Biomedical subjects

W C Chen

Publications and source records attributed to W C Chen.

At least 127 records · Page 7Linked to original sources

PubMed1997

Nutritional factors that affect the production of cholesterol oxidase by Rhodococcus equi no. 23.

Some nutritional factors affecting the production of cholesterol oxidase (COX) by Rhodococcus equi no. 23 were investigated. Cholesterol and yeast extract respectively were the best carbon source and nitrogen source for the COX production. The optimum concentration of cholesterol and yeast extract was found to be about 0.1% and 0.4-0.5% (w/v) respectively. In addition, NH4Cl, NaCl and Tween 80 also exhibited enhancing effects on COX production, being maximal at 0.1% (w/v), 0.2% (w/v) and 1.0% (v/v) respectively. Moreover, optimal enzyme production occurred in medium that had an initial pH of 7.0.

Biotechnology↗

PubMed1996

Increased protein kinase C isoform gamma in the hippocampus of pentylenetetrazol-induced chemoshocked mouse.

Protein kinase C (PKC) activity, Western blot analysis of PKC alpha, -beta and -gamma, endogenous substrate protein phosphorylation and Western blot analysis of neuromodulin were studied in the cortex, striatum, hippocampus and cerebellum of mouse brain after pentylenetetrazol-induced chemoshock. The PKC isozymes and endogenous substrates in the crude cytosolic and membrane fractions of these four brain regions were partially purified by DE-52 columns eluted with buffer containing 100 or 200 mM KCl. Almost the same PKC activity in the cortex, striatum, hippocampus and cerebellum was found. This kinase activity was increased in the membrane fractions of hippocampus from chemoshocked mice, while that in other brain regions was not changed. On further analysis by immunoblotting, this increased activity was found to be due to the increase of PKC gamma isozyme. The in vitro phosphorylation of neuromodulin was also found to be increased in the hippocampus of chemoshocked mice, while the level of neuromodulin was not changed after chemoshock. Therefore, an increase of PKC gamma alone, but not neuromodulin, in the hippocampus contributed to the increased phosphorylation of this substrate in chemoshocked mice.

Animals↗

PubMed1996

Potentiation of bradykinin-induced inositol phosphates production by cyclic AMP elevating agents and endothelin-1 in cultured astrocytes.

Cultured astrocytes express bradykinin (BK) receptors, which are coupled to phospholipase C (PLC) through G-protein to mediate phosphoinositide (PI) hydrolysis. The regulation of this BK receptor-G protein-PLC pathway by cAMP and endothelin-1 (ET-1) was explored by short-term (20 min) and long-term (24 h) treatment with 100 mu M dibutyryl cyclic AMP (dBcAMP) or 10 nM ET-1. Short-term treatment of cells with dBcAMP had no effect on BK-induced PI hydrolysis; however, long-term treatment resulted in potentiation of the BK response. Similar effects were seen after 10 mu M forskolin pretreatment of the cells. We further explored the site of action of 24 h dBcAMP pretreatment and found that AlF(4)-, ionomycin- or A3187-induced PI hydrolysis was not affected but (3H)BK binding was increased. These results indicate that the site of action of dBcAMP is the BK receptor and Scatchard plot analysis showed that the Bmax was increased but the Kd decreased. Cycloheximide (0.5 mu M) blocked the increase in (3H)BK binding, indicating that new synthesis of receptor protein might occur during 24 h pretreatment with dBcAMP. Twenty minutes pretreatment of cells with ET-1 resulted in desensitization of the ET-1 induced P1 response, while the BK response was unaffected. After 24 h pretreatment with ET-1, desensitization to ET-1 still occurred, while BK-induced PI hydrolysis was markedly potentiated. (3H)BK binding and AlF(4)--induced but not A23187- or ionomycin-induced PI hydrolysis were increased, indicating that the site of action of long-term ET-1 treatment was the BK receptor and G protein; Scatchard analysis showed an increase in Bmax but no effect on Kd. These effects were blocked by cycloheximide, indicating that new synthesis of both receptor protein and G protein might occur during 24 h pretreatment with ET-1. (3H)Thymidine uptake was inhibited or potentiated by dBcAMP and ET-1, respectively. Possible dBcAMP-induced differentiation and ET-1-induced proliferation may contribute to the increased expression of receptor proteins.

Aluminum Compounds↗

PubMed1996

ATP-evoked inositol phosphates formation through activation of P2U purinergic receptors in cultured astrocytes: regulation by PKC subtypes alpha, delta, and theta.

ATP-induced phosphoinositide (PI) hydrolysis was studied in cultured astrocytes. To characterize the P2 purinergic receptor-mediated effects of ATP, the subtype-specific agonists 2-methylthio ATP (2-MeSATP), UTP, and alpha, beta-methylene ATP were compared. ATP, UTP, or 2-MeSATP induced a dose-dependent increase of inositol phosphates (IP) accumulation; alpha, beta-methylene ATP and adenosine had no effect. The order of potency was ATP > or = UTP >> 2-MeSATP. Cross-desensitization experiments indicated that ATP interacted with both P2U and P2Y receptors. P2U was the predominant P2 receptor in mediating PI hydrolysis in astrocytes. The effect of ATP, UTP, or 2-MeSATP was markedly inhibited by pretreatment of cells with pertussis toxin (PTX), indicating that both P2U and P2Y receptors coupled to phospholipase C through PTX-sensitive G protein. Short-term (10 min) treatment of cells with 1 microM TPA attenuated ATP, UTP, and 2-MeSATP-induced PI breakdown; however, long-term (24 h) pretreatment resulted in marked potentiation of both ATP and UTP, and restoration of 2-MeSATP responses. In a further analysis of the effect of TPA, 10 min and 1.5 h pretreatment attenuated ATP-and UTP-induced PI breakdown, but this inhibitory action was lost after 3 h of treatment. Both 6 and 24 h pretreatments resulted in a potentiation. Western blot analysis showed translocation of protein kinase C (PKC) alpha, -delta, and -theta from the cytosol to the membrane following 10 min and 1.5 h treatments, and restoration to basal levels in the membrane fraction was seen after 3 h of treatment. On the other hand, partial and complete down-regulation of these three isoforms was seen after 6 and 24 h of treatment, respectively. PKC eta was translocated but not down-regulated by TPA. These results suggested that PKC alpha, -delta, and -theta, not -eta may exert tonic inhibition on P2U receptor-mediated PI turnover in unstimulated astrocytes.

Adenosine Triphosphate↗

PubMed1996

Structural requirements for the edema-inducing and hemolytic activities of mastoparan B isolated from the hornet (Vespa basalis) venom.

Mastoparan B (MP-B) is a cationic tetradecapeptide isolated from the black-bellied hornet (Vespa basalis) venom. It has a primary structure (LKLKSIVSWAKKVL-CONH2) distinct from other vespine mastoparans. The peptide caused a dose-dependent swelling in rat hind paw and showed a potent hemolytic activity in guinea pig red blood cells. Studies on the structure activity relationship of the peptide showed that replacing lysine at position 2 (Lys2) by asparagine (Asn) in the MP-B sequence caused about 40% decrease in its edema-inducing activity at 50 micrograms/paw and 90% decrease in hemolytic activity at 30 microM of the peptide, while the same substitution at Lys4 did not cause a significant change in either activity. Replacing either Lys11 or Lys12 by leucine (Leu) caused little or no decrease in the edema-inducing and hemolytic activities. Decreases in both activities were observed when both Lys11 and Lys12 were replaced by Leu. On the other hand, replacing tryptophan at position 9 (Trp9) by tyrosine or phenylalanine in MP-B sequence almost abolished its hemolytic activity, while the edema-inducing activity was only partially inhibited. Circular dichroism spectra of the peptides measured in 20% trifluoro-ethanol revealed that substitution of Lys and Trp did not cause a significant change in the conformation of MP-B. it appears that Lys2 is crucial for both hemolytic and edema-inducing activities of MP-B, while Trp9 is of special importance to the hemolytic activity of MP-B. Lys11 and Lys12 in MP-B probably play a lesser role in both activities.

Amino Acid Sequence↗

PubMed1996

Protective effects of Gynostemma pentaphyllum in gamma-irradiated mice.

Radiation protective effects of Gynostemma Pentaphyllum (Gp) were investigated in gamma-irradiated mice. Animals were sacrificed on days 5, 15, 25 and 35 after gamma-irradiation. GOT, GPT, serum IgG and leukocyte counts were measured. Proliferation of splenocytes stimulated by mitogens, such as PHA, Con A, and LPS were detected and compared. The results showed that all parameters measured in this study were decreased and proliferation of splenocytes stimulated by mitogens were repressed in gamma-irradiated mice. Gp helped to recover the decreased leukocyte counts, GOT, GPT and IgG in serum and the proliferation of splenocytes stimulated by PHA, LPS and Con A in the gamma-ray irradiated mice.

Animals↗

PubMed1996

Effects of Glycyrrhizae and Glycyrrhizic acid on radiation injury in mice.

The effects of Glycyrrhizae (GL) and Glycyrrhizic acid (GA) on promoting the recovery of mice from radiation injury were investigated. Two hundred ICR strain male mice, 6-8 weeks old, were randomly divided into four groups. Group A was the normal control. Group B, the experimental control, was treated with 4 Gy gamma-ray irradiation. Groups C and D, the experimental groups, were treated with 500 mg/kg of GL (oral administration) and 5 mg/kg body weight of GA (i.p.), respectively, for ten days after gamma-ray irradiation. Eight mice in each group were sacrificed on days 5, 12, 26 and 33 post irradiation to measure the weights of spleen, thymus and testes, and the biosynthetic rates of DNA in these organs. The results revealed that 4 Gy gamma-ray irradiation evidently inhibited the weights of spleen, thymus and testes, and their DNA biosynthetic rates. GL and GA enhanced the recovery of these organs in mice from the injury of gamma-ray irradiation.

Animals↗

PubMed1996

Effects of low dose gamma-ray irradiation on peripheral leukocyte counts and spleen of mice.

OBJECTIVE: To study the effects of low dose gamma-ray irradiation on peripheral leukocyte counts and spleen weight of mice. MATERIALS AND METHODS: Two hundred male mice of ICR strain were divided into four groups. Group A served as normal control. Groups B, C and D, the experimental groups were treated with 5, 50 and 100 cGy (exposure dose in air) of whole body gamma-ray irradiation respectively. The leukocyte counts and its differential counts, body weight and the spleen weight of mice were measured on days 1, 5, 12, 19, 26 and 33 after irradiation. The relative spleen weight derived from the data of body weight and spleen weight was also calculated in tested animals. RESULTS: The leukocytes and its differential counts and relative spleen weight in mice decreased after 100 cGy gamma-ray irradiation. Fifty cGy gamma-ray irradiation could inhibit the leukocyte and its differential counts. The lowest dose, 5 cGy had no considerable damage. CONCLUSIONS: One hundred cGy of 137Cs gamma-ray irradiation had an inhibitory effect on counts of total leukocyte, lymphocyte, neutrophil, monocyte, spleen weight and body weight, while 50 cGy gamma-ray irradiation had an evident inhibition on peripheral leukocytes and its differential counts in mice. However, 5 cGy gamma-ray irradiation had no obvious inhibition in the tested mice in the period of the investigation.

Animals↗

PubMed1996

Effects of glycyrrhizae and glycyrrhizic acid on cellular immunocompetence of gamma-ray-irradiated mice.

OBJECTIVE: To investigate the effects of glycyrrhizae (GL) and glycyrrhizic acid (GA) on cellular immunocompetence in the gamma-ray-irradiated mice. MATERIALS AND METHODS: Tested mice of ICR strain were treated with GL and GA for 10 days continuously after 4 Gy gamma-irradiation. The counts of total leukocytes, lymphocytes, neutrophils and monocytes in peripheral blood of mice were measured. The blastogenic responses of splenocytes to mitogens, such as PHA, PWM, Con A and LPS were also detected. The cellular immunocompetence was measured by 3H-thymidine incorporation in each tested mouse. RESULTS: The leukocytes and their differential counts decreased in gamma-irradiated mice. The blastogenic responses of splenocytes to mitogens were inhibited by gamma-ray irradiation. GL and GA were effective in enhancing the recovery of leukocyte count and the blastogenic responses of splenocytes to mitogens, such as PHA, PWM, Con A and LPS from the inhibition of 4 Gy gamma-irradiation. CONCLUSIONS: Four Gy gamma-ray irradiation can decrease leukocytes and their differential counts, and the blastogenic responses of splenocytes of mice. GL and GA can help the recovery of the cellular immunocompetence in the gamma-irradiated mice.

Animals↗

PubMed1996

Effects of gypenosides on cellular immunity of gamma-ray-irradiated mice.

OBJECTIVE: To investigate the effects of gypenosides (Gs) on cellular immunocompetence in the gamma-ray-irradiated mice. MATERIALS AND METHODS: Tested mice of ICR strain were treated continuously with Gs for 10 days before or after 4 Gy gamma-irradiation. Body weight and splenic weight of mice were measured. The blastogenic response of splenocytes to mitogens, such as PHA, Con A and LPS were also detected. The cellular immunocompetence was measured by 3H-thymidine incorporation in each tested mouse. RESULTS: Body weight as well as splenic weight decreased in gamma-ray-irradiated mice. The blastogenic responses of splenocytes to mitogens were inhibited after gamma-ray irradiation. To treat with Gs was effective to enhance the recovery of body weight, splenic weight and immunocompetence in gamma-ray-irradiated mice from radiation damage. CONCLUSIONS: Four Gy gamma-ray irradiation could decrease splenic weight and cellular immunocompetence of mice. Gs could help the recovery of the splenic weight and cellular immunocompetence in gamma-ray-irradiated mice.

Animals↗

PubMed1996

Photodynamic treatment of subcutaneous tumors in mice with photofrin II and Argon ion laser.

OBJECTIVE: To investigate the combined effects of photofrin (Pf) II and laser irradiation on mice bearing subcutaneous tumors. METHOD: Ehrlish ascites tumor cells (1 x 10(7)) were implanted subcutaneously into the breast area of ICR mice. The tumors, when grew up to 0.55 +/- 0.15cm3, was administered of laser irradiation (514.5nm, 112.5mW/cm2 for 11.12 min with a total energy 75j/cm2) after intraperitoneal injection of Pf II (5, 7.5, 10 and 15mg/kg body weight) once a day for three successive days. RESULTS: The mortality rate (MR120) in the tumor control was 93.7% and the mean survival time (MST120) was 46.6 days. The best therapeutic effect (50% mortality rate, 53.8% tumor control rate and mean survival time 86 days) was observed in the group treated with 7.5mg of Pf II per kg of body weight and total irradiation energy of 75J/cm2 (112.5mW/cm2 for 11.12 min) with 514.5nm argon ion laser light. CONCLUSIONS: The effect on the survival rate of tumor cells and synthetic rates of DNA, RNA and protein were obviously inhibited, as the dose of pf II and laser irradiation increased.

Animals↗

PubMed1996

[The effect of blood AST, ALT and lactate after short and middle distance exercise training].

Twenty-four nursing college students aged 16 and 17 years were selected as research subjects and divided into two groups. Group A comprised 12 individuals who were trained for short distance running (5km/day) over a four-week period, while group B was trained for middle distance running (7km/day) during the same period. Blood AST (aspartate aminotransferase), ALT (alanine aminotransferase) and lactate were performed at rest (before training) and after exercise every week. After both short and middle distance exercise training, the lactate values after 1-3 week(s) training period were persistently higher than those before training and the differences between then are significant. However, the lactate value after 4 weeks training period is lower than that after the third week training. There are significant differences between the AST values after 1-4 week(s) training period and those before exercise in short distance exercise training. There are no significant differences between the AST values after training and those before exercise in middle distance exercise training. The ALT values after 1-4 week(s) training period were lower than those before exercise in short and middle distance exercise training. In conclusion, after 4 weeks training, the lactate and AST values can't reduce to those before training in middle distance exercise training, and the lactate value in short distance exercise training is the same as former. Further investigation is needed.

Adolescent↗

PubMed1996

Inverted papilloma of the urinary bladder.

BACKGROUND: Inverted papillomas are rare in the lower urinary tract. It is a histologically benign tumor with low grade malignant potential. Association with transitional cell carcinoma has also been reported. METHODS: Eight cases of inverted papilloma of the urinary bladder were diagnosed at this hospital between November 1990 and May 1994. There were one female and seven males with an average age of 63.5 years. We analyze their clinical presentations, histological findings and the outcome of treatments. RESULTS: Four patients presented with hematuria, and four with obstructive symptoms. Four were solid pedunculated tumors; three were papillary pedunculated; and one was a papillary sessile tumor. All tumors were solitary with four located in the bladder neck, two in the lateral wall, one in the interureteral ridge, and one in the trigonal area. A 77-year-old man whose tumor coexisted with an infiltrative transitional cell carcinoma was treated with partial cystectomy. The other seven patients were treated by transurethral resection. All the tumors were of the trabecular type and three of them (37.5%) harbored calcium oxalate crystals. There was no evidence of recurrence in a median follow-up of 18 months. CONCLUSIONS: Inverted papillomas of urinary bladder are benign tumors, which can be treated successfully by transurethral resection and fulguration of tumor bed. However, precautionary studies are necessary to exclude the coexistence of malignancy and annual follow-up with cystourethroscopy is mandatory.

Adult↗

PubMed1996

Renal cell carcinoma with renal pelvic extension simulating transitional cell carcinoma: a case report.

A case of renal cell carcinoma (RCC) with unusual extension into renal pelvis is reported. The radiographic findings simulate closely to those of transitional cell carcinoma (TCC) of the renal pelvis. Histopathological study of the extirpated tumor revealed RCC with invasion of renal pelvis. It is emphasized that it is occasionally difficult to distinguish TCC with renal invasion from RCC with renal pelvic extension. In addition, decision of surgical approach should be considered preoperatively in these cases.

Carcinoma, Renal Cell↗

PubMed1996

Adult Wilms' tumor: a case report.

Wilms' tumor (nephroblastoma) is the most common intraabdominal tumor in children; its three primary components are blastemal, epithelial and stromal, with predominance of tri-phasic lesion. The tumor is rare in adults, in whom the Wilms' tumor accounts for less than 1%. The case presented here concerns a case of 46-year-old female with stage II, Wilms' tumor, composed of purely mono-phasic differentiated epithelial component with favorable histology. The patient received radical nephrectomy, than post-operative chemotherapy and radiotherapy as recommended by National Wilms' Tumor Study. With the advent of modern chemotherapy, the adult Wilms' tumor can have a better prognosis than previously. Because of the rarity of adult Wilms' tumor and its unusual histo-morphology, this case is described and the literature, reviewed.

Abdomen↗

PubMed1996

A model for investigating effect of shock waves on intracellular calcium mobilization.

BACKGROUND: Shock wave lithotripsy (SWL) has become a non-invasive standard treatment for urolithiasis; however, it has some unwanted bioeffects. A cell model using calcium (Ca) imaging of cultured Madin-Darby canine kidney (MDCK) cells has been established in this laboratory to study the effects of shock waves on intracellular free Ca mobilization of renal tubular cells. METHODS: Digital video imaging of fura-2 fluorescence was used to measure both resting and stimulated intracellular free Ca concentrations in single cultured MDCK cells. Pharmacological agents including adenosine-5'-trisphosphate (ATP), bradykinin and thapsigargin, were used as Ca mobilizing agents. RESULTS: ATP, bradykinin and thapsigargin all elicited a robust transient increase in intracellular Ca concentration. CONCLUSIONS: A cell model was established to investigate the effect of shock waves on single kidney cells. This provided an opportunity to determine how shock waves affect the regulation of intracellular Ca concentrations in kidney cells; in addition, it allows investigation, for the first time at the single cell level, of whether blocking Ca entry in kidney cells plays any role in the mechanism by which some Ca channel blockers, e.g. nifedipine and verapamil, protect patients of urolithiasis from shock wave-induced renal damage.

Adenosine Triphosphate↗

PubMed1996

Deliberate hypotensive anesthesia with labetalol in reconstructive surgery for scoliosis.

BACKGROUND: Anesthesia for surgical reconstruction of scoliosis presents a great challenge for anesthesiologists. One of the main concerns is massive bleeding. Hypotensive anesthesia has been advocated for the purpose of diminishing operative blood loss. On the other hand, some authors reported that the blood loss mostly depends on surgical technique, rather than anesthetic technique. We hereby evaluate the efficacy of deliberate hypotensive anesthesia and compare its merits and faults with that of normotensive anesthesia in scoliosis surgery performed by a single surgical and anesthetic team. METHODS: The effect of deliberate hypotensive anesthesia on intraoperative blood loss, blood transfusion, and length of surgery in patients who underwent Cotrel Duvosset Instrumentation for scoliosis was assessed. Twenty patients (Group A) were given isoflurane as the main anesthetic agent and their blood pressure was maintained at the preoperative level. These patients were compared with twenty patients (Group B) who were anesthetized with isoflurane and their intraoperative mean blood pressure was lowered and controlled at 50 mmHg by intravenous labetalol. All these forty operations were done by a single surgical and anesthetic team. The results were analyzed by the Student's t-test. RESULTS: Deliberate hypotensive anesthesia was found to significantly decrease the average blood loss by nearly 55 per cent, reduce the need for transfusion by nearly 53 per cent, and shorten the average operating time by over one hour. No complications attributable to the specific anesthetic technique occurred. CONCLUSIONS: The findings of this study suggest that deliberate hypotensive anesthesia with labetalol and isoflurane may be of benefit in scoliosis surgery by reducing blood loss, the need of blood replacement and operating time.

Adolescent↗

PubMed1995

Immunogenicity of mastoparan B, a cationic tetradecapeptide isolated from the hornet (Vespa basalis) venom, and its structural requirements.

Mastoparan B (MP-B) is a cationic tetradecapeptide (LKLKSIVSWAKKVL-CONH2, mol. wt 1611) isolated from the black-bellied hornet (Vespa basalis) venom. The small peptide itself was capable of inducing antibodies without prior conjugation to a protein carrier in rabbits and mice. The mouse antibody was found to be of IgG1 isotype with kappa-type light chain. The peptide antigen was able to form insoluble complexes with the specific antibody, suggesting that MP-B possessed more than one epitope in its molecule. The finding that MP-B was able to bind with both mouse and rabbit antibodies in sandwich ELISA supports this contention. Synthetic MP-B analogues in which lysine at position 2, 4, 11 or 12 was replaced by neutral amino acids such as asparagine or leucine showed a significant decrease in their antibody-binding activities. Substitution of lysine at position 4 (Lys4) caused the most marked inhibition in its binding activity. However, replacing tryptophan at position 9 by tyrosine caused a relatively small reduction in its binding activity. Replacing both Lys2,4 by asparagine or removing Lys-containing segments at amino or carboxyl terminus in MP-B sequence caused a remarkable decrease in the antibody-binding and immunogenic activities of the peptide. The Lys residues located at amino and carboxyl terminal segments of MP-B, especially Lys4, appear to play a critical role in the binding interaction and the immunogenicity of the peptide.

Amino Acid Sequence↗