Liquid medication dosing errors in children: role of provider counseling strategies

OBJECTIVE

To examine the degree to which recommended provider counseling strategies, including advanced communication techniques and dosing instrument provision, are associated with reductions in parent liquid medication dosing errors.

METHODS

Cross-sectional analysis of baseline data on provider communication and dosing instrument provision from a study of a health literacy intervention to reduce medication errors. Parents whose children (<9 years) were seen in 2 urban public hospital pediatric emergency departments (EDs) and were prescribed daily dose liquid medications self-reported whether they received counseling about their child's medication, including advanced strategies (teachback, drawings/pictures, demonstration, showback) and receipt of a dosing instrument. The primary dependent variable was observed dosing error (>20% deviation from prescribed). Multivariate logistic regression analyses were performed, controlling for parent age, language, country, ethnicity, socioeconomic status, education, health literacy (Short Test of Functional Health Literacy in Adults); child age, chronic disease status; and site.

RESULTS

Of 287 parents, 41.1% made dosing errors. Advanced counseling and instrument provision in the ED were reported by 33.1% and 19.2%, respectively; 15.0% reported both. Advanced counseling and instrument provision in the ED were associated with decreased errors (30.5 vs. 46.4%, P = .01; 21.8 vs. 45.7%, P = .001). In adjusted analyses, ED advanced counseling in combination with instrument provision was associated with a decreased odds of error compared to receiving neither (adjusted odds ratio 0.3; 95% confidence interval 0.1-0.7); advanced counseling alone and instrument alone were not significantly associated with odds of error.

CONCLUSIONS

Provider use of advanced counseling strategies and dosing instrument provision may be especially effective in reducing errors when used together.

Use of active ingredient information for low socioeconomic status parents' decision-making regarding cough and cold medications: role of health literacy

OBJECTIVE

Parent administration of multiple medications with overlapping active ingredients places children at risk for overdose. We sought to examine how parents use active ingredient information as part of the process of selecting a cough/cold medication for their child and how health literacy plays a role.

METHODS

Experimental study of parents of children presenting for care in an urban public hospital pediatric clinic. Parents were asked to determine which of 3 cough/cold medications could be given to relieve a child's cold symptoms, as part of a scenario in which they had already given a dose of acetaminophen; only 1 did not contain acetaminophen. Primary dependent variable: correct selection of cough/cold medication by using active ingredient as the rationale for choice. Primary independent variable: parent health literacy (Newest Vital Sign test).

RESULTS

Of 297 parents, 79.2% had low health literacy (Newest Vital Sign score 0-3); 35.4% correctly chose the cough/cold medication that did not contain acetaminophen. The proportion of those who made the correct choice was no different than expected from chance alone (Goodness of fit test; χ(2) = 2.1, P = .3). Only 7.7% chose the correct medication and used active ingredient as the rationale. Those with adequate literacy skills were more likely to have selected the correct medication and rationale (25.8% vs 3.0% (P = .001); adjusted odds ratio 11.1 (95% confidence interval 3.6-33.7), after we adjusted for sociodemographics, including English proficiency and education.

CONCLUSIONS

Many parents, especially those with low health literacy, do not use active ingredient information as part of decision-making related to administering multiple medications.

Readability, suitability, and characteristics of asthma action plans: examination of factors that may impair understanding

OBJECTIVE

Recognition of the complexity of asthma management has led to the development of asthma treatment guidelines that include the recommendation that all pediatric asthma patients receive a written asthma action plan. We assessed the readability, suitability, and characteristics of asthma action plans, elements that contribute to the effectiveness of action plan use, particularly for those with limited literacy.

METHODS

This was a descriptive study of 30 asthma action plans (27 state Department of Health (DOH)-endorsed, 3 national action plans endorsed by 6 states).

OUTCOME MEASURES

(1) readability (as assessed by Flesch Reading Ease, Flesch-Kincaid, Gunning Fog, Simple Measure of Gobbledygook, Forcast), (2) suitability (Suitability Assessment of Materials [SAM], adequate: ≥ 0.4; unsuitable: <0.4), (3) action plan characteristics (peak flow vs symptom-based, symptoms, recommended actions).

RESULTS

Mean (SD) overall readability grade level was 7.2 (1.1) (range = 5.7-9.8); 70.0% were above a sixth-grade level. Mean (SD) suitability score was 0.74 (0.14). Overall, all action plans were found to be adequate, although 40.0% had an unsuitable score in at least 1 factor. The highest percent of unsuitable scores were found in the categories of layout/typography (30.0%), learning stimulation/motivation (26.7%), and graphics (13.3%). There were no statistically significant differences between the average grade level or SAM score of state DOH developed action plans and those from or adapted from national organizations. Plans varied with respect to terms used, symptoms included, and recommended actions.

CONCLUSIONS

Specific improvements in asthma action plans could maximize patient and parent understanding of appropriate asthma management and could particularly benefit individuals with limited literacy skills.

Health literacy assessment of labeling of pediatric nonprescription medications: examination of characteristics that may impair parent understanding

OBJECTIVE

Poor quality and variability of medication labeling have been cited as key contributors to medication misuse. We assessed the format and content of labels and materials packaged with common pediatric liquid nonprescription medications.

METHODS

Descriptive study. A total of 200 top-selling pediatric oral liquid nonprescription medications (during the 52 weeks ending October 30, 2009) categorized as analgesic, cough/cold, allergy, and gastrointestinal products, with dosing information for children <12 years (representing 99% of U.S. market for these products) were reviewed. The principal display panel (PDP) and FDA Drug Facts panel (side panel) of each bottle, and associated box, if present, were independently examined by 2 abstractors. Outcome measures were content and format of active ingredient information and dosing instructions of the principal display panel and Drug Facts panel.

RESULTS

Although almost all products listed active ingredients on the Drug Facts panel (side panel), nearly 1 in 5 (37 [18.5%]) did not list active ingredients on the PDP. When present, mean (SD) font size for PDP active ingredients was 10.7 (5.0), smaller than product brand name (32.1 [15.0]) and flavor (13.1 [4.8]); P < .001. Most products included directions in chart form (bottle: 167 [83.5%], box: 148 [96.1%], P < .001); mean (SD) font size: 5.5 (0.9; bottle), 6.5 (0.5; box), P < .001. Few products expressed dosing instructions in pictographic form: 4 (2.6%) boxes and 0 bottles. Nearly all products included the Food and Drug Administration-mandated sections.

CONCLUSIONS

The format and content of labels for nonprescription pediatric liquid medications could be improved to facilitate parent understanding of key medication information, including active ingredient information and dosing instructions.

Perceived barriers to care and attitudes towards shared decision-making among low socioeconomic status parents: role of health literacy

OBJECTIVE

Although low parent health literacy (HL) has been linked to poor child health outcomes, it is not known whether differences in perceptions related to access to care and provider-parent partnership in care are potential contributing factors. We sought to assess whether parent HL is associated with differences in perceived barriers to care and attitudes regarding participatory decision-making with the provider.

METHODS

This was a cross-sectional analysis of data collected from parents presenting with their child to an urban public hospital pediatric clinic in New York City. Dependent variables were caregiver-reported barriers to care (ability to reach provider at night/on weekends, difficult travel to clinic) and attitudes towards participatory decision-making (feeling like a partner, relying on doctor's knowledge, leaving decisions up to the doctor, being given choices/asked opinion). The primary independent variable was caregiver HL (Short Test of Functional Health Literacy in Adults [S-TOHFLA]).

RESULTS

A total of 823 parents were assessed; 1 in 4 (27.0%) categorized as having low HL. Parents with low HL were more likely to report barriers to care than those with adequate HL: trouble reaching provider nights/weekends, 64.9% vs. 49.6%, (p < 0.001, adjusted odds ratio [AOR] 1.7, 95% confidence interval [95% CI] 1.2-2.4); difficult travel, 15.3% vs. 8.0%, (p = 0.004, AOR 1.8, 95% CI 1.1-3.0). Low HL was also associated with not feeling like a partner (28.8% vs. 17.1%; AOR 2.0; 95% CI 1.4-3.0), preference for relying on the doctor's knowledge (68.9% vs. 52.2%; AOR 1.7; 95% CI 1.2-2.4), and preference for leaving decisions up to the doctor (57.7% vs. 33.3%; AOR 2.2; 95% CI 1.6-3.1).

CONCLUSIONS

Addressing issues of parent HL may be helpful in ameliorating barriers to care and promoting provider-parent partnership in care.

Interventions aimed at decreasing obesity in children younger than 2 years: a systematic review

OBJECTIVE

To assess the evidence for interventions designed to prevent or reduce overweight and obesity in children younger than 2 years.

DATA SOURCES

MEDLINE, the Cochrane Central Register of Controlled Trials, CINAHL, Web of Science, and references from relevant articles.

STUDY SELECTION

Included were published studies that evaluated an intervention designed to prevent or reduce overweight or obesity in children younger than 2 years.

DATA EXTRACTION

Extracted from eligible studies were measured outcomes, including changes in child weight status, dietary intake, and physical activity and parental attitudes and knowledge about nutrition. Studies were assessed for scientific quality using standard criteria, with an assigned quality score ranging from 0.00 to 2.00 (0.00-0.99 is poor, 1.00-1.49 is fair, and 1.50-2.00 is good).

DATA SYNTHESIS

We retrieved 1557 citations; 38 articles were reviewed, and 12 articles representing 10 studies met study inclusion criteria. Eight studies used educational interventions to promote dietary behaviors, and 2 studies used a combination of nutrition education and physical activity. Study settings included home (n = 2), clinic (n = 3), classroom (n = 4), or a combination (n = 1). Intervention durations were generally less than 6 months and had modest success in affecting measures, such as dietary intake and parental attitudes and knowledge about nutrition. No intervention improved child weight status. Studies were of poor or fair quality (median quality score, 0.86; range, 0.28-1.43).

CONCLUSIONS

Few published studies attempted to intervene among children younger than 2 years to prevent or reduce obesity. Limited evidence suggests that interventions may improve dietary intake and parental attitudes and knowledge about nutrition for children in this age group. For clinically important and sustainable effect, future research should focus on designing rigorous interventions that target young children and their families.

Use of a pictographic diagram to decrease parent dosing errors with infant acetaminophen: a health literacy perspective

OBJECTIVE

Medication dosing errors by parents are frequent. We sought to whether a pictographic dosing diagram could improve parent ability to dose infant acetaminophen, and to determine whether pictogram benefit varies by health literacy level.

METHODS

We conducted an experimental study of parents presenting with their children to an urban public hospital pediatric clinic. Caregivers were randomized to dose infant acetaminophen with a standard dropper using text-only or text-plus-pictogram instructions (pictographic diagram of dose). The primary outcome variable was dosing accuracy (error defined as >20% deviation above/below dose; large overdosing error defined as >1.5 times recommended dose). Caregiver health literacy was assessed by means of the Newest Vital Sign measure.

RESULTS

A total of 299 parents were assessed (144 text-only instructions; 155 text plus pictogram); 77.9% had limited health literacy (Newest Vital Sign score 0-3). Text-plus-pictogram recipients were less likely to make an error compared to text-only recipients (43.9% vs 59.0%, P = .01; absolute risk reduction, 15.2% [95% confidence interval, 3.8-26.0]; number needed to treat, 7 [4-26]). Of text-plus-pictogram recipients, 0.6% made a large overdosing error compared to 5.6% of text-only recipients (absolute risk reduction, 4.9% [0.9-10.0]; number needed to treat, 20 [10-108]). Pictogram benefit varied by health literacy, with a statistically significant difference in dosing error evident in the text-plus-pictogram group compared to the text-only group among parents with low health literacy (50.4% vs 66.4%; P = .02), but not for parents with adequate health literacy (P = .7).

CONCLUSIONS

Inclusion of pictographic dosing diagrams as part of written medication instructions for infant acetaminophen may help parents provide doses of medication more accurately, especially those with low health literacy. High error rates, even among parents with adequate health literacy, suggest that additional study of strategies to optimize dosing is needed.

Evaluation of consistency in dosing directions and measuring devices for pediatric nonprescription liquid medications

CONTEXT

In response to reports of unintentional drug overdoses among children given over-the-counter (OTC) liquid medications, in November 2009 the US Food and Drug Administration (FDA) released new voluntary industry guidelines that recommend greater consistency and clarity in OTC medication dosing directions and their accompanying measuring devices.

OBJECTIVE

To determine the prevalence of inconsistent dosing directions and measuring devices among popular pediatric OTC medications at the time the FDA's guidance was released.

DESIGN AND SETTING

Descriptive study of 200 top-selling pediatric oral liquid OTC medications during the 52 weeks ending October 30, 2009. Sample represents 99% of the US market of analgesic, cough/cold, allergy, and gastrointestinal OTC oral liquid products with dosing information for children younger than 12 years.

MAIN OUTCOME MEASURES

Inclusion of measuring device, within-product inconsistency between dosing directions on the bottle's label and dose markings on enclosed measuring device, across-product use of nonstandard units and abbreviations, and presence of abbreviation definitions.

RESULTS

Measuring devices were packaged with 148 of 200 products (74.0%). Within this subset of 148 products, inconsistencies between the medication's dosing directions and markings on the device were found in 146 cases (98.6%). These included missing markings (n = 36, 24.3%) and superfluous markings (n = 120, 81.1%). Across all products, 11 (5.5%) used atypical units of measurement (eg, drams, cc) for doses listed. Milliliter, teaspoon, and tablespoon units were used for doses in 143 (71.5%), 155 (77.5%), and 37 (18.5%) products, respectively. A nonstandard abbreviation for milliliter (not mL) was used by 97 products. Of the products that included an abbreviation, 163 did not define at least 1 abbreviation.

CONCLUSION

At the time the FDA released its new guidance, top-selling pediatric OTC liquid medications contained highly variable and inconsistent dosing directions and measuring devices.

Health literacy and quality: focus on chronic illness care and patient safety

Despite a heightened focus on improving quality, recent studies have suggested that children only receive half of the indicated preventive, acute, or chronic care. Two major areas in need of improvement are chronic illness care and prevention of medical errors. Recently, health literacy has been identified as an important and potentially ameliorable factor for improving quality of care. Studies of adults have documented that lower health literacy is independently associated with poorer understanding of prescriptions and other medical information and worse chronic disease knowledge, self-management behaviors, and clinical outcomes. There is also growing evidence to suggest that health literacy is important in pediatric safety and chronic illness care. Adult studies have suggested that addressing literacy can lead to improved patient knowledge, behaviors, and outcomes. Early studies in the field of pediatrics have shown similar promise. There are significant opportunities to evaluate and demonstrate the importance of health literacy in improving pediatric quality of care. Efforts to address health literacy should be made to apply the 6 Institute of Medicine aims for quality-care that is safe, effective, patient centered, timely, efficient, and equitable. Efforts should also be made to consider the distinct nature of pediatric care and address the "4 D's" unique to child health: the developmental change of children over time; dependency on parents or adults; differential epidemiology of child health; and the different demographic patterns of children and their families.

The health literacy of parents in the United States: a nationally representative study

OBJECTIVE

To assess the health literacy of US parents and explore the role of health literacy in mediating child health disparities.

METHODS

A cross-sectional study was performed for a nationally representative sample of US parents from the 2003 National Assessment of Adult Literacy. Parent performance on 13 child health-related tasks was assessed by simple weighted analyses. Logistic regression analyses were performed to describe factors associated with low parent health literacy and to explore the relationship between health literacy and self-reported child health insurance status, difficulty understanding over-the-counter medication labeling, and use of food labels.

RESULTS

More than 6100 parents made up the sample (representing 72600098 US parents); 28.7% of the parents had below-basic/basic health literacy, 68.4% were unable to enter names and birth dates correctly on a health insurance form, 65.9% were unable to calculate the annual cost of a health insurance policy on the basis of family size, and 46.4% were unable to perform at least 1 of 2 medication-related tasks. Parents with below-basic health literacy were more likely to have a child without health insurance in their household (adjusted odds ratio: 2.4 [95% confidence interval: 1.1-4.9]) compared with parents with proficient health literacy. Parents with below-basic health literacy had 3.4 times the odds (95% confidence interval: 1.6-7.4) of reporting difficulty understanding over-the-counter medication labels. Parent health literacy was associated with nutrition label use in unadjusted analyses but did not retain significance in multivariate analyses. Health literacy accounted for some of the effect of education, racial/ethnic, immigrant-status, linguistic, and income-related disparities.

CONCLUSIONS

A large proportion of US parents have limited health-literacy skills. Decreasing literacy demands on parents, including simplification of health insurance and other medical forms, as well as medication and food labels, is needed to decrease health care access barriers for children and allow for informed parent decision-making. Addressing low parent health literacy may ameliorate existing child health disparities.

Association of low caregiver health literacy with reported use of nonstandardized dosing instruments and lack of knowledge of weight-based dosing

OBJECTIVE

Caregivers of young children frequently measure doses of liquid medications incorrectly. Use of nonstandardized dosing instruments and lack of knowledge that dosing is weight-based contribute to dosing errors. We sought to assess whether low caregiver health literacy was associated with these outcomes.

METHODS

This was a cross-sectional analysis of caregivers presenting to an urban pediatric emergency room. Dependent variables were caregiver reported use of nonstandardized dosing tools and knowledge of weight-based dosing. The independent variable was caregiver health literacy (Test of Functional Health Literacy in Adults [TOFHLA]).

RESULTS

Two hundred ninety-two caregivers were assessed: 23.3% reported use of nonstandardized liquid dosing instruments, and 67.8% were unaware of weight-based dosing. Caregivers who were unaware of weight-based dosing were more likely to use nonstandardized dosing tools (28.3% vs 12.8%; P = .003). In unadjusted analyses, overall health literacy, reading comprehension, and numeracy were all associated with both dependent variables. In analyses adjusting for child age, health care experiences, and caregiver acculturation and education, inadequate/marginal overall health literacy was associated with lack of knowledge of weight-based dosing (adjusted odds ratio [AOR] 2.3; P = .03), whereas lower reading comprehension was associated with both lack of knowledge (AOR 2.0; P = .03) and reported use of nonstandardized instrument (AOR 2.4; P = .007).

CONCLUSIONS

Low health literacy, in particular reading comprehension, was associated with reported use of nonstandardized dosing instruments and lack of knowledge regarding weight-based dosing. Both caregiver health literacy and sociodemographic factors should be considered in the design of interventions to prevent medication administration errors.

The mechanisms of neuronal death produced by mitochondrial toxin 3-nitropropionic acid: the roles of N-methyl-D-aspartate glutamate receptors and mitochondrial calcium overload

Previous studies showed that 3-nitropropionic acid, an irreversible inhibitor of succinate dehydrogenase, produced neuronal death secondary to perturbed intracellular calcium homeostasis. However, the response of intramitochondrial calcium ([Ca(2+)](m)) to 3-nitropropionic acid remains unknown. In this study, we investigated the roles of and relationships among [Ca(2+)](m) overload, mitochondrial reactive oxygen species, and mitochondrial membrane depolarization in 3-nitropropionic acid-induced neuronal death. Following 1 mM 3-nitropropionic acid treatment on primary rat neuronal cultures, there was a gradual increase of [Ca(2+)](m) beginning at 2-4 h post 3-nitropropionic acid application, and a twofold increase of mitochondrial reactive oxygen species at 4 h. These were followed by mitochondrial membrane depolarization at 6-8 h post-treatment. By inhibiting [Ca(2+)](m) uptake, Ruthenium Red attenuated the production of reactive oxygen species, and prevented the 3-nitropropionic acid-induced mitochondrial membrane depolarization and 70% of apoptotic neuronal death (P<0.001). Inhibition of caspase activation attenuated the elevation of [Ca(2+)](m) (P<0.001), indicating that caspase activation plays a role in the elevation of [Ca(2+)](m). MK-801, an antagonist of N-methyl-D-aspartate (NMDA) glutamate receptors, prevented 3-nitropropionic acid-induced [Ca(2+)](m) elevation, caspase-3 activation, mitochondrial depolarization, and neuronal death. We conclude that the activation of NMDA glutamate receptor contributes to mitochondrial alterations induced by 3-nitropropionic acid. Inhibition of its activation and [Ca(2+)](m) overload with subsequent mitochondrial membrane depolarization can therefore attenuate the neuronal death induced by 3-nitropropionic acid.

Regulation of the subcellular distribution and gene expression of GABA(A) receptor by microtubules and microfilaments in cultured brain neurons

Mechanisms underlying the intracellular transport of gamma-aminobutyric acid(A) receptor (GABA(A)R) were examined in the cultured neurons derived from chicken embryo brains. In situ trypsinization of the cultures and (3)H-flunitrazepam (FNZ) binding assay were employed to determine the cell surface and intracellular distribution of the receptor. A 3-h treatment of the cells with 1 microM of colchicine, a microtubule depolymerizer, reversibly raised the proportion of intracellular GABA(A)R density by about 36% and decreased that of the cell surface receptors by 18% from respective control values, whereas the 3-h incubation with 2 microM of cytochalasin D, a microfilament disrupter, did not cause significant changes. These treatments failed to alter the total number of the (3)H-FNZ binding sites of the neurons and the affinity of the ligand. Moreover, the exposure to colchicine seemed to produce a stronger cytoplasmic immunostaining of the GABA(A)R alpha subunits in many neurons without affecting the total cellular level of the proteins, in accordance with the increased fraction of intracellular (3)H-FNZ binding. However, in the neurons exposed to cytochalasin D, there was an increase of around 28% in the total content of alpha(1)+51kDa proteins. In addition, the colchicine or cytochalasin D treatment inhibited approximately 21 or 18% of the rate of general protein synthesis in the culture. Notably, in situ hybridization assay showed that the GABA(A)R alpha(1) or alpha(2) mRNA was present in 92 +/- 2% or 94 +/- 2% of the cytochalasin D-treated neurons, both of which were higher than 71 +/- 2-74 +/- 3% of the control and colchicine-treated cells. The data suggest that by regulating the intracellular transport, the microtubular system participates in the maintenance of normal subcellular distribution of GABA(A)R in the neurons. By contrast, the organization of microfilaments may play a role in modulating the gene expression of GABA(A)R subunits.

Amphetamine induces differential changes in the gene expression of metabotropic glutamate receptor 5 in cultured cortical and hippocampal neurons

Mechanisms underlying the short-term effects of amphetamine (AMPH) were examined by monitoring the expression of metabotropic glutamate receptor 5 (mGluR5) in cultured rat neurons. The cortical and hippocampal neurons were incubated with 0.1-100 microM of AMPH for 1 h or 1 microM of AMPH for 10 min to 3 h. Immunocytochemical and in situ hybridization (ISH) analyses revealed that the levels of mGluR5 immunoreactivity and mRNA in the cortical neurons were initially increased with the treatment time and dosage, to reach maximal elevations of 34 and 53% from control values following 1 h incubation of 1 microM, and then returned toward the controls. When the cortical neurons were preincubated with the antagonist, alpha-methyl-4-carboxyphenylglycine (MCPG) to mGluRs, before treated with 1 M of AMPH for 1 h, the levels of mGluR5 protein and mRNA became 120 and 116% of control values. In hippocampal neurons, the AMPH treatment persistently upregulated the mGluR5 protein by 50-62%; however, the mRNA responded with the bell-shaped pattern to the treatment times and doses, with 20-43% increases from controls. These modifications of the receptor were reversible, since removal of AMPH resulted in regular levels of the receptor. Notably, the AMPH-generated increases in mGluR5 protein and mRNA were completely blocked by the pretreatment with cycloheximide and actinomycin D, respectively. The data indicate differential responsive patterns of mGluR5 in the cortical and hippocampal neurons to the drug perturbation. The action of AMPH may involve regulation to transcriptional and translational events in the neurons, and the activation of the MCPG-sensitive receptors.

Changes in the gene expression of GABA(A) receptor alpha1 and alpha2 subunits and metabotropic glutamate receptor 5 in the basal ganglia of the rats with unilateral 6-hydroxydopamine lesion and embryonic mesencephalic grafts

By using an animal model of parkinsonism, we examined the expression of GABA(A) receptor (R) and metabotropic glutamate receptor (mGluR) 5 in the basal ganglia after transplantation with dopamine-rich tissue. The adult rats were unilaterally lesioned by the injection of 6-hydroxydopamine to their left medial forebrain bundles. At 5-10 weeks following the dopaminergic denervation, the levels of GABA(A)R in the left caudate-putamen and globus pallidus were about 20 and 16% lower than that of the right intact (control) sides, as shown by [3H]flunitrazepam binding autoradiography on the brain sections. However, the receptor density increased to around 132 and 130% of control levels in the entopeduncular nucleus and substantia nigra pars reticulata of the lesioned sides. Furthermore, in situ hybridization analysis exhibited parallel trends of changes in the levels of the GABA(A)R alpha1 and alpha2 subunit and mGluR5 mRNAs in the neurons of the brain regions with that of the proteins detected by the binding assay. A number of the rats 5 weeks postlesion were transplanted with the ventral mesencephalon of the embryonic rat into their left striata. Five weeks later, the changes in the [3H]flunitrazepam binding seemed to be recovered by approximately 50-63% on the grafted sides of the areas. Moreover, the transplantation appeared to produce a nearly complete reversal of the lesion-induced alterations in the levels of the mRNAs. Thus, the data indicate the mechanism of gene regulation for the modified expression of the receptors and could implicate the participation of the receptors in the pathogenesis of Parkinson's disease.

Effect of amphetamine on the expression of the metabotropic glutamate receptor 5 mRNA in developing rat brain

Mechanisms underlying the acute effects of amphetamine (AMP) were examined by monitoring the expression of metabotropic glutamate receptor 5 (mGluR5) and specific 3H-glutamate binding in the developing rat brain. Each of the postnatal day (P) 4, P21 and P60 rats received one intraperitoneal injection of AMP, 5 mg/kg or saline and were sacrificed one hour later. In situ hybridization analysis revealed that the AMP treatment raised the levels of the mGluR5 mRNA by 9-28% in the neurons of the layer 5 of motor and somatosensory cortices, whereas reduced the levels by 12-28% in the layer 5 of perirhinal cortex and the ventromedial part of caudate-putamen of the 3 ages. In the layer 2/3 neurons of cingular cortex, an 18% higher and 14% and 22% lower than control levels of the mRNA were detected in the P4 and in the P21 and P60 rats injected with AMP. Moreover, the levels of mGluR5 mRNA in the hippocampi and dentate gyri were elevated by AMP to 110-151% of controls in the rats of 3 ages. Reversible 3H-glutamate binding assay showed an increase of 25% and a 12% decrease in the binding levels in the cortices of AMP-treated P4 and P21 rats. The AMP administration also produced a 27% reduction and 62% elevation in the binding of the hippocampi of P4 and P60 rats. The results reveal age- and region-dependent changes in the expression of the glutamate receptors induced by AMP and may indicate differential plastic capability of the neurons to the drug perturbation.

An enzyme-linked immunosorbent assay for the detection of antibody to avian reovirus by using protein sigma B as the coating antigen

An enzyme-linked immunosorbent assay using the expressed protein sigma B as the coating antigen (sigma B-ELISA) for detecting antibody to avian reovirus (ARV) in chickens was developed and compared with a conventional ELISA. Both ELISA s and a serum neutralisation (SN) test were used to test the sera from experimentally vaccinated and farm chickens. The sigma B-ELISA could clearly distinguish the SN-positive and -negative sera in 38-week-old chickens. The correlation rate between SN and a sigma B-ELISA was 100 per cent (65/65), and that between SN and conventional ELISA was 84 per cent (55/65). With the sigma B-ELISA, all SN-negative sera had low absorbance values (below 0.06), and the absorbance values correlated closely with the SN titres. However, the sera which were antibody-negative by SN had various absorbance values, ranging from 0.07 to 0.39 in the conventional ELISA. Hence, the sigma B-ELISA had lower non-specific binding reactions than the conventional ELISA against sera from ARV -negative birds. Antibody against ARV could be detected by sigma B-ELISA after vaccination. Absorbance values peaked 4 weeks after vaccination at 2 weeks of age and were maintained until the birds were 27 weeks old. The results suggest that the presence of antibody against viral protein sigma B in birds may be used as a good indicator by the sigma B - ELISA for detecting immune status of a chicken flock or to detect chickens infected with ARV.

Characterization of avian reovirus non structural protein sigmaNS synthesized in Escherichia coli

The coding region of avian reovirus S1133 genomic segment S4, encoding the non structural protein sigmaNS, was inserted into expression vector pET28a and the protein was expressed in Escherichia coli BL21(DE3) as a fusion protein containing a C-terminal peptide with six tandem histidines (His-tag). The expressed protein (esigmaNS) consistent with the expected molecular size of the avian reovirus protein sigmaNS synthesized in infected cells was readily purified by His-Bind Resin. The esigmaNS was further confirmed to be indistinguishable from viral sigmaNS by immunoblot analysis. The esigmaNS binds 32P-labeled ssRNA probe produced by run-off transcription of clone pGEM-3Zf(+)S4. The binding activity is blocked by heterologous yeast rRNA, but not by homologous avian reovirus dsRNA and heterologous infectious bursal disease virus dsRNA and salmon sperm dsDNA. Therefore, the ssRNA-binding activity of the expressed protein sigmaNS is non sequence-specific, similar to that previously described for viral sigmaNS purified from avian reovirus infected cell extracts. In addition, the recent data also show that the optimal salt (NaCl) concentration and pH for its binding are 100-150 mM and 7.0, respectively, in terms of the UV cross-linking and RNase A treatment of the reaction mixtures prior to the denaturing gel analysis.

Synthesis in Escherichia coli of avian reovirus core protein varsigmaA and its dsRNA-binding activity

The genome segment S2 of p6ian reovirus (ARV) S1133 was cloned and sequenced. The entire S2 nucleotide sequence is 1325 bp long with one long open reading frame that encodes a protein of 415 amino acids, corresponding to varsigmaA, a major core protein of ARV. S2 possesses a pentanucleotide, TCATC, at the 3'-terminus of its plus strand, common to other known genome segments of ARV and to 10 genome segments of mammalian reovirus. Amino acid sequence analysis revealed that varsigmaA contains a carboxy-terminal region (one-fourth of the protein) that is formed from alpha-helices and beta-turns, and the remainder (three-fourths of the protein) is formed predominantly from beta-strands and beta-turns. Analysis of binding activity to poly(rI)-poly(rC)-agarose suggested that ARV protein A present in total virus-infected chicken embryo fibroblasts (CEF) had dsRNA-binding activity. To further characterize the binding activity, protein varsigmaA was subsequently expressed in Escherichia coli BL21(DE3) cells as a fusion protein and isolated by metal chelate affinity chromatography. The expressed protein evarsigmaA was further purified through a Superdex 75 HR 10/30 column after digestion of the purified fusion peptide with enterokinase. The expressed protein evarsigmaA has the same molecular weight as virion protein varsigmaA purified from ARV-infected CEF and is indistinguishable from virion protein varsigmaA by immunoblot analysis. The evarsigmaA binds cooperatively alpha (32)P-labeled dsRNA probe produced by run-off transcription of clone pGEM-3Zf(+)S4. The binding reaction is blocked by homologous ARV dsRNA or heterologous infectious bursal disease virus dsRNA and poly(rI)-poly(rC), but not by salmon sperm DNA. The results indicate that the expressed protein evarsigmaA has dsRNA-binding activity similar to that of varsigmaA obtained from infected cells, and its binding is sequence-independent.

Toxicity of tunicamycin to cultured brain neurons: ultrastructure of the degenerating neurons

Our previous study has shown that tunicamycin irreversibly downregulates the expression of GABA(A)R and causes cell death in cultured brain neurons by biochemical and light microscopic methods. In this study, we examined mechanisms underlying the degeneration of the neurons mainly employing electron microscopic analysis. Cultured neurons derived from embryonic chicken brains were incubated with 5 microg/ml of tunicamycin (TM) for 24 h, followed by continual incubation or removal of TM for additional 3 h or 24 h. Neurons treated with TM for 24 h showed dilated rough endoplasmic reticulum (rER), nuclear envelope and components of Golgi apparatus, in addition to the degranulation of rER and disaggregation of ribosomal rosettes. In neurons subjected to the prolonged incubation, some ribosomes reattached to the membranes of rER; the polyribosomes reappeared, and the swelling of Golgi apparatus subsided. However, the distention of rER persisted, and an uncommon spindle-like structure appeared in the perikarya. This structure is implicated to involve the neuronal degeneration. Moreover, extracellular cell debris was increased with time of incubation. The ratio of the light neurons, defined as containing lower cytoplasmic matrix density than the untreated control, decreased from 28% at 3 h to 3% at 24 h after the removal of TM, and 45% at further 3 h to 6% at further 24 h incubation of TM, whereas dense neurons only appeared in the two 24 h groups, as 44% and 34%. The light neurons resemble necrotic cells, but the dense neurons exhibit distinct morphological features from necrosis and apoptosis. The gel electrophoresis assay revealed the absence of DNA fragmentation in all cultures. In addition, whole cell recordings exhibited a 40% decrease of the GABA-elicited current in the neurons exposed to TM for 24 h. The results indicate irreversible toxicity of chronic TM treatment to the neurons and suggest differential mechanisms for the neuronal death among various populations of cells. It is evident that the N-glycosylation plays a critical role for neuronal survival.

Effects of pentobarbital on the expression of GABAA receptor beta 1 mRNA in the hippocampus: differential responses of CA1 and CA3

Effects of barbiturates have been linked to the inhibitory GABAA receptor in the brain. The present study examines changes in the expression of GABAA receptor in the hippocampus of pentobarbital treated rat. Intraperitoneal pentobarbital injections were administered once daily for 9 days at an increasing dose schedule, 30 mg/kg at day 1-3, 60 mg/kg day 4-6, and 90 mg/kg day 7-9. Within each of the three dosage periods, the duration of sleep and extent of reduction in body temperature of the rats decreased with time. Two hours after the 9th injection, 3H-muscimol binding of the hippocampal homogenates of the animals showed that the maximal number of binding sites (Bmax), 10.2 +/- 1.6 pmol/mg protein, was not significantly greater than 9.5 +/- 1.2 of saline control, but strikingly about 7-fold control level of beta 1 mRNA was seen in the pyramidal cells of CA1 and CA2, as revealed by in situ hybridization analysis with digoxigenin-cRNA probes. However, when the rats were withdrawn from pentobarbital injection for 24 hours and 7 days, the Bmax of the hippocampi was lowered to 7.3 +/- 1.0 and 5.1 +/- 0.7, respectively, and the expression of beta 1 mRNA in CA1-2 returned toward control. The pentobarbital treatment did not significantly alter the affinity of the radioligand to the receptor in the hippocampus and the expression of beta 1 mRNA in CA3 and CA4. The results suggest the plasticity of the beta 1 mRNA in CA1-2 as well as differential involvement of CA1-2 and CA3-4 in response to the pentobarbital perturbation.