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Biomedical subjects

T W Chen

Publications and source records attributed to T W Chen.

At least 55 records · Page 3Linked to original sources
PubMed1991

Sieving and reflection coefficients for sodium salts and glucose during peritoneal dialysis in rats.

The two-part studies reported herein address peritoneal membrane ultrafiltrate (UF) characteristics during peritoneal dialysis exchanges in rats. In the studies of part 1, the sieving coefficients for sodium, chloride, and total solutes during hydrostatic UF after instillation of rat serum into the peritoneal cavity of rats were calculated. Thirty-six rats were divided into six groups (N = 6) according to the following peritoneal dialysis exchange cycle times: 60, 120, 180, 240, 480, and 960 min. Thirty milliliters of pooled rat serum were infused i.p. with the animal being conscious except during infusion and drainage. The study showed in the early phase of exchanges, when oncotic and osmotic pressure gradients were absent, net UF presumably due to capillary hydrostatic pressure and sodium sieving during such UF. Sieving coefficients for sodium (0.72), chloride (0.77) and total solutes (0.73) were determined by using standard formulae. In the second part of these studies, the kinetics of fluid movement after the instillation of 5% dextrose solution into the peritoneal cavity of rats were analyzed. A very low UF rate was observed early in the exchange when the glucose gradient between the dialysis solution and blood was at its peak. The UF rate gradually increased as the sodium entered the dialysis solution from the blood. At the time of low UF rate with high glucose gradient, presumably the osmotic pressure generated by the glucose in the dialysis solution was countered by the osmotic pressure of solutes in plasma, i.e., sodium and its anions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[In vitro cytotoxicity of Ganoderma lucidum on oral cancer cells].

The extract from the mycelium of Ganoderma lucidum was diluted into serial concentrations and added into in vitro cultured oral cancer and normal cell lines. After incubation for 24 hours, the survival fraction was determined by MTT colorimetric assay. The result revealed that the ID50 was about 3mg/ml and the total lethal dosage was beyond 4 mg/ml. This toxic effect was the same in both cancer and normal cells. Not only was there no difference between cancer and normal cells, but also the high dosage required in toxicity leads to the conclusion that the GL has no direct cytotoxic effect in cancer treatment.

Antineoplastic Agents, Phytogenic↗
PubMed1990

Renal excretion of zinc in patients with chronic uremia.

Though uremic patients have been reported to have subnormal zinc levels in plasma and an abnormal zinc metabolism, data on their renal excretion of zinc are still unavailable. In our study, 55 nondialyzed uremic patients had a markedly lower concentration of zinc in plasma and a lower urinary zinc excretion. They had a higher excretory fraction of zinc in the renal tubules and a higher ratio of zinc to creatinine excretion than normal subjects. We found that the total daily excretion of zinc, calcium, phosphate and ammonia was reduced, and that the ratio of calcium or ammonia to creatinine excretion decreased in uremic patients. Urinary zinc excretion was correlated with renal creatinine clearance (r = 0.50, p less than 0.001) in both normal subjects and uremic patients, but ammonia excretion was correlated with zinc excretion in normal subjects only. In uremia, urinary zinc excretion was correlated with urinary calcium (r = 0.55, p less than 0.001) and urinary phosphate excretion (r = 0.30, p less than 0.05). We conclude that the increased ratio of zinc to creatinine excretion and the excretory fraction of zinc in the renal tubules of uremic patients may increase the urinary zinc excretion, but a severe diminution of the glomerular filtered load of zinc may be the major factor in decreasing the urinary zinc excretion in uremia.

Adult↗
PubMed1990

Renal excretion of oxalate in patients with chronic renal failure or nephrolithiasis.

This study was carried out in order to investigate renal oxalate excretion in a group of normal subjects (n = 40), a group of patients with uremia (n = 52) and a group with nephrolithiasis (n = 34). We found that the mean concentrations of oxalate in the 24-hour urine specimens of both patient groups were below the normal range. Although the renal creatinine clearance (CCR) was significantly decreased in some stone patients (n = 14), decreased renal oxalate clearance was noted only in those patients with severe renal failure. Thus, plasma oxalate was found to be elevated only in patients with chronic renal failure (mean +/- SD, 49.7 +/- 12.4 mumol/l), while the normal value was 17.0 +/- 6.7 mumol/l. The mean tubular excretion fraction of oxalate was also found to increase markedly in uremia with a mean of 26.3 +/- 17.3% (in normal subjects, 11.7 +/- 7.5%), but their mean daily urinary excretion of oxalate decreased to 63.2 mumol/day (mean value of 232.6 mumol/day in normal subjects). A positive correlation was observed between oxalate and creatinine, and between oxalate and calcium excretion, which was not found in normal subjects or patients with kidney stones. In nephrolithiasic patients, the daily excretion of oxalate, calcium and phosphate had no discernible increment and the mean excretory ratio of oxalate, calcium or phosphate to creatinine was all within normal limits. But when the CCR of stone patients was below 80 ml/min, their daily excretion of oxalate and calcium decreased significantly (p less than 0.01) and the excretory ratio of phosphate to creatinine markedly increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Interzeta-globin gene hypervariable regions in Chinese: application to genetic diagnosis of adult polycystic kidney disease.

In order to investigate the interzeta-globin gene hypervariable regions (IZHVR) in Chinese, DNA samples from 114 unrelated normal individuals were analyzed using the restriction endonuclease BglII and hybridized with a 32P-labeled zeta-globin probe. Four polymorphic fragments containing IZHVR with different frequencies were found: 11.3 kb, 0.24; 10.8 kb, 0.50; 10.4 kb, 0.05, and 10.0 kb, 0.21. Using these polymorphic fragments as linkage markers, we were able to trace the affected siblings in a three-generation Chinese family with a history of adult polycystic kidney disease.

China↗
PubMed1988

Pancreatic enzymes in uremic patients with or without dialysis.

One hundred thirty blood samples from 87 patients with renal failure, but without abdominal pain, were analyzed for blood urea nitrogen (BUN), creatinine, amylase, p-isoamylase, and lipase simultaneously. We found that 74, 78, and 80% of the patients had hyperamylasemia, hyperisoamylasemia, and hyperlipasemia. None had amylase higher than five times the upper limit. A few patients (2.3%) had lipase elevated to more than 10 times the upper limit. No significant change of pancreatic enzyme level was noted as a result of hemodialysis, but a significant amount of amylase was removed from the circulation in patients receiving intermittent peritoneal dialysis. Significantly lower pancreatic enzyme levels were observed in patients with less impairment of renal function. We conclude that elevation of pancreatic enzymes in uremic patients is more frequent and more extensive than most articles indicate, and that the extent of increase is related more to renal function than to the modalities of dialysis the patients received.

Adult↗
PubMed1988

A New UV-A/B Protecting Pigment in the Terrestrial Cyanobacterium Nostoc commune.

A new ultraviolet (UV)-A/B absorbing pigment with maxima at 312 and 330 nanometers from the cosmopolitan terrestrial cyanobacterium Nostoc commune is described. The pigment is found in high amounts (up to 10% of dry weight) in colonies grown under solar UV radiation but only in low concentrations in laboratory cultures illuminated by artificial light without UV. Its experimental induction by UV as well as its capacity to efficiently protect Nostoc against UV radiation is reported.

Journal Article↗
PubMed1984

Activities of fatty acid desaturases and fatty acid composition of liver microsomes in rats fed beta-carotene and 13-cis-retinoic acid.

The fatty acid composition of microsomal lipids and the activities of delta 9- and delta 6-desaturases in liver microsomes of rats fed diets supplemented with beta-carotene and two levels of 13-cis-retinoic acid were studied. Four groups of male, weanling rats were fed semipurified diets containing 0 or 100 mg beta-carotene per kg diet, and 20 or 100 mg 13-cis-retinoic acid per kg diet. After 11 weeks of feeding, the rats were killed, liver microsomes were prepared and assayed for delta 9-desaturase and delta 6-desaturase activities. The activity of delta 9-desaturase was lower in liver microsomes of rats fed beta-carotene-supplemented diet or the diet supplemented with the higher level of 13-cis-retinoic acid. Microsomal delta 6-desaturase activity was, however, higher in liver of rats fed 13-cis retinoic acid; there was no effect of beta-carotene on delta 6-desaturase activity. The fatty acid compositional data on total lipids of liver microsomes were consistent with the diet-induced changes in fatty acid desaturases. Phospholipid composition of liver microsomes was also altered as a result of feeding beta-carotene or 13-cis-retinoic acid-containing diets. The proportions of phosphatidylethanolamine were generally higher, whereas those of phosphatidylcholine were lower in the experimental groups as compared with the control.

Animals↗
PubMed1983

Effect of probenecid on the pharmacokinetics of aminophylline.

The authors investigated the effect of probenecid on the pharmacokinetics of aminophylline. Seven normal volunteers served as their own controls in a crossover study. In the first phase, subjects received an oral dose of aminophylline after an overnight fast. In the second phase, probenecid was given orally 30 minutes prior to the administration of aminophylline. Serum and urine theophylline levels were determined by high performance liquid chromatography. Statistical analysis showed that probenecid had no significant effect on any of the pharmacokinetic parameters measured. Probenecid appears to have little or no influence on the liver metabolism of theophylline.

Aminophylline↗
PubMedDate not supplied

Total paracentesis in non-alcoholic cirrhotics with massive ascites: mid-term effects on systemic and hepatic haemodynamics and renal function.

Single total paracentesis (4.8-11 L) was performed in 23 patients with hepatitis B surface antigen (HBsAg)-positive cirrhosis and massive ascites and its effects on systemic and hepatic haemodynamics and renal function were examined over 5 days. Severe hypotension occurred in six (26.1%) patients from 6 to 54 h after paracentesis. In the remaining 17 patients, compared to the baseline, there was an increase in the cardiac output (6.1 +/- 0.3 vs 6.7 +/- 0.3 L/min, P < 0.001) and a decrease in right atrial pressure (8.8 +/- 0.8 vs 4.3 +/- 0.7 mmHg, P < 0.001), systemic vascular resistance (1160 +/- 61 vs 976 +/- 50 dyne.s.cm-5, P < 0.001), and wedged hepatic venous pressure 30 min after completion of paracentesis. After 5 days, right atrial pressure, systemic vascular resistance and wedged hepatic venous pressure returned to baseline, while the cardiac output dropped to a level lower than the baseline (5.7 +/- 0.7 L/min, P < 0.05). Hepatic venous pressure gradient had returned to baseline after 5 days. Serial tests of serum creatinine level showed an increase from day 3 (1.34 +/- 0.14 vs 1.04 +/- 0.10 mg/dL, P < 0.05). On day 5, creatinine clearance (55.7 +/- 5.4 vs 41.9 +/- 5.3 mL/min, P < 0.05) and effective renal plasma flow (351 +/- 32 vs 293 +/- 29 mL/min, P < 0.05) were decreased, compared to the baseline. Based on these data, infusion of a volume expander may be necessary for total paracentesis to avoid systemic haemodynamic complications in non-alcoholic cirrhosis.

Ascites↗
PubMedDate not supplied

Human peritoneal mesothelial cells produce nitric oxide: induction by cytokines.

OBJECTIVE: To investigate the induction of nitric oxide synthase type II (iNOS) in human peritoneal mesothelial cells (HPMC) using cytokines and bacterial lipopolysaccharide (LPS). DESIGN: Confluent monolayers of HPMC were exposed to cytokines [tumor necrosis factor alpha (TNFalpha), interleukin-1 beta (IL-1beta), interferon gamma (IFNgamma)] or LPS, individually or in various double and triple combinations, for 24-72 hours. Concentrations of nitrate and nitrite in the media were quantified using the Griess reaction and used as indirect indices of nitric oxide (NO) production. The expression of iNOS was assessed using reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot. RESULTS: Neither single cytokines nor LPS was able to induce iNOS mRNA or NO production. Both double combinations of TNFalpha + IFNgamma and IL-1beta + IFNgamma were able to induce iNOS mRNA expression, but only TNFalpha + IFNgamma induced significant NO production. The triple combination of TNFalpha + IFNgamma + IL-1beta induced even more NO production than TNFalpha + IFNgamma. There was no constitutive NO synthase type III (eNOS) expression in HPMC. CONCLUSIONS: Certain combinations of cytokines could stimulate cultured HPMC to produce NO, and HPMC might be a source of intraperitoneal NO production during peritonitis.

Blotting, Western↗
PubMedDate not supplied

Peritoneal transfer of carbon dioxide in the rat.

In the authors' previous rat studies (Kidney Int 39: 608-617, 1991), peritoneal clearances (Cp) representing near exclusively diffusive CO2 transfer were evaluated: for isosmotic (0.37% dextrose) and hyperosmotic (15% dextrose) solutions with pH 7.2-7.3, Cp CO2 were 1.20 +/- 0.08 and 1.84 +/- 0.04 ml/min, respectively. In the present studies peritoneal transfer parameters (D/B, Cp) of CO2 gas, HCO3-, and total CO2 (tCO2) in anesthetized rats have been compared (n = 22) using solutions with dextrose contents as mentioned above but with a pH of 6.5 or 7.6; how much Cp CO2 measurements obtained with solutions at these pH values differ from Cp shown earlier with solutions of pH 7.2-7.3 has also been evaluated. When the pH was the same, transfer parameters of CO2 gas, HCO3-, and tCO2 were significantly higher under hyperosmotic conditions. The use of solutions with a pH different from 7.2-7.3 resulted in higher Cp of CO2 gas: with isosmotic solutions at pH 6.5 and 7.6, mean increases were 25 and 75%, respectively; with hyperosmotic solutions respective increases were 45 and 134%. The authors conclude that dialysis solution pH, especially under hyperosmotic conditions, significantly changes parameters of diffusive CO2 transfer in the rat. For evaluation of peritoneal blood flow from diffusive transfer parameters of CO2 gas, smaller overestimation can be expected when dialysis solution pH is slightly under than overadjusted compared to blood pH.

Animals↗