Biomedical subjects

C L Tsai

Publications and source records attributed to C L Tsai.

At least 19 recordsLinked to original sources

PubMed2001

Effects of estrogen and neurotransmitters on the primary cultures of tilapia brain from different ages.

The effects of estrogen and neurotransmitters on the proliferation of brain cells were investigated in the primary cultures of tilapia brain from different ages. Treatment of brain cells that were cultured on day 1, 3, 5, 7, 10, 30, and 180 posthatching with serotonin (5-HT), resulted in a significant increase of the Brdu(+)-cell number. By contrast, norepinephrine (NE) resulted in a significant decrease and gamma-aminobutyric acid (GABA) had no effect. 17 beta-Estradiol (E(2)) significantly increased the Brdu(+)-cell number when the brain cells were cultured after 5 days of age, but had no effect when cultured on day 1 or 3 of age. These results indicate that the proliferation of brain cell is enhanced by 5-HT at each stage. This effect is mimicked by E(2) when given after 5 days of age. Conversely, NE has an effect to depress the proliferation of brain cells. Whereas, GABA has no effect.

Age Factors↗

PubMed2001

Lateral approach without ligament release in total knee arthroplasty: new concepts in the surgical technique.

A lateral approach without ligament release was performed in 475 primary total knee arthroplasties (TKAs) in 344 patients and 50 revision TKAs in 39 patients. Deformities of the genu varum or valgum were corrected by accurate bone cut; no ligament releases were required other than to achieve adequate exposure. A lateral approach allowed both self-centering of the extensor mechanism and knee closure in complete flexion. Better range of motion was achieved. More than 90 degree active flexion usually occurred 3 days postoperatively. Postoperative roentgenograms showed all knees had good varus and valgus stability, which was sustained with time, except 1 with late genu recurvatum due to inadequate polyethylene thickness and the other with a broken tibial base plate. Complications such as disruption of patellar blood supply and knee instability, more frequently observed in the medial approach with ligament release, did not occur. The results suggest that this new technique is safe and may give better outcomes.

Arthroplasty, Replacement, Knee↗

PubMed2001

Estradiol and para-chlorophenylalanine downregulate the expression of brain aromatase and estrogen receptor-alpha mRNA during the critical period of feminization in tilapia (Oreochromis mossambicus).

The period of maximal feminizing action of 17beta-estradiol (E(2)) upon sex ratio is before 10 days posthatching in tilapia (Oreochromis mossambicus). The effect of E(2) at this time is mimicked by para-chlorophenylalanine (p-CPA), a serotonin (5-hydroxytryptamine; 5-HT) synthesis inhibitor. The effect of E(2) on sexual differentiation may be mediated by the 5-HT system, which is consistent with the suggestion in mammals. The masculinizing actions of 17alpha-methyltestosterone (MT) are most potent later at up to day 20 of age, and may depend on MT induction of aromatase activity. In the present study, the effects of gonadal steroids and p-CPA on brain aromatase and estrogen receptor (ER) mRNA expression during the critical period of sexual differentiation were investigated. Treatment of tilapia with E(2) resulted in a significant decrease in the expression of brain aromatase and ERalpha between days 0 and 10, but not subsequently. The effect of E(2) at this time can be mimicked by p-CPA. Treatment of tilapia with MT, by contrast, resulted in a significant increase in brain aromatase, ERalpha and ERbeta mRNA expression when given between days 10 and 20. The downregulation of brain aromatase and ERalpha mRNA expression by E(2) before 10 days of age and, in turn, the upregulation of brain aromatase and ERalpha and ERbeta mRNA expression by MT at up to day 20 of age coincide with the period in which E(2) and MT have the maximal effect on gonadal feminization and masculinization, respectively.

Actins↗

PubMed2000

Temperature affects the development of central neurotransmitter systems of tilapia, Oreochromis mossambicus.

The effects of temperature on the development of central neurotransmitter systems were investigated with tilapia, Oreochromis mossambicus. Zero-day-old (the hatching day) tilapia were kept at four different temperatures: 20 (lower), 24 (control), and 28 and 32 degrees C (elevated), respectively. On the 5th day, brain serotonin (5-HT), norepinephrine (NE), gamma-aminobutyric acid (GABA), and glutamate (Glu) contents were quantified by a high-performance liquid chromatograph with electrochemical detection. Similar experiments were performed on the 5-, 10-, 15-, 20-, and 25-day-olds. The results showed that aquatic temperature influenced brain 5-HT, NE, Glu, and GABA contents during its respective restricted period. The influence of both lower and elevated temperatures on the neurotransmitter content, either increasing or suppressing, is dependent on its developing stage. The facts provide an evidence that the development of central neurotransmitter systems is influenced by aquatic temperature during its specific effective period.

Animals↗

PubMed2000

Effects of temperature on the deformity and sex differentiation of tilapia, Oreochromis mossambicus.

The effects of temperature on the deformity and sex differentiation of tilapia, Oreochromis mossambicus, were investigated. Zero- (the hatching day), 5-, and 10-day-old tilapia were respectively divided into 4 groups that were reared at 20, 24, 28, and 32 degrees C for 5 days. Percentages of deformity were significantly increased when tilapia were kept in the elevated temperatures (28 and 32 degrees C) before 5 days old during this experiment, whereas the lower temperature (20 degrees C) had no effect on the development of morphology. On the other hand, exposure to the lower temperature before 10 days old induced a high proportion of females whereas a high proportion of males was induced by the elevated temperature after 10 days old during this experiment. These results indicate that morphological development is influenced by temperature, particularly by the elevated temperature during a restricted developmental period. Both lower and elevated temperatures induce the gonadal feminization and masculinization, respectively, during its restricted developmental period. J. Exp. Zool. 286:534-537, 2000.

Animals↗

PubMed2000

Age-related differences in the secretion of calcitonin in male rats.

The mechanism of hypercalcitoninemia associated with aging was investigated in male rats. To mimic some of the hormonal changes with aging, orchidectomized (Orch) and hyperprolactinemic rats were used to mimic the physiological status of aging. Orch and haloperidol-induced hyperprolactinemic rats aged 3, 8, and 17 months were infused with CaCl2 and then bled from a jugular catheter following the CaCl2 challenge. Rat thyroid gland was incubated with Locke's medium at 37 degrees C for 30 minutes. Compared with 8- and 3-month-old rats, 17-month-old rats exhibited the lowest levels of plasma testosterone and the highest levels of plasma prolactin (PRL) and calcitonin (CT). The release of CT in the thyroid glands in vitro was highest in 17-month-old rats. Orchidectomy decreased rat plasma CT and thyroid CT release in vitro. Hyperprolactinemic rats had higher levels of plasma PRL and CT compared with control animals. The release of thyroid CT in vitro was greater in hyperprolactinemic rats. These results suggest that the hypersecretion of CT in 17-month-old rats may be due in part to hyperprolactinemia.

Aging↗

PubMed2000

Effects of gonadal steroids on brain serotonergic and aromatase activity during the critical period of sexual differentiation in tilapia, Oreochromis mossambicus.

The effects of gonadal steroids on brain serotonin (5-HT) and aromatase activity during the critical period of sexual differentiation were investigated in tilapia, Oreochromis mossambicus. Treatment of tilapia with 17beta-oestradiol (E2) between days 7 and 10 posthatching resulted in a significant increase in the female : male ratio as determined at day 90, and a significant reduction in brain 5-HT content. Treatment between days 10 and 20, or between days 20 and 30, had no significant effect. Since the 5-HT system may influence sexual differentiation, we examined the effects of para-chlorophenylalanine (p-CPA), a 5-HT synthesis inhibitor. As with E2, treatment of tilapia with p-CPA between days 7 and 10 posthatching resulted in a significant increase in the female : male ratio. Again, treatment between days 10 and 20, or between days 20 and 30, had no significant effect. Both p-CPA and E2 significantly depressed brain aromatase activity when administrated between days 7 and 10, but not subsequently. In tilapia treated between days 7 and 10, the brain 5-HT content was lowered by E2 to an extent similar to that seen with p-CPA, which is consistent with the suggestion that the effect of E2 on sexual differentiation may be mediated by the 5-HT system. Treatment of tilapia with 17alpha-methyltestosterone (MT), by contrast, resulted in a reduction in the female : male ratio, and treatment was most effective when given between days 10 and 20. The period of maximal effect of MT upon sex ratio appears to coincide with the ability of MT to induce an increase in brain aromatase activity.

Aging↗

PubMed2000

Simplified rat intubation using a new oropharyngeal intubation wedge.

Our new oropharyngeal intubation wedge made from a plastic 3-ml syringe has been used successfully for the expansion of the oropharyngeal cavity and visualization of vocal cords for endotracheal intubation in the rat. All the animals we used tolerated the intubation and ventilation procedures in a series of experiments. After the proper setting of the respirator, vital signs were maintained within normal range. The postmortem examination and measurements in the upper airway confirmed that the endotracheal tube was properly sited and also demonstrated the precise size of the device that should be used. The main advantages of this method include low cost, simplicity, and reliability. Furthermore, because no expensive, elaborate, difficult-to-operate, or hard-to-get special equipment is needed, this technique can be used in every laboratory.

Animals↗

PubMed2000

Comparative anti-caries effects of tablet and liquid fluorides in cleft children.

Children with cleft lip and/or palate are at a higher risk for developing caries of the primary incisors compared with non-cleft children. To determine whether fluoride in tablet or liquid form would be more efficacious with children with cleft lip and/or palate, a two-year clinical investigation was conducted to test the anti-caries effects. One-hundred and fifteen cleft children (59 boys and 56 girls) between 22 and 26 months old were randomly selected into control, tablet and liquid fluoride groups. The amount of administered fluoride was 0.25 mg F daily in non-fluoridated Taiwan. Dental examinations were conducted using mirrors and #23 explorers. Caries were assessed using the DMF index in the baseline, first year and second year. The results showed that children in the tablet and liquid groups had a significantly lower DMFT increment than in the control group (p < 0.05). In the DMFS index, children in the liquid group showed a significantly lower caries increment than in the control group (p < 0.01), and children in the tablet group presented a borderline, but non-significant statistical difference when compared with the control group (p = 0.065). No significant statistical difference was found in either DMFT or DMFS between tablet and liquid fluoride administrations (p = 0.521 and p = 0.383, respectively). It is concluded that dietary fluoride supplements in liquid form show efficacy in reducing early childhood caries in the cleft children. Liquid fluoride showed slightly better numerical anti-caries effect than tablet fluoride, which is possibly due to its ease of administration with small children.

Analysis of Variance↗

PubMed1999

Effects of gonadal steroids on the GABA and glutamate contents of the early developing tilapia brain.

The effects of gonadal steroids on the gamma-aminobutyric acid (GABA) and glutamate (Glu) contents of the early developing brain were investigated. Seven-day-old (7 days post-hatch) tilapia were divided into three groups which were continuously treated with 100 mg/kg diet 17beta-estradiol (E2), 100 mg/kg diet methyltestosterone (MT), and a normal diet, respectively. Until 10, 20, and 30 days old, the GABA and Glu contents of the brains were detected by HPLC-ECD. The brain GABA and Glu contents, before 30 days old, significantly increased with age. These results demonstrate that before 30 days old is a developing period of both GABA and Glu systems in the tilapia brain. During this period, both E2 and MT have a facilitative effect on the GABAergic and Gluergic system during a restricted effective period.

Animals↗

PubMed1999

Effects of gonadal steroids on the serotonin synthesis and metabolism in the early developing tilapia brain.

The effects of gonadal steroids on serotonin (5-HT) synthesis and metabolism in the early developing brain were investigated. Seven-day-old (7 days post-hatch) tilapia, Oreochromis mossambicus were continuously treated with 17beta-estradiol (E2), methyltestosterone (MT) and para-chlorophenylalanine (p-PCA) up to the age of 30 days. The brain 5-HT content, before 30 days, increased with age. The result indicates that this is a developing period of the central 5-HTergic system. During this developing period, the activity of tryptophan hydroxylase (TPH) and monoamine oxidase (MAO) was not altered by age. Both E2 and MT influence the central 5-HT content during its restricted developmental period. E2 has an initial inhibitory effect and then a facilitative effect while MT only has a facilitative effect. The initial inhibitory effect of E2 is mediated by decreasing TPH activity and increasing MAO activity to decrease the 5-HT content. The facilitative effect of both E2 and MT is suppressed by p-CPA.

Aging↗

PubMed1999

Oxidative injury induced by synthetic humic acid polymer and monomer in cultured rabbit articular chondrocytes.

Humic substance has been proposed as one of the causative factors of Kashin-Beck disease (KBD), an endemic osteoarthritic disorder with necrosis of chondrocytes widely prevalent in some regions of China. In order to exclude the complications of natural humic substance, here we prepared phenolic polymers of synthetic humic acid (SHA) by oxidation of phenolic monomer, the protocatechuic acid (PCA). The biological effects of SHA and PCA on primary culture of rabbit articular chondrocytes were investigated. We found that not only SHA but also PCA caused chondrocyte injury, as evidenced by the loss of cell viability measured with methylthiazol tetrazolium (MTT) assay and the increased release of intracellular lactate dehydrogenase (LDH). Both SHA and PCA could result in lipid peroxidation and glutathione (GSH) depletion in chondrocytes, indicating that oxidative stress may be involved in chondrocyte injury. Furthermore, a marked increase in intracellular calcium level ([Ca2+]i) occurred after chondrocytes treated with SHA or PCA. These results suggest that chondrocyte injury elicited by SHA or PCA may be mediated through the occurrence of oxidative stress and the disruption of intracellular Ca2+ homeostasis. Data also suggest that the monomeric phenolic acid may be considered one of the causative factors of KBD in addition to humic substance.

Animals↗

PubMed1999

Effects of hyperprolactinemia on calcitonin secretion in male rats.

The role of prolactin (PRL) in calcitonin (CT) release by the thyroid C cell in male rats was studied. Anterior pituitary (AP)-grafted male rats were characterized by hyperprolactinemia. Brain cortex (CX)-grafted male rats were used as control animals. AP- and CX-grafted rats were infused intravenously with CaCl2 and bled from the jugular catheter at 0, 30, 60, and 120 minutes following the CaCl2 challenge. Rat thyroid gland was incubated with or without 3-isobutyl-1-methylxanthine (IBMX) at 37 degrees C for 30 minutes. Thyroid C cells were incubated in culture medium at 37 degrees C for 60 minutes. Cyclic adenosine 3',5'-monophosphate (cAMP) in rat thyroid tissues following incubation with IBMX was extracted by 65% ethanol. AP-grafted rats had higher plasma levels of PRL and CT compared with CX-grafted rats. Both the release of CT and accumulation of cAMP in thyroid glands were higher in AP-grafted versus CX-grafted rats. Direct administration of ovine PRL (oPRL) on the thyroid glands did not increase CT secretion in vitro. Thyroid C cells of AP-grafted rats secreted more CT compared with CX-grafted rat cells. These results suggest that hyperprolactinemia increases the release of CT by thyroid C cells in rats through a cAMP-dependent pathway caused by an indirect effect of PRL.

Animals↗

PubMed1999

Arecoline cytotoxicity on human oral mucosal fibroblasts related to cellular thiol and esterase activities.

Betel quid (BQ) chewing is associated with an increased risk of oral submucous fibrosis (OSF) and oral cancer in India and many south-east Asian countries. Recently, we have shown that arecoline is cytotoxic to cultured human oral mucosal fibroblasts. This study investigated protective effects of various agents against the cytotoxicity of arecoline and its mechanisms. Arecoline, at concentrations of 0.2 and 0.4 mM, decreased the cell numbers by 38% and 63%, respectively. At a concentration of 2 mM, N-acetyl-L-cysteine [a glutathione (GSH) synthesis precursor] could prevent arecoline-induced cytotoxicity. The decrease in cell numbers was reduced to 17% relative to control. Extracellular addition of esterase at a concentration of 0.1 U/ml could almost completely protect the oral mucosal fibroblast (OMF) from arecoline-induced cytotoxicity. Arecoline is a muscarinic receptor agonist. However, atropine, a muscarinic receptor antagonist was unable to protect the cells from arecoline cytotoxicity at a concentration of 10 microM. Pretreatment of OMF with 50 microM buthionine sulfoximine (a cellular GSH synthesis inhibitor) or 0.5 mM diethylmaleate (a cellular GSH depleting agent) potentiated the cytotoxic effects of arecoline. These results indicate that cytotoxicity of arecoline on OMF is associated with cellular GSH levels and esterase activities. Factors that induce the GSH synthesis or esterase activity of oral mucosal cells can be used for future chemoprevention of BQ chewing-related lesions.

Acetylcysteine↗

PubMed1999

Caries prevalence and bottle-feeding practices in 2-year-old children with cleft lip, cleft palate, or both in Taiwan.

OBJECTIVE: The purposes of this study were to investigate the caries prevalence in cleft lip, cleft palate, or both in children under the age of 2 years and to evaluate parental attitudes toward bottle-feeding, dental care, and their relationship to baby bottle tooth decay (BBTD) in Taiwan. DESIGN: Randomized and prospective study. SETTING: Institutional setting. PATIENTS AND METHODS: One hundred twenty-three 2-year-old children (68 boys and 55 girls) with cleft lip, cleft palate, or both were selected for this study. A questionnaire that asked questions about knowledge of oral health, knowledge and beliefs about BBTD, children's feeding habits, children's dental care, and parenting attitudes toward children with clefts was completed by the parents or caretakers. Children were divided into bottle-feeding and non-bottle-feeding groups according to the questionnaire responses of parents or caretakers. Each child was examined with a dental mirror and explorer under focused flashlight using defs index to determine the presence of BBTD. RESULTS: Thirty-nine percent (48) subjects reported a bottle-feeding habit; the overall prevalence of BBTD was 15.4%. The habit of bottle-feeding was significantly related to BBTD (p = .019). The defs score for children who were bottle-fed was significantly higher than children who were not bottle-fed (p = .045). Parents or caretakers of both bottle-feeding and non-bottle-feeding children showed no significant differences in their attitudes toward bottle-feeding and feeding habits (p > .05). However, parents of non-bottle-fed children had significantly better dental care than parents of bottle-fed children in brushing frequency (p < .001) and brushing before bed (p < .001). CONCLUSIONS: Children with clefts who took a bottle to bed showed an increased risk of developing BBTD. The parents or caretakers of bottle-fed children also showed a lack of motivation to perform regular preventive dental home care for their children. This suggests that oral health promotion programs should begin in infancy for children with clefts and their parents.

Attitude to Health↗

PubMed1998

Oxidative stress induced by humic acid solvent extraction fraction in cultured rabbit articular chondrocytes.

Kashin-Beck disease (KBD), an endemic, chronic osteoarthritic disorder with necrosis of chondrocytes, commonly occurs in China. The humic substance present in the drinking water of endemic areas has been proposed as one of the causative factors. In this study an in vitro cell culture system was used to investigate the damaging effects of humic acid (HA), a constituent of humic substance, on cultured rabbit articular chondrocytes. The commercial Aldrich humic acid (AHA) was fractionated with a series of organic solvents including n-hexane, benzene, ethyl acetate, and methanol. Among the several fractions of AHA, the ethyl acetate fraction (AHA-[EA]) displayed the most potent inhibitory effect on the survival of chondrocytes in clonogenic assays. Cellular injury induced by AHA-[EA] was evaluated by measuring cell viability with methylthiazol tetrazolium (MTT) and by determining the release of intracellular lactate dehydrogenase (LDH). Incubation of chondrocytes with AHA-[EA] (100-500 microg/ml) for 12 h produced a concentration-dependent decrease in cell viability and increase in LDH release. In addition, AHA-[EA] triggered lipid peroxidation manifested by elevated malondialdehyde (MDA) formation. In chemiluminescence assay, AHA-[EA] at the concentrations of 150-600 microg/ml caused 6- to 15-fold increases of luminol-amplified chemiluminescence responses, which are considered to reflect the production of hydrogen peroxide (H2O2). Moreover, pretreating the cells with 500-750 U/ml of catalase significantly prevented the loss of cell viability, while superoxide dismutase (SOD) enhanced the adverse effect of 300 microg/ml AHA-[EA]. Data suggest that the injury to chondrocytes induced by AHA-[EA] may be first through O2.- production, which is then converted into H2O2, thus initiating lipid peroxidation and leading to chondronecrosis observed in KBD.

Animals↗

PubMed1998

Catalase prevents estradiol-induced chondrocyte cytotoxicity.

Osteoarthritis is a common geriatric disease and estrogen may play an important role in this disease. Estradiol may cause chondrocyte damage as suggested by in vitro and in vivo data. One of the possible mechanisms of estradiol-induced chondrocyte damage was thought to be related to free radicals. Whether catalase, a known free radical scavenger, can prevent estradiol-induced chondrocyte damage was tested using a chondrocyte culture system. The results of this study suggest that catalase can significantly reduce the estradiol-induced damage to chondrocytes. Apparently, catalase alters the molecular structure of estradiol as indicated by the absorption spectrum of estradiol with time. The modified estradiol may decrease its toxicity to the chondrocytes. However, the contents of free radicals in the treated chondrocytes have no significant difference from the untreated control cells. Studies to further investigate the mechanism or prevention of estradiol-induced chondrocyte damage in osteoarthritis are warranted.

Animals↗

PubMed1998

Effects of ovarian steroid hormones and thyroxine on calcitonin secretion in pregnant rats.

In the present study, the roles of ovarian steroid hormones and thyroxine (T4) in regulating the secretion of calcitonin (CT) in pregnant rats were examined. The levels of plasma progesterone, pre- and post-CaCl2 plasma CT, and recovery time of plasma CT and calcium after calcium challenge were greatest in midterm pregnant rats. The levels of basal plasma progesterone, CT, calcium, and recovery time of plasma CT after calcium challenge were less in late pregnant rats, but basal plasma estradiol was highest in late pregnancy. The concentrations of plasma T4 were gradually decreased in rats during pregnancy. Regardless of the presence of estradiol, administration of progesterone in ovariectomized (Ovx) rats resulted in an increase of plasma T4 as well as the basal and calcium-induced secretion of CT. Administration of estradiol alone did not alter the CaCl2-induced levels but decreased the post-CaCl2 levels of plasma calcium in Ovx rats. The basal levels of plasma CT were decreased in Ovx rats treated with T4. These results suggest that the hypercalcitoninemia in midterm pregnant rats is due to an increased secretion of progesterone. Hypocalcitoninemia in late pregnant rats, however, is due in part to lower plasma calcium.

Animals↗