of a melC1 mutation. Mutations in cutR and cutS were generated by gene replacement. The resulting mutants exhibited accelerated and increased production of the polyketide antibiotic, actinorhodin, which could be reversed by introduction of cutR on a plasmid. cutRS was also shown to repress actinorhodin production in the closely related species, Streptomyces coelicolor A3(2). The cutRS operon is the second two-component system found in Streptomyces that negatively regulates secondary metabolism.

Amino Acid Sequence↗

PubMed1996

Clinical features of tuberculosis associated with HIV infection in Taiwan.

To understand the clinical characteristics and outcome of tuberculosis (TB) in patients with acquired immunodeficiency syndrome (AIDS) in Taiwan, we reviewed the medical records of 118 adult AIDS patients who were hospitalized at National Taiwan University Hospital between January 1988 and September 1995. Among them, 29 (24.6%) had TB. The mean age of the AIDS patients with TB was 37 years (range, 25-66 yr). Most patients were in the advanced stages of AIDS when human immunodeficiency virus (HIV) infection and/or TB were first diagnosed. The mean CD4+ lymphocyte count was 0.037 x 10(9)/L (range, 0-0.152 x 10(9)/L) at the time TB was diagnosed. There was no statistically significant difference in the mean CD4+ lymphocyte count between patients with isolated pulmonary TB and those with extrapulmonary involvement. Twenty-two patients (75.8%) had extrapulmonary TB with the most common site being the lymph nodes (72.7%). Clinical symptoms were nonspecific, and the chest physical examination was not helpful in the diagnosis. Acid-fast bacilli were detected in sputum smears from eight patients (36.4%). A primary tuberculosis pattern (hilar adenopathy, pleural effusion, middle or lower lobe infiltrates) in the chest radiographs was the most common radiologic finding (36.4%) in patients with pulmonary TB. The reactivation pattern (predominant upper-lobe infiltrates with or without cavitation) could only be found in cases of pulmonary TB without extrapulmonary involvement. Atypical patterns (diffuse interstitial infiltrates mimicking Pneumocystis carinii pneumonia or other patterns) and normal chest radiographs were noted in nearly one-third of the patients with pulmonary TB. A good response to antituberculosis drugs and a favorable outcome were demonstrated in the patients, except for two with drug-resistant Mycobacterium tuberculosis infection. Early identification of TB in HIV-infected patients requires clinical awareness of the unusual clinical presentations, especially among patients in the advanced stages of AIDS.

AIDS-Related Opportunistic Infections↗

PubMed1996

Etiology of lymphadenopathy in patients with AIDS in Taiwan.

From 1986 to 1995, we retrospectively reviewed the records of 40 of 125 patients (32.0%) with acquired immunodeficiency syndrome (AIDS) who presented with extrainguinal lymphadenopathy. Most of the patients had an advanced stage of HIV infection with a mean CD4 lymphocyte count of 44/mm3. AIDS-defining opportunistic infections and malignancies were present in most patients and the neck region was the most common site of involvement. The etiology of lymphadenopathy was established in 26 patients. Tuberculous lymphadenitis was the most common cause, followed by lymphadenopathic Kaposi's sarcoma, benign reactive hyperplasia, cryptococcal lymphadenitis and disseminated Mycobacterium avium complex infection. Characteristic histopathologic findings were detected in 19 patients and 7 had presumptive tuberculous infections. The remaining 14 patients had no definitive etiology for their lymphadenopathy. As the causes are variable and the number of HIV/AIDS cases is increasing in Taiwan, more patients with lymphadenopathy, especially in the early stages of HIV infection will be encountered. Therefore, it is essential that diagnostic histopathologic and microbiologic studies be performed for appropriate and timely treatment.

Acquired Immunodeficiency Syndrome↗