Rifampicin exacerbates isoniazid-induced toxicity in human but not in rat hepatocytes in tissue-like cultures

BACKGROUND AND PURPOSE

Rifampicin has been extensively reported to exacerbate the hepatotoxicity of isoniazid in patients with tuberculosis. However, this was controversially claimed by previous reports using rat models. This study evaluated the effect of rifampicin on isoniazid-induced hepatocyte toxicity by using human and rat hepatocytes in tissue-like culture.

EXPERIMENTAL APPROACH

Hepatocytes in tissue-like gel entrapment were used to examine isoniazid toxicity, as shown by cell viability, intracellular glutathione content and albumin secretion. For demonstration of the differential effects of rifampicin on human and rat hepatocytes, induction by rifampicin of cytochrome P450 (CYP) 2E1, a major enzyme associated with isoniazid hepatotoxicity, was detected by 4-nitrocatechol formation and RT-PCR analysis.

KEY RESULTS

Rifampicin (12 microM) enhanced isoniazid-induced toxicity in human hepatocytes but not in rat hepatocytes. Enhanced CYP 2E1 enzymic activity and mRNA expression were similarly detected in human hepatocytes but not in rat hepatocytes. Both rat and human hepatocytes in gel entrapment were more sensitive to isoniazid treatment compared with the corresponding hepatocytes in a monolayer culture.

CONCLUSIONS AND IMPLICATIONS

The difference in induction of CYP 2E1 by rifampicin between rat and human hepatocytes accounted for the difference in exacerbation of isoniazid hepatocyte toxicity by rifampicin, with more significant toxicity in gel entrapment than in monolayer cultures. Thus, human hepatocytes in tissue-like cultures (gel entrapment) could be an effective model for hepatotoxicity research in vitro, closer to the in vivo situation.

Associations between postnatal weight gain, change in postnatal pulmonary function, formula feeding and early asthma

BACKGROUND

A study was undertaken to examine factors that might influence lung function during infancy and to test the hypothesis that change in weight during infancy is negatively associated with change in lung function.

METHODS

Weight, length and maximal flow at functional residual capacity (V'maxFRC) were measured at ages 1 and 12 months. V'maxFRC was adjusted for length. Asthma symptoms and age at introduction of formula feeds were identified from questionnaires. Groups were dichotomised by V'maxFRC at 1 month and change in V'maxFRC.

RESULTS

154 infants were assessed at ages 1 and 12 months. The change in V'maxFRC was inversely associated with change in weight (r = -0.18, r2 = 0.13, p<0.001). The group with lower V'maxFRC at 1 month and reduced change in V'maxFRC over infancy had the greatest weight gain (p = 0.003) and increased risk for asthma symptoms by 3 years (p = 0.017) but not afterwards. Exclusive breast feeding to 6 months was associated with a mean reduction in weight gain at age 12 months in comparison with earlier introduction of formula milk (mean difference 0.65 kg, p = 0.001), and was also associated with reduced asthma symptoms at 3 years (odds ratio 0.44, p = 0.043) but not at 6 or 11 years of age.

CONCLUSIONS

Weight gain in infancy is inversely associated with change in lung function during infancy. Postnatal weight gain may be indirectly associated with early transient asthma symptoms via an influence on lung growth during infancy, and this is potentially modifiable by breast feeding. These associations could be relevant to the clinically recognised syndrome of the "fat happy wheezer".

Protracted effects of chronic oral haloperidol and risperidone on nerve growth factor, cholinergic neurons, and spatial reference learning in rats

The primary therapeutic agents used for schizophrenia, antipsychotic drugs, ameliorate psychotic symptoms; however, their chronic effects on cognition (or the physiologic processes of the brain that support cognition) are largely unknown. The purpose of this rodent study was to extend our previous work on this subject by investigating persistent effects (i.e. during a 14 day drug-free washout period) of chronic treatment (i.e. ranging from 45 days to 6 months) with a representative first and second generation antipsychotic. Drug effects on learning and memory and important neurobiological substrates of memory, the neurotrophin, nerve growth factor (NGF) and its receptors, and certain components of the basal forebrain cholinergic system were investigated. Behavioral effects of oral haloperidol (2.0 mg/kg/day), or risperidone (2.5 mg/kg/day) were assessed in an open field, a water maze task, and a radial arm maze procedure and neurochemical effects in brain tissue were subsequently measured by enzyme-linked immunosorbent assays (ELISAs). The results indicated that both antipsychotics produced time-dependent and protracted deficits in the performance of a water maze procedure when compared with vehicle-treated controls, while neither drug was associated with significant alterations in radial arm maze performance. Interestingly, haloperidol, but not risperidone, was detectible in the rodent brain in appreciable levels for up to 2 weeks after drug discontinuation. Both antipsychotics were also associated with reduced levels of NGF protein in the basal forebrain and prefrontal cortex and significant (or nearly significant) decreases in phosphorylated tropomyosin-receptor kinase A (TrkA) protein and the vesicular acetylcholine transporter (depending on the brain region analyzed). Neither antipsychotic markedly affected TrkA or p75 neurotrophin receptor levels. These data in rats indicate that chronic treatment with either haloperidol or risperidone may be associated with protracted negative effects on cognitive function as well as important neurotrophin and neurotransmitter pathways that support cognition.

Behavioural symptoms of children with HIV infection living in the Dominican Republic

OBJECTIVE

The purpose of this report is to describe behavioural problems encountered in a group of Dominican children living with Human Immunodeficency Virus/Acquired Immunodeficiency Syndrome (HIV/AIDS) in the Dominican Republic. They were not receiving antiretroviral treatment.

METHOD

The participants were 43 children with HIV infection (2 to 8 years of age) who were attending an immunology clinic in the largest paediatric hospital in the Dominican Republic. All of the participants were vertically infected with the HIV virus (mother-to-child transmission) and had a very low socio-economic status. The children's caregivers were administered the Child Behavioural Checklist (CBCL) by trained psychologists to determine the caregivers 'perception of the children's behavioural problems. Behavioural findings were examined according to the CBCL age format: younger children (under 5 years of age) and older children (over 6 years of age).

RESULTS

Descriptive statistics revealed a high proportion of the children, both younger (approximately 40%) and older (46%) scored in the borderline/clinical ranges for internalizing problems, including anxiety, withdrawn-depressed and somatic complaints. In addition, 46% of the older children were perceived as having externalizing problems (rule breaking and aggressive behaviour).

CONCLUSION

These findings suggest that a high incidence of behavioural and mood problems may be prevalent among Dominican children with HIV Thefindings are discussed in terms of future research to examine other risk factors that might contribute to the high rate of maladaptive behaviours observed in the present report, including the contribution of socio-economic status, caregiver illness, caregiver education and parental loss.

Three-dimensional elemental mapping of phosphorus by quantitative electron spectroscopic tomography (QuEST)

We describe the development of quantitative electron spectroscopic tomography (QuEST), which provides 3-D distributions of elements on a nanometer scale. Specifically, it is shown that QuEST can be applied to map the distribution of phosphorus in unstained sections of embedded cells. A series of 2-D elemental maps is derived from images recorded in the energy filtering transmission electron microscope for a range of specimen tilt angles. A quantitative 3-D elemental distribution is then reconstructed from the elemental tilt series. To obtain accurate quantitative elemental distributions it is necessary to correct for plural inelastic scattering at the phosphorus L(2,3) edge, which is achieved by acquiring unfiltered and zero-loss images at each tilt angle. The data are acquired automatically using a cross correlation technique to correct for specimen drift and focus change between successive tilt angles. An algorithm based on the simultaneous iterative reconstruction technique (SIRT) is implemented to obtain quantitative information about the number of phosphorus atoms associated with each voxel in the reconstructed volume. We assess the accuracy of QuEST by determining the phosphorus content of ribosomes in a eukaryotic cell, and then apply it to estimate the density of nucleic acid in chromatin of the cell's nucleus. From our experimental data, we estimate that the sensitivity for detecting phosphorus is 20 atoms in a 2.7 nm-sized voxel.

On the feasibility of visualizing ultrasmall gold labels in biological specimens by STEM tomography

Labeling with heavy atom clusters attached to antibody fragments is an attractive technique for determining the 3D distribution of specific proteins in cells using electron tomography. However, the small size of the labels makes them very difficult to detect by conventional bright-field electron tomography. Here, we evaluate quantitative scanning transmission electron microscopy (STEM) at a beam voltage of 300 kV for detecting 11-gold atom clusters (Undecagold) and 1.4 nm-diameter nanoparticles (Nanogold) for a variety of specimens and imaging conditions. STEM images as well as tomographic tilt series are simulated by means of the NIST Elastic-Scattering Cross-Section Database for gold clusters embedded in carbon. The simulations indicate that the visibility in 2D of Undecagold clusters in a homogeneous matrix is maximized for low inner collection semi-angles of the STEM annular dark-field detector (15-20 mrad). Furthermore, our calculations show that the visibility of Undecagold in 3D reconstructions is significantly higher than in 2D images for an inhomogeneous matrix corresponding to fluctuations in local density. The measurements demonstrate that it is possible to detect Nanogold particles in plastic sections of tissue freeze-substituted in the presence of osmium. STEM tomography has the potential to localize specific proteins in permeabilized cells using antibody fragments tagged with small heavy atom clusters. Our quantitative analysis provides a framework for determining the detection limits and optimal experimental conditions for localizing these small clusters.

VEGF-D expression in lung adenocarcinoma with or without acquired resistance to gefitinib and normal lung

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Background: VEGF-D is related with pathogenesis and metastasis of lung cancer, however, its relationship with resistance to gefitinib in NSCLC remains unknown. Methods: Lung adenocarcinoma, normal lung tissues adjacent to the carcinoma and adenocarcinoma with acquired resistance to gefitinib including some metastastic lymph nodes were obtained during operation. Relative quantitation of VEGF-D gene expression was performed by SYBR Green real-time PCR with beta actin gene as the endogenous control. VEGF-D expression of each group was analyzed by comparing them qualitatively and quantitatively. The expression ratios were compared by Fisher’s exact test and expression levels were compared by two-related-samples nonparametric test. Results: CVEGF-D expression ratio of lung adenocarcinoma with acquired resistance to gefitinib (16.7%, 1/6) was not different from lung adenocarcinoma (50%, 7/14, P=0.325) but was significantly lower than that of normal lung (93.8%, 15/16, P=0.001). The logarithmically transformed VEGF-D relative expression levels in six lung adenocarcinomas and the matched normal lung tissues, which were 2.214±0.376 and 3.388±0.209, were found to be significantly different from each other by the analysis of Wilcoxon signed ranks test (P=0.028). Conclusions: VEGF-D expression is in a high-level state in normal lung tissues while in low-level or absent in lung adenocarcinoma with or without acquired resistance to gefitinib, suggesting that the role VEGF-D plays in normal lung tissue could be different from in lung adenocarcinoma with or without acquired resistance to gefitinib.

No significant financial relationships to disclose.

Identification of Bacteroides fragilisby a modified immuno polymerase chain reaction (mIPCR), using a specific monoclonal antibody

Bacteroides fragilis is the anaerobic species most commonly isolated from human clinical specimens, and is resistant to many antimicrobial agents. A monoclonal antibody, mAb4H8 (IgG3), reacting with a specific epitope in the lipopolysaccharide (LPS) isolated from most of the B. fragilis strains, was produced and employed with modified Immuno Polymerase Chain Reaction (mIPCR) for identification of B. fragilis with a detection limit of 10(4) cfu/mL bacterial suspension. A number of bacterial strains were examined, including B. fragilis, Bacteroides spp. other than B. fragilis and other genera. All the B. fragilis strains with the immunodominant (beta1,6-linked D-galactosyl chain) epitope were positive. None of the other strains showed the positive reaction. The results indicate that mIPCR assay with mAb4H8 has a high specificity and high sensitivity.

A heterologous prime-boost vaccination regime using DNA and a vaccinia virus, both expressing GRA4, induced protective immunity against Toxoplasma gondii infection in mice

SUMMARYThe dense granule antigen 4 (GRA4) is known as an immundominant antigen of Toxoplasma gondii and, therefore, is considered as a vaccine candidate. For further evaluation of its vaccine effect, a recombinant plasmid and vaccinia virus, both expressing GRA4, were constructed, and a heterologous prime-boost vaccination regime was performed in a mouse model. The mice immunized with the heterologous prime-boost vaccination regime showed a high level of specific antibody response against GRA4 and a significantly high level of gamma interferon (IFN-gamma) production and survived completely against a subsequent challenge infection with a lethal dose of T. gondii. In addition, the formation of cysts was inhibited in the mice vaccinated with the heterologous prime-boost vaccination regime. These results demonstrate that the heterologous prime-boost vaccination regime using DNA and a vaccinia virus, both expressing GRA4, could induce both humoral and cellular immune responses and provide effective protection against lethal acute and chronic T. gondii infections in mice.

Oral haloperidol or risperidone treatment in rats: temporal effects on nerve growth factor receptors, cholinergic neurons, and memory performance

First and second generation antipsychotics (FGAs and SGAs) ameliorate psychotic symptoms of schizophrenia, however, their chronic effects on information processing and memory function (i.e. key determinants of long term functional outcome) are largely unknown. In this rodent study the effects of different time periods (ranging from 2 weeks to 6 months) of oral treatment with the FGA, haloperidol (2.0 mg/kg/day), or the SGA, risperidone (2.5 mg/kg/day) on a water maze repeated acquisition procedure, the levels of nerve growth factor receptors, and two important cholinergic proteins, the vesicular acetylcholine transporter and the high affinity choline transporter were evaluated. The effects of the antipsychotics on a spontaneous novel object recognition procedure were also assessed during days 8-14 and 31-38 of treatment. Haloperidol (but not risperidone) was associated with impairments in water maze hidden platform trial performance at each of the time periods evaluated up to 45 days, but not when tested during days 83-90. In contrast, risperidone did not impair water maze task performance at the early time periods and it was actually associated with improved performance during the 83-90 day period. Both antipsychotics, however, were associated with significant water maze impairments during the 174-180 day period. Further, haloperidol was associated with decrements in short delay performance in the spontaneous novel object recognition task during both the 8-14 and 31-38 day periods of treatment, while risperidone was associated with short delay impairment during the 31-38 day time period. Both antipsychotics were also associated with time dependent alterations in the vesicular acetylcholine transporter, the high affinity choline transporter, as well as tyrosine kinase A, and p75 neurotrophin receptors in specific brain regions. These data from rats support the notion that while risperidone may hold some advantages over haloperidol, both antipsychotics can produce time-dependent alterations in neurotrophin receptors and cholinergic proteins as well as impairments in the performance of tasks designed to assess spatial learning and episodic memory.

Beta2-Adrenoceptor polymorphisms and asthma phenotypes: interactions with passive smoking

The aim of the present study was to assess the effects of possible interactions between beta(2)-adrenoceptor gene polymorphisms and passive smoking on forced expiratory volume in one second (FEV(1)), forced vital capacity (FVC) and exhaled nitric oxide (eNO) in children aged 11 yrs. A cross-sectional analysis of the longitudinal cohort was conducted for associations between beta(2)-adrenoceptor gene polymorphisms and lung function and eNO with regard to passive smoking. Among children exposed to tobacco smoke, those with Arg16 (at least one Arg allele) exhibited lower adjusted mean FEV(1) (2.19 versus 2.38 L) and FVC (2.43 versus 2.64 L) than Gly16 homozygotes. Those with Gln27 (at least one Gln allele) also exhibited a lower adjusted mean FEV(1) relative to Glu27 homozygotes (2.24 versus 2.39 L). Among children with no exposure to smoking, those with Arg16 or Gln27 showed lower adjusted geometric mean eNO levels compared with Gly16 homozygotes (15.4 versus 30.9 ppb) and Glu27 homozygotes (18.0 versus 49.7 ppb). In conclusion, passive smoking had a significant effect on associations between beta(2)-adrenoceptor gene polymorphisms and asthma-related phenotypes, enhancing the relationship between Arg16 and lung function and removing the relationship between Arg16 or Gln27 and exhaled nitric oxide levels.

Epimedium-derived phytoestrogen exert beneficial effect on preventing steroid-associated osteonecrosis in rabbits with inhibition of both thrombosis and lipid-deposition

OBJECTIVES

This study tested the effect of Epimedium-derived phytoestrogen (PE) on preventing steroid-associated osteonecrosis (ON) in rabbit model.

METHODS

Thirty 28-week-old male New-Zealand white rabbits were divided into control group (CON; n=14) and PE group (PE; n=16; 5 mg/kg body weight/day) after receiving an established inductive protocol for inducing steroid-associated ON. Before and after inductive protocol, Dynamic-MRI was employed on bilateral femora for local intra-osseous perfusion, blood samples were examined for coagulation, fibrinolysis and lipid-transportation, and marrow samples were quantified for adipogenesis-gene mRNA expression. Six weeks later, bilateral femora were dissected for Micro-CT-based micro-angiography, and then ON lesion, intravascular thrombosis and extravascular fat-cell-size were examined histopathologically.

RESULTS

The incidence of ON in the PE group (31%) was significantly lower than that in the CON group (93%). Compared to the CON group, local intra-osseous perfusion was maintained in the PE group. Blocked trunk vessels were seldom found in micro-angiography of the PE-treated rabbits. Thrombosis incidence and fat-cell-size were both significantly lower in the PE group than those in the CON group. During the early period after induction, indicator of coagulation, fibrinolysis, lipid-transportation and adipogenesis-gene expression were found with significantly changing pattern in the PE group compared to the CON group.

CONCLUSION

PE was able to exert beneficial effect on preventing steroid-associated ON in rabbits with inhibition of both thrombosis and lipid deposition.

Floc size distributions in dissolved air flotation of Winnipeg tap water

A bench-scale continuous flow dissolved air flotation (DAF) system was operated using Winnipeg tap water. Three different dosages of alum were applied: 41.7 mg l(-1), 25.5 mg l(-1) and 15.5 mg l(-1). Floc size distributions formed at different coagulant dosages were analyzed to identify characteristics of floc size distribution optimal for flotation. Alum dose of 25.5 mg l(-1) was found to be optimal for the bench scale DAF unit in this study. At this dosage, the DAF effluent achieved a turbidity of 0.25 NTU and color of 3.8 TCU, significantly lower than that for the tap water. The optimum floc size distribution at the dose of 25 mg l(-1) had the logarithmic mean size of 27 microm which was close to the size of air bubbles produced by the saturator in this study (30 microm). The results of this study suggest that the DAF treatment process is optimized when the logarithmic mean floc size and bubble size are equal.

Quenching Properties of a Self-Referenced Fluorescence Oxygen Nanosensor under a Wide-Field Intrinsic Optical Signal Imaging System

Wide-field intrinsic optical signal (IOS) imaging is an excellent method to map in vivo neurological metabolic changes during brain activity. It has a spatial resolution of 50-100&#956;m and a wide imaging field of several cm²that cannot be achieved by regular microscopic imaging. A nano-encapsulated fluorescence dye sensor that is specifically sensitive to oxygen level was fabricated by using electrostatic layer-by-layer (LbL) self-assembly technique. Fluorescence images of the nanosensor solution were collected by a wide-field IOS imaging system under different oxygen concentrations. Mathematical models for nanosensor fluorescence were developed based on the imaging results. Correlations between the nanosensor fluorescence and oxygen concentration models indicate an inverse quenching relationship between the nanosensor fluorescence and oxygen concentration.

Using electrostatic self-assembled gradient nanosensor phantoms for calibration of an optical intrinsic signal imaging system

Wide-field optical intrinsic signal (OIS) imaging has been used in functional cortex mapping for its excellent spatial resolution. To compensate for its low temporal resolution, extrinsic dye signals have been introduced. Fluorescence spectroscopy in the form of nanoengineered sensors has also been used to detect biochemical signals of molecular interactions. In this paper, oxygen-sensitive dye Ru(dpp)/sub 3//sup 2+/ was immobilized into nano-sized spheres by electrostatic layer-by-layer (LbL) self-assembly, and then deposited on glass slides as intensity gradients. By comparing gradient ratios and ratios of function dye Ru(dpp)/sub 3//sup 2+/ and reference dye between epi-fluorescence microscope and an OIS imaging system, the feasibility and efficiency of nano-sized oxygen sensors in OIS imaging were studied.

Quantification and thickness correction of EFTEM phosphorus maps

We describe a method for correcting plural inelastic scattering effects in elemental maps that are acquired in the energy filtering transmission electron microscope (EFTEM) using just two energy windows, one above and one below a core edge in the electron energy loss spectrum (EELS). The technique is demonstrated for mapping low concentrations of phosphorus in biological samples. First, the single-scattering EELS distributions are obtained from specimens of pure carbon and plastic embedding material. Then, spectra are calculated for different specimen thicknesses t, expressed in units of the inelastic mean free path lambda. In this way, standard curves are generated for the ratio k0 of post-edge to pre-edge intensities at the phosphorus L2,3 excitation energy, as a function of relative specimen thickness t/lambda. Thickness effects in a two-window phosphorus map are corrected by successive acquisition of zero-loss and unfiltered images, from which it is possible to determine a t/lambda image and hence a background k0-ratio image. Knowledge of the thickness-dependent k0-ratio at each pixel thus enables a more accurate determination of the phosphorus distribution in the specimen. Systematic and statistical errors are calculated as a function of specimen thickness, and elemental maps are quantified in terms of the number of phosphorus atoms per pixel. Further analysis of the k0-curve shows that the EFTEM can be used to obtain reliable two-window phosphorus maps from specimens that are considerably thicker than previously possible.