Biomedical subjects

Y J Lin

Publications and source records attributed to Y J Lin.

At least 37 records · Page 2Linked to original sources

PubMed2000

Fourth branchial cyst presenting with neonatal respiratory distress.

Fourth branchial cysts are quite rare. A neonate with a left lateral neck mass and respiratory distress was found to have a fourth branchial cyst, which was diagnosed with computed tomography and endoscopy. The characteristic computed tomography findings included an air-containing neck cyst, which was located at the anteromedial site of the common carotid artery with mediastinal extension. Endoscopic examination revealed an internal opening at the apex of the pyriform sinus, communicating with the cyst. Total excision of the cyst was performed, and the specimen, which showed ciliated columnar epithelium with a subepithelial lymphoid infiltrate, thyroid follicles, and thymic tissue, histologically confirmed the diagnosis.

Branchioma↗

PubMed2000

'Sloughing-off' of heterochromatin in Werner's syndrome cells during high-temperature phosphate incubation.

Previous investigations of cells undergoing rapid division revealed the presence of heterochromatic 'dots' in chromosomes as well as numerous chromocentres in interphase nuclei. Such structures were seen in human embryonic cells, as well as cells from organisms capable of regeneration, and cells from various malignancies. Cells with a reduced capacity for reproduction were found to be virtually devoid of nuclear chromocentres and chromosome dots after incubation in phosphate buffer at high temperature. The lack of heterochromatin in such cells (Werner's syndrome) thereby explained their reduced capacity for cell division and the resultant rapid rate of aging in individuals afflicted. Re-examination of such slides containing these cells revealed that chromocentres and chromosome dots were present initially, but the incubation process resulted in a 'sloughing-off' of such structures. The incubation process left these heterochromatic structures intact in malignant and control cells, inferring a link between cell proliferation and stable intact heterochromatin. These findings implicate heterochromatin as the object of the purported chromosomal instability factor characteristic of Werner's syndrome. The loss of heterochromatin did not result in chromosome breakage, suggesting that heterochromatin may not be an integral part of chromosome structure, but rather a surface feature or covering.

Cell Division↗

PubMed2000

'Glowing' chromosomes in cells undergoing rapid division.

Previous investigations in which metaphase plates of cells in rapid division were incubated in phosphate buffer at high temperature revealed numerous heterochromatic dots in chromosomes after Giemsa staining. In contrast, chromosomes from cells with a reduced capacity for reproduction were devoid of such dots, or the dots were sloughed-off into rings and patches of heterochromatin. In two types of cells which were rapidly dividing, namely HeLa cells (cervical cancer) and cells from regenerating planaria, phosphate incubation followed by Giemsa staining revealed an 'aura' or 'glowing' effect on the chromosomes, consisting of a densely staining core surrounded by a lightly stained periphery. This finding might be developed into a diagnostic test for certain malignancies, for cells undergoing dedifferentiation, or for tissues undergoing regeneration.

Animals↗

PubMed2000

Buccal absorption of triclosan following topical mouthrinse application.

PURPOSE: To determine clinically the buccal absorption and plaque retention of triclosan from a mouthrinse containing 0.03% triclosan. MATERIALS AND METHODS: 15 ml of the triclosan oral rinse (N=9) or placebo mouthrinse (N=12) was used twice daily for 21 days in humans. Blood, dental plaque and the expectorated oral rinse were collected prior to, during the treatment period at given intervals, and 8 days after the treatment. Dental plaque and blood samples were collected 1 hr and 4 hr after the morning rinse, respectively. The oral retention of triclosan was calculated by subtracting the amount of triclosan recovered in the expectorate from the triclosan dose applied (4.50 mg) in the mouthrinse. Plasma samples were analyzed for free triclosan (the parent molecule) and its glucuronide and sulfate conjugates, whereas dental plaque was analyzed only for total triclosan. RESULTS: No significant treatment-related adverse effects were observed during the clinical phase of the study. The average daily oral retention of triclosan was calculated to be 0.660 mg, which is 7.33% of the triclosan dose applied (2 x 4.50 mg). Plaque contained an average 20.5-46.4 microg of triclosan per g of plaque collected. At various sampling times, mean plasma concentrations were: no detectable triclosan, 63.8-86.3 microg/ml of triclosan glucuronide and 8.23-18.0 ng/ml of triclosan sulfate. The mean total triclosan plasma concentration ranged from 74.5 to 94.2 microg/ml with plateau concentrations reached after 2 days of dosing. Eight days after the last treatment the triclosan plasma concentration returned to baseline levels (< 2 ng/ml).

Absorption↗

PubMed2000

Clinical evidence for the lack of triclosan accumulation from daily use in dentifrices.

PURPOSE: To demonstrate through clinical pharmacokinetic studies that triclosan does not accumulate in blood or plasma in human subjects who regularly use triclosan-containing dentifrice. MATERIALS AND METHODS: Three clinical pharmacokinetic studies were conducted to assess the blood or plasma levels of triclosan following toothbrushing with dentifrice formulations containing triclosan. In Study 1, both a single-dose and a multiple-dose phase were conducted. In the single-dose phase, subjects brushed one time with 1.25 g dentifrice containing 0.3% triclosan (3.75 mg triclosan dose) and ingested all of the dentifrice. Blood samples were collected at multiple time points from pre-dose to 72 hrs post-dose and analyzed for total triclosan levels. In the multiple-dose phase, these same subjects brushed three times daily as in the single-dose phase. This pattern was followed for 12 consecutive days. Blood samples were taken for triclosan analysis at multiple time points up to 48 hrs after the first dose of day 12. Study 2 was a parallel, open-labeled clinical study to compare triclosan blood levels from twice daily brushing with 1 gm of dentifrice containing 0.2% triclosan to twice daily ingestion of 20 ml of a 0.01% triclosan aqueous solution over a period of 21 days. Blood samples were taken for triclosan analysis at baseline and at 4 hrs after the morning dose on days 7, 14, and 21. Study 3 was a parallel, double-blind, 12-wk brushing study with dentifrice containing 0.2% triclosan or a matching placebo. Blood samples were taken for triclosan analysis at baseline and at 3 and 12 wks at 4 hrs after the morning dose. RESULTS: In the single-dose study, Triclosan was absorbed into the systemic circulation with a T(1/2) of the terminal plasma concentration ranging between 6-63 hrs. The mean AUC(0-inf) after a single dose was found to be 2,809 ng x hr/ml. After 12 days of three times daily toothbrushing and ingestion of the dental slurry, the mean triclosan plasma concentration was 352 ng/ml in the steady state period, and the mean AUC in a 24-hr period (AUC24) was found to be 8,460 ng x hr/ml. This AUC24 was normalized for the number of brushings for comparison to the AUC(0-inf) after a single brushing. There was no significant (P = 0.93) difference between these AUC values suggesting a complete elimination of daily triclosan dose and no increase in the triclosan level during repeated brushing/ingestion. In the two other dentifrice studies, the triclosan blood concentration appeared to reach a steady state level by day 7 and was maintained at the steady state level (14 to 21 ng/ml) for up to 12 wks. These results support the conclusion that the elimination of a daily triclosan dose is complete and no accumulation of triclosan was observed even after three times daily toothbrushing with 1.25 g dentifrice containing 0.3% triclosan and full ingestion of the dentifrice.

Anti-Infective Agents, Local↗

PubMed1999

Prevention of chronic lung disease in preterm infants by early postnatal dexamethasone therapy.

Recent studies suggest that early dexamethasone therapy may lessen the pulmonary inflammation in preterm infants with respiratory distress syndrome (RDS). To investigate whether early (<12 hr) postnatal dexamethasone therapy would reduce the incidence of chronic lung disease (CLD), a randomized, double-blind, controlled trial was conducted in 40 infants (birth weights from 500 to 1,999 gm) who had severe RDS and required mechanical ventilation within 6 hr of birth. All infants received one dose of Survanta before they were randomly assigned to control (saline placebo) or dexamethasone-treated groups (0.5 mg/kg/d for 1 week, then tapered over 3 weeks). Sequential analysis was performed with the end point of assessment being the presence or absence of CLD on postnatal Day 28. Statistical significance favoring dexamethasone was reached when 12 consecutive pairs in which one infant had CLD and the other did not have CLD showed that ten pairs favored dexamethasone and two pairs favored control treatment. Among the survivors, 12/15 were extubated in the dexamethasone group and 9/16 in the control group at the end of study. Infants in the treated group had transient hyperglycemia and hypertension. There was no difference between the groups in mortality and in incidence of sepsis or intraventricular hemorrhage. We conclude that early postnatal dexamethasone therapy is potentially effective in the lessening of CLD in preterm infants. To substantiate our result, large randomized controlled trials are needed and warranted.

Anti-Inflammatory Agents↗

PubMed1999

Effect of simulated sunlight on atrazine and metolachlor toxicity of surface waters.

Atrazine and metolachlor are the two most widely used herbicides in the United States; through non-point-source runoff both herbicides may cause toxicity to aquatic organisms. Toxicity changes were measured for atrazine and metolachlor in surface waters after exposure to simulated sunlight (0, 20, and 40 kJ/m2) using a Xenon Weather-Ometer. A Microtox toxicity test, using the marine luminescent bacterium Vibrio fischeri, was conducted on deionized, river, and bay water samples mixed with atrazine or metolachlor herbicide (12 mg/liter) after exposure to simulated sunlight. Microtox test (EC50%) results demonstrated that the toxicity decreased with increasing light intensity for both herbicides in river and bay water. These results also indicate that the toxicity of the bay water, with high concentrations of organic and suspended matter, was reduced, for both herbicides, compared with the toxicity of the river water, possibly through photodegradation of pesticides.

Acetamides↗

PubMed1999

Prospective randomized comparison between pylorus-preserving and standard pancreaticoduodenectomy.

BACKGROUND: Pancreaticoduodenectomy, with either gastrectomy (Whipple procedure) or pylorus-preserving pancreaticoduodenectomy (PPPD), is a complex procedure. Technical diversity, variation and sampling bias exist among surgeons. Previous reports comparing these two procedures are retrospective and not randomized. These factors should be considered seriously and eliminated in comparisons between the two procedures. METHODS: From August 1994 to August 1997, a prospective randomized comparison was conducted between the Whipple procedure and PPPD performed by the same surgeon with the same approach and same anastomotic fashion for periampullary cancer. After exclusion of seven patients, 31 patients were eligible for the study, 16 receiving PPPD and 15 a Whipple procedure. No significant difference in the age, sex distribution, tumour localization or staging was noted between the two groups. RESULTS: One operative death after PPPD and no operative death after the Whipple procedure resulted in a 3 per cent mortality rate in the 31 patients. Median duration of the Whipple operation was 235 (range 195-305) min, with a median blood loss of 500 (range 230-3100) ml and a median blood transfusion of 0 (range 0-10) units. In the patients who had PPPD, median operating time was 230 (range 170-275) min, median blood loss was 350 (range 100-1200) ml and median blood transfusion was 0 (range 0-4) units. There were two minor leaks from the pancreaticojejunostomy after the Whipple procedure and no leakage after PPPD, resulting in 6 per cent minor leakage in 31 patients. These outcomes were not significantly different. Delayed gastric emptying was observed more frequently after PPPD (six of 16 patients) than after the Whipple procedure (one of 15 patients), with marginal significance (P = 0.08, two-sided Fisher's exact test). CONCLUSION: In this prospective randomized study, both PPPD and the Whipple procedure were associated with low mortality and operative morbidity rates. There was no significant difference between PPPD and Whipple resection in terms of operative mortality and morbidity, operating time, blood loss and blood transfusion. PPPD was associated with more frequent delayed gastric emptying, although study of more patients is needed to confirm this.

Adult↗

PubMed1999

Early dexamethasone therapy and blood cell count in preterm infants.

OBJECTIVE: To assess the effects of early postnatal dexamethasone therapy on hematologic values in preterm infants. MATERIALS AND METHODS: We reviewed the hematologic data of 179 preterm infants who participated in a double-blind clinical trial of early postnatal dexamethasone therapy (<12 hours after birth) for the prevention of chronic lung disease. One group (86 infants) received saline and the other group (93 infants) received dexamethasone. Dexamethasone was given intravenously every 12 hours in tapering doses: 0.25 mg/kg on days 1 to 7, 0.12 mg/kg on days 8 to 14, 0.05 mg/kg on days 15 to 21, and 0.02 mg/kg on days 21 to 28. Blood samples were obtained on days 0, 3, 7, 10, 14, 21, and 28. None of the infants received prenatal steroid therapy. RESULTS: Multiple regression analysis revealed significant differences in the values versus time curves of the white blood cell, neutrophil, lymphocyte, basophil, and eosinophil counts between the two groups. The white blood cell count was significantly higher in the dexamethasone group on days 7 through 14, and this was associated with significantly higher numbers of segmented neutrophils and band forms and significantly lower numbers of lymphocytes and eosinophils. The hematocrit and platelet counts were similar in the two groups throughout most of the trial. Except for platelet count, steroid therapy did not alter the hematologic values for infants with bacteremia. CONCLUSION: Dexamethasone affects white blood cell, segmented neutrophil, lymphocyte, basophil, and eosinophil counts in neonates. This should be taken into consideration when evaluating preterm infants who are receiving dexamethasone.early dexamethasone therapy; neonatal blood count; preterm infant; respiratory distress syndrome.

Bacteremia↗

PubMed1999

The role of pulmonary inflammation in the development of pulmonary hypertension in newborn with meconium aspiration syndrome (MAS).

1. There was no clear correlation between the tracheal aspirate cytokines and the elevation of pulmonary arterial pressure in newborn piglets with MAS. The use of dexamethasone significantly suppressed tracheal aspirate cytokines but did not significantly alter pulmonary arterial pressure. Dexamethasone significantly increased the cardiac stroke volume and blood pressure. 2. Early dexamethasone therapy (< 12 hrs) for one week in infants with MAS significantly improved pulmonary ventilation and facilitated weaning from mechanical ventilation. 3. The mechanisms for the improvement in cardiopulmonary status following early dexamethasone therapy in MAS remain unclear. An overall improvement in cardiac hemodynamics, along with a significant decrease in lung inflammation may be responsible for the improvement.

Animals↗

PubMed1999

Serum hepatocyte growth factor levels in patients with inflammatory lung diseases.

HGF is a pulmotrophic factor in the regeneration of an injured lung. However, the physiological role of HGF in vivo remains largely unknown. We studied HGF in patients with inflammatory lung diseases to investigate the clinical significance of HGF and compared with C-reactive protein (CRP) in inflammatory lung diseases. Forty-seven patients with inflammatory lung diseases (16 tuberculosis, 18 pneumonia, and 13 chronic obstructive pulmonary disease (COPD)) were studied. Fifty normal, healthy individuals were analyzed as normal control subjects. Serum HGF levels were measured by enzyme-linked immunosorbent assays (ELISA). Serum CRP levels were also performed. The mean +/- SE numbers of serum HGF levels in the patients with inflammatory lung diseases (4.33 +/- 0.41 ng/ml) were significantly elevated when compared with those in normal control subjects (0.36 +/- 0.02 ng/ml) (p < 0.0001). Serum HGF levels in patients with COPD was significantly lower than those were with tuberculosis or pneumonia (p < 0.05). There was a significant correlation between serum HGF levels and CRP in inflammatory pulmonary diseases (r = 0.48, p = 0.00087). The significantly decreased serum HGF levels in patients with improved inflammatory lung diseases were also observed subsequently. Our results suggest that secreted HGF may play an important role in bronchial epithelium reconstruction during respiratory inflammation.

Adolescent↗

PubMed1999

Effect of dexamethasone on the intestinal first-pass metabolism of indinavir in rats: evidence of cytochrome P-450 3A [correction of P-450 A] and p-glycoprotein induction .

Indinavir, a potent and specific inhibitor of HIV protease, is a known substrate of cytochrome P-450 (CYP) 3A and p-glycoprotein. The purpose of this study is to investigate and compare the inducing effect of dexamethasone (DEX) on CYP3A and p-glycoprotein in the hepatic and intestinal first-pass metabolism of indinavir in rats. Pretreatment of rats with DEX had little effect on the pharmacokinetics (Cl and T(1/2)) after i.v. administration of indinavir, whereas DEX markedly altered the peak concentration (C(max)) and bioavailability of indinavir after oral dosing. The C(max) decreased from 2.8 microM in control rats to 0.28 microM in DEX-treated rats, and bioavailability decreased from 28 to 12.4%. The decreased bioavailability after DEX pretreatment was due mainly to an increase in first-pass metabolism. Intestinal first-pass metabolism (E(G)) increased from 6% in control rats to 34% in DEX-treated rats, and hepatic first-pass metabolism (E(H)) increased from 65 to 82%. Analysis of in vitro kinetic data revealed that the increased intestinal and hepatic metabolism by DEX was attributed to an increase in the V(max), as a result of CYP3A induction, without a significant change in the K(m) values. DEX pretreatment also induced p-glycoprotein in the intestine and liver of rats. p-Glycoprotein appeared to increase the intestinal metabolism of indinavir whereas it had little effect on the hepatic metabolism of indinavir. Although it has been suggested that the role of intestinal metabolism for some drugs is quantitatively greater than that of hepatic metabolism in the overall first-pass metabolism, the contribution of intestinal metabolism to the overall first-pass metabolism of indinavir in rats is not quantitatively as important as the hepatic metabolism, regardless of DEX induction.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1999

Further studies on chromocentres and their implications in regeneration.

Previous investigations using a number of invertebrates, as well as regenerative tissues/organs of various vertebrates, have promulgated the hypothesis that heterochromatin, in the form of nuclear chromocentres, is correlated with the ability to regenerate. In order to test the universality of this hypothesis, cells from a variety of additional animals were examined for the presence of nuclear chromocentres. In accordance with the hypothesis, cells from these organisms contained numerous chromocentres. Evidence indicates that chromocentres, double minute chromosomes, chromosome 'dots', and telomeres may be different forms of the same heterochromatin entity.

Animals↗

PubMed1998

NH2-terminally truncated HER-2/neu protein: relationship with shedding of the extracellular domain and with prognostic factors in breast cancer.

We identified an NH2-terminally truncated HER-2/neu product of M(r) 95,000 with in vitro kinase activity by Western blotting and immunoprecipitations using domain-specific antibodies. p95 levels correlated with the extracellular domain (ECD) shed from different cells under varied conditions. Both ECD and p95 were at approximately 20-fold lower levels in SKOV3 ovarian carcinoma cells, as compared to BT474 breast carcinoma cells. Both were stimulated by treatment of cells with the phorbol ester tumor promoter phorbol 12-myristate 13-acetate and the lysosomotrophic agent chloroquine. The hydroxamate inhibitor of metalloproteases, TAPI, suppressed both p95 and ECD in a dose-dependent fashion, with maximal inhibition at < or = 10 microM in BT474 cells. Cancer tissues were analyzed by Western blotting and scored for p95HER-2/neu and for p185HER-2/neu expression. Breast and ovarian cancer tissues were both found to express p95HER-2/neu in addition to p185HER-2/neu. Of 161 breast cancer tissues, 22.4% expressed p95, 21.7% overexpressed p185, and 14.3% were p95 positive and overexpressed p185. A higher proportion of node-positive patients (23 of 78) than node-negative patients (9 of 63) expressed p95 in all tumors combined (P = 0.032). In the group that overexpressed p185, those that contained p95 were associated with node-positive patients (15 of 21), whereas those that were p95 negative were associated with node-negative patients (8 of 11; P = 0.017). Neither p95- nor p185-rich patients significantly correlated with tumor size or with hormone receptor status in this study. Our findings show that breast cancers, which express the HER-2/neu oncogene, are heterogeneous with respect to HER-2/neu protein products. p95HER-2/neu appears to distinguish tumors that have metastasized to the lymph nodes from those in node-negative patients.

3T3 Cells↗

PubMed1998

Extended life-span and stress resistance in the Drosophila mutant methuselah.

Toward a genetic dissection of the processes involved in aging, a screen for gene mutations that extend life-span in Drosophila melanogaster was performed. The mutant line methuselah (mth) displayed approximately 35 percent increase in average life-span and enhanced resistance to various forms of stress, including starvation, high temperature, and dietary paraquat, a free-radical generator. The mth gene predicted a protein with homology to several guanosine triphosphate-binding protein-coupled seven-transmembrane domain receptors. Thus, the organism may use signal transduction pathways to modulate stress response and life-span.

Amino Acid Sequence↗

PubMed1998

Elastase in hyperpnea-induced guinea pig airway constriction.

Aerosolized elastase has been shown to produce airway constriction in guinea pigs. In this study, we examined whether endogenous elastase plays a role in isocapnic hyperpnea-induced airway constriction using an elastase inhibitor, eglin-c. The study was divided into three experiments. In the first experiment, we used an elastase inhibitor, eglin-c, to suppress hyperpnea-induced bronchoconstriction. Twenty-two young male Hartley guinea pigs were divided into three groups: control (n=8), eglin-c(1) (a lower dose of eglin-c, n=7), and eglin-c(2) (a higher dose of eglin-c, n=7). In the second experiment, we tested whether eglin-c affects pulmonary function following 15 min of normal air ventilation in two groups of animals: control (n=8) and eglin-c (n=8). In the third experiment, animals were divided into two groups: control (n=7) and compound 48/80 (a mast cell degranulating agent, n=7). Airway function was examined in the anesthetized-paralyzed animal. In the first and third experiments, 15 min of isocapnic hyperpnea caused marked decreases in dynamic respiratory compliance, forced expiratory flow at 0.1 s and maximal expiratory flow at 50% total lung capacity, demonstrating hyperpnea-induced airway constriction. This bronchoconstriction was significantly attenuated by eglin-c and by pretreatment with compound 48/80. In the second experiment, eglin-c did not significantly affect bronchial function following normal air ventilation. These data suggest that elastase released from mast cells directly or indirectly induces hyperpnea-induced bronchoconstriction.

Animals↗

PubMed1998

U-37883A potently inhibits dopamine-modulated K+ channels on rat striatal neurons.

An 85 pS K+ channel of rat caudate-putamen neurons, which is activated by dopamine D2 receptors and inhibited by sulfonylurea drugs, was studied using cell-attached patch-clamp electrophysiology. This channel was inhibited by externally-applied U-37883A (4-morpholinecarboximidine-N-1-adamantyl-N'-cyclohexyl hydrochloride), a blocker of vascular ATP-sensitive K+ channels, with a half-maximal effect at a concentration of approximately 0.1 microM. Channel inhibition occurred in a time-dependent fashion when U-37883A was applied to the membrane from a back-filled patch pipette. Inhibition was associated with a decrease in fractional open time, but was voltage-insensitive and did not alter channel conductance, suggesting an effect on channel gating at a site largely insensitive to the electrical field of the channel. U-37883A was about 50 times more potent at inhibiting this channel than was the sulfonylurea drug glibenclamide. This relative potency, opposite to that found in pancreatic tissue, indicates that U-37883A is a useful tool to distinguish amongst different subtypes of sulfonylurea-sensitive K+ channels.

Adamantane↗

PubMed1998

Low and high frequency electroacupuncture at Hoku elicits a distinct mechanism to activate sympathetic nervous system in anesthetized rats.

To address the effect of electroacupuncture (Ea) on autonomic nerve activity, the responses of rhythmic micturition contraction (RMC), urine excretion (UE), blood pressure (BP), renal sympathetic nerve activity (RNA) and pelvic parasympathetic nerve activity (PNA) to Ea were investigated in urethane-anesthetized rats. The acupoint Hoku (Li-4) was tested with two different stimulation frequencies (2 Hz and 20 Hz). Elongation of the RMC cycle and an increase in UE associated with the elevation of BP and RNA was elicited during Ea at Hoku. However, the pressor response induced by low frequency Ea (LFEa) was different from that by high frequency Ea (HFEa), i.e. a tonic effect was elicited by LFEa, while a phasic one was induced by HFEa. These results imply that: (1) Ea at Hoku may selectively activate the sympathetic, but not the parasympathetic nervous system, (2) Ea at Hoku with a different stimulation frequency may elicit a distinct mechanism to activate the sympathetic nervous system and (3) Ea at Hoku may ameliorate the hyperactive bladder in clinical therapy.

Acupuncture Points↗