Biomedical subjects

Y S Lin

Publications and source records attributed to Y S Lin.

At least 145 records · Page 8Linked to original sources

PubMed1991

Inhibition of the delayed-type hypersensitivity response by staphylococcal enterotoxin B-induced suppressor T cells.

Staphylococcal enterotoxin B (SEB) is a member of a family of gram-positive bacterial exotoxins which act as superantigens in both mouse and man. The administration of this toxin has been shown to inhibit antibody responses in vivo. We have previously shown that SEB is a potent inducer in vitro of multiple T suppressor cell populations. The present studies show that administration of microgram quantities of this toxin result in a reduced capacity to manifest a delayed-type hypersensitivity (DTH) response. In addition, we find that the failure to generate a normal DTH response appears to be due to the generation of a T suppressor cell population following SEB administration. Adoptive transfer studies show that the suppressor cells bear the CD5+ I-J+ CD4- CD8- Thy 1+ surface phenotype. The relationship of these cells to suppressor T cell populations generated following in vitro activation by SEB is discussed.

Animals↗

PubMed1991

Fetal alcohol syndrome: report of a case.

Fetal alcohol syndrome is an uncommon occurrence in Taiwan, especially in the southern area. We report here a case who demonstrated severe intrauterine growth retardation with major limb reduction, chest hypoplasia and characteristic facial dysmorphism-short palpebral fissures, hypoplastic philtrum, and a thin upper lip. The mother had been consuming large quantities of alcohol, 6 bottles of "rice wine" per day (800 grams of absolute alcohol per day) during the pregnancy. The maternal serum level of ethanol was as high as 173 mg/dl. According to previous reports, we causally suggest that maternal ethanol abuse may be related to fetal anomalies in this case.

Adult↗

PubMed1991

Clinical validation of two equations in antenatal prediction of Chinese fetal weight by ultrasonography.

The purpose of this series is to prospectively validate the Chinese equations for predicting fetal weight developed in a previous study. A total of 640 Chinese fetuses were examined antenatally for biparietal diameter (BPD), abdominal circumference (AC) and femur length (FL) by real-time ultrasonography within two days of delivery. The results showed the actual birth weight (BW) to be highly correlated with the estimated body weight for both the equation using BPD and AC (EBW1) (r = 0.888, p less than 0.0001) and the equation using BPD, AC and FL (EBW2) (r = 0.890, p less than 0.0001). Our results demonstrate that the Chinese equations developed by Hsieh et al are a better fit for Chinese fetuses than the foreign equations are. Also, the two Chinese equations predict fetal weight well between 2,000 g and 4,000 g, but further modification is needed in cases where the BW is less than 2,000 g or greater than 4,000 g.

Asian People↗

PubMed1990

Depression of prothymosin alpha production in murine thymus correlates with staphylococcal enterotoxin-B-induced immunosuppression [corrected].

Prothymosin alpha [corrected] (ProT alpha) and thymosin beta 4 [corrected] (T beta 4) were isolated from murine thymus and characterized by microsequence analysis. Murine T beta 4 has an identical sequence to bovine T beta 4, whereas murine ProT alpha is highly homologous to rat Pro T alpha. Murine Pro T alpha differs from rat Pro T alpha at two positions, Glu100 and Asp108 of the rat sequence are substituted by aspartic and glutamic acid, respectively, in murine Pro T alpha. The amount of Pro T alpha in murine thymus was found to be reduced after in vivo treatment with staphylococcal enterotoxin B [corrected] (SEB), a superantigen which stimulates T cells bearing specific V beta receptors. Results from the anti-SRBC (sheep erythrocyte) plaque-forming cell assay showed that the antibody response of the spleen cells from these animals was also suppressed. On the other hand, the amount of T beta 4 was not changed significantly. Our studies suggest that the suppression of SEB on antibody response correlates with the depression of Pro T alpha production in the thymus.

Amino Acid Sequence↗

PubMed1990

How different eukaryotic transcriptional activators can cooperate promiscuously.

A striking characteristic of many different eukaryotic transcriptional activators is their ability to activate gene expression synergistically. Thus, for example, the rat glucocorticoid receptor and the yeast activator GAL4 cooperatively activate transcription of a mammalian gene bearing binding sites for each of the proteins: activation by both activators is greater than the sum of the effects of each working alone. It would seem unlikely that these two proteins from such different organisms directly interact; rather, the idea has been suggested that these and at least some other eukaryotic activators can work synergistically by simultaneously touching some part of the transcriptional machinery. An important prediction of this idea is that synergy between two such activators would be seen under conditions where each is present at concentrations sufficiently high to saturate its site on DNA. In this paper we use transcription in vitro to confirm that prediction using a derivative of the yeast activator GAL4 and the mammalian transcription factor ATF. The accompanying paper describes a similar conclusion comparing the effects of singly and multiply bound GAL4 molecules.

Activating Transcription Factors↗

PubMed1990

A mechanism for synergistic activation of a mammalian gene by GAL4 derivatives.

In prokaryotes and eukaryotes many gene activators work synergistically. For example, two dimers of lambda repressor interact to promote binding of these proteins to DNA, a reaction that is crucial at the repressor concentrations found in lysogens. In this case one of the bound dimers activates transcription, evidently by touching RNA polymerase. In another example, the yeast transcriptional activator GAL4, which can stimulate transcription in many eukaryotes, binds to multiple sites on DNA to activate transcription synergistically; the presence of two such sites can elicit a level of transcription more than twice that found with a single site. In this paper we show that synergistic activation by each of several GAL4 derivatives involves a mechanism different from that illustrated by the lambda repressor: multiple activator molecules can work synergistically under conditions in which their binding sites on DNA are saturated. The accompanying paper shows that under similar conditions of activator excess, GAL4 derivatives work synergistically with a heterologous mammalian gene activator. These results support the idea that eukaryotic activators can cooperate not by directly interacting but by simultaneously touching some component(s) of the transcriptional machinery.

Binding Sites↗

PubMed1990

Characterization and genetic restriction of suppressor-effector cells induced by staphylococcal enterotoxin B.

The capacity of the staphylococcal enterotoxins to stimulate all T cells bearing certain (but not all) TCR has generated a great deal of interest. This stimulation appears to involve specific binding of the toxin to class II Ags and subsequent stimulation via the TCR. Previous studies from this laboratory have demonstrated that staphylococcal enterotoxin B (SEB) induces multiple T suppressor cell populations that inhibit both primary and secondary plaque-forming cell responses. Efforts to characterize these suppressor cell populations have demonstrated that the suppressor population active early in the antibody response expresses the Lyt-1-2+ cell surface phenotype, whereas depletion analysis suggests that the population active late in an ongoing response bears the Lyt-1+2+ cell-surface markers. In the present study, enrichment for this late acting effector population with the use of sequential panning with anti-Lyt mAb reveals significant suppressive activity at both the initiation and effector phases of a 5-day Mishell-Dutton coculture. Additional experiments using I-J disparate strains of mice have demonstrated a genetic restriction at the "I-J" gene locus between the cells mediating SEB-induced suppression and their target. Depletion of SEB-primed splenocytes with anti-I-J mAb suggests that both the early and late effector cells bear I-J molecules on their surface. Taken together, these results show that SEB induces suppressor cell populations with properties similar to those exhibited by Ag-specific cell circuits.

Animals↗

PubMed1990

Requirement for accessory cells in suppression of MOPC-315 IgA secretion by staphylococcal enterotoxin B-induced T-suppressor cells.

Staphylococcal enterotoxin B (SEB) is a potent polyclonal activator of both human and murine T cells. We previously reported data which show that SEB-induced T cells suppress antibody secretion by various mouse plasmacytoma cell lines. This suppression of antibody secretion was found to be both idiotype and isotype nonspecific, and the suppressor cell bears the CD5-positive CD8-negative cell surface phenotype. The present studies demonstrate that accessory cells are required in the SEB-primed spleen cell (SEB-PSC) population in order for this population to mediate suppression. The suppressive activity of SEB-PSC is abrogated following accessory cell depletion by passage over Sephadex G-10 columns. B cell depletion using nylon-wool also abrogates suppression mediated by SEB-PSC. The addition of nonelicited adherent peritoneal exudate cells (PECs) restores suppressive activity to accessory cell-depleted SEB-PSC. The restoration of suppression by the PECs is not major histocompatibility complex restricted, since both syngeneic and allogeneic PECs can carry out this activity. In addition, it is not necessary for the accessory cells to be metabolically active in order to participate in the suppressive activity. This is based on results demonstrating that glutaraldehyde fixation, at levels reported to eliminate metabolic activity, does not affect the ability of PECs to restore suppression to Sephadex G-10-depleted SEB-PSC. The results are consistent with the well established requirement for accessory cells in the function of antigen-induced suppressor T cells.

Animals↗

PubMed1990

Immunosuppressive activity of staphylococcal enterotoxin B. I. Characterization of staphylococcal enterotoxin-B-induced suppressor cells.

Staphylococcal enterotoxin B (SEB) binds specifically to major histocompatibility complex class II molecules on the surface of accessory cells and stimulates virtually all T cells bearing certain, but not all, T cell-receptor V beta alleles. We have previously shown that this superantigen is a potent inducer of multiple regulatory T cell populations. In the present report we show that SEB induces a population of suppressor T cells which inhibits the generation of alloantigen-induced cytotoxic T cell activity. Using both negative- and positive-selection analysis, we found that this suppressor population is a CD4- CD8- CD5+ IL-2R+ T cell. This cell population inhibited both syngeneic and allogeneic cytotoxic T lymphocyte activity, but the cell population which inhibited allogeneic CTL activity was radiation sensitive. In addition, allogeneic SEB-primed cells appeared to develop cytolytic activity as a result of the additional stimulation in the mixed-lymphocyte reaction culture. The relationship of the SEB-primed CD4- CD8- CD5+ T cells to related regulatory T cell populations is discussed.

Animals↗

PubMed1990

Immunosuppressive activity of staphylococcal enterotoxin B. II. Activation of suppressor-effector cells by a staphylococcal enterotoxin B-induced suppressor factor.

The capacity of staphylococcal enterotoxins to stimulate all T cells bearing certain T cell receptors has recently generated a great deal of interest. These toxins are believed to bind directly both to the TCR:CD4 complex via its V beta domains and to class II MHC molecules on accessory cells prior to T cell activation. Previous studies from this laboratory have demonstrated that staphylococcal enterotoxin B (SEB) is capable of inducing multiple T suppressor cell populations which can inhibit in vitro antibody responses. Additional studies have demonstrated that the suppressive activity of these cells is mediated, at least in part, by an I-J-restricted suppressor factor. Efforts to characterize the inhibitory activity of this factor have demonstrated that the suppressive element is capable of activating both early and late acting suppressor cell populations in vitro. Analysis by both positive and negative selection shows that cells bearing the Lyt1-2+ surface marker phenotype are active early, whereas Lyt1+2+ cells are active both early and late in the antibody response. Additional experiments using various strains of mice as sources of suppressor factor and of naive splenocyte populations have demonstrated that activation of suppressor-effector cells by this suppressor factor is restricted at the I-J, but not Igh, gene locus. These studies suggest that this SEB-induced suppressor factor alone provides the signals necessary for the induction and activation of suppressor-effector cell activity.

Animals↗

PubMed1990

[Influence of dexamethasone on electrical activities in cultured rat beating myocardial cells infected with Coxsackie B-2 virus].

The effects of dexamethasone (Dex) on electrical activities in cultured rat beating myocardial cells infected with 100 TCID-50 Coxsackie B-2 virus (CB2V) was evaluated by conventional intracellular microelectrode technique. The frequency began to increase, the beating % decreased, and multiform arrhythmias were shown in the infected group 24 h post-challenge. Meanwhile, the cytopathic effect (CPE) appeared rapidly from 1+ to 3+. In the infected and Dex-treated group, the beating % was higher and the arrhythmias and CPE were less than in the infected group at the same intervals. The numbers of non-beating cells increased parallel to the incubation time in the infected group. Decreases of maximal diastolic potential (MDP), maximal upstroke rate (Vmax), overshoot (OS) and action potential amplitude (APA), and abbreviation of action potential duration (APD50 and APD100) in infected and Dex-treated group were less than those in control group during 24-96 h post-challenge. Premature beats, tachycardia, bradycardia and fibrillation occurred in the early stages after infection. It is surmised that steroids can probably save the lives of patients with severe myocarditis if Dex was supplemented.

Action Potentials↗

PubMed1990

Effect of astragalus membranaceus on electric activities of cultured rat beating heart cells infected with Coxsackie B-2 virus.

Astragalus membranaceus (AM) which has a protective effect on rat beating heart cells infected experimentally with Coxsackie B-2 virus was evaluated on the basis of changes in morphologic and electric activity of the cells. Rhythm, beating frequency, beating percentage, cardiac cellular damage and cytopathic effects (CPE) were monitored every 24 h after challenge; electric activities parameters were measured by conventional intracellular microelectrode technique. Significant protective effects were demonstrated when AM was given in the early period of infection. The results suggest that AM should be valuable in preventing and treating acute myocarditis caused by Coxsackie B virus.

Action Potentials↗

PubMed1990

General anesthesia with propofol (continuous intravenous infusion) supplemented with nitrous oxide: comparison with isoflurane.

Thirty adult surgical patients (ASA I-II) undergoing superficial operations of short duration (about 1h) were arbitrarily divided into two groups. In group A (n = 15), anesthesia was induced with propofol, 2 mg/kg, iv. After endotracheal intubation with the aid of succinylcholine (1 mg/kg, iv), anesthesia was maintained by continuous iv infusion of propofol (0.05-0.2 mg/kg/min) with nitrous oxide and oxygen (2:1). In group B (n = 15), induction and endotracheal intubation were accomplished using thiopental (4 mg/kg, iv) and succinylcholine (1 mg/kg). Anesthesia was maintained with isoflurane (0.5-2.0%), nitrous oxide and oxygen (2:1). Atracurium was used in both groups as muscle relaxant. Hemodynamic responses to laryngoscopy and endotracheal intubation and during operation were not significantly different between the two groups. However, recovery to verbal command and orientation was significantly more rapid in the propofol group (7.8 +/- 4.8 min and 11.2 +/- 5.1 min) than in the isoflurane group (15.6 +/- 4.9 min and 22.6 +/- 6.0 min). In conclusion, continuous propofol infusion combined with nitrous oxide and muscle relaxant is suggested as a better method compared with isoflurane for short operations because of more rapid complete recovery.

Adult↗

PubMed1990

A new approach to suppress bucking before extubation--lidocaine through modified endotracheal tube.

The conventional endotracheal tube was modified with an epidural catheter adhered on the concave aspect of it. The opening of the catheter is at the proximal margin of the cuff. Local anesthetic can be injected into the trachea, then desensitize the tracheal mucosa nearby the cuff. Thirty-four female gynecological patients underwent abdominal total hysterectomy were studied and divided into three groups. In group 1, anesthesia was maintained without special management. In groups 2 and 3, 2 mL gentian violet stained 4% lidocaine solution was administered intratracheally by two different methods 60-120 minutes before the conclusion of the surgery. The peak cuff pressures generated by the awakening patients were 53.8 +/- 2.2 cm H2O (mean +/- SE) in group 1, 47.3 +/- 2.5 cmH2O (Group 2) and 36.4 +/- 1.6 cmH2O Group 3) respectively. Bucking before awakening was also evaluated clinically and showed 100%, 73% and 0% in each group. Intratracheal administration of lidocaine in dose of 2 mL 4% showed significant effect for the suppression of bucking during the recovery of general anesthesia in group 2 and 3 compared with the group 1. Lidocaine administered through the catheter of modified endotracheal tube also resulted in less increase in the peak cuff pressure and even no clinically observed bucking than direct administered through the endotracheal tube. Gag reflex was preserved in all patients and none had suffered from aspiration postoperatively.

Adult↗

PubMed1990

Estimation of the length of nasopharyngeal airway in Chinese adults.

Nasopharyngeal airway should be placed to reach the tongue base without contact with the epiglottis. The correct length of the nasopharyngeal airway in Chinese adults was estimated in seventy-three surgical patients under general anesthesia (30 males and 43 females, aged 18-82 yr). Measurements were performed with a soft, uncuffed, ID 6.0 mm endotracheal tube (Portex) introduced through the nasopharyngeal passage. The proper tip placement of the tube was evaluated under direct laryngoscopy. The Nostril-epiglottis distance (N-E distance) is 15.31 +/- 1.09 cm (mean +/- SD) for all cases, 16.03 +/- 1.04 cm for male cases and 14.97 +/- 0.95 cm for female cases. There are correlation between the N-E distance and the height (p less than 0.001, r = 0.41), and between the N-E distance and the N-A distance (The distance from nose tip to mandibular angle) (p less than 0.004, r = 0.324). Linear regression analysis relating the N-E distance to the height and the N-E distance to the N-A distance were also statistically significant (p less than 0.001 and p less than 0.01, respectively).

Adolescent↗

PubMed1989

Similarities between prokaryotic and eukaryotic cyclic AMP-responsive promoter elements.

Organisms as diverse as bacteria and man contain genes that show transcriptional induction when the intracellular concentration of cAMP is increased. This regulated transcriptional response is mediated through specific promoter elements located, in general, upstream from the transcription start site. In Escherichia coli the element responsible for cAMP-mediated transcriptional induction is the binding site for the cAMP-receptor protein (CAP). In mammalian cells the cAMP regulatory element is composed of one or more binding sites for various transcription factors. In many instances the cAMP regulatory element contains binding sites for a family of proteins referred to as ATF. Here we provide evidence that some prokaryotic and mammalian cAMP-response elements are functionally related. First, we show that mammalian ATF binds specifically to some E. coli CAP sites, and conversely E. coli CAP binds specifically to some mammalian ATF sites. Second, we demonstrate that an E. coli CAP binding site can confer cAMP-inducibility onto a mammalian gene when assayed in transfected mammalian cells.

Adenovirus Early Proteins↗

PubMed1989

Immunomodulatory activity of staphylococcal enterotoxin-B. The induction of an I-J-restricted suppressor factor.

Staphylococcal enterotoxin-B (SEB), a common cause of food-borne intoxication, is a potent polyclonal T cell activator. Previous studies from this laboratory and others have shown that SEB has the capacity to nonspecifically inhibit antibody responses both in vivo and in vitro. We have shown that the inhibitory activity of SEB is mediated, in part, by the activation of a CD8+, CD4-, and CD5- suppressor cell population. The present studies show that the activity of the SEB-induced suppressor cell population is mediated by a soluble factor. This factor nonspecifically inhibits both primary and secondary in vitro antibody responses. Delayed addition analysis demonstrates that the factor must be present early in the ongoing antibody response to exhibit suppressive activity. Monoclonal anti-I-J antisera block the activity of the factor, and eluates (but not filtrates) collected from monoclonal anti-I-J immunoaffinity columns possess suppressive activity. Furthermore, the activity is restricted at the "I-J" gene locus, but is not restricted at the Igh locus. Finally, size-exclusion chromatographic analysis shows that the factor possesses an apparent Mr of 26 kDa. These studies suggest that SEB induces the production of a suppressive factor with properties similar to those exhibited by Ag-induced, and typically Ag-specific, suppressor factors.

Adjuvants, Immunologic↗

PubMed1989

Reliability of the Doppler pressure half-time method for assessing effects of percutaneous mitral balloon valvuloplasty.

The mitral valve areas determined by Doppler pressure half-time and by cardiac catheterization with use of the Gorlin formula were compared in 18 adult patients who underwent percutaneous mitral balloon valvuloplasty. Doppler measurements and catheterization were performed simultaneously before, immediately after and 24 to 48 h after valvuloplasty. A high correlation between Doppler- and catheterization-derived mitral valve areas was found before mitral valvuloplasty (r = 0.81, Y = 0.88X + 0.1, SEE = 0.11 cm2) and 24 to 48 h after valvuloplasty (r = 0.84, Y = 0.70X + 0.67, SEE = 0.20 cm2). In contrast, the correlation immediately after valvuloplasty was only moderate (r = 0.72, Y = 0.43X + 1.1, SEE = 0.49 cm2). The Doppler-derived mitral valve area (2.41 +/- 0.61 cm2) immediately after valvuloplasty was significantly larger than the catheterization-derived area (2.08 +/- 0.39 cm2, p less than 0.05). In conclusion, the Doppler echocardiographic measurement performed with the pressure half-time method may lead to significant error immediately after mitral balloon valvuloplasty, but clinically accurate measurement can be obtained 24 to 48 h after valvuloplasty.

Adult↗