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PubMed2002

Sevoflurane anaesthesia in children after induction of anaesthesia with midazolam and thiopental does not cause epileptiform EEG.

BACKGROUND: Sevoflurane is a methyl ether anaesthetic commonly used for induction and maintenance of general anaesthesia in children. Sevoflurane is a non-irritant and acts quickly so induction is usually calm. However, inhalation induction with high concentrations of sevoflurane can cause convulsion-like movements and seizure-like changes in the electroencephalogram (EEG). Little is known about the EEG during maintenance of anaesthesia with sevoflurane, so we planned a prospective trial of sevoflurane maintenance after i.v. induction with benzodiazepine and barbiturate, which is another common induction technique in children. METHODS: EEG recordings were made before premedication with midazolam (0.1 mg kg(-1) i.v.), during induction of anaesthesia with thiopental (5 mg kg(-1)), and during maintenance with sevoflurane (2% end-tidal concentration in air/oxygen without nitrous oxide) in 30 generally healthy, 3- to 8-year-old children having adenoids removed. Noise-free EEG data of good quality were successfully recorded from all 30 children. RESULTS: Two independent neurophysiologists did not detect epileptiform discharges in any of the recordings. CONCLUSION: Premedication with midazolam, i.v. induction with thiopental and maintenance of anaesthesia with 2% sevoflurane in air does not cause epileptiform EEG patterns in children.

Anesthesia, General↗
PubMed2006

Do induction cooktops interfere with cardiac pacemakers?

AIMS: In induction cooktops, coils produce time-varying magnetic fields that induce eddy currents in the ferromagnetic bottom of a pot or pan, thereby heating it, while the cooktop itself remains cool. Interference with pacemaker sensing could conceivably be produced by voltages induced directly by induction or indirectly by leakage currents. METHODS AND RESULTS: A worst-case pacemaker-patient (PP) model representing left-sided implantation of a unipolar pacemaker was used for measurement of induced voltages, to judge whether induction cooktops could interfere with pacemaker sensing. Eleven induction cooktops of European manufacture were tested using the PP model. The pacemaker sensitivity with respect to 24 kHz voltages, amplitude-modulated at 100 Hz, was investigated in 244 devices. The current passing through the body of a grounded patient touching a metal pot was determined by measuring the voltage from hand to hand and between electrodes placed on the thorax to simulate an implanted unipolar pacing system underneath. The results obtained were complex. If the pot is positioned concentrically with the induction coil, the smallest pot produced the largest stray field, but the induced voltage always remained below the critical value of 100 mV. With eccentrically positioned large pots, voltages of up to 800 mV could be induced. The induced voltage could always be reduced to </=60 mV by maintaining a distance of 35 cm. The most sensitive pacemaker reacted at 90.5 mV. Because of leakage current, approximately 2% of the voltage between pot and ground appears across the pacemaker's sensing input. CONCLUSION: Patients are at risk if the implant is unipolar and left-sided, if they stand as close as possible to the induction cooktop, and if the pot is not concentric with the induction coil. Unipolar pacing systems can sense interference generated by leakage currents if the patient touches the pot for a long period of time. The most likely response to interference is switching to an asynchronous interference mode. Patients with unipolar pacemakers are at risk only if they are not pacemaker-dependent.

Adult↗
PubMed1995

Induction of CD5 on B and T cells is suppressed by cyclosporin A, FK-520 and rapamycin.

The expression of CD5 can be induced on murine B-2 cells by anti-IgM, a recognized analog of thymus-independent 2 type (TI-2) antigen. Given that cyclosporin A (CsA) sensitivity is a distinguishing feature of TI-2 type B cell activation, we asked whether the in vitro induction of CD5 on B cells by anti-mu is CsA sensitive. We report that anti-mu induced CD5 expression on B-2 cells was inhibited by CsA as well as FK-520 and rapamycin. When L-685,818, a FK-520 and rapamycin antagonist, was added to anti-mu stimulated B cell cultures containing FK-520 or rapamycin, but not CsA, suppression was abrogated and complete induction of CD5 was seen. When we used either CD4+CD8+ thymocytes or peripheral T cells activated by phorbol ester and ionomycin, the cell surface induction of CD5 was also partially blocked by CsA, FK-520 and rapamycin. Moreover, in both B and T cells, the same immunosuppressive drugs did not affect constitutive CD5 expression but only blocked de novo induction. To determine the level of CD5 regulation, we activated T cells using phorbol myristate acetate (PMA)/ionomycin and report that CD5 induction was sensitive to actinomycin D (AcD). Similarly, the induction of CD5 on anti-mu activated B cells was blocked by AcD. In addition, T cells that were activated by PMA/ionomycin expressed more abundant CD5 mRNA than CsA or FK-520 treated cells. Based on the CsA-sensitive regulation of CD5 we thought that the CsA-sensitive nuclear factor of activated T cells (NFAT) might be involved in CD5 regulation. We report evidence by Western blot analysis that NFATp is expressed by both resting and TI activated B cells but apparently not CD4+CD8+CD5+ thymocytes. We conclude that in both B and T cells the induction of CD5 requires transcriptional regulation, and that the inhibition of CD5 expression by the immunosuppressive drugs CsA, FK-520 and rapamycin requires drug-immunophilin complex formation.

Animals↗
PubMed2004

In vivo kinetics of micronuclei induction by bifunctional alkylating antineoplastics.

The aim of the present study was to determine in vivo the kinetics of micronucleated polychromatic erythrocyte (MN-PCE) induction in mice, as an approach for studying the mechanism of micronuclei induction by mitomycin C, cis-diamine dichloroplatinum, busulfan and bis-chloroethylnitrosourea, bifuctional alkylating antineoplastic agents having different patterns of crosslink induction. The kinetics of MN-PCE induction was established by scoring the frequency of MN-PCE in 2000 PCE in peripheral blood, for periods of 8 or 10 h after acute treatment and up to 80 h, with different doses of the agent. The kinetics of MN-PCE induction and particularly the times of maximal induction by different bifunctional alkylating agents were compared with the kinetics previously obtained for ethylnitrosourea, methylnitrosourea and 6-mercaptopurine, agents that cause MN-PCE mainly in the first, second and third divisions after exposure, respectively. The results obtained in the present study allow us to conclude that: (i) bifunctional alkylating agents have very different efficiencies of genotoxic and cytotoxic action; (ii) all assayed bifunctional alkylating agents induced micronuclei during the first cell division, owing to the mistaken repair of primary lesions, e.g. excision; (iii) busulfan and bis-chloroethylnitrosourea showed an additional late mechanism of micronuclei induction, which is expressed at the third division and seems to be related to the mismatch repair process.

Animals↗
PubMed1982

Comparative evaluation of intravenous agents for rapid sequence induction--thiopental, ketamine, and midazolam.

The pharmacologic effects of ketamine, midazolam, and a midazolam-ketamine combination were compared with thiopental for rapid induction of general anesthesia. Thiopental, 4 mg/kg, 1.5 mg/kg ketamine, 0.3 mg/kg midazolam, or 0.15 mg/kg midazolam, and 0.75 mg/kg ketamine, were administered intravenously in a randomized fashion to 80 patients undergoing emergency surgery. Adequacy of induction, hemodynamic changes, and postoperative effects were assessed during and after a standardized induction-maintenance anesthetic technique. Midazolam had the slowest onset (15-60 s) and longest duration of action. During induction, thiopental decreased mean arterial pressure (MAP) by 11%, ketamine increased MAP by 10%, while neither midazolam nor the midazolam-ketamine combination significantly changed MAP. Heart rate (HR) increased during induction in all groups; however, the increase was significantly less in the combination group. After intubation, MAP and HR increased to the same extent in all four groups. Significantly more patients who received ketamine for induction were disoriented during emergence. Midazolam most effectively produced anxiolysis and antegrade amnesia. Significantly more patients who received thiopental felt depressed postoperatively, and 95% required parenteral opiate analgesics in the recovery room. Dreaming was highest after ketamine (55%) and lowest after midazolam (0%) and the combination (5%). Thus, midazolam effectively attenuated both the cardiostimulatory responses and unpleasant emergence reactions associated with ketamine. The author concludes that both midazolam and the midazolam-ketamine combination are safe and effective induction agents for emergency surgery, which may offer an advantage over thiopental in situations where hemodynamic stability is crucial. Furthermore, midazolam effectively attenuates the side effects of ketamine.

Adult↗
PubMed1989

Low-dose intramuscular ketamine for anesthesia pre-induction in young children undergoing brief outpatient procedures.

The authors sought to determine whether intramuscular ketamine (2 mg/kg) would facilitate inhaled induction of anesthesia in those children who are uncooperative. Thirty-five children were anesthetized with halothane and nitrous oxide for insertion of tympanotomy tubes. Twenty of those children were deemed by the anesthesiologist to be uncooperative and received 2 mg/kg of ketamine im prior to induction of anesthesia. The onset time (time from ketamine administration until induction of inhaled anesthesia could be started) was 2.7 +/- 0.3 min. The quality of the subsequent acceptance of inhaled induction with halothane was excellent in 61% of the patients and adequate in the remaining 39%. The recovery and discharge times were compared with those observed in 15 matched children who accepted induction of anesthesia via a mask without the use of ketamine. Recovery time was not prolonged, but home discharge was delayed by an average of 13 min in the ketamine group (P less than 0.04). Low-dose im ketamine was found to be an acceptable pre-induction drug in young children who are uncooperative for an inhaled induction of anesthesia.

Ambulatory Surgical Procedures↗
PubMed1992

Induction and maintenance characteristics of anesthesia with desflurane and nitrous oxide in infants and children.

To determine the induction and maintenance characteristics of desflurane in pediatric patients, the authors anesthetized 206 infants and children aged 1 month to 12 yr with nitrous oxide plus desflurane and/or halothane in oxygen. Patients were assigned to one of four groups: anesthesia was 1) induced and maintained with desflurane after premedication with an oral combination of meperidine, diazepam, and atropine; 2) induced and maintained with desflurane; 3) induced with halothane and maintained with desflurane; or 4) induced and maintained with halothane. An unblinded observer recorded time to loss of consciousness (lid reflex), time to intubation, and clinical characteristics of the induction and maintenance of anesthesia. Moderate-to-severe laryngospasm (49%) and moderate-to-severe coughing (58%) occurred frequently during induction of anesthesia with desflurane; the incidence of these was not altered by premedication. In contrast, laryngospasm and coughing were rare during induction of anesthesia with halothane. In unpremedicated patients, time to loss of lid reflex (mean +/- SD) was similar for desflurane (2.4 +/- 1.2 min) and halothane (2.1 +/- 0.8 min). During induction of anesthesia, before laryngoscopy and intubation, mean arterial pressure less than 80% of baseline was more common with halothane; heart rate and mean arterial pressure greater than 120% of baseline were more common with desflurane. Intraoperatively, heart rate greater than 120% of baseline was more common with desflurane; blood pressures were similar for the two anesthetics. The authors conclude that the high incidence of airway complications during induction of anesthesia with desflurane limits its utility for inhalation induction in pediatric patients. Anesthesia can be safely maintained with desflurane if induced with a different anesthetic.

Anesthesia, Inhalation↗
PubMed1999

Changes in electroencephalogram and autonomic cardiovascular activity during induction of anesthesia with sevoflurane compared with halothane in children.

BACKGROUND: This study was design to assess clinical agitation, electroencephalogram (EEG) and autonomic cardiovascular activity changes in children during induction of anesthesia with sevoflurane compared with halothane using noninvasive recording of EEG, heart rate, and finger blood pressure. METHODS: Children aged 2-12 yr premedicated with midazolam were randomly assigned to one of three induction techniques: 7% sevoflurane in 100% O2 (group SevoRAPID); 2%, 4%, 6%, and 7% sevoflurane in 100% O2 (group SevoINCR); or 1%, 2%, 3%, and 3.5% halothane in 50% N2O-50% O2 (group HaloN2O). An additional group of children who received 7% sevoflurane in 50% N2O-50% O2 (group SevoN2O) was enrolled after completion of the study. Induction was videotaped. EEG, heart rate, and finger blood pressure were continuously recorded during induction until 5 min after tracheal intubation and analyzed in frequency domain using spectral analysis. RESULTS: Agitation was more frequent when anesthesia was induced with 100% O2 compared to the mixture of oxygen and nitrous oxide. No seizures were recorded in any group. In the four groups, induction of anesthesia was associated with an increase in EEG total spectral power and a shift toward the low-frequency bands. Sharp slow waves were present on EEG tracings of the three sevoflurane groups, whereas slow waves and fast rhythms (spindles) were observed in the halothane group. Sevoflurane induced a greater withdrawal of parasympathetic activity than halothane and a transient relative increase in sympathetic vascular tone at loss of eyelash reflex. CONCLUSIONS: Agitation observed during sevoflurane induction was not associated with seizures. Sevoflurane induction induced a marked inhibition of parasympathetic control of heart rate.

Anesthesia, Inhalation↗
PubMed2001

Relation between initial blood distribution volume and propofol induction dose requirement.

BACKGROUND: Propofol induction dose is variable and depends on many factors, including initial volume of distribution and early disposition. The authors hypothesized that preadministration blood distribution volumes, cardiac output (CO), and hepatic blood flow (HBF) could be examined to establish a propofol induction dose. METHODS: Propofol dose required to reach loss of consciousness, when infused at infusion rate per lean body mass (LBM) of 40 mg x kg(-1) x h(-1), was determined in 75 patients aged 11-85 yr. CO, blood volume (BV), central blood volume (CBV), and HBF were measured with indocyanine green pulse spectrophotometry. Univariate least squares linear regression analysis was used to individually analyze the relation between propofol induction dose and patient characteristics, including LBM, baseline distribution volumes, CO, and HBF. Stepwise multiple linear regression models were used to select important predictors of induction dose. RESULTS: Although there was a significant correlation between the induction dose and each of the eight variables of age, sex, LBM, hemoglobin, CO, BV, CBV, and HBF, only factors of age (partial r = -0.655), LBM (partial r = 0.325), CBV (partial r = 0.540), and HBF (partial r = 0.357) were independently associated with the induction dose (R2 = 0.85) when all variables were included in a multivariate model. CONCLUSIONS: At a constant propofol infusion rate of 40 mg x kg(-1) x h(-1) as a function of LBM in patients with American Society of Anesthesiologists physical status I or II, the induction dose can be determined from four variables: age, LBM, CBV, and HBF.

Adolescent↗
PubMed1997

Induction of tolerance with nondepleting anti-CD4 monoclonal antibodies is associated with down-regulation of TH2 cytokines.

BACKGROUND: Induction of tolerance with anti-CD4 has mainly focused on monoclonal antibodies (mAbs) that deplete CD4+ T cells. In this study, the mechanisms by which nondepleting anti-CD4 mAbs induce tolerance in the Dark Agouti to PVG rat heart graft model were examined. METHODS: Five anti-CD4 mAbs were tested. Immunohistology and cytokine mRNA profiles were analyzed within grafts. Effects of combining anti-CD4 therapy with alloantibody (alloAb), interleukin (IL)-4, and anti-IL-4 mAb were also examined. RESULTS: All mAbs tested induced indefinite graft survival (>150 days), with blocking of alloAb production. Exogenous alloAb did not restore rejection. Similar T cell receptor alphabeta+, CD8+, IL-2 receptor+ T cell, macrophage, and natural killer cell infiltration and comparable MHC II and intercellular adhesion molecule-1 levels were seen in rejecting and tolerant grafts. mRNA for IL-2, interferon-gamma, lymphotoxin, tumor necrosis factor-alpha, transforming growth factor-beta, cytolysin, and granzyme-A/B was comparable, although inducible nitric oxide synthase was slightly reduced in tolerant grafts. IL-4 and IL-5 were significantly reduced in tolerant grafts, although IL-6, IL-10, and IL-13 levels were similar; this was consistent with partial T helper (Th)2 response inhibition, which was also manifested by inhibited alloAb. The combination of alloAb, IL-4, or anti-IL-4 mAb with anti-CD4 did not prevent tolerance induction. CONCLUSIONS: This study demonstrated that anti-CD4 mAb therapy did not inhibit activation and infiltration of Th1 and CD8+ effector T cells. Preferential induction of Th2 responses, especially IL-4, was not essential for the induction of tolerance. Our studies also found no evidence to support induction of anergy or transforming growth factor-beta as mechanisms of tolerance induction. These results question whether IL-4 is required for induction of transplantation tolerance.

Animals↗
PubMed2006

Membrane sweeping at initiation of formal labor induction: a randomized controlled trial.

OBJECTIVE: To determine the benefit of membrane sweeping at initiation of labor induction in conjunction with formal methods of labor induction. METHODS: Two hundred seventy-four women at term with a singleton fetus in cephalic presentation and intact membranes were randomly assigned to receive membrane sweeping or no membrane sweeping at initiation of formal labor induction with either dinoprostone pessary or amniotomy. Outcome measures included mode of delivery, induction-to-delivery interval, dinosprostone dose, any oxytocin use and duration of oxytocin use in labor, visual analog score for pain associated with sweeping, and visual analog score for satisfaction with the birth process. RESULTS: Two hundred sixty-four women (136 sweep and 128 no sweep) had their data analyzed. Ten women (4 sweep and 6 no sweep) were excluded because of exclusion criteria infringements. Swept women had higher spontaneous vaginal delivery rate (69% compared with 56%, P = .041), shorter induction to delivery interval (mean 14 compared with 19 hours, P = .003), fewer that required oxytocin use (46% compared with 59%, P = .037), shorter duration of oxytocin infusion (mean 2.6 compared with 4.3 hours, P = .001) and improved visual analog score for birth process satisfaction (mean 4.0 compared with 4.7, P = .015). The reduction in dinoprostone dose used (mean 1.2 compared with 1.3, P = .082) was not significant. Postsweeping visual analog score for pain (mean 4.7 compared with 3.5, P < .001) was significantly increased. CONCLUSION: Membrane sweeping at initiation of labor induction increased the spontaneous vaginal delivery rate, reduced oxytocic drug use, shortened induction to delivery interval, and improved patient satisfaction. LEVEL OF EVIDENCE: I.

Adult↗
PubMed2006

Maternal morbidity associated with cesarean delivery without labor compared with induction of labor at term.

OBJECTIVE: To estimate the maternal morbidity associated with cesarean deliveries performed at term without labor compared with morbidity associated with induction of labor at term. METHODS: A 15-year population-based cohort study (1988-2002) using the Nova Scotia Atlee Perinatal Database compared maternal outcomes in nulliparous women delivering by cesarean delivery without labor and nulliparous women at term undergoing induction of labor for planned vaginal delivery with singleton, cephalic presentation. RESULTS: A total of 5,779 pregnancies satisfied inclusion and exclusion criteria, 879 of which were cesarean deliveries without labor. There were no maternal deaths. There was no difference in wound infection, puerperal febrile morbidity, blood transfusion or intraoperative trauma. After controlling for potential confounders, women undergoing cesarean delivery without labor were less likely to have complications of early postpartum hemorrhage (relative risk 0.61, 95% confidence interval 0.42-0.88, number needed to treat 32) and composite maternal morbidity (relative risk 0.71, 95% confidence interval 0.52-0.95, number needed to treat 34) compared with women undergoing induction of labor. Subgroup analyses of maternal outcomes after induction of labor in women by method of delivery were also performed and demonstrated additional risks of traumatic morbidity after induction of labor. The highest morbidity was found in the assisted vaginal delivery and cesarean delivery in labor groups. CONCLUSION: Early postpartum hemorrhage and composite maternal morbidity were decreased in cesarean delivery without labor compared with induction of labor. Hemorrhagic and traumatic morbidities with labor induction are increased after assisted vaginal delivery and cesarean delivery in labor compared with cesarean delivery without labor.

Adult↗
PubMed2003

Hearing aid users benefit from induction loop when using digital cellular phones.

OBJECTIVE: Hearing aid users have recently been reported to experience problems with electromagnetic interference when using digital cellular phones. This study was undertaken to investigate the possible benefit of an induction loop system developed for use with some cellular phone models, and also to compare the possible benefit in two languages (Finnish and American English) as well as the benefit with two hearing aid technologies (analog versus digital). DESIGN: The study was performed in controlled laboratory conditions at two tertiary care hearing health care centers, one in Oulu, Finland and the other in Dallas, in the United States. The subjects were experienced users of behind-the-ear hearing aids and served as their own controls in three different listening conditions. Thirty-two eligible subjects (20 in Oulu and 12 in Dallas) participated in three test conditions: 1. call with a landline phone, 2. call with a digital cellular phone alone and 3. call with a digital cellular phone coupled to an induction loop. RESULTS: Sentence recognition scores and subjective judgments using a visual analog scale revealed the poorest results with the digital cellular phone alone. When the induction loop was used with the digital cellular phones, sentence recognition scores and the visual analog scale scores were comparable to the scores obtained with a landline phone. The mean sentence recognition score for analog hearing aids was 62.4% (95% confidence interval 50.2 to 74.6) with the landline phone, 12.6% (-1.6 to 26.9) with the digital cellular phone alone, and 63.3% (44.2 to 82.3) when using the digital cellular phone with the induction loop. For digital hearing aids, the sentence recognition scores were 62.4% (51.9 to 72.9), 37.4% (18.0 to 56.8) and 57.6% (39.0 to 76.2), respectively. There was no significant difference in performance between the two centers. However, when using the digital cellular phone alone, there was no drop in the sentence recognition scores with the few (N = 5) digital hearing aids in Dallas. The subjects ranked the digital cellular phone alone as the poorest test condition and the digital cellular phone with an induction loop as the best. CONCLUSIONS: Induction loops appear to offer one possible solution for the incompatibility problem between hearing aids and digital cellular phones. However, the generalizability of the results must be viewed cautiously, because testing included only one induction loop and two digital cellular phone models.

Adult↗
PubMed1976

The induction of interferon by temperature-sensitive mutants of Sindbis virus: its relationship to double-stranded RNA synthesis and cytopathic effect.

Sindbis virus strain AR339 induces interferon by 3 h after infection at 39 degrees C and by 8 h after infection at 30 degrees C. The time course of interferon induction between 4 and 9 h after infection at the restrictive temperature (39 degrees C) was measured for 24 temperature-sensitive (ts) mutants, all of which induced interferon by 16 h after infection. Mutants showing total RNA synthesis at 39 degrees C greater than 10% of the wild-type level induced interferon with kinetics similar to the wild-type. Of those mutants showing 1 to 10% of the wild-type level of RNA synthesis at 39 degrees C, four induced interferon with kinetics similar to the wild type, whereas six showed a lag in induction. Nine mutants, showing 0 to 5% of the wild-type level of RNA synthesis at 39 degrees C, and the wild type, were examined for single and double-stranded RNA synthesis at 30 and 39 degrees C, using a combination of lithium chloride precipitation and CF11 cellulose chromatography. Six of these mutants showed a lag in interferon induction at 30 degrees C, while three showed no lag. For all nine mutants, double-stranded RNA synthesis at 39 degrees C was undetectable, although easily detectable for the wild type. Both the wild type and the mutants synthesized double-stranded RNA at 30 degrees C. For all mutants, time of interferon induction at 39 degrees C was correlated with c.p.e. as measured by trypan blue uptake 30 h after infection. The mutant F104, showing undetectable RNA synthesis and a long lag in interferon induction at 39 degrees C, was examined for interferon induction in a temperature shift system. Only 1/2 h at 30 degrees C, before a shift to 39 degrees C, was required for interferon to be induced with wil-type kinetics, and this was correlated with an increased c.p.e. 30 h after infection. Increased RNA synthesis and infectious virus production were detectable at 30 degrees C after an initial hour at 30 degrees C. It is concluded that, for interferon to be induced with normal kinetics, early virus functions are required, but that normal levels of double-stranded RNA synthesis are not necessary. The events which lead to interferon induction also lead to visible c.p.e.

Cell Line↗
PubMed2002

Apoptosis induction by the Therien and vaccine RA27/3 strains of rubella virus causes depletion of oligodendrocytes from rat neural cell cultures.

The induction of cell death by the Therien strain of rubella virus (RVT), and the vaccine RA27/3 strain, was investigated in mixed glial cell cultures derived from the rat CNS. Cell death induction in Vero and rat glial cells by RVT and RA27/3 was dependent on virus replication. In both cell types and for both virus strains, cell death induction had the hallmarks of apoptosis, as detected by DNA laddering, terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling staining and Annexin V staining. For rat mixed glial cells, the depletion of oligodendrocytes was due to the induction of apoptosis for both virus strains. The induction of apoptosis in H358a cells, which carry a homozygous deletion of the p53 gene, indicated that a p53-independent pathway can be involved. The induction of cell death by RVT and RA27/3 in Vero and rat glial cells was associated with caspase-3 activity. It is concluded that rubella virus (RV) induces apoptosis in oligodendrocytes in rat glial cell cultures by a caspase-dependent pathway and that similar mechanisms occur for both the RVT laboratory strain and the vaccine RA27/3 strain. The tropism of both strains of RV for oligodendrocytes and the induction of apoptosis in such cells may have important implications for the mechanism of virus neuropathogenesis.

Animals↗
PubMed1966

Effects of univalent cations on the inductive formation of nitrate reductase.

An investigation has been made to determine the effectiveness of univalent cations as cofactors for the inductive synthesis of nitrate reductase. In these experiments K(+) functions more effectively as the univalent cation activator than other univalent cations. Substitution of Rb(+) for K(+) resulted in enzyme formation at a rate of about one-half of that obtained with K(+). Sodium, Li(+), or NH(4) (+) either failed to stimulate or completely inhibited the inductive formation of the enzyme. When no univalent cations were present in the induction medium, enzyme formation was delayed for an initial 3-hour period in contrast to the normal one-hour delay in enzyme formation where adequate K(+) was present in the induction medium. During the period of inductive formation of nitrate reductase the activity of pyruvic kinase, a constitutive enzyme, was assayed under conditions where adequate K(+) was present. Results indicate that the presence of the different univalent cations in the induction medium had no striking effect on the activity of this enzyme during the induction period.

Ions↗
PubMed1999

Anticipating endoplasmic reticulum stress. A novel early response before pathogenesis-related gene induction

When it is attacked by a pathogen, a plant produces a range of defense-related proteins. Many of these are synthesized by the rough endoplasmic reticulum (RER) to be secreted from the cell or deposited in vacuoles. Genes encoding endoplasmic reticulum (ER)-resident chaperones, such as the lumenal binding protein (BiP), are also induced under these conditions. Here, we show that BiP induction occurs systemically throughout the plant. Furthermore, this induction occurs rapidly and precedes expression of genes encoding pathogenesis-related (PR) proteins. The underlying signal transduction pathway was shown to be independent of the signaling molecule salicylic acid and the unfolded protein response pathway. In addition, BiP induction was independent of PR gene induction. Overproduction of BiP alone was not sufficient to cause induction of PR gene expression; however, limiting the amount of BiP in the ER lumen via superimposed ER stress inhibited the induction of PR gene expression. We propose that the induction of BiP expression during plant-pathogen interactions is required as an early response to support PR protein synthesis on the RER and that a novel signal transduction pathway exists to trigger this rapid response.

Journal Article↗
PubMed1992

Induction of the 72-kD heat shock protein in xeroderma pigmentosum complementation group A fibroblasts.

In mammalian cells, 72-kD heat shock protein (HSP72) is the major stress-inducible protein that is thought to play a protective role against the various environmental stresses. In order to know the induction mechanism of HSP72, we examined the HSP72 in DNA repair-deficient xeroderma pigmentosum group A fibroblasts (XP2OSSV) and normal fibroblasts (WI38VA13) by the indirect immunofluorescence method using a monoclonal antibody specific for the inducible 72-kD protein. Heat-shock treatment of the same survival fraction (5% survival) induced HSP72 in xeroderma pigmentosum (XP) and normal cells. However, as compared with XP cells, normal cells showed the induction of HSP72 more rapidly and strongly. When XP and normal cells were irradiated with UVC at the same survival dose (10% survival), apparent induction of HSP72 was observed in both cell lines. In the case of UVC irradiation at the same dose (1.0 J/m2), though XP cells showed the induction of HSP72, HSP72 was not induced in normal cells. In both cell lines, heat-shock treatment caused more rapid induction of HSP72 than UV irradiation. These results suggest that the induction mechanism of HSP72 might be different between heat-shock treatment and UV irradiation. In addition, in the case of UV irradiation, the extent of DNA damage after DNA repair or the cell death might be involved in the induction of HSP72.

Cell Line, Transformed↗