Convergent functional genomics of genome-wide association data for bipolar disorder: comprehensive identification of candidate genes, pathways and mechanisms

Given the mounting convergent evidence implicating many more genes in complex disorders such as bipolar disorder than the small number identified unambiguously by the first-generation Genome-Wide Association studies (GWAS) to date, there is a strong need for improvements in methodology. One strategy is to include in the next generation GWAS larger numbers of subjects, and/or to pool independent studies into meta-analyses. We propose and provide proof of principle for the use of a complementary approach, convergent functional genomics (CFG), as a way of mining the existing GWAS datasets for signals that are there already, but did not reach significance using a genetics-only approach. With the CFG approach, the integration of genetics with genomics, of human and animal model data, and of multiple independent lines of evidence converging on the same genes offers a way of extracting signal from noise and prioritizing candidates. In essence our analysis is the most comprehensive integration of genetics and functional genomics to date in the field of bipolar disorder, yielding a series of novel (such as Klf12, Aldh1a1, A2bp1, Ak3l1, Rorb, Rora) and previously known (such as Bdnf, Arntl, Gsk3b, Disc1, Nrg1, Htr2a) candidate genes, blood biomarkers, as well as a comprehensive identification of pathways and mechanisms. These become prime targets for hypothesis driven follow-up studies, new drug development and personalized medicine approaches.

The transport barrier of epithelia: a comparative study on membrane permeability and charge selectivity in the rabbit

The transport barrier of the epithelial presents one of the major problems limiting the effective use of these tissues as alternate delivery routes for macromolecules such as peptides and proteins. In the present study, two membrane transport properties, namely, the permeability and permselectivity of the shunt pathway, were investigated and compared in various tissues including the nasal, tracheal, bronchial, buccal, rectal, vaginal, corneal, epidermal, duodenal, jejunal, ileal, and colonic epithelia. Membrane permeability was evaluated using a combined method based on electrical conductance and flux measurements of a hydrophilic fluorescent probe, 6-carboxy fluorescein (CF). Membrane permselectivity or the charge discriminating ability of the membrane was evaluated by KCl diffusion potential measurements. The results indicate that all epithelia under investigation possess a relatively high degree of permeation barrier and are highly selective for the absorption of positively charged solutes. Shunt path permeability was found to vary greatly among tissues from different epithelia, whereas membrane charge selectivity was relatively constant in these tissues. A good correlation was observed between membrane electrical conductance and steady-state flux of CF, indicating a paracellular transport of the compound. The rank order of the intrinsic membrane permeability was as follows: intestinal approximately nasal greater than or equal to bronchial greater than or equal to tracheal greater than vaginal greater than or equal to rectal greater than corneal greater than buccal greater than skin. Membrane permselectivity, expressed as the ratio of transport number (positive over negative), ranges from 1.78 for the buccal to 1.33 for the rectal epithelium.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence and distribution of selected occlusal characteristics in the US population, 1988-1991

The inclusion of occusal traits as part of the oral health component of the Third National Health and Nutrition Examination Survey, Phase 1, 1988-91, provided an opportunity to assess several occlusal characteristics in the US population: diastema > or = 2 mm, alignment of lower and upper anterior teeth, posterior crossbite, overbite, and overjet. Household questionnaires asked whether the individual had ever received orthodontic treatment. Prevalence of clinical measures of occlusal characteristics and orthodontic treatment was estimated for over 7,000 sample persons from 8 to 50 years of age, representing approximately 150 million non-institutionalized people in the United States. These findings present the first estimates of occlusal status of the US non-institutionalized population in more than 25 years. Eight percent of the population had severe overbite of 6 mm or more. The average overbite was 2.9 mm. Maxillary diastemas > or = 2 mm were observed in 19% of 8-11-year-olds, 6% of 12-17-year-olds, and 5% of adults 18-50 years old. Twenty-five percent and 22% of persons had zero mm of malalignment in maxillary and mandibular incisors, respectively. Conversely, 11% and 15% of persons had 6 mm or more displacement of maxillary and mandibular molars, respectively. Posterior crossbite affects less than 10% of this population, and less than 10% had overjet of 6 mm or more. Non-Hispanic black adults had the least amount of malalignment in mandibular incisors. Three times as many non-Hispanic blacks compared with non-Hispanic whites and Mexican-Americans had diastemas > or = 2 mm. Comparisons with published data from the National Health Examination Survey (1966-70) indicated a 20% increase of 12-17-year-olds with overbite in the normal range (0-3 mm). Almost 20% of adults ages 18-50, as well as 18% of children, have had orthodontic treatment.

Prevalence of incisor trauma in persons 6-50 years of age: United States, 1988-1991

Traumatic injuries to the teeth are among the most serious of dental conditions, yet little is known about the prevalence of tooth or dental trauma at the national level. The National Institute of Dental Research (NIDR) modified existing indices for specific use in national epidemiologic studies of tooth trauma among both children and adults. The NIDR index was developed not only to track the status of the tooth from sound (no evidence of trauma) through missing due to trauma, but also to reflect selected sequelae of trauma. The index is based on clinical, non-radiographic evidence of tooth inujury and treatment received in the eight permanent incisors, including a positive history of injury obtained from the subject. The trauma assessment index was applied immediately following the caries examination for dentate participants ages 6-50 years old (n=7,707) in Phase 1 of the NHANES III oral examination. This article reports the first national overall and age-specific population-based prevalence of dental trauma among gender, racial, and ethnic groups. There is a higher prevalence of incisal trauma, of both maxillary and mandibular incisors, in males than females, in both the younger and older age groups. The prevalence of incisal trauma of both maxillary and mandibular incisors in whites and blacks in both younger and older age categories is similar. The study found that half of the individuals with trauma had only one incisor tooth classified as having trauma. Males and older age groups showed larger numbers of traumatized teeth. Further study and examination of methodological issues are desirable for additional understanding of incisal trauma in the general population .

MRI and plain radiography in the assessment of displaced fractures of the waist of the carpal scaphoid

We treated 50 patients with fractures of the waist of the scaphoid in a below-elbow plaster cast for up to 13 weeks. Displacement of the fragments was assessed independently by two observers using MRI and radiographs performed within two weeks of injury.

The MRI assessments showed that only the measurement of sagittal translation of the fragments and an overall assessment of displacement had satisfactory inter- and intra-observer reproducibility and revealed that nine of the 50 fractures were displaced. Only three of the 49 fractures with adequate follow-up failed to unite, and all were displaced with more than 1 mm of translation in the sagittal plane. If the MRI assessment of displacement of the fracture was used as the measurement of choice, assessment of displacement on the initial scaphoid series of radiographs showed a sensitivity of between 33% and 47% and a positive predictive value of between 27% and 86%. Neither observer was able correctly to identify more than 33% to 47% of the displaced fractures from the plain radiographs. Although the overall assessment of displacement and gapping and translation in the coronal plane on the plain radiographs influenced the rate of union, none of these parameters identified all three fractures which failed to unite.

We conclude that the assessment of displacement of scaphoid fractures on MRI can probably be used to assess the likelihood of union although the small number of nonunions limits the power of the study. In contrast, the assessment of displacement on routine radiography is inaccurate and of less value in predicting union.

P-element mutations affecting embryonic peripheral nervous system development in Drosophila melanogaster

The Drosophila embryonic peripheral nervous system (PNS) is an excellent model system to study the molecular mechanisms governing neural development. To identify genes controlling PNS development, we screened 2000 lethal P-element insertion strains. The PNS of mutant embryos was examined using the neural specific marker MAb 22C10, and 92 mutant strains were retained for further analysis. Genetic and cytological analysis of these strains shows that 42 mutations affect previously isolated genes that are known to be required for PNS development: longitudinals lacking (19), mastermind (15), numb (4), big brain (2), and spitz (2). The remaining 50 mutations were classified into 29 complementation groups and the P-element insertions were cytologically mapped. The mutants were classified in five major classes on the basis of their phenotype: gain of neurons, loss of neurons, organizational defects, pathfinding defects and morphological defects. Herein we report the preliminary phenotypic characterization of each of these complementation groups as well as the embryonic lacZ expression pattern of each P-element strain. Our analysis indicates that in most of the P-element insertion strains, the lacZ reporter gene is not expressed in the developing PNS.

Bcl-xL blocks transforming growth factor-beta 1-induced apoptosis by inhibiting cytochrome c release and not by directly antagonizing Apaf-1-dependent caspase activation in prostate epithelial cells

The mechanism by which transforming growth factor-beta1 (TGF-beta1) induces apoptosis of prostate epithelial cells was studied in the NRP-154 rat prostate epithelial cell line. TGF-beta 1 down-regulates expression of Bcl-xL and poly(ADP-ribosyl)polymerase (PARP), promotes cytochrome c release, up-regulates expression of latent caspase-3, and activates caspases 3 and 9. We tested the role of Bcl-xL in this cascade by stably overexpressing Bcl-xL to prevent loss by TGF-beta 1. Clones overexpressing Bcl-xL are resistant to TGF-beta 1 with respect to induction of apoptosis, cytochrome c release, activation of caspases 9 and 3, and cleavage of PARP; yet they remain sensitive to TGF-beta 1 by cell cycle arrest, induction of both fibronectin and latent caspase-3 expression, and loss of PARP expression. We show that Bcl-xL associates with Apaf-1 in NRP-154 cells; but this association does not inhibit the activation of caspases 9 and 3 by cytochrome c. Together, our data suggest that TGF-beta1 induces apoptosis through loss of Bcl-xL, leading to cytochrome c release and the subsequent activation of caspases 9 and 3. Moreover, our data demonstrate that the antiapoptotic effect of Bcl-xL occurs by inhibition of mitochondrial cytochrome c release and not through antagonizing Apaf-1-dependent processing of caspases 9 and 3.

The incidence of orofacial injuries in sports: a pilot study in Illinois

This pilot study of sports-related injuries in Illinois confirms that football players do not encounter orofacial injuries as often as other athletes. The authors attribute this to mandatory use of faceguards and mouth protectors in football and recommend that mouthguards be used by all players of contact sports.

Diagnostic x-ray spectra: a comparison of spectra generated by different computational methods with a measured spectrum

A number of computer codes, developed using semi-empirical models, are available to compute x-ray spectra from a tungsten target for different tube parameters. In this study x-ray spectra measured with a high-purity germanium detector are compared with those computed using the empirical models and previously published measured data. The computer codes used to generate the spectra are based on models proposed by Birch et al. and Tucker et al. The measured x-ray spectra agreed well with the computed x-ray spectra using the model of Tucker et al. whereas the model of Birch et al. produced a "harder" x-ray spectrum compared to the measured spectra. Our measured x-ray spectra compared well with the previously published measured spectral data of Fewell et al.

Periodontal health of 14-17-year-old US schoolchildren

This paper describes the findings related to periodontal health in 14-17-year-old children who participated in the National Survey of Oral Health in US Schoolchildren, conducted by the National Institute of Dental Research (NIDR) during 1986-87. Gingivitis was observed in approximately 60 percent of children in this age group. The proportion of examined sites per child with gingivitis, however, was less than 6 percent. Gingivitis was most common in molar areas in the maxilla and incisor areas in the mandible. Supragingival calculus was observed in nearly 34 percent of the children, and subgingival calculus in approximately 23 percent. The proportion of teeth per child with calculus was approximately 8 percent for supragingival and 4 percent for subgingival calculus. Both types of calculus showed a predilection for molars in the maxilla and incisors and cuspids in the mandible. The mean periodontal attachment loss was 0.33 mm. The teeth most frequently affected by attachment loss of 2 mm or more were maxillary molars and bicuspids, followed by mandibular molars and cuspids.

Expression of beta-defensin genes in bovine alveolar macrophages

Bovine alveolar macrophages (BAM) were examined for the expression of beta-defensins and to determine whether their expression could be upregulated by bacterial lipopolysaccharide (LPS), as observed with beta-defensins expressed in bovine tracheal epithelial cells. Four beta-defensins were expressed constitutively in BAM, with bovine neutrophil beta-defensin (BNBD)-4 and BNBD-5 being the most predominant. This is the first evidence of beta-defensin gene expression in a mature myeloid cell. LPS had no effect on beta-defensin expression in BAM, even though tumor necrosis factor alpha (TNF-alpha) production was induced. Nonbacterial inflammatory particles had little effect on beta-defensin gene expression or TNF-alpha production in BAM. We hypothesize that constitutively expressed beta-defensins of alveolar macrophages may have a role in lung host defense.

Regulation of tight junction permeability by calcium mediators and cell cytoskeleton in rabbit tracheal epithelium

The present study investigates the mechanisms controlling tight junction permeability of the tracheal epithelium, with an emphasis on the regulatory role of intra- and extracellular calcium as well as the cell cytoskeleton. The tracheas were isolated from rabbits and their junctional permeability barrier was investigated in vitro by means of transepithelial electrical resistance measurements and flux measurements of the radiolabeled paracellular tracer, 14C-mannitol. The effects of intra- and extracellular calcium were studied using the calcium ionophore A 23187 and EGTA, and that of the cytoskeleton was investigated using cytochalasin B. Intracellular calcium of the tracheal epithelium was monitored microfluorometrically using the specific calcium indicator, Fura-2 AM (acetoxymethyl ester). The results indicate that the tight junction permeability of the trachea was significantly increased upon treatment with all three of the test compounds, as evidenced by a substantial decrease in transepithelial electrical resistance and an increase in transepithelial flux of 14C-mannitol. The effects of EGTA and cytochalasin B on the tight junction permeability are fully reversible upon removal of the compounds from the bathing media. On the other hand, tissues treated with the calcium ionophore demonstrate a partial or no recovery in membrane permeability, depending on the intracellular calcium levels. Moderate and transient increases in intracellular calcium caused a partial reversibility of the membrane resistance, while high and sustained intracellular calcium levels induce a complete irreversibility of the membrane resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

Study of the efficacy of toothpaste containing casein phosphopeptide in the prevention of dental caries: a randomized controlled trial in 12- to 15-year-old high caries risk children in Bangalore, India

Casein phosphopeptide (CPP) has the potential to be added to mouth rinses, gels, toothpastes, chewing gums and confectioneries. Until now CPP has been studied in vitro, in situ and in animals, but clinical trials are lacking. This study was conducted to evaluate the efficacy of CPP-containing toothpaste in preventing dental caries in schoolchildren. The study was conducted among 150 schoolchildren randomly divided into three groups, each using one of three types of toothpastes: (a) containing 2% w/w CPP; (b) containing 1,190 mg/kg fluoride as 0.76% sodium monofluorophosphate (SMFP); (c) placebo toothpaste without CPP or fluoride. Students brushed with the given toothpastes for 24 months. Oral hygiene and caries experience were assessed at baseline, 12 and 24 months. The increments in caries lesions were calculated and analyzed to assess the caries-preventive effect. A significant reduction in caries increment was observed among students using CPP toothpaste or SMFP toothpaste, compared with the group using the placebo toothpaste. The reduction in caries increment was not significantly different between the CPP and SMFP groups. Oral Hygiene Index score increased from the 12-month to the 24-month examination. It is concluded that CPP can be effectively incorporated into calcium carbonate-based toothpaste and that toothpaste containing CPP is effective in preventing caries. Toothpaste containing 2% CPP seemed to have an efficacy similar to paste containing 1,190 mg/kg SMFP in the prevention of caries.

Developmental enamel defects in primary teeth in children with cerebral palsy, mental retardation, or hearing defects: a review

Developmental enamel defects in primary teeth have been found at least twice as frequently in children with cerebral palsy or mental retardation as in control children, and frequently also in children with sensori-neural hearing deficits. The developing tooth germ is sensitive to a range of systemic disturbances, some of which may also affect neurologic development. Because the enamel cannot recover once it is damaged, it may provide a repository of information on the timing and nature of insults potentially affecting other ectodermally derived structures, including the brain. This paper reviews the literature on developmental defects of enamel in primary teeth, asking whether these might be useful as biological markers of the timing and in some cases the nature of insults. Among systemic factors related to development of enamel that might also have implications for neurologic development are certain genetic disorders including tuberous sclerosis, premature birth, neonatal nutritional disturbances (especially hypocalcemia), viral infections (such as rubella and cytomegalovirus during gestation), thyroid disorders, and maternal diabetes. It is concluded that further research is warranted concerning whether developmental defects of dental enamel can be useful markers for the timing of intra-uterine or perinatal events associated with certain neurologic and sensory disorders of children.

Off-axis x-ray spectra: a comparison of Monte Carlo simulated and computed x-ray spectra with measured spectra

The off-axis x-ray spectra from a constant potential x-ray generator were measured with a high purity germanium spectrometer cooled to liquid nitrogen temperature. The measured spectra were compared with off-axis x-ray spectra calculated using a code based on the semiempirical model developed by Tucker et al. and Monte Carlo simulated x-ray spectra using the EGS4 code system. In this study, both the Tucker model, and the EGS4 code system, were found to produce off-axis bremsstrahlung x-ray spectra which agreed well with the spectra measured at three emerging angles. In the measured and the EGS4 generated spectra the total K-characteristic peaks were in increasing order, as observed in the anode to cathode direction, whereas the Tucker model produced maximum total K-characteristic peaks at the 6 degrees anode side, and lesser amounts at the central axis and the 6 degrees cathode side. Large differences in the total K-characteristic lines is seen among the three different methods. The EGS4 code system was able to produce x-ray spectra for a combination of target materials.

Tryptophan Metabolism Along the Kynurenine Pathway Downstream of Toll-like Receptor Stimulation in Peripheral Monocytes

Tryptophan degradation along the kynurenine pathway is of central importance for the immune function. Toll-like receptors (TLRs), representing the first line of immune defence against pathogens, are expressed in various cell types. The most abundant expression is found on monocytes, macrophages and dendritic cells. The aim of this study was to investigate whether stimulation with different TLR ligands induces the kynurenine pathway in human peripheral monocytes. Cell supernatants were analysed using a liquid chromatography/mass spectrometry to measure kynurenine, kynurenic acid (KYNA), quinolinic acid (QUIN) and tryptophan. Stimulation of TLR-2, TLR-3, TLR-4, TLR-7/8 and TLR-9 was found to induce the production of kynurenine, but only stimulation of TLR-3 increased levels of further downstream metabolites, such as KYNA and QUIN. Stimulation of TLR-1, TLR-5 and TLR-6 did not induce the kynurenine pathway. Taken together, this study provides novel evidence demonstrating that TLR activation induces a pattern of downstream tryptophan degradation along the kynurenine pathway in monocytes. The results of this study may implicate that TLRs can be used as new drug targets for the regulation of aberrant tryptophan metabolism along this pathway, a potential therapeutic strategy that may be of importance in several disorders.

A fast, high spatial resolution optical tomographic scanner for measurement of absorption in gel dosimetry

A fast tomographic optical density measurement system has been constructed and evaluated for application in Fricke 3D gel dosimetry. Although the potential for full three-dimensional radiation dosimetry with Fricke gel dosimeters has been extensively reported, its application has been limited due to a lack of fast optical density measurement systems. In this work, the emphasis of the design has been to achieve a short scan time through the use of precision optics and minimal moving parts. The system has been demonstrated in the laboratory to be able to achieve better than 1mm resolution and a scanning time per tomographic slice of 2.4 seconds. Full volumetric sampling of a 10 cm diameter by 7cm long cylinder can be achieved in 3 minutes. When applied with a Fricke based gel dosimeter a linear response between reconstructed CT number and absolute dose was better than 3%.

Consumer product-related tooth injuries treated in hospital emergency rooms: United States, 1979-87

The database of the National Electronic Injury Surveillance System was used to analyze episodes of consumer product-related traumatic injuries to teeth treated in hospital emergency room in the United States from 1979 through 1987. Results showed a slight but consistent increase in episodes of such injuries during this 9-yr period. Over 75% of such episodes occurred in persons under 15 yr of age. Over 60% of the tooth injuries in such episodes could be crudely classified into the following types by descending rank order: avulsed-, broken-, loosened-, chipped-, intruded-teeth and soft tissue injuries. The most common categories of consumer products and activities associated with such episodes were sports and play, followed by falls on floors, stairs or showers, and bicycles and other wheeled vehicles. The age composition of specific episodes of dental injuries varied considerably for different products and activities, suggesting a need for specific strategies for prevention of episodes of consumer product-related injuries to teeth for different age categories of the population.

High-performance liquid chromatographic determination of insulin in rat and human plasma

A rapid and simple isocratic chromatographic procedure for the determination of insulin in human and rat plasma using reversed-phase (RP) high-performance liquid chromatography with an ultraviolet/visible detector is described. The method includes extraction of insulin from human and rat plasma into dichloromethane, followed by back-extraction into 0.05 N hydrochloric acid. The organic phase was evaporated under a stream of nitrogen. The aqueous phase was filtered and a 100 microliters aliquot was analyzed on a RP-C18 column eluted with a mobile phase consisting of a mixture of 74 vol of 0.2 M sodium sulfate anhydrous adjusted to pH 2.3 with phosphoric acid and 26 vol of acetonitrile. The flow rate was 1.2 ml/min and the wavelength was set at 214 nm. The calibration curve was linear over the range of 75-800 microIU/ml. The precision of the assay expressed as coefficients of variation was less than 6% over the entire concentration range. The recovery for insulin ranged from 79 to 81% from human and rat plasma, with coefficients of variation less than 6%. The intra- and interassay coefficients of variation were less than 5.7%. The limit of detection was 50 microIU/ml.

Comparison of variables affecting the surgical outcomes of tubularized incised plate urethroplasty in adult and pediatric hypospadias

INTRODUCTION

The American Academy of Pediatrics recommends operating on hypospadias between the ages of 6-12 months. Since most births in developed countries are conducted in a hospital, parents are likely to be well informed and counseled about the hypospadias. However, significant numbers of births in developing countries are still conducted at home, with illiteracy, poverty and ignorance often leading to late presentation at the hospital. Reported hypospadias-repair complication rates are higher in adults compared with those having surgery in childhood. The present study's objective was to evaluate the factors affecting surgical outcome in hypospadias patients undergoing tubularized and tubularized incised plate urethroplasty (TIPU) in adulthood compared with childhood.

MATERIALS AND METHODS

A prospective study of 60 adult patients >16 years, and 60 pediatric patients <5 years who underwent TIPU for primary hypospadias between May 2008 and May 2012. Patients were operated on by a single surgeon, under similar circumstances, and were pre-operatively examined to assess meatal location, chordee, and torsion; they were also examined intra-operatively for quality of spongiosum and urethral plate width. The outcomes were assessed by patient/parents for satisfaction regarding cosmesis, urinary stream and complications.

RESULTS

The age of the patients varied from 16 to 27 years, with a mean of 20.8 years in adults, and 6 months to 5 years, with a mean of 2.1 years, in children. The type of hypospadias, degree of curvature, quality of spongiosum and urethral plate width were comparable in both groups, but complication rates were higher in adults (16.7%) than in the pediatric (6.7%) group (Figure 1A-D). Meatal stenosis responded well to dilatation, but fistulae required revision surgery and had a cure rate of 100%. The median follow-up was 37 months in adults, and 39 months in children.

DISCUSSION

The higher complication rates in adults may be due to more frequent erections; increased susceptibility to infection along with relatively reduced vascularity lead to poor wound healing and increased complication rates. The limitation of the study was the small number of patients with mid and proximal hypospadias having lesser incidences in comparison with distal hypospadias. Adequate number of patients in these subgroups could have further strengthened the statistical correlation. Secondly, there was no objective criterion like uroflowmetry to assess urinary stream.

CONCLUSIONS

Complication rates were higher in adults undergoing TIPU compared with pediatric patients, which was also statistically significant in distal hypospadias. The important factors in surgical outcome were: severity of hypospadias, degree of curvature, quality of spongiosum, and urethral plate width.

Repeated LPS Injection Induces Distinct Changes in the Kynurenine Pathway in Mice

The immune system has been recognized as a potential contributor to psychiatric disorders. In animals, lipopolysaccharide (LPS) is used to induce inflammation and behaviors analogous to some of the symptoms in these disorders. Recent data indicate that the kynurenine pathway contributes to LPS-induced aberrant behaviors. However, data are inconclusive regarding optimal LPS dose and treatment strategy. Here, we therefore aimed to evaluate the effects of single versus repeated administration of LPS on the kynurenine pathway. Adult C57BL6 mice were given 0.83 mg/kg LPS as a single or a repeated injection (LPS + LPS) and sacrificed after 24, 48, 72, or 120 h. Mice receiving LPS + LPS had significantly elevated brain kynurenine levels at 24 and 48 h, and elevated serum kynurenine at 24, 48 and 72 h. Brain kynurenic acid and quinolinic acid were significantly increased at 24 and 48 h in mice receiving LPS + LPS, whereas serum kynurenic acid levels were significantly decreased at 24 h. The increase of brain kynurenic acid by LPS + LPS was likely unrelated to the higher total dose as a separate group of mice receiving 1.66 mg/kg LPS as single injection 24 h prior to sacrifice did not show increased brain kynurenic acid. Serum quinolinic acid levels were not affected by LPS + LPS compared to vehicle. Animals given repeated injections of LPS showed a more robust induction of the kynurenine pathway in contrast to animals receiving a single injection. These results may be valuable in light of data showing the importance of the kynurenine pathway in psychiatric disorders.