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Biomedical subjects

W C Chen

Publications and source records attributed to W C Chen.

198 records · Page 11Linked to original sources
PubMed1978

Dissociation between ion permeability and the lethal action of polyene antibiotics on Candida albicans.

Kinetic data on potassium release from and killing of Candida albicans by the four polyene antibiotics amphotericin B, amphotericin B methyl ester hydrochloride, nystatin, and nystatin methyl ester hydrochloride are presented. The nystatins were relatively more effective than the amphotericins in causing potassium release rather than killing. These data suggest that the aqueous channels or pores formed by the polyene antibiotics are not central to the lethal action of the drugs.

Amphotericin B↗
PubMed1977

Kinetics of association of amphotericin B with vesicles.

Amphotericin B associates with vesicles prepared from phosphatidylcholines. The influence of lipid composition on the initial rate of amphotericin B association with vesicles was examined using stopped-flow kinetic measurements. A relationship was found between the tightness of packing of phosphatidylcholine molecules in the vesicles and the initial rate of amphotericin B association. Shortening of the fatty acyl chain length of saturated phosphatidylcholines and increasing the number of double bonds in the fatty acyl chains of unsaturated phosphatidylcholines enhance the initial rate, whereas addition of cholesterol of the bilayers reduces the rate. The initial rate of association with phosphatidylcholine-sterol vesicles follows the order, thiocholesterol greater than androst-5-en-3beta-ol greater than epicholesterol greater than ergosterol greater than cholesterol and is thus inversely related to the order of phospholipid-sterol affinity, as revealed by permeability, surface area, and magnetic resonance measurements. These data suggest that the initial rate of amphotericin B uptake into vesicles depends on competition between lipid-lipid and amphotericin-lipid interactions.

Amphotericin B↗
PubMed1976

Mechanical properties of the dog renal capsule.

The renal capsule is an important determinant of whole kidney volume/pressure relationships. To gain further insights into its possible role we examined the mechanical properties of the dog renal capsule using standard materials testing procedures. From each of four locations on the kidney surface, the following mechanical properties of the renal capsule were determined: elastic modulus (force/unit of cross-sectional area theoretically required to double the length of the specimen), tensile stiffness (force/unit width theoretically required to double the length of the specimen), ultimate strength (stress at time of fracture of the specimen), and maximum strain (percent strain at time of the fracture of the specimen). We found that the elastic modulus of the renal capsule from all capsular sites was substantially greater than values previously reported for dog aorta. The stiffness of the capsule covering the anterior-posterior surface of the kidney was found to be about 50% greater than the stiffness of the capsule covering the lateral and polar surfaces of the kidney. The ultimate strength of the anterior-posterior capsule was significantly greater than that of the lateral or polar capsule. This finding may explain the clinical observation that the spontaneous rupture of the renal capsule and parenchyma associated with the acute swelling of transplant rejection is confined almost exclusively to the lateral and polar portions of the renal capsule and cortex. The mean maximum strain at each capsular site was about 35%. This degree of circumferential expansion corresponds to about a doubling of kidney volume. Thus, this observation suggests that the renal capsule is at risk to undergo spontaneous rupture when renal volume increases of this magnitude are observed.

Animals↗
PubMedDate not supplied

AM-404 elevates renal intracellular Ca(2+), questioning its selectivity as a pharmacological tool for investigating the anandamide transporter.

The effect of N-(4-hydroxyphenyl)-arachidonamide (AM-404), a drug commonly used to inhibit the anandamide transporter, on intracellular free Ca(2+) levels ([Ca(2+)](i)) was studied in Madin Darby canine kidney (MDCK) cells. [Ca(2+)](i) was measured using fura-2 as a Ca(2+) indicator. Between 2 and 40 microM, AM-404 increased [Ca(2+)](i) in a concentration-dependent fashion with an EC(50) value of 20 microM. Removal of extracellular Ca(2+) abolished the [Ca(2+)](i) signals. The [Ca(2+)](i) increase was nearly abrogated by 10 microM La(3+), but was insensitive to 50 microM Ni(2+) and 10 microM of nifedipine, nimodipine, nicardipine, and verapamil. At a concentration that did not increase [Ca(2+)](i), AM-404 (1 microM) did not alter the [Ca(2+)](i) increases induced by 10 microM ATP and 1 microM bradykinin. AM-404 (5 microM) also increased [Ca(2+)](i) in Chang liver cells, PC3 human prostate cancer cells, BFTC human bladder cancer cells, and MG63 human osteoblast-like cells. Together, this study shows for the first time that AM-404 at concentrations commonly used to inhibit the anandamide transporter in various systems induced an increase in [Ca(2+)](i) in different cell types. The [Ca(2+)](i) increase was solely due to extracellular Ca(2+) influx. Thus caution must be exercised in using AM-404 as a selective inhibitor of the anandamide transporter.

Adenosine Triphosphate↗
PubMedDate not supplied

Massive pulmonary hemorrhage in polyarteritis nodosa (PN); report of a case.

We report a case of massive pulmonary hemorrhage which emerged in the course of polyarteritis nodosa (PN). Pulmonary hemorrhage was the major manifestation which determined the mortality of this patient, though severe renal failure concurrently developed. The diagnosis of PN should be considered in all cases of pulmonary hemorrhage coexisting with renal failure. As pulmonary hemorrhage can be life-threatening, early diagnosis is essential for the prompt start of adequate therapy.

Acute Kidney Injury↗
PubMedDate not supplied

Mutation analysis of human LEFTY A and LEFTY B genes in children with Ivemark syndrome.

The search for genes responsible for the abnormal development of the left-right (L/R) asymmetry has been conducted but no definite results have been reported. Recently, two human homologus mouse lefty1 genes, LEFTY A and LEFTY B, were analyzed for mutations in patients with the L/R anomalies. However, only two mutations were found in a survey of 126 patients. We collected genomic DNA from 10 children with Ivemark syndrome, a disease with anomalies in L/R asymmetry. Mutation analysis of LEFTY A and LEFTY B genes using single strand conformation polymorphism and direct sequencing was performed, but no mutations were found. This indicates that the L/R asymmetry anomaly in Ivemark syndrome may not be caused by the mutation of LEFTY A and LEFTY B genes. Other genes responsible for the anomalies of L/R asymmetry should be further investigated.

Abnormalities, Multiple↗
PubMedDate not supplied

Food protein-induced enterocolitis syndrome: report of one case.

We report a 76-day old infant who got diarrhea within the first week of life. He was treated as acute gastroenterocolitis and kept on feeding with regular infant formula. Because the symptoms persisted, the feeding formula was shifted to soy-based formula then to the highly-hydrolyzed formula and got improvement. But severe bloody diarrhea, vomiting, dehydration and fever developed after feeding with regular infant formula again. Based on the history and clinical presentations, cow's milk allergy was suspected. He received total parenteral nutrition for 5 days then fed with highly-hydrolyzed formula with slowly increasing amount. Thereafter tests for total eosinophil counts, total serum IgE, milk specific IgE antibodies and milk extract skin prick test were all unremarkable. Under the impression of food protein-induced enterocolitis syndrome (FPIES), a double-blind placebo-controlled food challenge (DBPCFC) with infant formula was performed. Regular infant formula induced severe vomiting, diarrhea, fever, acidosis and elevation of absolute neutrophil counts (ANC) of peripheral blood by 27,640/mm3. Based on the laboratory findings and challenge results, the patient fit the diagnostic criteria of food protein-induced enterocolitis syndrome.

Enterocolitis↗
PubMedDate not supplied

Study on the concentrations of cerebrospinal fluid immunoglobulin G and albumin in children.

Concentrations of immunoglobulin G (IgG) and albumin in cerebrospinal fluid (CSF) and serum were measured in 118 "normal" Chinese children from birth to 15 years old to obtain the reference values for the evaluation of the blood-brain barrier (BBB) function. The values of the CSF/serum IgG ratio, CSF/serum albumin ratio and IgG index (IgG ratio/albumin ratio) were then calculated for each subject. A relation was found between the content of IgG in CSF and serum depending on age. The gradual decrease of CSF IgG and IgG ratio during the first 6 months indicated a postnatal impediment of the diffusion of IgG from the blood to the CSF. In the meanwhile the CSF/serum albumin ratio continued to drop until the age of one year. The slower slope of the decrement of the latter ratio further demonstrated the differential permeability of the BBB in favor of the shift of small molecular protein. The change of the protein permeability within the first year of life shows a characteristic of the maturational process of the BBB. Nevertheless, IgG index has no age-dependent variation throughout the childhood period. It remains constant in the absence of inflammation within the central nervous system.

Adolescent↗
PubMedDate not supplied

The study of pollen and Der p mite-specific IgE antibodies in children with allergic rhinitis.

UNLABELLED: The role of pollens and house dust mites in perennial chronic rhinitis has been investigated for the Taipei area. Fifty-four serum specimens were collected from children with chronic rhinitis. EIA kits (Phadezyme RAST) were used to detect specific IgE antibody of nine allergens, including house dust mite (Der p) and eight common pollens. The children were divided into allergic (AR) and nonallergic (NAR) groups, based on the results of skin tests, inhalant allergen-specific IgE screen (Phadiatop), physical examination, past history and family history. The results showed: (1) 41 (76%) patients were defined as allergic rhinitis; (2) Der p specific IgE was detected in 41 (100%) AR patients and 7 (54%) NAR patients (P < 0.005), a strong positive reaction (> 2+) in 83% AR and none NAR patients (P < 0.005); (3) one, or more than one, pollen-specific IgE were found in 13 (32%) AR and 4 (31%) NAR patients. No strong positive reaction was detected in either group. THE CONCLUSION: (1) three-fourths of the children with chronic rhinitis are allergic by nature; (2) house dust mite is the major allergen of allergic rhinitis; (3) in the Taipei area, pollen does not play an important role for children with allergic rhinitis.

Adolescent↗
PubMedDate not supplied

Cerebrospinal fluid interleukin-6, interleukin-8, and tumor necrosis factor-alpha in children with central nervous system infections.

Concentrations of interleukin-6 (IL-6), interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-alpha) in cerebrospinal (CSF) samples were determined from 11 control and 42 children with central nervous system infections including 11 patients with bacterial meningitis, 20 patients with aseptic meningitis, 11 patients with encephalitis. The CSF IL-6, IL-8 and TNF-alpha concentrations in patients with bacterial meningitis were significantly higher than those with aseptic meningitis, encephalitis and the control groups. CSF IL-6, IL-8 and TNF-alpha levels in patients with aseptic meningitis were also significantly higher than those in the control group. There was no significant increase of CSF IL-6, IL-8 and TNF-alpha concentrations in patients with encephalitis compared to the control group. CSF IL-6 and TNF-alpha concentrations were decreased in patients with bacterial meningitis after treatment. CSF IL-8 levels were significantly decreased in both bacterial and aseptic meningitis groups at recovery period. There were no correlation between CSF IL-6, IL-8 and TNF-alpha levels and other parameters including CSF leukocytes, protein, sugar, IgG levels and IgG indexes in patients with bacterial meningitis. These results suggest that IL-6, IL-8 and TNF-alpha are important mediators in the meningeal inflammatory process in patients with meningitis. The levels of these mediators are good indicators for the extent of the meningeal inflammation.

Adolescent↗
PubMedDate not supplied

Patch testing in the detection of cutaneous reactions caused by carbamazepine.

Carbamazepine is a widely used antiepileptic drug associated with various side effects including skin eruptions. Peroral provocation test with any suspected drug is a reliable method of investigating the etiology: however, it is both laborious and potentially dangerous to the patient. Patch testing has been reported with variable success in skin drug reactions. Four cases (one male, three females) with epileptic seizures were reviewed; all had received carbamazepine therapy with appropriate dosage, then suffered from various cutaneous reactions including maculopapular exanthema, exfoliative dermatitis, erythema multiforme and Stevens-Johnson syndrome after the initial therapy for two weeks to one month. Skin patch test was done with 1% and 10% carbamazepine in petrolatum applied on the back, then read at 48 and 72 hours. All four patients had positive allergic patch test reactions to carbamazepine. One patient had extreme (+3), one had strong (+2) and another two had weak (+) reactions. There were no any skin reaction to vehicle and control cases. This limited study demonstrates that patch testing may be useful in the detection or confirmation of any type of exanthematous eruption caused by carbamazepine.

Adolescent↗