Biomedical subjects
Publications and source records attributed to S C Chang.
The title compound, C7H13N3O2(2+).2Cl-, has distances and angles quite similar to those of histidine hydrochloride monohydrate [Donohue & Caron (1964). Acta Cryst. 17, 1178-1180], except for the distances within the ester functionality.
Alterations in the glycosylation of human IgG have been shown to occur in rheumatoid arthritis (RA). However, the precise nature and location of these changes have not been fully established. Therefore we carried out a detailed analysis of the oligosaccharides chemically released from intact human serum IgG and fragments of the molecule. Serum samples were from three healthy ('normal') individuals, and from four patients with RA. Site-specific glycolsylation of the glycoprotein was shown to occur, which extended to sites even within the Fab fragment. These were differences in galactosylation, sialylation and the presence of a bisecting N-acetylglucosomide. Disease related alterations were also shown to be site-specific. In particular, an increase in the proportion of agalactosylated oligosaccharides occurred on the Fc fragment in RA (P=0.057), but, in contrast to previous reports there was an increase on the light chain in the proportion of fully galactosylated, bisected and core fucosylated oligosaccharides (from 13% of total in normal to between 18 and 35% in RA, P=0.057)). There was also an Fab-specific increase in oligosaccharides bearing a bisecting N-acetylglucosamine and a core fucose (P=0.075) The site-specific glycosylation changes described in this paper reveal the complexity of the regulatory mechanism, perhaps reflecting the many levels at which regulation can occur.
Giardiavirus encapsidates a 6.2-kb double-stranded (ds) RNA within a capsid that consists of a major 100-kDa capsid protein (p100) and a minor 190-kDa protein (p190). In this study, two nonhomologous 6.2-kb ds RNAs cohabiting in Giardia lamblia trophozoites were found to be separately encapsidated into two distinct virions, one (designated GLV[p100]) whose capsid consists of p100 and p190, and the other (designated GLV[p95]) whose capsid consists of a 95-kDa protein (p95) and a minor p190-equivalent protein. Both types of virions were enriched in the membranous fraction of a lysate from virus-infected G. lamblia cells. Separation of these virions was achieved by CsCl gradient centrifugation following osmotic rupture of the viral particles. By these treatments, the 6.2-kb ds RNA was removed from GLV[p100] whereas that in GLV[p95] remained unchanged, and the two 6.2-kb ds RNAs that had been purified by this protocol displayed differential hybridization properties to viral cDNA probes. Western blotting and peptide mapping experiments show that p100 and p95 were closely related proteins, but each had distinct amino acid sequences. Virus purification and pulse-chase experiments show that GLV[p100] was selectively secreted into the medium whereas GLV[p95] remained within the trophozoites of G. lamblia toward the late phase of cell growth. Secretion of GLV[p100] was not inhibited by Brefeldin A. These findings demonstrate the cohabitation of multiple Giardiavirus species in G. lamblia.
A technique of suprafascial flap elevation to prevent donor site problems is described, based on careful intraoperative observation of the anatomical relations of all involved structures in a series of over 400 free forearm flaps used in various reconstructive procedures.
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.
From 1982 to 1994, 45 patients (1.22 episodes per 10,000 discharged patients) were treated for citrobacter bacteremia at National Taiwan University Hospital (Taipei). All patients had at least one underlying disease. Citrobacter bacteremia most commonly occurred in patients with malignancies (48.9%) or hepatobiliary stones (22.2%). Intraabdominal tumors comprised the majority (59.1%) of malignancies. Bacteremia commonly originated from sites such as the abdominal cavity (51.1%), urinary tract (20%), and lung (11.1%). Polymicrobial bacteremia was diagnosed in 15 patients (33.3%); for nine (60%) of these patients, the source of the infection was intraabdominal. Prior treatment with a third-generation cephalosporin was significantly associated (P < .01) with the development of multidrug resistance among the isolates. The mortality associated with citrobacter bacteremia was 17.8%. Poor prognostic factors included pneumonia, altered mental status on presentation, hypothermia, oliguria, septic shock, deterioration in mental status, hyperbilirubinemia, azotemia, and thrombocytopenia. Combination therapy, as compared with other regimens, improved the outcome of citrobacter bacteremia.
The accumulation of mitochondrial DNA (mtDNA) mutations has been suggested to be an important contributor to human aging and degenerative diseases. The lung is exposed to ambient air and makes direct contact with the external environment. Numerous potentially noxious agents may damage lung tissues directly or indirectly through free-radical-mediated reactions. In previous studies, we demonstrated an age-dependent increase of mtDNA mutations in various human tissues. We hypothesize that the accumulation of the 4,977 bp (base pairs) deleted mtDNA in human lung tissues is also age-dependent. Using the polymerase chain reaction technique, we determined the incidence of the 4,977 bp-deleted mtDNA in 127 human lung specimens from 34-wk gestation to 79 yr of age. The results showed that 77 lung biopsies (60.6%) contained the 4,977 bp-deleted mtDNA, which started to appear in lung tissues after the fourth decade of life. The incidence apparently increased from 14.3% (one of seven) of the subjects in the 30- to 39-yr age group to 77.8% (two of 27) of the subjects in the 70- to 79-yr age group (p < 0.0001). The mean (+/- SEM) proportion of the 4,977 bp-deleted mtDNA in lung tissues significantly increased from 0.007 +/- 0.007% of the subjects in the 30- to 39-yr age group to 0.833 +/- 0.330% of those in the 70- to 79-yr age group (p < 0.005). Other factors such as sex, pulmonary function indices, and smoking status did not have statistically significant impact on the amount of the deleted mtDNA. These findings suggest that the accumulation of the 4,977 bp-deleted mtDNA is associated with aging human lung.
OBJECTIVE: The half-moon sign is defined as a shadow seen on the lateral chest radiograph consisting of a smooth, partially demarcated opacity with the rounded portion of the half moon projecting over the aortic lumen at the level of the aortic arch, but the rest of the opacity merging with the aorta. In this study, we intended to evaluate the clinical usefulness of half-moon sign in aiding a diagnosis of saccular aneurysm of the aortic arch. METHODS: This series consisted of 57 patients with aortic arch aneurysm and 46 patients with a variety of nonvascular intrathoracic masses that presented as soft-tissue masses adjacent to the aortic arch on the frontal chest radiographs. The half-moon sign was evaluated independently by two senior chest radiologists who had no knowledge of the final causes. RESULTS: The half-moon sign was shown on the lateral chest radiographs in 5 of 10 patients with saccular aortic arch aneurysm but absent in 47 patients with fusiform aortic arch aneurysm. Furthermore, this roentgen sign was not seen on the lateral chest radiographs in 46 patients with nonvascular intrathoracic masses. In this selected population, the sensitivity and specificity of the half-moon sign in aiding a diagnosis of saccular aneurysm of the aortic arch were 50% and 100%, respectively. CONCLUSION: The half-moon sign shown on the lateral chest radiograph is highly suggestive of the saccular aortic arch aneurysm.
Gemella morbillorum was isolated from the blood of a 38-year-old woman with a 4-week history of fever. An echocardiogram showed a left atrial tumor. The patient was successfully treated by antibiotic therapy and early surgical excision of the tumor. Histological examination of the excised tumor revealed a typical myxoma with infiltrates of neutrophils and remnants of bacteria. To the best of our knowledge, this is the first reported case of infected left atrial myxoma caused by G. morbillorum.
PURPOSE: Photodynamic therapy (PDT) has considerable potential for the treatment of superficial bladder neoplasia. Problems of detrusor muscle scarring and prolonged cutaneous photosensitivity with current photosensitizers may be reduced by using the new photosensitizer precursor, 5-aminolevulinic acid (ALA). We studied the fluorescence distribution of protoporphyrin IX (PpIX, the active derivative of ALA) in rat urinary bladder after intravesical administration of ALA as the first step to undertaking PDT using locally administered ALA. MATERIALS AND METHODS: Solutions of varying concentrations of ALA and pH were given intravesically to Wistar rats. The bladder was removed 1 to 24 hours later for measurement of the tissue levels of PpIX by fluorescence microscopy in the layers of the bladder wall. RESULTS: The stability of the ALA solution steadily decreased as the pH was increased from 2.1 to 7. The best value was pH 5.5, at which the stability of the solution and the urothelial tolerance were both acceptable. The maximum PpIX fluorescence intensity ratio between urothelium and the underlying muscle layer was 11 to 1. This was seen 5 hours after instillation of 1% ALA solution at pH 5.5. A 10% ALA solution gave higher levels of PpIX in the urothelium, but less selectivity between layers. CONCLUSIONS: Under appropriate conditions, intravesical instillation of ALA can be used to sensitize the bladder urothelium with a ratio between urothelial and muscle concentrations of PpIX of up to 11:1.
PURPOSE: Photodynamic therapy (PDT) has the potential to treat extensive premalignant lesions and microinvasive tumors in the bladder, but its use has been hampered by the risk of detrusor muscle damage and prolonged skin photosensitivity. We have shown that the rat urothelium can be sensitized by selectively using a 10% solution of 5-aminolevulinic acid (ALA) at pH 5.5 administered intravesically. This paper evaluates the photodynamic effects on sensitized bladders. MATERIALS AND METHODS: The bladders ofs Wistar rats were instilled with ALA solutions of different concentrations at pH 5.5 and subsequently treated with laser light at 630 nm. Bladders were harvested 1 to 7 days after PDT for histological assessment. RESULTS: Under optimum conditions (10% intralipid diffusion medium, light dose 50J) uniform urothelial necrosis was seen after 1 to 2 days; it healed in 7 days without damage to the underlying muscle layer although some increase in collagen was seen in the lamina propria. Overtreatment or poor light distribution resulted in muscle necrosis and scarring. CONCLUSIONS: Selective urothelial necrosis is possible with PDT using intravesical ALA. There is now sufficient data for pilot clinical trials to start photodynamic therapy for management of superficial bladder cancer or carcinoma in situ.
The incidence of nosocomial candidemia increased 27-fold over the past 13 years at National Taiwan University Hospital. In order to investigate its predisposing factors, clinical manifestations and prognostic determinants, a prospective observational study of nosocomial candidemia was undertaken at the hospital. From 1 May 1994 to 30 April 1995, 118 consecutive adult patients with 120 Candida spp blood isolates were analyzed. Clinical presentations included fever (100%) with a median duration of 3 days, diarrhea within 7 days of candidemia (27.9%) and macronodular skin emboli (7.6%). Laboratory studies showed worsening azotemia (35.6%), elevation of aminotransferase (28.3%), leukocytosis (27.1%) and thrombocytopenia (23.3%). Use of multiple antibiotics, retained vascular catheters and parenteral nutritional support were the three most common predisposing factors for candidemia. C. albicans was the most common isolate (50%), followed by C. tropicalis (20%), C. glabrata (14%), C. parapsilosis (9.2%). C. guilliermondii (2.5%), and C. Krusei (1.7%). C. tropicalis was more frequently the cause of candidemia in patients with leukemia and neutropenia, while C. glabrata was more commonly seen in patients receiving fluconazole prophylaxis. A severity scoring system adopted from prospective bacteremia studies proved to be highly predictive of mortality in candidemic patients. The overall case fatality rate was 70/118 (59.3%), and 51/70 (72.9%) were attributable to candidemia. In a multivariate analysis, the prognostic factors adversely influencing outcome were: higher severity scores, no removal of the catheter, persistent candidemia and lack of antifungal therapy.
Liposarcoma is a rare mediastinal tumor. The treatment of choice is surgical resection. However, recurrence is not uncommon. In this report, recurrence of liposarcoma with local extension to chest wall is described in a 70-year-old Chinese male who had liposarcoma located in the anterior mediastinum and underwent tumor resection 5 years before. Long-term follow-up is indicated in patients with mediastinal liposarcoma because there may be an interval of several years between resection and recurrence.
Mucoid impaction of the trachea simulating a tumor has been rarely reported. We report such a case tomographically presenting as a tumor in a 75-year-old woman with chronic obstructive pulmonary disease (COPD). A rapid change in the shape of tracheal shadow with sharp angle was also shown tomographically. It is suggested that a changing shadow in the trachea demonstrated by tomography may be of value in distinguishing mucoid impaction of the trachea from true neoplasm.
This study investigated the roles of NMDA and AMPA receptors in the amygdala and medial prefrontal cortex in formation and retrieval of affective memory. In a one-trial step-through inhibitory avoidance task, groups of rats with cannulae implanted into these two regions received infusion of 2.5 micrograms APV or 0.3 micrograms CNQX 5 min before training, shortly after training or 5 min prior to the 1-day or 21-day retention test. Results showed that pre- or posttraining intra-amygdala infusion of APV or CNQX induced a persistent retention deficit with the pretraining treatment causing a greater effect. Pre- or posttraining infusion of CNQX into the medial prefrontal cortex also induced a persistent retention deficit with the posttraining treatment causing a greater effect. Pre- or posttraining infusion of APV into the medial prefrontal cortex impaired 21-day retention but not 1-day retention. Pretraining infusion of lidocaine into either structure caused a retention deficit, which was not attenuated by activating the other structure with glutamate. Pretest intra-amygdala infusion of CNQX impaired memory expression in the 1-day test, while infusion of CNQX into the medial prefrontal cortex impaired memory expression in the 21-day test. Pretest APV infusion into either structure had no effect on memory expression. These findings suggest that the amygdala and medial prefrontal cortex may be contained in a circuitry responsible for formation of affective memory. The consolidation process involves the NMDA and AMPA receptors in both structures. Further, retrieval of recent affective memory engages amygdala AMPA receptors, whereas retrieval of remote affective memory engages AMPA receptors in the medial prefrontal cortex.
A hospital-based case-control study was designed herein to investigate the relationship between parity, breast feeding and breast cancer in Taiwan. Reproductive histories of patients with breast cancer confirmed by either pathology or cytology were assessed by questionnaire and compared with age-matched healthy controls. One hundred and fourteen cases and 228 age-matched controls were recruited for this study. According to those results, women having had more than three full-term pregnancies, age at first full-term pregnancy younger than 30, and breast feeding for more than 3 years displayed significantly protective effects against breast cancer. Following adjustment for ethnicity and menopausal status, women with more than three full-term pregnancies and younger than 30 years old at first full-term pregnancy had a decreased risk of breast cancer. However, duration of breast feeding was not related to breast cancer, after adjustment for ethnicity and menopausal status. The effect of number of full-term pregnancies on the risk of breast cancer was found to be independent of the effect of age at first full-term pregnancy. Moreover, the effect of age at first full-term pregnancy and number of full-term pregnancies was also independent of the effect of breast feeding.
Forty-two cases of necrotizing fasciitis (NF) surgically confirmed between January 1991 and October 1995 were retrospectively reviewed. This was done in order to describe the underlying diseases, clinical presentations, etiology and outcome of NF and to assess the prognostic value of a simplified severity scoring system. The system scores changes in consciousness status, body temperature, blood pressure and ventilation to determine the likely outcome of NF. Twenty-five men and 17 women with a median age of 51 years (range, 17-87 yr) were included. Diabetes mellitus (57.1%) was the most common underlying disease. The mean duration of symptoms before admission was 8 days (median, 7 d; range, 1-30 d). The extremities (66.7%) were most commonly involved. Initial clinical presentations within 48 hours of admission included skin erythema and swelling at the affected site (97.6%), pyrexia (61.9%), hypotension (33.3%), altered consciousness (28.6%), bullous lesions (26.2%) and crepitus (9.5%). The mean number of isolated pathogens was 1.8 (range, 0-6). Eight patients had mixed aerobic and anaerobic infections. The attributable case fatality rate was 23.8%. Higher severity score (> or = 4 points), hypotension, altered consciousness, respiratory failure requiring ventilator support, elevation of alanine aminotransferase levels > twofold, serum creatinine > 177 mumol/L, thrombocytopenia (< 100 x 10(9)/L), and worsening symptoms and signs within 48 hours of admission were associated with higher fatality rates (p < 0.05).
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.