Biomedical subjects

Y-C Chen

Publications and source records attributed to Y-C Chen.

28 records · Page 2Linked to original sources

PubMed2004

From finch to fish to man: role of aquaporins in body fluid and brain water regulation.

Charles Darwin, in his Origin of the Species, noted that different species of finches on the Galapagos Islands had adapted their beak size based on where they sought their food. Homer Smith, in his book From Fish to Philosopher, discussed the evolution of the nephron from a single conduit in salt water vertebrates, to nephrons with large glomerular capillaries and proximal and distal tubules in fresh water vertebrates, to smaller glomerular capillaries in amphibians, to nephrons with loops of Henle to allow for urinary concentration and dilution in mammals. The kidney with its million nephrons has emerged as the vital organ for regulating body fluid composition and volume. With the recent discovery of aquaporin water channels, our understanding of volume regulation has been greatly enhanced. This article reviews current knowledge regarding: 1) the unifying hypothesis of body fluid volume regulation; 2) brain aquaporins and their role in pathophysiologic states; and 3) function and regulation of renal aquaporins in the syndrome of inappropriate antidiuretic hormone secretion (SIADH).

Animals↗

PubMed2004

Lack of detrimental effects of nitric oxide inhibition in bile duct-ligated rats with hepatic encephalopathy.

BACKGROUND: The pathogenetic mechanisms of hepatic encephalopathy (HE) are not fully understood. Vasodilatation induced by nitric oxide (NO) may be involved in the development of HE. There is no comprehensive data concerning the effects of NO inhibition on HE in chronic liver disease. METHODS: Male Sprague-Dawley rats weighing 240-270 g at the time of surgery were selected for experiments. Secondary biliary cirrhosis was induced by bile duct ligation (BDL). Counts of movements were compared between BDL rats and rats receiving a sham operation. In another series of experiments, BDL rats received either Nomega-nitro-L-arginine methyl ester (L-NAME, 25 mg kg-1 day-1 in tap water) or tap water (control) from the 36th to 42nd days after BDL. Besides motor activities, plasma levels of tumour necrosis factor (TNF)-alpha and nitrate/nitrite, liver biochemistry tests and haemodynamics were determined after treatment. RESULTS: Compared with the sham-operated rats, the total, ambulatory and vertical movements were significantly decreased in the BDL rats (P </= 0.001). The L-NAME group had a significantly higher mean arterial pressure than that of the control group (119.0 +/- 2.5 mmHg vs. 97.3 +/- 2.8 mmHg, P = 0.002). However, the counts of motor activities, plasma levels of TNF-alpha and nitrate/nitrite, and serum biochemistry tests were not significantly different between the L-NAME and control groups. CONCLUSIONS: Bile duct ligation may induce HE evidenced by a decrease in motor activities. However, chronic L-NAME administration did not have significantly detrimental or therapeutic effects on the severity of encephalopathy in BDL rats.

Animals↗

PubMed2003

Hepatosplenic fungal infection in patients with acute leukemia in Taiwan: incidence, treatment, and prognosis.

Nosocomial fungal infection increases gradually and has become the leading pathogen at National Taiwan University Hospital since 1993. From January 1995 through May 2002, hepatosplenic fungal infection (HSF) was diagnosed in 37 (7.4%) of the 500 adult patients with acute leukemia who received chemotherapy at this hospital. There was no significant difference in the incidence of HSF between the patients with acute myeloid leukemia and those with acute lymphoblastic leukemia, or between the patients treated with high-dose chemotherapy and those with conventional or low-dose chemotherapy. Candida tropicalis was the leading pathogen, followed by Candida albicans. The computed tomography scan showed multiple hypodense lesions in the liver (89%), spleen (70%), and kidney (27%). Eighteen patients were initially treated with fluconazole and 19 with amphotericin B. Nineteen patients received the planned chemotherapy after the diagnosis of HSF. Among them, eight patients underwent hematopoietic stem cell transplantation and seven patients survived more than 100 days post-transplantation; none of these patients had relapse of prior HSF. Twenty-three patients (62%) died during a median follow up of 10 months, but only seven died due to HSF. In conclusion, a substantial percentage of patients with acute leukemia acquired HSF after chemotherapy and carried high mortality. However, HSF itself is not a contraindication for subsequent chemotherapy and hematopoietic stem cell transplantation.

Acute Disease↗

PubMed2003

Cyclooxygenase expression in splanchnic hyposensitivity to glypressin of bleeding portal hypertensive rats.

BACKGROUND: Prostacyclin mediates, at least partly, the splanchnic vascular hyporesponsiveness to glypressin in bleeding portal hypertensive rats. This study investigated the relative contribution of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) in the splanchnic hyposensitivity to glypressin in rats with portal hypertension induced by partial portal vein ligation (PVL). METHODS: Fourteen days after the operation, the rats were divided into without- and with-bleeding groups. Three series of PVL rats were used to investigate (i). the haemodynamic effects of glypressin (0.07 mg x kg(-1) intravenously), (ii). COX-1/COX-2 mRNA expression over abdominal aorta and superior mesenteric artery and (iii). plasma levels of 6-keto-prostaglandin-F1alpha. In rats with a hypotensive haemorrhage, 4.5 mL of blood was withdrawn and 50% of the withdrawn blood was re-infused before blood and vessel sampling or the administration of glypressin. RESULTS: Splanchnic hyposensitivity to glypressin was demonstrated in the haemorrhage-transfused PVL rats with enhanced COX-1 expression of superior mesenteric artery and increased plasma levels of 6-keto-prostaglandin-F1alpha. There were no differences in the COX-2 expression of superior mesenteric artery and COX-1 and COX-2 expressions of abdominal aorta between without- and with-bleeding groups. CONCLUSION: In portal hypertensive rats with acute haemorrhage, COX-1 over-expression in the superior mesenteric artery plays a role in mediating the splanchnic hyposensitivity to glypressin.

Animals↗

PubMed2003

Systematic variation of polymer jacketed fibres and the effects on tip etching dynamics.

Using a chemically etched fibre probe through a plastic jacket provides a simple way to smooth a tip's surface. Convection flow in the plastic tube and lateral diffusion with fixed meniscus height has been proposed to explain such improvement. Fibres with additive thin polymer layers and bare fibres with thick untapered/tapered plastic layers have been prepared to verify the dominant mechanism. The additive layers greatly change the tip's geometry and bare-fibres with untapered plastics cannot form tips. This confirmed that lateral diffusion dominates the etching process. Based on our investigation, we propose a new non-meniscus end-etching method by using tapered plastics. Unlike etching methods with meniscus, the end-etching method can regularly form very smooth tips. It is insensitive to vibrations and temperature drifts and also suitable for most fibres.

Journal Article↗

PubMed2002

Splenic actinomycotic abscess in a patient with acute myeloid leukemia.

Actinomycosis is a gram-positive anaerobic bacterium. Actinomyces organisms are important constituents of the normal flora of mucous membranes and are considered opportunistic pathogens. The three major clinical presentations of actinomycosis include the cervicofacial, thoracic, and abdominopelvic regions. Actinomycosis infection in patients with febrile neutropenia is uncommon and actinomycosis splenic involvement in acute leukemia patients is very rare. We describe a man with acute myeloid leukemia and splenic actinomycotic abscess that developed after chemotherapy following prolonged neutropenia.

Actinomycosis↗

PubMed2002

Anorectal dysfunction in women with urinary incontinence or lower urinary tract symptoms.

OBJECTIVES: (1) To evaluate the prevalence of anorectal dysfunction among women with urinary storage or voiding symptoms; and (2) to investigate the risk factors associated with anorectal symptoms. METHODS: A sample of 320 women who attended the urogynecology outpatient clinic for urodynamic evaluation were requested to complete a structured questionnaire. The information collected included the medical, surgical, gynecological, and obstetric histories of the patients. Anal incontinence was defined as involuntary leakage of solid or liquid feces or gas. Constipation was defined as less than three bowel movements per week. Prevalence was estimated for anal incontinence and for constipation. A chi-square test was used to compare risk factors between women with and without anal incontinence or constipation. We used a multi-variable logistic regression analysis to estimate the association between other variables. RESULT: Forty-nine (15.9%) women reported having anal incontinence according to the above definition. Of those 49 women, 11 (3.6%) experienced leakage of liquid and/or solid feces and 38 (12.3%) had flatus incontinence. Constipation was reported by 100 (31.5%) of the women. A multiple logistic regression analysis revealed that the main risk factor associated with anal incontinence and constipation was the presence of uterovaginal prolapse (odds ratio=5.02; 95% CI=2.19-11.5 for anal incontinence; odds ratio=1.78; 95% CI=1.03-3.09 for constipation). CONCLUSION: Our results demonstrate a relatively high prevalence of anal incontinence or constipation among women suffering from urinary dysfunction. Uterovaginal prolapse is the main risk factor associated with anorectal dysfunction.

Adult↗

PubMed2002

Clinical and biological implications of partial tandem duplication of the MLL gene in acute myeloid leukemia without chromosomal abnormalities at 11q23.

The clinical and biological features of acute myeloid leukemia (AML) with 11q23/MLL translocations are well known, but the characteristics of AML with partial tandem duplication of the MLL gene have not been explored comprehensively. In this study, MLL duplication was analyzed, in 81 AML patients without chromosomal abnormalities at 11q23, using Southern blotting, genomic DNA polymerase chain reaction (PCR), reverse-transcription PCR and complementary DNA sequencing. Nine patients showed partial tandem duplication of the MLL gene, including eight (12%) of the 68 with normal karyotype. Seven patients showed fusion of exon 6/exon 2 (e6/e2), one, combination of differentially spliced transcripts e7/e2 and e6/e2, and the remaining one, combination of e8/e2 and e7/e2. Among the patients with normal karyotype, children aged 1 to 15 showed a trend to higher frequency of MLL duplication than other patients (2/5 or 40% vs 6/62 or 10%, P = 0.102). The patients with tandem duplication of the MLL gene had a significantly higher incidence of CD11b expression on leukemic cells than did those without in the subgroup of patients with normal karyotype (75% vs 28%, P = 0.017). There were no significant differences in the expression of lymphoid antigens or other myeloid antigens between the two groups of patients. In adults, the patients with MLL duplication had a shorter median survival time than those without (4.5 months vs 12 months, P = 0.036). In conclusion, partial tandem duplication of the MLL gene is associated with increased expression of CD11b on leukemic blasts and implicates poor prognosis in adult AML patients. The higher frequency of MLL duplication in children older than 1 year, than in other age groups, needs to be confirmed by further studies.

Acute Disease↗

PubMed2002

Cryptococcaemia: clinical features and prognostic factors.

BACKGROUND: Limited data are available on the clinical significance of cryptococcaemia, which occurs in 10-30% of patients with cryptococcal diseases. AIM: To describe the clinical features of cryptococcaemia and identify its prognostic factors. STUDY DESIGN: Retrospective cohort study. METHODS: All adult patients with Cryptococcus neoformans isolated from blood culture at the National Taiwan University Hospital, Taipei, 1981-2001, were included. Demographic and clinical information was obtained from medical records. RESULTS: Fifty-two patients were diagnosed and treated for cryptococcaemia. Acquired immunodeficiency syndrome (24/52, 46%), immunosuppressive therapy (12/52, 23%) and decompensated liver cirrhosis (11/52, 21%) were the three major predisposing conditions. Forty-two patients (81%, n=52) had sepsis, including four patients with septic shock, when blood cultures were obtained. Of the 38 patients in whom lumbar puncture was done, cerebrospinal fluid culture showed meningeal involvement in 32 (84%). The 30-day fatality rate was 37%. Liver cirrhosis, septic shock at presentation, an initial APACHE II score >/=20, age >/=60 years and female gender were associated with mortality under univariate analysis. Starting antifungal therapy within 48 h after blood culture was associated with improved survival. Under multivariate analysis, liver cirrhosis remained a strong independent predictor of mortality at 30 days after blood culture (HR 16.3, 95%CI 2.6-101.7, p=0.003). DISCUSSION: Patients with cryptococcaemia have a high risk of mortality within 30 days. Sepsis and meningeal involvement are common. Those with liver cirrhosis have a particularly poor prognosis.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

Polymorphisms in GSTT1 and p53 and urinary transitional cell carcinoma in south-western Taiwan: a preliminary study.

Little is known about the relevance of genetic polymorphisms to arsenic-related bladder cancer. A preliminary case-control study was conducted to explore the association between genetic polymorphisms of GSTT1, p53 codon 72 and bladder cancer in southern Taiwan, a former high arsenic exposure area. Fifty-nine urinary transitional cell carcinoma (TCC) patients from a referral centre in south-western Taiwan and 81 community controls matched on residence were recruited from 1996 to 1999. A questionnaire was administered to obtain arsenic exposure and general health information. Genotypes of p53 codon 72 and GSTT1 were analysed by polymerase chain reaction-restriction fragment length polymerase. The combined variant genotypes (heterozygous or homozygous variant) of p53 codon 72 and GSTT1 null were observed in 29% of cases and in 44% of controls, respectively. In this preliminary study, bladder cancer risk was slightly elevated for subjects carrying the variant genotype of p53 codon 72 or in subjects carrying the GSTT1 null genotype. Variants in p53 codon 72 increased the risk of bladder cancer among smokers. However, the results were not statistically significant and larger confirmatory studies are needed to clarify the role of candidate gene polymorphisms and bladder cancer risk in arsenic exposed populations.

Adult↗