Safety evaluation of the genotoxicity and subchronic toxicity of standardized Bacopa extract (Bacognize®) from Bacopa monnieri

Bacopa monnieri is an important medicinal plant widely used in various food systems and gaining interest these days for its health benefits such as boosting brain function and improving quality of life. The objective of the present study was to examine the safety of Bacognize®, a standardized botanical extract obtained from the whole herb Bacopa monnieri (L.) Wettst., in subchronic toxicity and genotoxicity studies conducted in compliance with Good Laboratory Practice (GLP) and test guidelines established by the Organization for Economic Cooperation and Development (OECD). In the subchronic toxicity study, treatment with Bacognize® did not result in any toxicologically significant treatment-related changes in clinical observations, and in the clinical pathology as studied by hematology, serum chemistry, urinalysis, and terminal necropsy. Treatment-related adverse effects were not observed in ophthalmic examinations, body weights, body weight gains, feed consumption, and organ weights. The results of genotoxicity studies as assessed by gene mutations in Salmonella typhimurium, in vitro chromosome aberrations and in vivo micronucleus test did not reveal any genotoxicity of Bacognize ®. The no-observed-adverse-effect level (NOAEL) for Bacognize® was established based on the subchronic study and was determined as at least 1000 mg/kg bw/day. These results indicate that Bacognize® does not cause significant adverse effects and suggest its tolerability up to 1000 mg/kg (highest dose tested) for the daily administration of 90 days in rats.

The Future of Uncertainty Factors with in Vitro Studies Using Human Cells

New approach methodologies (NAMs), including in vitro toxicology methods such as human cells from simple cell cultures to 3D and organ-on-a-chip models of human lung, intestine, liver, and other organs, are challenging the traditional “norm” of current regulatory risk assessments. Uncertainty Factors continue to be used by regulatory agencies to account for perceived deficits in toxicology data. With the expanded use of human cell NAMs, the question “Are uncertainty factors needed when human cells are used?” becomes a key topic in the development of 21st-century regulatory risk assessment. M.D., PhD, the coauthor of an article detailing uncertainty factors within the U.S. EPA, and L.E., PhD., Executive Vice President, Science, Emulate, who is involved in developing organ-on-a-chip models, debated the topic. One important outcome of the debate was that in the case of in vitro human cells on a chip, the interspecies (animal to human) uncertainty factor of 10 could be eliminated. However, in the case of the intraspecies (average human to sensitive human), the uncertainty factor of 10, additional toxicokinetic and/or toxicodynamic data or related information will be needed to reduce much less eliminate this factor. In the case of other currently used uncertainty factors, such as lowest observable adverse effect level to no-observed adverse effect level extrapolation, missing important toxicity studies, and acute/subchronic to chronic exposure extrapolation, additional data might be needed even when using in vitro human cells. Collaboration between traditional risk assessors with decades of experience with in vivo data and risk assessors working with modern technologies like organ chips is needed to find a way forward.

Application of the 3Rs principles in the development of pharmaceutical generics

Although the 3Rs are broadly applied in nonclinical testing, a better appreciation of the 3Rs is needed in the field of differentiated or value-added pharmaceutical generics because the minor changes in formulation, dosage form, indication, and application route often do not require additional safety testing. The US FDA and the EU EMA have comprehensive regulations for such drugs based on quality, therapeutic equivalence, and safety guidelines. However, no scientific publications on how the concept of replacement and reduction from 3Rs principles can be applied in the safety assessment of differentiated generics were found in the public domain. In this review, we discuss the application of 3Rs in nonclinical testing requirements for differentiated generics. Practical examples are provided in the form of case studies from regulated markets. We highlight the need for utilization of existing data to establish equivalence (differentiated generic vs innovator) in efficacy and safety. The case studies indicate that data requirements from animal experiments have been reduced to a large extent in some major markets without compromising quality and safety. In this context, we also highlight the problem that on a global scale, a true reduction of animal experiments will only be achieved when all countries adopt similar practices.

Serum C-reactive protein and neutrophil-to-lymphocyte ratio as predictors of survival in cirrhotic patients with systemic inflammatory response syndrome and bacterial infection

BACKGROUND

Cirrhotic patients are prone to infections due to underlying immune dysfunction in them. We aimed to study the role of inflammatory markers, serum C-reactive protein (CRP) and neutrophil-to-lymphocyte ratio (NLR), in predicting infection, blood culture positivity, and short-term (1 month) mortality in hospitalized cirrhotic patients.

METHODS

This prospective study was done over a period of 14 months (October 2017 to November 2018). Patient data included age, gender, etiology of cirrhosis, reason for admission, and comorbidity. Laboratory tests included blood chemistry and blood cell counts, and blood and urine culture. The specific tests included were CRP and NLR. Survival of patients in the following 1 month was noted. Area under receiver operating characteristic curve (AUROC), sensitivity, specificity, predictive values, diagnostic accuracy were calculated and logistic regression analysis performed. A p-value < 0.05 was considered significant.

RESULTS

Two hundred and eight patients formed the study cohort. The median age was 51.5 years and male predominance was noted. Alcohol-related liver disease (49%) was the commonest etiology. The infection rate was 62%, culture positivity was 58.5%, and mortality was 30.8%. NLR and CRP were significantly higher in those with documented infection (culture positive or negative) and among nonsurvivors. Optimal cutoffs for NLR and CRP to predict infection were 5.86 and 33.7, respectively. The risk of having an infection was 7.5 times and about 15 times if NLR and CRP were above the cutoffs. The risk of 1-month mortality was 2-3 times higher if patients had NLR and CRP above the cutoffs. The combination of NLR and CRP (≥ 5.86 and ≥ 33.7, respectively) increased specificity and diagnostic accuracy for infection.

CONCLUSION

NLR and CRP were independently good predictors of infection and 1-month survival among the patients with cirrhosis of liver included in this study.

Interpretation of Benign Gastric Mucosal Lesions Using Narrow-Band Imaging

The major drawback of conventional white light endoscopy (WLE) is that it lacks accuracy in diagnosis and differentiation of various benign and premalignant mucosal gastrointestinal lesions. To overcome this, image-enhanced endoscopy techniques, which provide high-definition images with good resolution and contrast enhancement, have been developed. One such technique is narrow-band imaging (NBI). NBI functions by filtering the illumination light. The red component of the standard red, green, and blue filters is rejected and the selected bandwidth of the blue and green light is transmitted. The present review highlights the role of NBI in diagnosis of benign gastric lesions like atrophic gastritis, Helicobacter pylori–related gastritis, intestinal metaplasia, and other rarer conditions. NBI is a simple procedure which does not require any additional equipment and does not have a long learning curve. Use of NBI in daily practice is likely to improve detection of mucosal abnormalities.

Genotoxicity Assessment of Nanomaterials: Recommendations on Best Practices, Assays, and Methods

Nanomaterials (NMs) present unique challenges in safety evaluation. An international working group, the Genetic Toxicology Technical Committee of the International Life Sciences Institute's Health and Environmental Sciences Institute, has addressed issues related to the genotoxicity assessment of NMs. A critical review of published data has been followed by recommendations on methods alterations and best practices for the standard genotoxicity assays: bacterial reverse mutation (Ames); in vitro mammalian assays for mutations, chromosomal aberrations, micronucleus induction, or DNA strand breaks (comet); and in vivo assays for genetic damage (micronucleus, comet and transgenic mutation assays). The analysis found a great diversity of tests and systems used for in vitro assays; many did not meet criteria for a valid test, and/or did not use validated cells and methods in the Organization for Economic Co-operation and Development Test Guidelines, and so these results could not be interpreted. In vivo assays were less common but better performed. It was not possible to develop conclusions on test system agreement, NM activity, or mechanism of action. However, the limited responses observed for most NMs were consistent with indirect genotoxic effects, rather than direct interaction of NMs with DNA. We propose a revised genotoxicity test battery for NMs that includes in vitro mammalian cell mutagenicity and clastogenicity assessments; in vivo assessments would be added only if warranted by information on specific organ exposure or sequestration of NMs. The bacterial assays are generally uninformative for NMs due to limited particle uptake and possible lack of mechanistic relevance, and are thus omitted in our recommended test battery for NM assessment. Recommendations include NM characterization in the test medium, verification of uptake into target cells, and limited assay-specific methods alterations to avoid interference with uptake or endpoint analysis. These recommendations are summarized in a Roadmap guideline for testing.

Bowel Cleansing Agents in Clinical Practice: A Cross-Sectional Study on Safety, Efficacy, and Predictor of Good Bowel Preparation

Background: A good bowel preparation for colonoscopy is the most important factor that has an impact on visualization and outcome of the procedure. Aim: The primary aim of the study was to assess the quality of bowel preparation as reported by the Boston Bowel Preparation Score (BBPS). The secondary aim of the study was to analyze the patient feedback on ease of administration, palatability, and side effects with the bowel preparation. Materials and Methods: Patients undergoing colonoscopy between March 2018 and September 2018 were enrolled in the study. Patients <18 years of age, those with the previous history of colorectal surgery, emergency procedures in an unprepared colon, and those not willing to participate were excluded from the study. Colon preparation of the patient was decided by senior consultants. A predesigned pro forma that included demography, indication for the procedure, preparation details, dietary recommendations the previous day if any, side effects, and patient’s comfort to preparation was completed by two-independent observers. The BBPS was used to assess the bowel preparation. A score of <5 was deemed inadequate. P < 0.05 was considered statistically significant. Results: The study cohort consisted of 141 patients, of which 78 were male (55.3%). Eighty (56.7%) patients received oral sulfate-based preparation and 61(43.4%) polyethylene glycol-based preparation. Nearly one third of cases reported the solution to be non palatable. 15.4% respondents reported nausea, vomiting and bloating as the major side effects of the preparation. The median duration of colonoscopy was 25 min (8–45 min). One hundred and eighteen patients (83.6%) had a BBPS score of ≥5. Sulfate preparation resulted in better bowel cleansing (P = 0.01). Age, gender, and dosing schedule of preparation, including bedtime dosing of stimulant laxative, did not alter the BBPS score. Conclusion: Sulfate- and polyethylene glycol-based preparations are commonly used for cleansing the colon. Bowel cleansing was adequate in most patients and sulfate-based yielded better bowel cleansing. Nearly 15.4% of patients reported side effects to these preparations.

Double‑Scope Peroral Endoscopic Myotomy Technique: Light at the End of the Tunnel!

Peroral Endoscopic Myotomy has become the preferred therapy for achalasia cardia.An important predictor of the success and safety of this technique remains the correct identification of the Esophago gastric junction and the extent of myotomy. However, this key step may be difficult in a subset of patients. The present case highlights the use of double scope technique to manage such technical issues.

Isolated Terminal Ileal Mucosal Changes: When is the Bite Indicated?

Aim: This study aims to determine the clinical presentation, and ileal mucosal changes during colonoscopy for which terminal ileal (TI) biopsies were taken at our center and to determine the specific histopathology which had the best yield for specific colonoscopy findings. Materials and Methods: Retrospective audit of all patients who underwent colonoscopy with ileoscopy between 2012 and 2016. All patients with TI mucosal changes and normal colonic mucosa, who underwent ileal biopsy, were included in this study. Patient data regarding age, gender, indication for ileocolonoscopy (screening for colorectal cancers, inflammatory bowel disease [IBD], or irritable bowel syndrome [IBS]) and histopathology changes were collected. Appropriate statistical tests were used and P < 0.05 was considered statistically significant. Results: One hundred and nine patients had isolated ileal lesions. The median age was 44.1 years (range 8–80 years). Men outnumbered women in a ratio of 82:27. The major clinical indications for ileocolonoscopy were IBS (64.2%), followed by IBD (22%). Ulcers (aphthoid) were the most frequent finding followed by mucosal nodularity and nonspecific findings. Ulcers in ileum were most often reported as chronic ileitis (46.2%), followed by nonspecific changes (35.2%) Biopsy from nodular ileal lesions, were predominantly nonspecific (74.4%), followed by acute (15.4%) and chronic ileitis (10.2%). About 50% of specimens with nonspecific ileal changes had nonspecific histological changes. Ileal ulcers had the highest sensitivity, PPV, and NPV for significant histological findings. Conclusion: Ileal ulcers are the significant colonoscopy findings where tissue biopsy is likely to yield a definitive diagnosis and justify specific management. Biopsies from nonspecific ileal changes and nodularity should be discouraged as it is unlikely to pick up any major abnormality.

An integrated approach to the safety assessment of food additives in early life

During the development of international standards by the Codex Alimentarius Commission, infant foods and their constituent ingredients are subject to rigorous risk analysis and are strictly regulated by many authorities. Various jurisdictions have approved only a limited number of additives specifically with regard to infant foods to fulfill specific technical requirements of quality. As part of the approval process, a rigorous safety assessment is essential to confirm that the use of additives does not pose any health risk for the consumer. An acceptable daily intake (ADI) may be derived from the toxicological databases. However, the ADI may not be applicable to infants because of the possible developmental sensitivities and potentially high exposure scenarios, leading to possible lower margins of safety than would often be determined for adult populations. There is interest in defining better food safety assessment approaches for pre-weaned infants aged less than 12–16 weeks. To confirm safe use in infants, we reviewed the suitability of the existing safety databases of six additives with historical uses in infant nutrition products. To determine further toxicity testing strategies, it is necessary to understand whether the chemical used in the additives is identical to endogenous physiological metabolites and/or whether immature organs of infants are targets of toxicity. Combined with an in-depth review of the existing relevant toxicological and nutritional studies, this integrated approach will facilitate decision-making. We propose a decision tree as a tool within this approach to help guide appropriate data requirements and identify data gaps. In cases of reasonable uncertainty, studies of targeted juvenile should be considered to investigate the safe use levels in food products.

The development and validation of methods for evaluating the immune system in preweaning piglets

The preweaning piglet has been found to be a valuable research model for testing ingredients used in infant formula. As part of the safety assessment, the neonates' immune system is an important component that has to be evaluated. In this study three concurrent strategies were developed to assess immune system status. The methods included (1) immunophenotying to assess circulating innate immune cell populations, (2) monitoring of circulating cytokines, particularly in response to a positive control agent, and (3) monitoring of localized gastrointestinal tissue cytokines using immunohistochemistry (IHC), particularly in response to a positive control agent. All assays were validated using white papers and regulatory guidance within a GLP environment. To validate the assays precision, accuracy and sample stability were evaluated as needed using a fit for purpose approach. In addition animals were treated with proinflammtory substances to detect a positive versus negative signal. In conclusion, these three methods were confirmed to be robust assays to evaluate the immune system and GIT-specific immune responses of preweaning piglets.

An infant formula toxicity and toxicokinetic feeding study on carrageenan in preweaning piglets with special attention to the immune system and gastrointestinal tract

A toxicity/toxicokinetic swine-adapted infant formula feeding study was conducted in Domestic Yorkshire Crossbred Swine from lactation day 3 for 28 consecutive days during the preweaning period at carrageenan concentrations of 0, 300, 1000 and 2250 ppm under GLP guidelines. This study extends the observations in newborn baboons (McGill et al., 1977) to piglets and evaluates additional parameters: organ weights, clinical chemistry, special gastrointestinal tract stains (toluidine blue, Periodic Acid-Schiff), plasma levels of carrageenan; and evaluation of potential immune system effects. Using validated methods, immunophenotyping of blood cell types (lymphocytes, monocytes, B cells, helper T cells, cytotoxic T cells, mature T cells), sandwich immunoassays for blood cytokine evaluations (IL-6, IL-8, IL1β, TNF-α), and immunohistochemical staining of the gut for IL-8 and TNF-α were conducted. No treatment-related adverse effects at any carrageenan concentration were found on any parameter. Glucosuria in a few animals was not considered treatment-related. The high dose in this study, equivalent to ~430 mg/kg/day, provides an adequate margin of exposure for human infants, as affirmed by JECFA and supports the safe use of carrageenan for infants ages 0-12 weeks and older and infants with special medical needs.

A 3-week dietary safety study of octenyl succinic anhydride (OSA)-modified starch in neonatal farm piglets

Octenyl succinic anhydride (OSA)-modified starch functions as both an emulsifier and emulsion stabilizer in foods, and is intended for use in infant formula, follow-on formula, and formulae for special medical purposes. These formulae predominantly include extensively hydrolyzed protein or free amino acids, rather than intact protein, which otherwise would provide emulsifying functionality. The study objectives were to evaluate (1) the safety of OSA-modified starch after three weeks of administration to neonatal farm piglets, beginning 2 days after birth and (2) the impact of OSA-modified starch on piglet growth. OSA-modified starch was added to formula at concentrations of 2, 4, and 20 g/L. The vehicle control, low-dose, and mid-dose diets were supplemented with Amioca™ Powder to balance the nutritional profiles of all formulations. There were no test article-related effects of any diet containing OSA-modified starch on piglet growth and development (clinical observations, body weight, feed consumption), or clinical pathology parameters (hematology, clinical chemistry, coagulation, urinalysis). In addition, there were no adverse effects at terminal necropsy (macro- and microscopic pathology evaluations). Therefore, dietary exposure to OSA-modified starch at concentrations up to 20 g/L was well tolerated by neonatal farm piglets and did not result in adverse health effects or impact piglet growth.

CYP1B1 detection

This unit describes procedures for measuring CYP1B1 gene expression by reverse transcription real-time PCR (qRT-PCR), CYP1B1 protein levels by western blotting, and CYP1B1 enzyme activity through conversion of 7-ethoxyresorufin substrate. To achieve specific measurement of CYP1B1 activity in the presence of CYP1A1 and CYP1A2, CYP1B1 inhibition and a subtractive approach have been adopted. 2,4,3',5'-Tetramethoxystilbene (TMS) is a potent and selective competitive inhibitor of CYP1B1 with an IC₅₀ of 3 nM for EROD and ~90 nM for E2 4-hydroxylation. Binding studies with purified CYP1B1 suggests that TMS interferes in the proximity of the heme region of CYP1B1 with high affinity. Compared to other potent inhibitors such as α-naphthoflavone, which is a known CYP1 family inhibitor with no selectivity between CYP1B1 and CYP1A2, TMS is ~50- and 520-fold selective for inhibition of CYP1B1 when compared to CYP1A1 and CYP1A2, respectively. Thus, TMS can serve as a helpful chemical scalpel for dissecting CYP1B1 activity from the overall activity of CYP1 family members against ethoxyresorufin.

Impact of yoga way of life on organizational performance

BACKGROUND

Organizational performance can be attributed to a number of factors. However, there are certain organizational factors, the presence or absence of which can determine the success or failure of the organization. There are different ways in which organizations try to improve their performance by working on such factors. In the research presented in this article, an attempt is made to find out whether adoption of the Yoga Way of Life by managers can have a positive impact on such organizational performance indicators.

AIMS

To measure effect of yoga way of life on five different indicators through an empirical study.

MATERIALS AND METHODS

The five indicators are job satisfaction, job involvement, goal orientation, affective organizational commitment and organizational citizenship behavior.

STATISTICS ANALYSIS

Pre- and post-data was measured using self-reported questionnaire. Independent T-test (Paired) and Pearson's correlation test were conducted using SPSS.

RESULTS AND CONCLUSION

The results of the study show that Yoga has a significant positive impact on four out of five of these indicators. Only job involvement does not show significant improvement. The construct used for measuring job involvement had a Chronbach alpha of 0.613, which is an indicator of moderate reliability, which could be the main reason for not getting positive result.

Activation of the aryl hydrocarbon receptor is the major toxic mode of action of an organic extract of a reference urban dust particulate matter mixture: the role of polycyclic aromatic hydrocarbons

Many of the toxic and carcinogenic effects of urban air pollution have been linked to polycyclic aromatic hydrocarbons (PAHs) adsorbed to airborne particulate matter (PM). The carcinogenic properties of PAHs in complex organic mixtures derived from PM have been chiefly attributed to their mutagenicity. Nevertheless, PAHs are also potent activators of the aryl hydrocarbon receptor (AhR), which may contribute to their nongenotoxic effects, including tumor promotion. As the genotoxicity of carcinogenic PAHs in complex mixtures derived from urban PM is often inhibited by other mixture constituents, the AhR-mediated activity of urban PM extracts might significantly contribute to the carcinogenic activity of such mixtures. In the present study, we used an organic extract of the urban dust standard reference material, SRM1649a, as a model mixture to study a range of toxic effects related to DNA damage and AhR activation. Both the organic extract and its neutral aromatic fraction formed a low number of DNA adducts per nucleotide in the liver epithelial WB-F344 cells model, without inducing DNA damage response, such as tumor suppressor p53 activation and apoptosis. In contrast, we found that this extract, as well as its neutral and polar fractions, were potent inducers of a range of AhR-mediated responses, including induction of the AhR-mediated transcription, such as cytochrome P450 1A1/1B1 expression, and the AhR-dependent cell proliferation. Importantly, these toxic events occurred at doses one order of magnitude lower than DNA damage. The AhR-mediated activity of the neutral fraction was linked to PAHs and their derivatives, as polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls were only minor contributors to the overall AhR-mediated activity. Taken together, our data suggest that more attention should be paid to the AhR-dependent nongenotoxic events elicited by urban PM constituents, especially PAHs and their derivatives.

Genetic toxicology in the 21st century: reflections and future directions

A symposium at the 40th anniversary of the Environmental Mutagen Society, held from October 24-28, 2009 in St. Louis, MO, surveyed the current status and future directions of genetic toxicology. This article summarizes the presentations and provides a perspective on the future. An abbreviated history is presented, highlighting the current standard battery of genotoxicity assays and persistent challenges. Application of computational toxicology to safety testing within a regulatory setting is discussed as a means for reducing the need for animal testing and human clinical trials, and current approaches and applications of in silico genotoxicity screening approaches across the pharmaceutical industry were surveyed and are reported here. The expanded use of toxicogenomics to illuminate mechanisms and bridge genotoxicity and carcinogenicity, and new public efforts to use high-throughput screening technologies to address lack of toxicity evaluation for the backlog of thousands of industrial chemicals in the environment are detailed. The Tox21 project involves coordinated efforts of four U.S. Government regulatory/research entities to use new and innovative assays to characterize key steps in toxicity pathways, including genotoxic and nongenotoxic mechanisms for carcinogenesis. Progress to date, highlighting preliminary test results from the National Toxicology Program is summarized. Finally, an overview is presented of ToxCast™, a related research program of the U.S. Environmental Protection Agency, using a broad array of high throughput and high content technologies for toxicity profiling of environmental chemicals, and computational toxicology modeling. Progress and challenges, including the pressing need to incorporate metabolic activation capability, are summarized.

Transcriptional responses to complex mixtures—A review

Exposure of people to hazardous compounds is primarily through complex environmental mixtures, those that occur through media such as air, soil, water, food, cigarette smoke, and combustion emissions. Microarray technology offers the ability to query the entire genome after exposure to such an array of compounds, permitting a characterization of the biological effects of such exposures. This review summarizes the published literature on the transcriptional profiles resulting from exposure of cells or organisms to complex environmental mixtures such as cigarette smoke, diesel emissions, urban air, motorcycle exhaust, carbon black, jet fuel, and metal ore and fumes. The majority of the mixtures generally up-regulate gene expression, with heme oxygenase 1 and CYP1A1 being up-regulated by all of the mixtures. Most of the mixtures altered the expression of genes involved in oxidative stress response (OH-1, metallothioneins), immune/inflammation response (IL-1b, protein kinase), xenobiotic metabolism (CYP1A1, CYP1B1), coagulation and fibrinolysis (plasminogen activator/inhibitor), proto-oncogenes (FUS1, JUN), heat-shock response (HSP60, HSP70), DNA repair (PCNA, GADD45), structural unit of condensed DNA (Crf15Orf16, DUSP 15), and extracellular matrix degradation (MMP1, 8, 9, 11, 12). Genes involved in aldehyde metabolism, such as ALDH3, appeared to be uniquely modulated by cigarette smoke. Cigarette smoke-exposed populations have been successfully distinguished from control nonexposed populations based on the expression pattern of a subset of genes, thereby demonstrating the utility of this approach in identifying biomarkers of exposure and susceptibility. The analysis of gene-expression data at the pathway and functional level, along with a systems biology approach, will provide a more comprehensive insight into the biological effects of complex mixtures and will improve risk assessment of the same. We suggest critical components of study design and reporting that will achieve this goal.

Inhibition of human cytochrome p450 1b1 further clarifies its role in the activation of dibenzo[a,l]pyrene in cells in culture

Metabolic activation and DNA adduct formation of the carcinogenic aromatic hydrocarbon dibenzo[a,l]pyrene (DBP) was investigated in human mammary carcinoma MCF-7 cells and human cytochrome P450 (CYP) 1B1-expressing Chinese hamster V79 cells in culture. It has been shown that DBP is metabolically activated to DNA-binding diol epoxides both in vitro and in vivo. To further establish the role of human CYP1B1 in the activation of DBP, both cell lines were cotreated with DBP and a selective chemical inhibitor of CYP1B1, 2,4,3' ,5'-tetramethoxy-stilbene (TMS). Results from DBP-DNA adduct analyses revealed the complete inhibition of DNA binding when cells were cotreated with DBP and TMS in comparison to DBP alone. Inactivation of CYP1B1 by TMS was also demonstrated through a decrease in the 7-ethoxyresorufin O-deethylase (EROD) activity in microsomes isolated from these cells. Emodin, 3-methyl-1,6,8-trihydroxyanthraquinone, an active ingredient of an herb, has been recently shown of being able to induce CYP1 gene expression. Examination of human CYP1B1 induction and EROD activity confirmed an increase in protein levels upon cotreatment with emodin and DBP. Despite increases in protein levels and enzyme activity, there was no significant change in DBP-DNA binding levels at very low substrate concentrations (17 nM). The data obtained in this study emphasize the central role of CYP1B1 in the activation of DBP in human cells in culture.

Competitive inhibition of carcinogen-activating CYP1A1 and CYP1B1 enzymes by a standardized complex mixture of PAH extracted from coal tar

A complex mixture of polycyclic aromatic hydrocarbons (PAH) extracted from coal tar, the Standard Reference Material (SRM) 1597, was recently shown to decrease the levels of DNA binding of the 2 strong carcinogens benzo[a]pyrene (BP) and dibenzo[a,l]pyrene (DBP) in the human mammary carcinoma-derived cell line MCF-7 (Mahadevan et al., Chem Res Toxicol 2005;18:224-231). The present study was designed to further elucidate the biochemical mechanisms involved in this inhibition process. We examined the effects of SRM 1597 on the metabolic activation of BP and DBP toward DNA-binding derivatives in Chinese hamster cells expressing either human cytochrome P450 (CYP) 1A1 or CYP1B1. SRM 1597 inhibited BP-DNA adduct formation through the entire exposure time in cells expressing human CYP1A1, while it significantly inhibited adduct formation only up to 48 hr when co-treated with DBP. Conversely, human CYP1B1-expressing cells were unable to catalyze PAH-DNA adduct formation on treatment with SRM 1597 alone, and on co-treatment with BP or DBP. The data obtained from biochemical experiments revealed that SRM 1597 competitively inhibited the activity of both human enzymes as analyzed by 7-ethoxyresorufin O-deethylation assays. While the Michaelis-Menten constant (K(M)) was <0.4 microM in the absence of SRM 1597, this value increased up to 1.12 (CYP1A1) or 4.45 microM (CYP1B1) in the presence of 0.1 microg/ml SRM 1597. Hence the inhibitory effects of the complex mixture on human CYP1B1 were much stronger when compared to human CYP1A1. Taken together, the decreases in PAH-DNA adduct formation on co-treatment with SRM 1597 revealed inhibitory effects on the CYP enzymes that convert carcinogenic PAH into DNA-binding metabolites. The implications for the tumorigenicity of complex environmental PAH mixtures are discussed.

Investigation of the genotoxicity of dibenzo[c,p]chrysene in human carcinoma MCF-7 cells in culture

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants that have been linked to certain human cancers. The fjord region PAH dibenzo[a,l]pyrene exhibits the highest levels of carcinogenic activity of all PAH as yet tested in rodent tumor models. Another hexacyclic aromatic hydrocarbon, dibenzo[c,p]chrysene (DBC), is a unique PAH that possesses one bay region and two fjord regions within the same molecule. Due to its structure, which is a merger of the fjord region PAHs benzo[c]phenanthrene, benzo[c]chrysene, and benzo[g]chrysene, DBC is of considerable research interest. In order to investigate the pathway of regioselective metabolism we have studied the cytotoxicity, metabolic activation and DNA adduct formation of DBC in human mammary carcinoma MCF-7 cells in culture. The cytotoxicity assay indicated undisturbed cell proliferation even at concentrations as high as 4.5 microM (1.5 micro g/ml) DBC. Concurrently, DNA adducts were detected in MCF-7 cells treated with DBC only in low amounts (0.6 pmol adducts/mg DNA). On the contrary, exposure to anti-DBC-1,2-diol-3,4-epoxide and anti-DBC-11,12-diol-13,14-epoxide, two putatively genotoxic metabolites of DBC, resulted in high levels of DNA adducts (33 and 51 pmol adducts/mg DNA, respectively). Although DBC was not efficiently transformed into DNA-reactive metabolites in MCF-7 cells in culture, the results from our study indicate that the two fjord region diol-epoxide derivatives of DBC may serve as ultimate genotoxic metabolites once they are enzymatically generated under certain circumstances in vitro or in vivo.

Indole-3-carbinol in the maternal diet provides chemoprotection for the fetus against transplacental carcinogenesis by the polycyclic aromatic hydrocarbon dibenzo[a,l]pyrene

The fetus and neonate are sensitive targets for chemically induced carcinogenesis. Few studies have examined the risk/benefit of chemoprotective phytochemicals, given in the maternal diet, against transplacental carcinogenesis. In this study, B6129 SF1/J (AHR(b-1/d)) and 129Sv/ImJ (AHR(d/d)) mice were cross-bred. The polycyclic aromatic hydrocarbon, dibenzo[a,l]pyrene (DBP), was administered to pregnant mice (15 mg/kg, gavage) on gestation day 17, and 2000 p.p.m. indole-3-carbinol (I3C), a chemoprotective phytochemical from cruciferous vegetables, was fed to half of the mice from gestation day 9 until weaning. Offspring born to dams fed I3C exhibited markedly fewer mortalities (P < 0.0001). Maternal dietary exposure to I3C also significantly lowered lung tumor multiplicity (P = 0.035) in offspring surviving to 10 months of age. The I3C chemoprotection was independent of either maternal or fetal AHR genotype. The bioavailability of DBP to fetal target tissue was demonstrated by assessing DNA covalent adduction with a (33)P-post-labeling assay. The bioavailability of I3C was determined by dosing a subset of pregnant mice with [(14)C]-I3C. Addition of chemoprotective agents to the maternal diet during pregnancy and nursing may be an effective new approach in reducing the incidence of cancers in children and young adults.

Reduction in tamoxifen-induced CYP3A2 expression and DNA adducts using antisense technology

Tamoxifen (TAM) is widely used in the treatment and prevention of breast cancer. There is clear evidence that cytochrome P450 (CYP) 3A enzymes play an important role in TAM metabolism, resulting in metabolites that lead to formation of TAM-DNA adducts. We have investigated the effect of CYP3A2 antisense (AVI-4472) exposure on CYP3A2 transcription, enzyme activity, translation, and TAM-DNA adducts, in livers of rats administered TAM (50 mg/kg body weight [bw]/day) for 7 days. The study design included administration of 0, 0.5, 2.5, or 12.5 mg AVI-4472/kg bw/day for 8 days, beginning 1 day before TAM exposure. The specific activity of CYP3A2 was increased after TAM administration, and decreased significantly (approximately 70%) in the presence of 12.5 mg AVI-4472. CYP3A2 protein levels, determined by immunoblot analysis, showed a similar pattern. Hepatic TAM-DNA adduct levels were measurable in all TAM-exposed groups. However, when rats were co-treated with 2.5 and 12.5 mg AVI-4472/kg bw/day, statistically significant (approximately 50%) reductions in TAM-DNA adduct levels (2.0-2.8 adducts/10(8) nucleotides) were observed compared to rats treated with TAM alone (5.1 adducts/10(8) nucleotides). Rat toxicology U34 arrays (Affymetrix) were used to investigate the modulation of gene expression patterns on co-administration of TAM with AVI-4472. Results indicated that several CYP genes were down regulated although no significant induction of CYP3A2 was observed in the TAM-exposed rats co-treated with AVI-4472. Overall the data suggest the utility of antisense technology in the redirection of TAM metabolism thereby lowering TAM genotoxicity in rat liver.

Long-term effects of a standardized complex mixture of urban dust particulate on the metabolic activation of carcinogenic polycyclic aromatic hydrocarbons in human cells in culture

Humans are exposed to complex mixtures of polycyclic aromatic hydrocarbons in the atmosphere. We examined the long term effects of a standard reference material (SRM) 1649a over time on the metabolic activation and DNA adduct formation by two carcinogenic PAHs, benzo[a]pyrene (BP) and dibenzo[a,l]pyrene (DBP) in the human mammary carcinoma derived cell line MCF-7. PAH-DNA adduct analysis, cytochrome P450 (CYP) enzyme activity, CYP1A1 and CYP1B1 protein expression were determined in cells treated with SRM 1649a alone or SRM 1649a with either BP or DBP for 24 to 120 h. Averaging over time, significantly higher levels of DNA adducts were observed in cells treated with BP or DBP alone than in co-treatments with SRM 1649a and BP or DBP. Ethoxyresorufin O-deethylase assay indicated a significant increase in activity in cells treated with BP alone and co-treated with SRM1649a in comparison to other treatment groups. Induction of CYP1A1 and CYP1B1 protein expression was observed by immunoblots in cells treated with BP alone or in co-treatments of SRM 1649a and BP or DBP. These data demonstrate the influence of the components of SRM 1649a in inhibiting the activation of BP or DBP by CYP enzymes in the formation of DNA adducts. It also suggests that the carcinogenic activity of PAH within a complex mixture may vary with composition and activation of the components present in the complex mixture.

Effect of a standardized complex mixture derived from coal tar on the metabolic activation of carcinogenic polycyclic aromatic hydrocarbons in human cells in culture

A complex mixture of polycyclic aromatic hydrocarbons (PAH) extracted from coal tar, standard reference material (SRM) 1597, has been shown to initiate tumor formation in mouse initiation-promotion assays in our laboratory [(2001) Carcinogenesis 22 (7), 1077-1086]. To determine the effects of SRM 1597 on PAH activation in human cells, we investigated the PAH-DNA adduct formation in the human mammary carcinoma-derived cell line MCF-7. We examined the effects of SRM 1597 on the metabolic activation to DNA binding derivatives of two carcinogenic PAHs, the bay region containing benzo[a]pyrene (B[a]P) and the more carcinogenic fjord region containing dibenzo[a,l]pyrene (DB[a,l]P). PAH-DNA adduct analysis by 33P-postlabeling and reversed phase high-performance liquid chromatography revealed a significant decrease in the levels of both B[a]P and DB[a,l]P DNA adduct formation on cotreatment with SRM 1597 in comparison to cells exposed to B[a]P or DB[a,l]P alone. However, the inhibition of PAH-DNA adduct formation only occurred within the first 48 h of exposure in cells cotreated with SRM 1597 and B[a]P. In contrast, SRM 1597 significantly inhibited the level of DB[a,l]P DNA adducts throughout the 120 h of exposure. Induction of human cytochrome P450 (P450) enzymes 1A1 and P4501B1 on treatment with SRM 1597 was observed by immunoblots. These results suggest that the important factors in determining the carcinogenic activity of PAH within a complex mixture would depend on the ability of other components of the mixture to promote or inhibit the activation of carcinogenic PAH by the induction of P450 enzymes followed by the formation of DNA adducts.

Neural tube defects in Pondicherry

OBJECTIVE

This study was carried out to identify the trend and the frequency of neural tube defects from July 1998 to June 2004.

METHODS

A total of 310 babies were born with neural tube defects with the overall frequency of 5.7/1000 births compared to 2.3/1000 births observed earlier in our hospital.

RESULTS

The most common defect was spina bifida (54.8%) followed by anencephaly (31.6%), and encephalocele (11.6%). More neural tube defects were observed in female and low birth weight babies, still births and unbooked mothers. Neural tube defect was significantly higher among babies born to parents of consanguineous marriage (p< 0.01). Associated congenital defects were observed in thirty nine (12.6%) cases.

CONCLUSION

The rise in the frequency of NTDS may indicate the current trend of NTDs in Southern India. A further prospective study is desired to measure the effectiveness of regular folic acid supplementation in bringing down this frequency.

Diesel exhaust particles cause increased levels of DNA deletions after transplacental exposure in mice

Diesel exhaust particles (DEP) are a major source of air-borne pollution and are linked to increased risk of disease including lung cancer. Here we investigated effects of exposure to DEP on the frequency of DNA deletions, levels of oxidative DNA damage and DNA adduct formation during embryonic development in mice. Pregnant dams were orally exposed to various doses of DEP (500, 250, 125, 62.5, 31.25 mg/kg/day) at embryonic days 10.5-15.5. We determined the frequency of 70 kb DNA deletions spanning exons 6-18 at the p(un) allele that results in black-pigmented spots in the unpigmented retinal pigment epithelium in the eyes of p(un)/p(un) offspring mice. DEP caused a significant increase in the frequency of DNA deletions. Levels of 8-OH deoxyguanosine indicating oxidative DNA damage were within the limits of the unexposed mouse embryos. 33P post-labeling analysis revealed very low levels of DNA adducts in the embryo tissue. Thus, transplacental exposure to DEP resulted in a significant increase in the frequency of DNA deletions in the mouse fetus and such genetic alterations in the offspring may have pathological consequences later in life.

Altered gene expression patterns in MCF-7 cells induced by the urban dust particulate complex mixture standard reference material 1649a

Human exposures to polycyclic aromatic hydrocarbon (PAH) occur in complex mixtures. Here, gene expression patterns were investigated using standard reference material (SRM) 1649a (urban dust). MCF-7 cells were exposed to SRM 1649a alone or SRM 1649a with either benzo[a]pyrene (BP) or dibenzo[a,l]pyrene (DBP) for 24 hours. Global analyses of the gene expression data revealed alterations of 41 RNA transcripts with at least 2-fold change (signal log ratio </= -1 or >/= 1) in response to SRM 1649a exposure. Increase in expression of cytochrome P450 (CYP) genes was observed in response to BP exposure (CYP1A1 and CYP1B1; signal log ratio of 4.7 and 2.5, respectively). An additive induction of CYP1A1 and CYP1B1 was observed with cotreatment of SRM 1649a and BP. On the contrary, no change in gene expression of CYP1A1 and CYP1B1 was observed when the cells were exposed to DBP. Furthermore, to study the effect of complex PAH mixtures on the metabolic activation of carcinogenic PAH to DNA-binding derivatives and to relate this with gene expression studies, PAH-DNA adduct formation was determined. SRM 1649a decreased the total level of BP-DNA adducts in comparison with BP alone. No significant difference in adduct levels was observed in response to either DBP alone or in combination with SRM 1649a. These results provide a transcriptional signature for chemical carcinogen exposure; in addition, they suggest a major factor in carcinogenic activity of PAH within complex mixtures is their ability to promote or inhibit the activation of carcinogenic PAH by the induction of CYP enzymes.

Effects of suberoylanilide hydroxamic acid and trichostatin A on induction of cytochrome P450 enzymes and benzo[a]pyrene DNA adduct formation in human cells

In this study, we investigated the effects of histone deacetylase (HDAC) inhibitors suberoylanilide hydroxamic acid (SAHA) and trichostatin A (TSA) on the metabolism of polycyclic aromatic hydrocarbons (PAH) in human mammary carcinoma derived MCF-7 cells in culture. Benzo[a]pyrene (B[a]P) induces cytochrome P450 (CYP) 1A1, CYP1B1 and other xenobiotic metabolizing enzymes. Results from our study indicated a significant increase in CYP activity in comparison to vehicle control in cells treated with SAHA or TSA as measured by ethoxyresorufin-O-deethylase assay. However, co-treatment with 1.0 microM SAHA and BP, reduced the mRNA levels of CYP1B1 relative to B[a]P alone. When co-treated with 1.0 microM TSA and BP, a reduction in the mRNA levels of both CYP1A1 and CYP1B1 was observed relative to BP alone. We further investigated to ascertain if the differential expression and activity of CYP1A1 and CYP1B1 influenced levels of B[a]P DNA adduct formation. MCF-7 cells co-treated with B[a]P and SAHA or TSA formed DNA adducts, although no significant differences in levels of DNA binding were revealed. These results suggest that while CYP enzyme activity and gene expression were affected by the HDAC inhibitors SAHA and TSA, they had no apparent influence on B[a]P DNA binding.

Carcinogenic polycyclic aromatic hydrocarbon-DNA adducts and mechanism of action

Polycyclic aromatic hydrocarbons (PAHs) are a class of widespread environmental carcinogens. Most of our knowledge of their mechanisms of metabolic activation to DNA-binding "ultimate carcinogenic" metabolites has come from analysis of the DNA interaction products formed by these highly reactive intermediates. Studies of their role in forming DNA-binding intermediates identical to those formed in vivo from the PAH itself have also allowed identification of the particular cytochrome P450 enzymes involved in activating various structural classes of carcinogenic PAHs. It has been established that PAHs, after metabolic activation in vivo, are capable of inducing mutations in oncogenes and, by inducing multiple mutations, may result in tumors. PAHs also cause changes in cellular gap-junction communication similar to those caused by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate. Thus, PAHs may also act through a promotional mechanism in addition to serving as tumor initiators. Previous studies on these mechanisms are described and summarized.

Tuberculin reactivity in tuberculous meningitis

OBJECTIVE

To study tuberculin reactivity in childhood tuberculous meningitis both in clinical and histopathological (HP) context.

METHODOLOGY

Children with tuberculous meningitis (TBM) were given tuberculin test by Mantoux technique, which was read at the end of 72 hours after the placement of skin test. Histopathological examination of the punch biopsy specimen of the tuberculin test site was performed and histopathological grading of the tuberculin reaction was compared with clinical reaction and clinical parameters.

RESULTS

Of the 50 children studied, 68% of them were malnourished and 42% had BCG scar. Tuberculin test was positive in 22 (44%) cases. Spearman analysis showed negative correlation between stage of TBM and the size of tuberculin reaction. BCG status did not affect the size of tuberculin reaction. Histopathological grade of the tuberculin reaction was found to be directly proportional to the size of the tuberculin reaction and it was not affected by the stage of TBM.

CONCLUSION

Tuberculin positivity is low in TBM irrespective of the nutritional status. At least some degree of inflammatory reaction can be seen at the site of tuberculin administration. In tuberculin negative cases, varying grades of cellular response in the absence of clinical induration can be seen in histopathology.

Dibenzo[a,l]pyrene induced DNA adduct formation in lung tissue in vivo

Polycyclic aromatic hydrocarbons (PAHs) are environmental carcinogens present in the atmosphere from combustion sources such as cigarette smoke, diesel exhaust, residential heating processes, and industrial coke production. To date, dibenzo[a,l]pyrene (DBP) has been found to be the strongest tumor-initiating PAH ever tested in rodent skin and mammary tumor models. Here we show for the first time that systemic exposure to DBP causes DNA damage in mouse lung tissue. C57BL/6 mice were gavaged with 1, 5 or 20 mg DBP/kg body weight, daily for 10 days. Toxicity of DBP was revealed by a decrease in body and organ weight of mice while no apparent cell death was observed on P815 mastocytoma cells (allograft model) in vitro. However, treatment of P815 cells in vitro with the ultimate carcinogenic metabolite of DBP, the fjord region (-)-anti-11,12-diol 13,14-epoxide [(-)-anti-DBPDE], resulted in the total loss of cell viability. Lungs from the animals were removed and subjected to DBP-DNA adduct analysis. A dose dependent adduct formation was revealed by 33P-postlabeling analysis of DNA from lung tissue. The majority of DNA adducts formed in lungs of mice after systemic exposure to DBP were contributed by (-)-anti-DBPDE. The data from this in vivo model are consistent with previous metabolic activation results obtained with DBP in human cells in culture.

The uses of carcinogen-DNA adduct measurement in establishing mechanisms of mutagenesis and in chemoprevention

DNA adducts generated by carcinogenic chemicals reflects human exposure and DNA adducts are related to tumor formation. Most chemical carcinogens require activation to reactive intermediates that bind to nucleophilic centers in proteins and nucleic acids thereby forming covalent adducts. Also, many of the chemicals considered carcinogenic for humans form covalent DNA adducts. Therefore, such DNA damage is generally considered to be causative and linked to tumor formation. In this article we have summarized the work done for many years on the role of DNA adduct formation as an indicator of their carcinogenicity. We have also addressed the important role for measurement of DNA adducts in studies with potential chemopreventive agents for which it is central to have a marker that can be measured more rapidly than changes in cancer incidence.

Effect of artificial mixtures of environmental polycyclic aromatic hydrocarbons present in coal tar, urban dust, and diesel exhaust particulates on MCF-7 cells in culture

Human exposure to polycyclic aromatic hydrocarbons (PAHs) occurs through complex mixtures. The National Institute of Standards and Technology has established standard reference materials (SRMs) for selected PAH mixtures that are composed of carcinogenic, noncarcinogenic, and weakly carcinogenic compounds, such as those derived from coal tar (SRM 1597), atmospheric particulate matter (SRM 1649), and diesel particulate matter (SRM 1650). To study the effects of PAHs with different carcinogenic potential in complex mixtures, and to investigate the metabolic activation of noncarcinogenic and weakly carcinogenic PAHs to DNA-binding derivatives, artificial mixtures (1597H, 1649H, and 1650H) were prepared in the laboratory. These artificial mixtures contained the same relative ratios of noncarcinogenic and weakly carcinogenic PAHs present in SRM 1597, SRM 1649, and SRM 1650. The human mammary carcinoma-derived cell line MCF-7 was treated with these artificial mixtures and analyzed for PAH-DNA adduct formation and the induction of cytochrome P450 (CYP) enzymes. We found that the artificial mixtures formed lower but detectable levels of DNA adducts 24 and 48 hr after treatment than benzo[a]pyrene. Induction of CYP enzyme activity was measured by the ethoxyresorufin-O-deethylase assay, and the expression of CYP1A1 and CYP1B1 was confirmed by immunoblots. Both noncarcinogenic and weakly carcinogenic PAHs present in the artificial mixtures have the ability to induce CYP1A1 and CYP1B1 in MCF-7 cells and contribute to DNA binding. Therefore, it is necessary to take into account the noncarcinogenic and weakly carcinogenic PAHs present in environmental mixtures in assessing the potential risk associated with human exposure.

Mutations induced by (-)-anti-11R,12S-dihydrodiol 13S,14R-epoxide of dibenzo[a,l]pyrene in the coding region of the hypoxanthine phosphoribosyltransferase (Hprt) gene in Chinese hamster V79 cells

The polycyclic aromatic hydrocarbon dibenzo[a,l]pyrene (DB[a,l]P) is an exceptionally potent carcinogen. Its direct DNA-reactive metabolite, the fjord region (-)-anti-11R,12S-dihydrodiol 13S,14R-epoxide [(-)-anti-DB[a,l]PDE], was used to investigate induction of mutations in the coding region of the hypoxanthine phosphoribosyltransferase (Hprt) gene in Chinese hamster V79 cells. Cells exposed to 1-10 nM (-)-anti-DB[a,l]PDE exhibited a close dose-responsive increase in the frequency of mutant clones resistant to 6-thioguanine. RNA was isolated from mutant clones and cDNAs were prepared by reverse transcription. The coding region of the cDNA of the Hprt gene was amplified by polymerase chain reaction and sequenced. Analysis of the DNA base sequence changes induced by (-)-anti-DB[a,l]PDE indicated that base substitutions were the most prevalent mutations, followed by exon deletions. Among the groups of V79 cells treated with low concentrations of (-)-anti-DB[a,l]PDE, most displayed high selectivity for both A:T-->T:A transversions and A:T-->G:C transitions, while cells exposed to a higher dose (10 nM) formed predominantly G:C-->T:A transversions. Also, the number of base substitutions per mutant clone increased with dose. In general, the mutation profiles induced by (-)-anti-DB[a,l]PDE exhibited a wide spectrum; in addition to base substitutions, deletions, insertions, frameshift mutations, as well as tandem mutations were detected. Analysis of the DNA adduct levels induced by (-)-anti-DB[a,l]PDE revealed that a concentration-dependent increase in the level of adduct formation preceded the concentration-dependent increase in mutational events in these cells and that an increasing proportion of DNA adducts at deoxyadenosine were formed with dose. The results of this study demonstrate a correspondence between the concentration and types of DNA adducts and the frequency and types of mutations induced by (-)-anti-DB[a,l]PDE in V79 cells.

Prognostic factors in childhood tuberculous meningitis

The risk factors affecting the outcome in 50 children with tuberculous meningitis were evaluated over a period of 20 months. Five children (10 per cent) had stage 1 disease, 29 (58 per cent) had stage II disease, and 16 (32 per cent) had stage III disease at admission. Seventeen cases (34 per cent) showed complete recovery, five (10 per cent) had mild, 14 (28 per cent) had moderate, and nine (18 per cent) had severe neurological sequelae. Five children (10 per cent) died. Younger age, tonic posturing, papilloedema, focal neurological deficit and stage at presentation were found to affect adversely the prognosis independently in children with tuberculous meningitis.