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Biomedical subjects

Y L Lai

Publications and source records attributed to Y L Lai.

At least 19 recordsLinked to original sources

Neural stem/progenitor cells survive and differentiate better in PD rats than in normal rats.

To investigate the effects of grafted neural stem/mesencephalic progenitor cells (NSCs/MP) on rotational behavior of Parkinson's disease (PD) rats and the influence of intracerebral environment on NSCs/MP, we observed the survival and differentiation of NSCs/MP transplanted into 6-hydroxydopamine (6-OHDA)-lesioned and intact striatums. NSCs/MP were prepared from E(11-15) rats and proliferated in serum-free medium with bFGF for several weeks. One day after being primed with serum/dbcAMP to differentiate, cell suspensions were grafted into 6-OHDA-lesioned and intact striatums respectively. It had been found that NSCs/MP were able to survive better and differentiate into more tyrosine hydroxylase (TH)-positive neurons in 6-OHDA-lesioned striatums than in intact ones, and apomorphine-induced rotations were obviously attenuated in MP graft models. The data suggested that NSCs/MP tend to survive and differentiate into TH-positive neurons in 6-OHDA-lesioned striatums. The data demonstrated that striatums in which DAergic terminals are destroyed by 6-OHDA undergo some changes and thus provide more appropriate conditions for NSCs/MP to differentiate into mature DAergic neurons. Furthermore, the finding that MP had greater relieving effects on rotational behavior than NSCs suggests that NSCs could not be used in clinical therapy of PD unless being induced into MP in vitro before transplantation.

Animals↗

Mesencephalic progenitors can improve rotational behavior and reconstruct nigrostriatal pathway in PD rats.

The aim of this study was to investigate the possibility of mesencephalic progenitors (MP) in treating Parkinson's disease (PD). MP were prepared from E(11-13) rats and proliferated in serum-free medium with basic fibroblast growth factor (bFGF) for 10 days. Cells were then collected and implanted into the striatum only--single grafts or simultaneously into the substantia nigra (SN) and the striatum--double grafts. Twelve weeks after transplantation, DiI, a fluorescent dye, was microinjected into the ipsilateral striatum. Using this strategy, it was found that MP of double grafts had more potent effects on rotational behavior than that of single grafts. Injection of the retrograde tracer DiI into the striatum resulted in fluorescent-labeled cells within the intranigral grafts in double grafts. These data greatly support that MP transplants could not only improve rotational behavior, but does help to re-establish nigrostriatal connections so that it may become one efficient way in treating PD.

Animals↗

Effect of circumferential undercut placement in the root canal wall on the retention of a tapered post in large and small root canals.

OBJECTIVES: This study examined the influence of root canal space and circumferential undercut placement in the dentine wall on the retention of a prefabricated Root Keeper post. METHODS: Twenty-four extracted single-rooted teeth, having narrow root canal spaces, were decoronated, treated endodontically, and then centrally embedded in resin blocks. All canal spaces were prepared with a no. 2 Peeso reamer to an 8mm depth, and half the specimens were successively treated with a no. 3 Peeso to depths of 5 and 8mm for the small canal group (SC) and large canal group (LC), respectively. An L-type keeper post (Aichi Steel Co.) was luted to each canal with resin cement. The assembly was thermocycled 2000 times (4-60 degrees C), and post retention was measured. Afterwards the dislodged post with the intact structure was sandblasted, and the canal was cleaned and slightly undercut using an inverted cone bur. Six treated posts were recemented for both grooved large canal (GLC) and grooved small canal (GSC) groups, and the repaired retentive strengths were measured. RESULTS: Keeper posts cemented in SC (84.26+/-31.85N) showed better (p<0.05) retention than those cemented in LC (41.92+/-22.36N). Interestingly, the repaired strengths of the recemented post increased in both GSC (104.29+/-11.89N) and GLC (96.65+/-6.91N). All posts, except for one in the GLC, failed at the keeper-post joint. CONCLUSIONS: Prefabricated Root Keeper posts had lower retentive strength in roots with a large canal space. Placement of a circumferential undercut in the root canal wall significantly enhanced the retention of the short tapered posts.

Cementation↗

Learning and memory in the mosquito Aedes aegypti shown by conditioning against oviposition deterrence.

Oviposition site choice by female mosquitoes, Aedes aegypti (L) (Diptera: Culicidae), was affected by rearing them in water treated with 0.016% of the repellent Mozaway trade mark containing citronella and neem. Given a choice between a bowl of repellent-treated and a bowl of untreated water, Ae. aegypti reared in untreated water strongly preferred to oviposit on the clean water (93-98%) instead of repellent-treated water. This demonstrates effective deterrence of oviposition by dilute Mozaway trade mark. Those reared in repellent-treated water were less deterred: 38-46% of their eggs were laid on the repellent-treated water and 54-62% on the clean water. Evidently the female mosquitoes reared in repellent-treated water were conditioned against oviposition site deterrence, as shown when choice tests were conducted 6 days post-emergence from the treated water. This demonstrates learning and memory in the mosquito Ae. aegypti, with implications for dengue vector surveillance and control.

Aedes↗

Endothelin-1 in citric acid aerosol inhalation-induced airway constriction of guinea pigs.

Endotheline-1 (ET-1) has been shown to enhance tachykinin-induced airway constriction. This study was designed to test whether ET-1 is involved in citric acid-induced bronchoconstriction. Forty-eight anesthetized-paralyzed guinea pigs were divided into six groups of 8 animals each: saline control; citric acid; ET-1; ET-1 + citric acid; BQ123 + ET-1 + citric acid; and BQ788 + ET-1 + citric acid. BQ123 and BQ788 are specific ETA and ETB receptor antagonists, respectively. Each animal in the saline control group received 50 breaths of 4 ml saline aerosol and in all citric acid-treated groups was given 50 breaths of 4 ml aerosol generated from 0.6 M citric acid. In all ET-1-treated groups, each animal was exposed to aerosol generated from 10(-8) M ET-1. The animal in the ET-1 + citric acid group was exposed to ET-1 5 min prior to the citric acid. For the last two groups, each animal was first exposed to aerosol generated from either 10(-5) M BQ123 or 10(-5) M BQ788. Five min later, the animal was exposed to ET-1; and then 5 min later was followed by citric acid. Dynamic respiratory compliance (Crs), forced expiratory volume in 0.1 sec (FEV(0.1)), and maximal expiratory flow at 30% total lung capacity (Vmax 30) were obtained before and 3-15 min after citric acid. Either citric acid or ET-1 inhalation caused significant decreases in Crs, FEV(0.1), and Vmax 30, indicating airway constriction. Citric acid-induced airway constriction, for most cases, was not significantly augmented by ET-1. However, either BQ123 or BQ 788 significantly attenuated the airway constriction induced by the combination of ET-1 and citric acid. Also, in an additional study, either BQ123 or BQ788 significantly attenuated citric acid-induced airway constriction. These data suggest that endogenous ET-1 plays an important role in citric acid aerosol-induced airway constriction in guinea pigs.

Administration, Inhalation↗

Construction of single-chain interleukin-12 DNA plasmid to treat airway hyperresponsiveness in an animal model of asthma.

Allergic asthma is strongly associated with the airway inflammation caused by the dysregulated production of cytokines secreted by the allergen-specific type-2 T helper (Th2) cells. Interleukin (IL)-12 is a heterodimeric cytokine, which strongly promotes the differentiation of naive CD4(+) T cells to the type-1 T helper (Th1) phenotype and suppresses the expression of Th2 cytokines. Therefore, immunotherapy with IL-12 has been suggested as a possible therapy for asthma. In previous studies, we developed a murine model of airway inflammation based on the purified, house dust-mite allergen Der p 1 (Dermatophagodies pteronyssinus) as a clinically relevant allergen. We hypothesized that the expression of IL-12 in the airway may represent an effective therapy for allergic airway diseases. In this study, we investigate whether the local transfer of the IL-12 gene to respiratory tissues modifies allergic inflammation and airway hyper-responsiveness (AHR) in our disease model. To enhance the in vivo delivery of the IL-12 gene, we expressed the murine single-chain IL-12 protein from a nonviral vector to which the two IL-12 subunits (p35 and p40) were linked by a 14- to 18-amino-acid linker. One of these single-chain IL-12s, containing an 18 amino-acid polypeptide linker, was stably expressed and had a high level of biological activity comparable to that of native IL-12 in vitro. In mice with Der p 1-induced asthma, the local administration of this IL-12 fusion gene into the lungs significantly prevented the development of AHR, abrogated airway eosinophilia, and inhibited type-2 cytokine production. These findings indicate that the local transfer of the single-chain IL-12 gene is effective in modulating pulmonary allergic responses and may be a convenient method for future applications of DNA vaccination.

Allergens↗

Reactive oxygen species and substance P in monocrotaline-induced pulmonary hypertension.

We attempted to evaluate whether the antioxidants 1,3-dimethyl-2-thiourea (DMTU) and hexa(sulfobutyl)fullerenes (FC(4)S) attenuate monocrotaline (MCT)-induced pulmonary hypertension (PH) by lowering lung substance P (SP) in Wistar rats. Sixty-three rats weighing 297 +/- 8 g were divided into six groups: control; MCT; capsaicin + MCT; MCT + DMTU-1; MCT + DMTU-2; and MCT + FC(4)S. Three weeks before the functional study, saline was injected into each control rat, whereas each MCT rat received 60 mg/kg sc MCT. Rats in the third group received capsaicin pretreatment followed by MCT. A 3-day injection of DMTU was performed during the early (DMTU-1) or the late (DMTU-2) post-MCT period. For the last group, each MCT-treated rat received a daily FC(4)S injection until the commencement of the functional study. Compared to the control group, MCT caused significant increases in pulmonary arterial pressure (Ppa), right ventricular hypertropy, pulmonary arterial medial thickness, lung SP level, and luminol-enhanced chemiluminescence counts in bronchoalveolar lavage. Both capsaicin and antioxidants significantly attenuated the above MCT-induced alterations. SP-induced acute increase in Ppa was exaggerated in MCT-treated rats. These results suggest that oxygen radicals play an important role in MCT-induced PH via elevating lung SP level.

Animals↗

Association between betel quid chewing, periodontal status and periodontal pathogens.

The present investigation examined whether an association exists between betel quid chewing and signs of periodontal disease and determined the prevalence of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis by polymerase chain reaction. The periodontal status of 34 betel quid chewers and 32 non-betel quid chewers were compared. A significantly higher prevalence of bleeding on probing was found in betel quid chewers than non-chewers among the subjects with higher plaque level, greater gingival inflammation, deeper probing depth or greater attachment loss. Also, the results suggested that betel quid chewers may harbor higher levels of infection with A. actinomycetemcomitans and P. gingivalis than non-betel quid chewers. The association persists after adjusting for severity of the clinical parameters. In conclusion, betel quid chewing was associated with a higher prevalence of bleeding on probing where higher clinical levels of disease existed, and with a likelihood of subgingival infection with A. actinomycetemcomitans and P. gingivalis.

Actinobacillus Infections↗

Catecholamines in hyperpnoea-induced airway constriction of guinea pigs.

1. We found previously that propranolol augments hyperpnoea-induced bronchoconstriction (HIB). This study was performed to investigate the underlying mechanism of this aug- menting action of propranolol. 2. In the first series, 45 young Hartley guinea-pigs were divided into five groups: control; propranolol; adrenalectomy; metoprolol and reserpine. Each animal underwent three periods: baseline, hyperpnoea, and recovery. For each animal 1 ml of arterial blood was sampled during the baseline and recovery periods. 3. Treatments of propranolol, metoprolol, and reserpine caused significant decreases in both dynamic respiratory compliance (Crs) and forced expiratory volume in 0.1 s (FEV0.1) during the baseline period. Hyperpnoea caused slight but not significant decreases in Crs, FEV0.1, and maximal expiratory flow at 50% total lung capacity (TLC) (V(max50)) during the recovery period in the control group. Propranolol, but not other treatments, significantly augmented these decreases (indicating HIB). Plasma noradrenaline and adrenaline levels in the reserpine group were not detectable. The above treatments or hyperpnoea did not induce any significant effect on the plasma noradrenaline level. Plasma adrenaline level of the control group was higher than that of either adrenalectomy or reserpine group during the baseline and the recovery periods. 4. In the second series, we avoided repeated blood samplings. Forty-eight animals were evenly divided into two groups: control and propranolol. Each group was again evenly divided into three subgroups: baseline; hyperpnoea, and recovery. Five minutes into the recovery period, we demonstrated HIB in the control group. In terms of V(max50), this HIB was significantly augmented by propranolol. Plasma noradrenaline and adrenaline levels, however, were not significantly altered by either hyperpnoea or propranolol. 5. Taken together, these data suggest that propranolol-augmented HIB has no direct relationship with decreased catecholamine activity.

Adrenalectomy↗

Breast reconstruction with TRAM flap after subcutaneous mastectomy for injected material (siliconoma).

Many patients throughout the world have had breast augmentation using injectable materials. In the Far East, an adulterated impure silicone has been used by non-medical persons and unlicensed 'cosmetic surgeons' as well as by licensed physicians. The injected material usually causes a granulomatous reaction, tenderness, erythema, pain or discomfort and even skin necrosis. Eventually, the injected breast becomes very hard and develops a distorted contour. Previous treatment was by subcutaneous mastectomy with immediate or delayed reconstruction using a silicone prosthesis. The results of this were often unsatisfactory. We obtained more satisfactory results in 11 patients who had the siliconoma removed by subcutaneous mastectomy and the breast reconstructed with a de-epithelialised TRAM flap.

Adult↗

Appropriateness of antibiotic use in the postpartum period.

OBJECTIVE: To determine the appropriateness of current postpartum antibiotic use in clinical practice. METHODS: Medical records were reviewed for all patients delivering in a 3-month period who received postpartum antibiotics during the delivery hospitalization. Subjects were excluded if they received a single postpartum antibiotic dose as part of a mitral valve prolapse prophylaxis protocol, or if they received no more than one postpartum antibiotic dose for surgical prophylaxis. Characteristics of postpartum antibiotic use were abstracted. RESULTS: Two hundred and eleven of 1537 (14%) delivering patients met the inclusion criteria. Seventy-four (35%) delivered vaginally and 137 (65%) delivered by Cesarean section. Postpartum fevers were found in 40 (54%) of vaginal delivery cases and 80 (58%) of women delivering by Cesarean section who received postpartum antibiotics (p = 0.54). For vaginal deliveries there were no differences in the duration of antibiotic use or number of antibiotic doses based on fever status. For Cesarean deliveries, a fever was associated with more antibiotic doses and a longer duration of antibiotic use. Physician justification for antibiotic use was documented in only 116 cases (55%). CONCLUSIONS: The high proportion of women receiving postpartum antibiotics having no evidence for infection or documented indication for therapy suggests that antibiotics may not be appropriately used in the postpartum period.

Adult↗

Life-extending therapies among patients with advanced cancer: patients' levels of pain and family caregivers' concerns about pain relief.

The purposes of this article are to explore the extent to which oncology unit patients with advanced cancer in Taiwan receive life-extending therapies and to examine the relationship of care goals (curative vs palliative) to levels of pain and family caregivers' concerns about pain reporting and analgesic administration. Forty pairs of patients with advanced cancer and their family caregivers (N = 80) were recruited from inpatient oncology units in Taiwan. Of these patients, 53% were receiving chemotherapy or radiotherapy for life-extending or curative reasons as opposed to palliative goals. Patients with advanced cancer who were receiving life-extending therapies experienced lower levels of pain intensity than did those who were not receiving life-extending therapies. Moreover, Taiwanese family caregivers of patients with advanced cancer had concerns about reporting pain and administering analgesics regardless of whether the patient was receiving life-extending therapies. However, the family caregivers whose patients were receiving life-extending therapies were less concerned about using analgesics than were those caregivers whose patients were not receiving life-extending therapies. Finally, family caregivers' concerns about pain management as measured by the Barriers Questionnaire-Taiwan (BQT) form were related to family caregivers' reluctance to report their patients' pain. Implications of this study are discussed in terms of palliative care and pain educational programs.

Adult↗

In vivo pressure-flow curve in unilateral rat lung ischemia-reperfusion injury.

The pressure-flow (P-Q) curve has been widely used in many studies to describe the effects of various factors on vascular hemodynamics. It is not clear, however, whether unilateral ischemia-reperfusion (IR) alters the P-Q curve of the rat lung. In this study, we developed an in vivo P-Q curve using the unilateral (left) rat lung before and after IR. Animals were divided into two groups: sham and IR. The protocol of the IR group consisted of three periods: baseline, ischemia, and reperfusion. P-Q curves were obtained by altering blood flow of the left lung during the baseline and the reperfusion periods. The sham group received the same operation without IR procedure. An additional group was used to compare pulmonary blood flow measured by the microsphere and the ultrasonic methods. IR treatment rotated the P-Q curve toward the left, indicating an increase in resistance in the left lung. However, this rotation was not found in the sham group. A significant correlation (r = 0.87, P < 0.01) between percentages of blood flow obtained by the microsphere and ultrasonic methods in both right and left lungs was demonstrated. Therefore, we demonstrated a simple and useful technique to evaluate changes in the P-Q curves caused by IR in the unilateral rat lung model.

Animals↗

Studies on anthracenes. 3. Synthesis, lipid peroxidation and cytotoxic evaluation of 10-substituted 1,5-dichloro-9(10H)-anthracenone derivatives.

The synthesis of a series of 1,5-dichloro-9(10H)-anthracenones bearing O-linked and N-linked substituents in the 10-position are described. Previous studies have shown that 9-acyloxy 1,5-dichloroanthracenes and 9-acyloxy 1,8-dichloroanthracenes displayed a potential cytotoxic effect. These results have encouraged us in further investigation of potential anthracenone derivatives. Therefore, a series of 10-substituted 1,8-dichloro-9(10H)-anthracenone derivatives were synthesized. These compounds were evaluated for their ability to inhibit the growth of human oral epidermoid carcinoma cells (KB cell line), human cervical carcinoma cells of ME 180 (GBM 8401) and Chinese hamster ovary (CHO) cells, respectively. Compounds 3c and 4c of this series compare favorably in the KB cellular assay with mitoxantrone. Compound 4c showed combined inhibitory action against KB, GBM and CHO cell growth, respectively. In addition, redox property of the compounds for the inhibition of lipid peroxidation in model membranes was determined. Compounds 4b and 4d exhibited stronger antioxidant activity than ascorbic acid, (+)-alpha-tocopherol and mitoxantrone, respectively.

Animals↗

Studies on anthracenes. 2. Synthesis and cytotoxic evaluation of 9-acyloxy 1,8-dichloroanthracene derivatives.

The synthesis and cytotoxic evaluation of 9-acyloxy 1,8-dichloroanthracene derivatives are described. The system selectively reduces the carbonyl group flanked by the peri substituents of the anthracenediones to give the corresponding 1,8-dichloro-9(10H)-anthracenone. Simple acylation of anthracenone occurred with appropriate acyl chlorides in CH2Cl2 with a catalytic amount of pyridine to give the 9-acyloxy-1,8-dichloroanthracene derivatives. Considerable interest has developed in the mechanism of how anthracenones achieve this desirable selectivity. These compounds were evaluated in vitro for their ability to inhibit the growth of human oral epidermoid carcinoma cells (KB cell line), human cervical carcinoma cells of ME 180 (GBM 8401) and Chinese hamster ovary (CHO) cells, respectively, as compared to mitoxantrone. The in vitro cytotoxicity evaluation of 9-acyloxy 1,8-dichloroanthracenes against these above cell lines revealed for most of the compounds a cytotoxic potency lower than that of mitoxantrone. The most active compounds were thus selected for further in vitro biological evaluation and structural modification.

Animals↗

Capsaicin pre- and post-treatment on rat monocrotaline pneumotoxicity.

Monocrotaline (MCT) produces respiratory dysfunction, pulmonary hypertension (PH), and right ventricular hypertrophy (RVH) in rats. Tachykinins, such as substance P (SP) and neurokinin A (NKA), may mediate these effects. The purpose of this study was to investigate the length of tachykinin depletion (via capsaicin treatment) is needed to prevent (or attenuate) PH and/or RVH. Six groups of rats were injected subcutaneously with saline (3 ml/kg); capsaicin followed by saline or MCT (60 mg/kg); or MCT followed 7, 11, or 14 days later by capsaicin. Capsaicin (cumulative dose, 500 mg/kg) was given over a period of 4-5 days. Respiratory function, pulmonary vascular parameters, lung tachykinin levels, and tracheal neutral endopeptidase (NEP) activity were measured 21 days after MCT or saline injection. Capsaicin significantly decreased lung levels of SP but not NKA. Both capsaicin pretreatment and posttreatment blocked the following MCT-induced alterations: increases in lung SP and airway constriction; decreases in tracheal NEP activity and dynamic respiratory compliance. Administration of capsaicin before or 7 days after MCT blocked MCT-induced PH and RVH. The above data suggest that the early tachykinin-mediated airway dysfunction requires only transient elevated tachykinins, while progression of late tachykinin-mediated effects (PH and RVH) requires elevated tachykinins for more than one week.

Animals↗

Mediators and oxygen radicals in hyperpnea-induced airway constriction of guinea pigs.

Leukotrienes (LTs), tachykinins (TKs), and oxygen radicals have been suggested to be important modulating factors for the hyperpnea-induced bronchoconstriction (HIB) of guinea pigs. In this study, we tested the hypothesis that LTs and oxygen radicals modulate HIB by triggering TK release. Eighty-five Hartley guinea pigs were divided into four groups: control, dimethylthiourea (DMTU), FPL 55712, and A63162. DMTU is the scavenger for hydroxyl radical. FPL 55712 is an antagonist of LT receptor, whereas A63162 is an inhibitor of lipoxygenase. Each group was further divided into three subgroups: baseline, hyperpnea, and recovery. Each animal was anesthetized, cannulated, paralyzed, and artificially ventilated. We measured dynamic respiratory compliance (Crs), maximal expiratory flow at 50% total lung capacity (V(max(50))), and forced expiratory volume in 0.1 s (FEV(0.1)) during the baseline and recovery periods. Hyperpnea caused significant decreases in Crs, V(max(50)), and FEV(0. 1), indicating HIB in the control group. Pretreatment with DMTU, FPL 5712, or A63162 attenuated HIB. Plasma substance P (SP) levels increased progressively during the experiment in all groups. However, both FPL 55712 and A63162, but not DMTU, significantly decreased SP levels. Similarly, lung malondialdehyde (MDA) contents increased progressively during the experiment in the control group. Neither FPL 55712 nor A63162 significantly affected the increase. On the contrary, DMTU significantly attenuated the increase in MDA during the recovery period. These results suggest that inhibition of LTs leads to suppression at SP levels and HIB, whereas DMTU attenuates HIB by means of other mechanisms.

Acetamides↗

Wood smoke-induced airway hyperreactivity in guinea pigs: time course, and role of leukotrienes and hydroxyl radical.

A prior airway exposure to wood smoke induces a tachykinin-dependent increase in airway responsiveness to the subsequent smoke inhalation in guinea pigs (Life Sci. 63: 1513, 1998). To further investigate the time course of, and the contribution of other chemical mediators to, this smoke-induced airway hyperresponsiveness (SIAHR), two smoke challenges (each 10 ml) separated by 30 min were delivered into the lungs of anesthetized guinea pigs by a respirator. In the control animals, the SIAHR was evidenced by the bronchoconstrictive response to the second smoke challenge (SM2) which was approximately 5.2-fold greater than that to the first challenge (SM1). This SIAHR was alleviated by shortening the elapsed time between SM1 and SM2 to 10 min or by extending it to 60 min, and was abolished by extending it to 120 min. This SIAHR was reduced by pretreatment with either MK-571 (a leukotriene D4-receptor antagonist) or dimethylthiourea (a hydroxyl radical scavenger), but was not affected by pretreatment with either pyrilamine (a histamine H1-receptor antagonist) or indomethacin (a cyclooxygenase inhibitor). The smoke-induced reduction in the neutral endopeptidase activity (a major enzyme for tachykinin degradation) measured in airway tissues excised 30 min post SM1 was largely prevented by pretreatment with dimethylthiourea. However, this reduction was not seen in airway tissues excised 120 min post SM1. These results suggest that 1) the SIAHR to inhaled wood smoke has a rapid onset time following smoke inhalation and lasts for less than two hours, 2) leukotrienes and hydroxyl radical may play contributory roles in the development of this SIAHR, and 3) hydroxyl radical is the major factor responsible for the smoke-induced inactivation of airway neutral endopeptidase, which may possibly participate in the development of this SIAHR.

Animals↗