Computer based medication error reporting: insights and implications

BACKGROUND

Despite the growing use of error reporting tools, the healthcare industry is inexperienced in receiving, understanding, and analyzing these reports.

OBJECTIVE

To assess the accuracy and define the epidemiology of medication error reports.

DESIGN, SETTING, AND PATIENTS

A retrospective cohort study of 581 error reports containing 1010 medication errors reported between July 2001 and January 2003 at a large academic children's institution.

MAIN OUTCOME MEASURES

Correct classification and types of medication errors.

RESULTS

Of the 1010 medication errors reviewed, 298 (30%) were prescribing errors, 245 (24%) were dispensing errors, 410 (41%) were administration errors, and 57 (6%) involved medication administration records (MAR). Following expert review, 208 errors (21%) were deleted because they had been inappropriately coded as errors and 97 (10%) were added as they were not initially coded despite having occurred. In addition, 352 medication error reports needed to have the subtype of error reclassified; 207 (59%) of these involved the reporter choosing the non-descript "other" category on the reporting tool (such as "Prescribing other") which was able to be reclassified by expert review. The overall distribution of error type categories did not change significantly with expert review, although only MAR errors were underreported by the reporters. The most common medications were anti-infectives (17%), pain/sedative agents (15%), nutritional agents (11%), gastrointestinal agents (8%), and cardiovascular agents (7%).

CONCLUSIONS

Despite clear imperfections in the data captured, medication error reporting tools are effective as a means of collecting reliable information on errors rapidly and in real time. Our data suggest that administration errors are at least as common as prescribing errors in children. Further research is needed, not only in the area of computerized physician order entry (CPOE) for children, but also on ways to make the dispensing and administration of medications safer.

Evidence for a Novel Endocrine Disruptor: The Pesticide Propanil Requires the Ovaries and Steroid Synthesis to Enhance Humoral Immunity

Steroid hormones are known to affect the humoral immune response to a variety of antigens. However, the mechanisms regulating these effects are poorly understood. The immunotoxic chemical propanil and estrogen have similar effects on the immune system including augmentation of humoral immune responses. Propanil enhances the number of phosphorylcholine (PC)-specific IgG2b, IgG3, and IgM antibody-secreting cells (ASCs) in the spleen four- to sixfold 7 days after vaccination of female C57BL/6 mice with heat-killed Streptococcus pneumoniae. Several experiments were performed to test the hypothesis that propanil increases the response via an estrogenic pathway. Ovariectomy abrogated the effect of propanil on the PC-specific ASC response. Both in vitro and in vivo assays indicate that propanil does not bind either estrogen receptor (ER) alpha or beta. Exogenous estradiol administration in ovariectomized mice failed to restore the effect of propanil on the PC response. Treatment of female mice with a pure ER antagonist, ICI 182,780, or the progesterone antagonist RU486 did not inhibit the increase in ASCs. These data suggest that estrogen and progesterone do not regulate the effect of propanil. However, complete inhibition of steroid synthesis with the gonadotropin-releasing hormone (GnRH) antagonist antide abrogated the increased response in propanil-treated mice, indicating a necessary role for steroid synthesis. Experiments in male mice demonstrated that propanil increased the number of ASCs comparable to female mice. However, orchiectomy did not inhibit this effect, suggesting that androgens do not regulate the amplification of the humoral response. These data suggest a novel role for the ovarian hormones in the regulation of the PC-specific antibody response.

CheX is a phosphorylated CheY phosphatase essential for Borrelia burgdorferi chemotaxis

Motility and chemotaxis are believed to be important in the pathogenesis of Lyme disease caused by the spirochete Borrelia burgdorferi. Controlling the phosphorylation state of CheY, a response regulator protein, is essential for regulating bacterial chemotaxis and motility. Rapid dephosphorylation of phosphorylated CheY (CheY-P) is crucial for cells to respond to environmental changes. CheY-P dephosphorylation is accomplished by one or more phosphatases in different species, including CheZ, CheC, CheX, FliY, and/or FliY/N. Only a cheX phosphatase homolog has been identified in the B. burgdorferi genome. However, a role for cheX in chemotaxis has not been established in any bacterial species. Inactivating B. burgdorferi cheX by inserting a flgB-kan cassette resulted in cells (cheX mutant cells) with a distinct motility phenotype. While wild-type cells ran, paused (stopped or flexed), and reversed, the cheX mutant cells continuously flexed and were not able to run or reverse. Furthermore, swarm plate and capillary tube chemotaxis assays demonstrated that cheX mutant cells were deficient in chemotaxis. Wild-type chemotaxis and motility were restored when cheX mutant cells were complemented with a shuttle vector expressing CheX. Furthermore, CheX dephosphorylated CheY3-P in vitro and eluted as a homodimer in gel filtration chromatography. These findings demonstrated that B. burgdorferi CheX is a CheY-P phosphatase that is essential for chemotaxis and motility, which is consistent with CheX being the only CheY-P phosphatase in the B. burgdorferi chemotaxis signal transduction pathway.

Spring migration of Northern Pintails from California's Central Valley wintering area tracked with satellite telemetry: routes, timing, and destinations

We used satellite transmitters to track the 2000–2003 spring migrations of adult female Northern Pintails (Anas acuta L., 1758) from California's Central Valley, USA. PTT-tagged Pintails departed during late February to mid-March, and 77%–87% stopped first in the region of south-central Oregon, extreme northwestern Nevada, and northeastern California (SONEC). Subsequently, most Pintails used migration strategies characterized by the length of stay in SONEC and subsequent destinations: (i) extended stay in SONEC, migrated late April to early May directly to Alaska over the Pacific Ocean (7%–23% annually); (ii) same timing as in i, but flew to Alaska along the Pacific Coast using stopovers (0%–28% annually); (iii) moderate period in SONEC, migrated late March to mid-April directly primarily to southern Alberta in Prairie Canada (17%–39% annually), with many moving to northern Canada or Alaska; or (iv) short period in SONEC, migrated early to late March to Prairie Canada via stopovers primarily in southern Idaho and western Montana (32%–50% annually), with some moving to northern Canada or Alaska. Pintails that bypassed SONEC used these same strategies or moved easterly. Pintails modified migration strategies relative to record cold temperatures and wetland abundance in the mid-continent prairie region.

Difficulty demonstrating estradiol-mediated Erk1/2 phosphorylation in MCF-7 cells

While some studies report that estradiol (E2) activates extracellular-signal regulated kinase (Erk1/2) in MCF-7 breast cancer cells, others report E2 does not activate this signaling pathway. This study attempted to resolve the conflicting reports by investigating experimental variables that could impact Erk1/2 activation using a high through-put assay that quantitatively assessed Erk1/2 phosphorylation. Variables tested included: cell staging and dosing regimes with and without charcoal-stripped serum, different MCF-7 cell sublines and culture densities and several E2 formulations and solvents. Levels of phosphorylated Erk1/2 were normalized to cellular protein rather than to total Erk1/2 protein because an antibody purported to recognize total Erk1/2 preferentially reacted with non-phosphorylated Erk1/2, potentially exaggerating the apparent level of Erk1/2 activation. Dosing MCF-7 cells with E2 containing small amounts of stripped serum induced Erk1/2 phosphorylation; however, this induction was largely attributed to serum factors. E2 administered in serum-free medium did not significantly alter Erk1/2 phosphorylation under any condition tested; immunocytochemistry corroborated this conclusion. While phosphatase inhibitors generally increased Erk1/2 phosphorylation, they did not impact E2-altered Erk1/2 phosphorylation. It remains important to resolve the basis of conflicting reports regarding E2-induced Erk1/2 activation due to the potential importance of this pathway on breast cancer and other processes.

The evolution of host resistance: tolerance and control as distinct strategies

In response to parasitic infection, hosts may evolve defences that reduce the deleterious effects on survivorship. This may be interpreted as a form of resistance, as long as infected hosts are able to either recover or reproduce. Here we distinguish two important routes to this form of resistance. An infected host may either: (1) tolerate pathogen damage, or (2) control the pathogen by inhibiting its growth. A model is constructed to examine the evolutionary dynamics of tolerance and control to a free-living microparasite, where both forms of resistance are costly in terms of other life-history traits. We do not observe polymorphism of tolerant genotypes. In contrast, the evolution of control may lead to disruptive selection, and ultimately dimorphism of extreme strains. The optimal host genotype also varies with the type of resistance-individuals invest more in tolerance and pay a greater cost. The free-living framework used makes the distinction between tolerance and control explicit but the distinction applies equally to directly transmitted parasites. Due to the evolutionary differences exhibited, it is important to design experiments that distinguish between the two forms of resistance.

Extracellular nitric oxide release mediates soluble guanylate cyclase-independent vasodilator action of spermine NONOate: comparison with other nitric oxide donors in isolated rat femoral arteries

Nitric oxide (NO) and NO donors exhibit actions that are not entirely mediated by soluble guanylate cyclase (sGC). The site of NO release may influence the involvement of sGC-independent effects. Here we use spermine NONOate (SPER/NO) to release NO extracellularly, compared with other NO donors. Isolated rat femoral arteries were perfused luminally and perfusion pressure monitored. Vessels were contracted with phenylephrine (2-14 microM) in the presence of an NO synthase inhibitor (N(omega)-nitro-L-arginine methyl ester; 20 microM). Vasodilator responses to NO donors were assessed before and after perfusion of an sGC inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one; ODQ; 20 microM), NO scavengers (hemoglobin; Hb & hydroquinone; HQ), and a superoxide generator (duroquinone; DQ). ODQ (20 microM) abolished the vasodilator responses to glyceryl trinitrate (10(-8) - 10(-3) M), and sodium nitroprusside (10(-8) - 10(-4) M), which release NO intracellularly. ODQ (20 microM) attenuated, but failed to abolish, the vasodilator responses to SPER/NO (10(-6) - 10(-3) M). ODQ abolished responses to S-nitrosoglutathione and S-nitroso-N-valeryl-D-penicillamine (10(-8) - 10(-4) M), but a small residual vasodilatation remained in response to 10(-3) M. In the presence of ODQ, the remaining vasodilatation to SPER/NO was all but abolished by scavengers of extracellular NO (Hb; 10 microM, HQ; 100 microM). Superoxide generation (DQ; 100 microM) also attenuated ODQ-resistant vasodilatation. The data suggest that, in rat femoral arteries, NO donors that are capable of releasing extracellular NO cause vasodilatation that is only partially mediated by sGC. Lack of augmentation of sGC-independent effects by superoxide suggests that they are not mediated by peroxynitrite.

Ozone exposure decreases the effect of a deep inhalation on forced expiratory flow in normal subjects

Sixteen healthy nonsmoking subjects (7 women), 21-49 yr old, were exposed in a climate chamber to either clean air or 300 parts/billion ozone on 4 days for 5 h each day. Before each exposure, the subjects had been pretreated with either oxidants (fish oil) or antioxidants (multivitamins). The study design was double-blind crossover with randomized allocation to the exposure regime. Full and partial flow-volume curves were recorded in the morning and before and during a histamine provocation at the end of the day. Nasal cavity volume and inflammatory markers in nasal lavage fluid were also measured. Compared with air, ozone exposure decreased peak expiratory flow, forced expiratory volume in 1 s, and forced vital capacity (FVC), with no significant effect from the pretreatment regimens. Ozone decreased the ratio of maximal to partial flow at 40% FVC by 0.08 ± 0.03 (mean ± SE, analysis of variance: P = 0.018) and at 30% FVC by 0.10 ± 0.05 ( P = 0.070). Ozone exposure did not significantly increase bronchial responsiveness, but, after treatment with fish oil, partial flows decreased more than after vitamins during the histamine test, without changing the maximal-to-partial flow ratio. The decreased effect of a deep inhalation after ozone exposure can be explained by changes in airway hysteresis relative to parenchymal hysteresis, due either to ozone-induced airway inflammation or to less deep inspiration after ozone, not significantly influenced by multivitamins or fish oil.

Combinatorial treatment of ovarian cancer cells with harringtonine and cisplatin results in increased cisplatin-DNA adducts

The current studies represent the first step in assessing the utility of harringtonine in combination with cisplatin as an improved approach for treating ovarian cancer. Three ovarian cancer cell lines, platinum-sensitive A2780, and platinum-resistant A2780/CP70 and OvCar-3, were exposed to their respective IC(50) dose of cisplatin for 1 h with or without a 24-h pretreatment with harringtonine. The level of platinum-DNA adducts was determined by atomic absorption spectrometry (AAS). These studies show for the first time that harringtonine pretreatment significantly increased the amount of platinum-DNA adducts in all ovarian cancer cell lines by 2-4 fold, immediately following 1-h exposure to cisplatin. Moreover, the level of cisplatin-DNA adducts in harringtonine-pretreated cells remained elevated by 3-4.7-fold for at least 6 h after cisplatin was removed, relative to cells only exposed to cisplatin. In all three cell lines the removal (repair) of platinum-DNA adducts was not significantly altered by harringtonine. In addition, the extent to which harringtonine altered the expression of select DNA damage response genes (p53, P16, ERCC1 and XPB) was determined using RT-PCR and Southern hybridization in A2780 and A2780/CP70 cells. The expression of ERCC1 and XPB RNAs were only modestly altered by harringtonine, consistent with a lack of effect of harringtonine on repair of cisplatin-DNA damage. However, harringtonine altered expression of p53 and P16 RNAs in both cell lines, although the down-regulation of p53 and P16 RNAs by harringtonine were more pronounced in A2780 cells. The novel observation that harringtonine augments platinum-DNA adducts in both platinum-sensitive and -resistant ovarian cancer cells indicates this combination of drugs may have utility in treating ovarian cancer and may be especially useful in managing platinum-resistant cancers. Additional studies are required to determine which sequence of these drugs is most beneficial, as well as the mechanism by which harringtonine increases cisplatin-DNA damage in ovarian cancer cells.

Administrative data based patient safety research: a critical review

Administrative data are readily available, inexpensive, computer readable, and cover large populations. Despite coding irregularities and limited clinical details, administrative data supplemented by tools such as the Agency for Healthcare Research and Quality (AHRQ) patient safety indicators (PSIs) could serve as a screen for potential patient safety problems that merit further investigation, offer valuable insights into adverse impacts and risks of medical errors and, to some extent, provide benchmarks for tracking progress in patient safety efforts at local, state, or national levels.

C/EBPβ activity and HPV-16 E6/E7 mRNA expression are not altered by imiquimod (ALDARA™) in human cervical cancer cells in vitro

OBJECTIVE

The purpose of this study was to determine the potential relationship between imiquimod and C/EBPbeta by investigating the extent to which imiquimod could alter C/EBPbeta binding activity to known sequences of the HPV-16 NCR, which could lead to the repression of HPV-16 E6/E7 oncogene expression, possibly impacting a major mechanism by which HPV causes cellular transformation.

METHODS

The effect of imiquimod treatment on C/EBPbeta binding activity to its consensus sequence as well as to two specific regions of the HPV-16 NCR was determined by electromobility shift assay (EMSA) in CaSki cervical cancer cells. HPV-16 E6/E7 gene expression was evaluated by RNase protection assay (RPA) in CaSki and in W12-E cells treated with imiquimod. In addition, C/EBPbeta mRNA expression and protein production in response to imiquimod were evaluated by reverse transcription polymerase chain reaction (RT-PCR) and Western blotting, respectively, in the cervical cancer cell lines, CaSki, HeLa, and C33A.

RESULTS

C/EBPbeta binding activity, mRNA expression, and protein production remained unchanged with imiquimod treatment. Initially, HPV-16 E6/E7 expression appeared to be increased with imiquimod treatment in CaSki cells, but this effect was not reproducible. HPV-16 E6/E7 expression was not reproducibly altered with imiquimod treatment in W12-E cells.

CONCLUSION

While these results indicate that imiquimod does not alter C/EBPbeta binding activity, nor does it appear to decrease HPV-16 E6/E7 oncogene expression in vitro, it remains possible that imiquimod may have utility in treating cervical dysplasia or cervical cancer via another mechanism.

Octamethylcyclotetrasiloxane exhibits estrogenic activity in mice via ERα

Octamethylcyclotetrasiloxane (D4) is a low molecular weight cyclic silicone used in the synthesis of larger silicone polymers and in the formulation of a variety of personal care products. The effects of oral D4 exposure in mice on serum estradiol levels, uterine wet weight, and uterine peroxidase activity were investigated. Additionally, in vitro estrogen receptor binding activity was evaluated. Serum estradiol levels decreased in a dose-dependent manner after exposure to 100 mg/kg to 1000 mg/kg D4. Studies with adrenalectomized animals demonstrated that the decreased serum estradiol levels were not due to elevated serum corticosterone levels. Uterine wet weights in ovariectomized mice were significantly increased in a dose-dependent manner by exposure to 250-1000 mg of D4/kg, but not by exposure to other silicone compounds tested (hexamethylcyclotrisiloxane, decamethylcyclopentasiloxane, decamethyltetrasiloxane, and octaphenylcyclotetrasiloxane). Uterine peroxidase activity, a marker for estrogenic activity, was also significantly increased in D4-exposed mice, but not in mice exposed to the other siloxanes. Pretreating mice with the estrogen receptor antagonist ICI 182,780 completely blocked the D4-induced increase in uterine weight, and ovariectomized estrogen receptor-alpha knockout mice showed no increases in uterine weights when orally exposed to D4 or estradiol. In an in vitro estrogen receptor binding assay, D4 showed significant competition with (3)H-estradiol for binding to estrogen receptor-alpha, but not estrogen receptor-beta. The data presented here indicate that D4 has weak estrogenic activity, and that these effects are mediated through estrogen receptor-alpha.

Inadequate peak expiratory flow meter characteristics detected by a computerised explosive decompression device

BACKGROUND

Recent evidence suggests that the frequency response requirements for peak expiratory flow (PEF) meters are higher than was first thought and that the American Thoracic Society (ATS) waveforms to test PEF meters may not be adequate for the purpose.

METHODS

The dynamic response of mini-Wright (MW), Vitalograph (V), TruZone (TZ), MultiSpiro (MS) and pneumotachograph (PT) flow meters was tested by delivering two differently shaped flow-time profiles from a computer controlled explosive decompression device fitted with a fast response solenoid valve. These profiles matched population 5th and 95th centiles for rise time from 10% to 90% of PEF and dwell time of flow above 90% PEF. Profiles were delivered five times with identical chamber pressure and solenoid aperture at PEF. Any difference in recorded PEF for the two profiles indicates a poor dynamic response.

RESULTS

The absolute (% of mean) flow differences in l/min for the V, MW, and PT PEF meters were 25 (4.7), 20 (3.9), and 2 (0.3), respectively, at PEF approximately 500 l/min, and 25 (10.5), 20 (8.7) and 6 (3.0) at approximately 200 l/min. For TZ and MS meters at approximately 500 l/min the differences were 228 (36.1) and 257 (39.2), respectively, and at approximately 200 l/min they were 51 (23.9) and 1 (0.5). All the meters met ATS accuracy requirements when tested with their waveforms.

CONCLUSIONS

An improved method for testing the dynamic response of flow meters detects marked overshoot (underdamping) of TZ and MS responses not identified by the 26 ATS waveforms. This error could cause patient misclassification when using such meters with asthma guidelines.

Acetaminophen exhibits weak antiestrogenic activity in human endometrial adenocarcinoma (Ishikawa) cells

The purpose of this study was to test the hypothesis that acetaminophen would alter an estrogen-regulated process in human cells that express endogenous estrogen receptor alpha and beta (ERalpha and ERbeta). Specifically, the extent to which acetaminophen altered the expression of estrogen-inducible alkaline phosphatase in endometrial adenocarcinoma (Ishikawa) cells and directly interacted with ERbeta and ERalpha was determined. Ishikawa cells were exposed to estradiol and/or to a range of concentrations of acetaminophen for four days, and alkaline phosphatase activity was measured spectrophotometrically. Acetaminophen inhibited both basal and estradiol-induced alkaline phosphatase activity in Ishikawa cells in a concentration-dependent manner. The reduction of Ishikawa cell alkaline phosphatase was not due to direct inhibition of enzyme activity by acetaminophen. Toxic effects of acetaminophen on Ishikawa cells were determined by measuring loss of cellular lactate dehydrogenase to culture medium. High concentrations of acetaminophen (>/=0.5 mM) induced lactate dehydrogenase release from cells and reduced the amount of cellular protein in culture dishes, indicating some acetaminophen-induced reduction of alkaline phosphatase activity might be attributed to toxic effects. However, lower concentrations of acetaminophen significantly reduced alkaline phosphatase activity in the absence of detectable toxicity. Acetaminophen also augmented 4-hydroxy-tamoxifen reduction of alkaline phosphatase activity. Competition binding assays with human ERalpha and ERbeta demonstrated 10(6)-fold molar excess acetaminophen did not directly interact significantly with the ligand-binding domain of either receptor. These studies indicate acetaminophen exerts weak antiestrogenic activity in Ishikawa cells without directly binding ERalpha or ERbeta.

Time domain and flow indices of bronchial hyperresponsiveness: association with asthma symptoms, atopy and smoking

Conventional measures of bronchial hyperresponsiveness (BHR) are only weakly associated with respiratory symptoms in epidemiological studies. Partial and maximal forced expiratory manoeuvres were recorded during histamine challenge testing in 1,959 young male farmers. Analysis was performed to test whether novel measures of BHR, using alternative flow and time domain indices, are more closely associated with asthma symptoms, smoking status and atopy than forced expiratory volume in one second (FEV1) and conventional measures of BHR. The first moments to 75% and 90% of the forced vital capacity (FVC) were calculated from full (F) and partial (P) forced expiratory manoeuvres (i.e. alpha1 75%F, alpha1 75%P), together with the instantaneous flows when 40% and 30% of the FVC remained to be expired (MEF40 and MEF30). BHR was measured by the provocative dose causing a 20% change (PD20) in the FEV1 and alpha1 75%, and also by the method of log dose slopes (LDS). Asthma was diagnosed from symptoms associated with asthma in 158 (8.1%) of the subjects. PD20 FEV1 could only be recorded in 190 subjects (9.7%), of whom only 48 had asthma, whereas LDSFEV1 was recorded in 1,725 (88%) subjects. From the prechallenge data, alpha1 75%, expressed as standardised residuals, showed the largest difference between smokers with and without asthma symptoms, and no indices showed significant differences between nonsmokers with and without asthma symptoms. From BHR data in both smokers and nonsmokers, LDSFEV1 showed one of the largest differences between those with and without asthma symptoms. With smoking status and atopy accounted for, the greatest partial correlation with asthma diagnosis was found for LDSMEF40P, and then for LDSFEV1, but LDSMEF40P was measurable in only just over one-half of the subjects. The authors conclude that time-domain indices are promising measures for longitudinal epidemiological studies concerning the relationship between bronchial hyperresonsiveness and environmental exposures. However, indices from the partial flow-volume loop suffer from censored data.

Caution in the use of 2-iminothiolane (Traut's reagent) as a cross-linking agent for peptides. The formation of N -peptidyl-2-iminothiolanes with bombesin (BN) antagonist (d -Trp6 ,Leu13 -ψ[CH2 NH]-Phe14 )BN6−14 and d -Trp-Gln-Trp-NH2

During a study aimed at generating a bispecific molecule between BN antagonist (D-Trp(6),Leu(13)-psi[CH(2)NH]-Phe(14))BN(6-14) (Antag1) and mAb22 (anti-FcgammaRI), we attempted to cross-link the two molecules by introducing a thiol group into Antag1 via 2-iminothiolane (2-IT, Traut's reagent). We found that reaction of Antag1 with 2-IT, when observed using HPLC, affords two products, but that the later eluting peptide is rapidly transformed into the earlier eluting peptide. To understand what was occurring we synthesized a model peptide, D-Trp-Gln-Trp-NH(2) (TP1), the N-terminal tripeptide of Antag1. Reaction of TP1 with 2-IT for 5 min gave products 1a and 3a; the concentration of 1a decreased with reaction time, whereas that of 3a increased. Thiol 1a, the expected Traut product, was identified by collecting it in a vial containing N-methylmaleimide and then isolating the resultant Michael addition product 2a, which was confirmed by mass spectrometry. Thiol 1a is stable at acidic pH, but is unstable at pH 7.8, cyclizes and loses NH3 to give N-TP1-2-iminothiolane (3a), ES-MS (m/z) [602.1 (M+H)(+)], as well as regenerating TP1. Repeat reaction with Antag1 and 2-IT allowed us to isolate N-Antag1-2-iminothiolane (3b), FAB-MS (m/z) [1212.8 (M+H)(+)] and trap the normal Traut product 1b as its N-methylmaleimide Michael addition product 2b, ES-MS (m/z) [1340.8 (M+H)(+)]. Thiol 1b is also stable at acidic pH, but when neutralized is unstable and cyclizes, forming 3b and Antag1.

Increased resting bronchial tone in normal subjects acclimatised to altitude

BACKGROUND

Normal subjects frequently experience troublesome respiratory symptoms when acclimatised to altitude. Bronchial hyperresponsiveness (BHR) and full and partial flow-volume loops were measured before and after ascent to 5000 m altitude to determine if there are changes in resting bronchial tone and BHR that might explain the symptoms.

METHODS

BHR to histamine was measured using a turbine spirometer to record partial and full flow-volume curves and expressed as log dose slopes. Twenty one subjects were tested at sea level and after acclimatisation at 5000 m altitude.

RESULTS

No significant change in log dose slope measurements of forced expiratory volume in 1 second occurred after acclimatisation, and the maximal expiratory flow with 30% of forced vital capacity remaining (MEF(30%)) rose on the full loop and fell on the partial loop. Their ratio (full divided by partial) rose on average by 0.28 (95% confidence limits 0.14 to 0.42) from the mean (SD) sea level value of 0.87 (0.20).

CONCLUSIONS

There is no increase in BHR in normal subjects acclimatised to altitude but an increase in resting bronchial tone occurs that could be released by deep inspiration. This may be the result of increased cholinergic tone.

Acetaminophen-induced proliferation of estrogen-responsive breast cancer cells is associated with increases in c-myc RNA expression and NF-kappaB activity

Studies reported here tested the hypothesis that acetaminophen stimulates proliferation of E2-responsive cells by inducing expression of E2-regulated genes. Ribonuclease protection assays compared the effects of acetaminophen and E2 on expression of selected genes (c-myc, c-fos, cyclin D1, bcl-2, bax, gadd45, mcl-1, p53, p21(CIP1/WAF1), and bcl-xL) in E2-responsive breast cancer (MCF-7) and endometrial adenocarcinoma (Ishikawa) cells as well as in E2-nonresponsive (MDA-MB-231) breast cancer cells. Acetaminophen and E2 increased c-myc RNA levels in MCF-7 cells, consistent with a mitogenic activity of these compounds in MCF-7 cells. However, the magnitude and time course of acetaminophen and E2 induction of c-myc differed. Neither acetaminophen nor E2 induced c-myc in MDA-MB-231 cells, whereas E2, but not acetaminophen, weakly induced c-myc expression in Ishikawa cells. Furthermore, in these 3 cell types, the expression patterns of the other genes differed dramatically in response to acetaminophen and to E2, indicating that acetaminophen does not activate ER as a transcription factor in the same manner as does E2. Additionally, gel shift assays demonstrated that in MCF-7 cells, acetaminophen increased NF-kappaB activity approximately 40% and did not alter AP-1 activity, whereas E2 increased AP-1 activity approximately 50% and did not increase NF-B activity. These studies indicate that acetaminophen effects on gene expression and cell proliferation depend more on cell type/context than on the presence of ER.

Recording flow in the first second of a maximal forced expiratory manoeuvre: influence of frequency content

The frequency content of the first second of the maximum forced expiratory manoeuvre (MFEM) was measured to determine if the currently accepted frequency limit of 20 Hz for MFEM is adequate for recording peak expiratory flow (PEF). The frequency response of a Fleisch pneumotachograph (PT) was measured and used to record MFEM from 24 patients attending a lung-function laboratory and 26 normal volunteers. The first 1.024 s of the signal recorded at 1,000 Hz for that blow with maximum PEF, underwent fast Fourier transformation using a triangular window function, applied after 0.75 s to reduce flow linearly to zero. All the frequencies above a set limit were removed, followed by inverse transformation to reconstitute the blow. The limits for this frequency cut-off were progressively varied from 100 Hz down to 15 Hz, with the resulting PEF being compared with the PEF from the reconstituted blow with no frequency reduction. The average+/-SD age for the group was 47+/-18 yrs and the average PEF was 450+/-187 L x min(-1), which, when expressed as a standardized residual, was 0.1+/-2.1, with a range from -4.5-3.9 indicating a good spread around normal values. Average rise time to PEF was 83+/-38 ms and dwell time >90% PEF was 45+/-25 ms. Cut-off >20 Hz reduced the mean PEF of the group by 8.5 L x min(-1) (95% confidence limit 5.5-11.4 L x min(-1)), whereas cut-off >30 Hz reduced mean PEF by 4.4 L x min(-1) (2.6-6.2). In the present study subjects, 30 Hz was on the 95th percentile of frequencies for defining the upper limit for 98% of the power spectrum for the first second of the blow. It has been shown that there are frequencies >20 Hz that contribute to peak expiratory flow enough to influence readings made using conventional hand-held peak expiratory flow meters, such as the mini-Wright. Devices used for recording flow from a maximum forced expiratory manoeuvre should therefore have an adequate frequency response of up to 30 Hz.