Molecular size distribution in pentavalent (A, C, Y, W, X) meningococcal polysaccharide conjugate vaccine by HPSEC-UV-MALS-RI method- a conceivable stability indicating parameter

Molecular size distribution (MSD) of polysaccharides serves as a key parameter that directly correlates to the immunogenicity of vaccine. MSD at meningococcal polysaccharide (A, C, Y and W) or conjugate bulk level is well established under detailed pharmacopeial and WHO guidelines. We report here, a newly developed method for determination of molecular size distribution of pentavalent Meningococcal conjugate vaccine comprising of A, C, Y, W and X (MenFive). Although serogroup specific molecular size could not be estimated here; lot to lot consistency monitoring, molecular aggregates distribution in final lot, are key takeaways of this method. Determination of MSD in pentavalent fill finished product was quite challenging. Various columns/detectors combination, buffers, physico-chemical conditions (temperature, 2-8 °C, 25 °C, 40 °C and 60 °C; flow rate, 0.3 mL to 0.8 mL), liquid/lyophilized formulations, were explored. Polymer-based packed columns were explored for estimation for MSD by aqueous size exclusion chromatography, using combinations of- Shodex OHPAK SB 807 HQ, Shodex OHPAK SB 806 HQ, G6000 PWXL, coupled with guard Shodex OHPAK SB-G-6B. MenFive showed heterogenous distribution of molecules ranging from 200 to 19000 kDa, indicating its complex nature. However, 1000-8000 kDa was dominant range, comprising of ≥ 50 % distribution of molecules, in both liquid as well as lyophilized formulations, with average molecular weight around 6000-6500 kDa. The molar mass distribution after slicing would provide an insight to the conformation of molecules through its presentation as HMW, LMW, aggregates and subsequently, the presence of dominant population of molecules of a particular molecular weight and its total contribution in the sample.

Method development and validation of unbound saccharide content (serogroup A, C, Y, W, X) in novel pentavalent meningococcal polysaccharide conjugate vaccine with two different carrier proteins

Exclusive DOC-HCl formulations were developed for free polysaccharide content estimation in Meningococcal serogroup A, C, Y, W and X from pentavalent meningococcal vaccine (A, C, Y, W, X). The DOC precipitation method reported herein stands as an alternative to the ultra-filtration method for free polysaccharide estimation. DOC content was optimized for all the serogroups at a single concentration, where as effective acid concentration was altered as per serogroup. Briefly, two DOC-HCl formulations were developed for intended purpose, one for TT conjugated serogroups Men A & Men X where as other for CRM conjugated serogroups Men C, Men Y and Men W with effective HCl concentration of 23 mM and 193 mM for precipitation of Protein-DOC complex respectively. Furthermore, an exclusive buffer/DOC-HCl formulation for estimation of Men X free polysaccharide in fill finished product was developed. Accuracy of the method was proven at 12.5 %, 25 %, 50 % and 100 % of test specification where recoveries were found in the range of 70-130 %. In case of repeatability, intra assay variation ranged from 2 % to 7 % whereas inter assay variation was noted to be 2-14 %. Specificity studied revealed no interference of assay components such as sample excipients, DOC, acids. Critical quality and stability-indicating characteristics were measured. Monovalent polysaccharide standards of Men A, C, Y, W and X were developed and assigned the unitage concentration 1.01, 1.10, 1.09, 1.08 and 1.00 mg/mL respectively. Linearity curve was optimized from 0.17 to 27 µg/mL for Men A and C whereas from 0.33 to 27 µg/mL for Men Y and W considering free polysaccharide content estimation. The study suggests that DOC-HCl method meets all the criteria for free polysaccharide estimation in multivalent vaccines with additional advantages of high throughput and sized independent separation hence can be used for quality control testing.

Quantitation of free cyanide using ion exchange chromatography in Neisseria meningitidis serogroups A, C, W, Y and X conjugates used in vaccine manufacture

Polysaccharide vaccines essentially used in the prevention of bacterial infections are known to be good immunogens when conjugated to an immunogenic protein using various cyanylating agents. Analysis of residual cyanide in polysaccharide conjugate vaccines is an ardent task due to the complexity of the sample matrices and the lack of suitable methods. We report a selective ion chromatography method with electrochemical detection using IonPac AS7 column for estimation of residual cyanide in meningococcal serogroups A, C, W, Y and X bulk conjugates in presence of other interfering ions. Gold electrode and Ag/AgCl reference electrode ensures sensitivity and reproducibility of cyanide quantitation. The calibration curve of the method is linear having r² ≥0.990 over the concentration range 1.45 ng/mL to 93.10 ng/mL. The recovery of cyanide in bulk conjugates ranged between 96.0% and 108.9%. The limits of detection and quantitation were 0.50 ng/mL and 1.45 ng/mL which corresponds to 0.31 ng/μg and 0.91 ng/μg of polysaccharide respectively. The method validation and feasibility study were performed using Men W and Men X bulk conjugates respectively with in house residual cyanide specification due to unavailability of pharmacopeia guidelines. The method is reproducible and can accurately quantify residual cyanide in purified meningococcal bulk conjugates.

An association of VDR gene polymorphism in hypovitaminosis D mediated secondary hyperparathyroidism in adolescent girls; a tertiary hospital study in central India

Vitamin D is required to maintain normal serum calcium and phosphate levels that help normal bone mineralization, nerve conduction, muscle contraction, immune function, cell proliferation, and differentiation. Interventions including vitamin D supplementation may not improve vitamin D deficiency, as various complex genomic actions could contribute to vitamin D deficiency in the Indian population. Thus, we assessed hypovitaminosis D's relationship with vitamin D receptor (VDR) gene polymorphism and evaluated parathyroid hormone (PTH) levels in seemingly healthy adolescent school-going girls. We included 100 school-going girls (aged 12-17 years) studying in four schools of different socio-economic strata of Bhopal, India. The selected participants were divided into four groups based on the school in which they were studying. Blood samples were tested for serum calcium, phosphorus, PTH, ALP, vitamin D 25(OH) D, and albumin levels.VDR polymorphism was detected through the PCR-RFLP. Data were analyzed using the chi-square test, ANOVA, and linear regression. The difference in the age, calcium, ALP, and vitamin D values between the four groups were significant (P < 0.05), whereas high PTH levels (80%) were found. A higher prevalence of homozygous polymorphic allele demonstrates a molecular signature for severe secondary hyperparathyroidism. Hypovitaminosis D ranged from 84.9% to 100%, and a high prevalence of VDR polymorphism was observed. Attention must be paid to the health of this age group of school-going girls as hypovitaminosis D and associated VDR gene polymorphism could be the reason for secondary hyperparathyroidism (SHPT), showing changes in bone mineral density in these adolescent girls to ensure their future health.

Metabolic syndrome in non-obese patients with OSA: learning points of a cross-sectional study from a tertiary care hospital in Central India

STUDY OBJECTIVES

Obesity is often considered mandatory for the diagnosis of Metabolic Syndrome (MS). Data on the prevalence of MS in non-obese patients with Obstructive Sleep Apnea (OSA) is scarce. This study was aimed to determine the prevalence of MS in non-obese patients with OSA.

METHODOLOGY

All consecutively diagnosed patients with OSA between October 2018 and November 2019 were screened for metabolic syndrome. Patients with OSA and BMI < 25 kg/m² (NOOSA) vs BMI > 25 kg/m² (obese OSA) were compared. Lean waist NOOSA was defined as BMI < 25 kg/m² and WC < 80 cm (32 in.) for women or < 90 cm (36 in.) for men.

RESULTS

During the study period, 502 patients were diagnosed with OSA. MS was observed in 35% of patients with NOOSA compared to obese patients with OSA (79%). In the NOOSA group, hypertension, impaired fasting glucose, diabetes mellitus and dyslipidemia were observed in 65, 48, 14 and 61% respectively and all of these parameters were significantly more common in the obese group (p < 0.001). Parameters of OSA severity (apnea-hypopnea index or AHI, time spent below 90% saturated or T90, and nadir oxygen) were significantly more severe in the obese group with OSA. Approximately 83% of patients in the NOOSA group had at least two metabolic risk factors, compared to the obese OSA group, in which 95% had two or more metabolic risk factors. Sixty-four percent of patients with NOOSA with lean waist had at least two metabolic risk factors. At BMI cut-offs of < 25, < 27 and < 30 kg/m2; 35, 46 and 57% of patients with OSA respectively had metabolic syndrome.

CONCLUSION

Metabolic syndrome was observed in approximately one in three patients with OSA and BMI < 25 kg/m². Approximately two of every three lean waist non-obese patients with OSA had at least two markers of metabolic syndrome. The role of OSA in the development of metabolic syndrome in non-obese individuals needs further exploration.

Abnormal Ambulatory Blood Pressure and Early Renal Dysfunction in Sickle Cell Disease

OBJECTIVES

There is sparsity of studies evaluating blood pressure in children with sickle cell disease (SCD), which have shown inconsistent results. Few of the studies have documented lower office blood pressure (BP) in SCD patients, whereas, others have shown presence of masked hypertension and abnormal ambulatory blood BP monitoring (ABPM). Thus, the present study was conducted to examine 24 h ABPM parameters and renal dysfunction in children with SCD and compare them with healthy controls.

METHODS

A cross-sectional study was conducted on 56 children (30 children having SCD and 26 controls). ABPM and evaluation of renal functions including serum creatinine, serum urea, urinary creatinine, urinary protein and specific gravity was performed.

RESULTS

Spot urinary protein to creatinine ratio was found to be higher in patients with SCD (63.3%) as compared to controls (p < 0.001). Proteinuria was observed in 1/4th of the SCD patients less than ten years of age. Masked hypertension was present in 2 (6.6%) patients, ambulatory hypertension in 4 (13.3%), ambulatory pre-hypertension in 1 (3.3%) and abnormal dipping in 60%. A statistically significant correlation of BMI for age Z-score and standard deviation score (SDS/Z) of 24 h systolic BP (r = 0.56, p = 0.002); estimated glomerular filtration rate (eGFR) with 24 h diastolic BP SDS (r = -0.52; p = 0.038) and age with e GFR (r = 0.54; p = 0.025) was found in the present study.

CONCLUSIONS

The present study corroborates that ABPM abnormalities (ambulatory hypertension, non-dipping pattern, ambulatory prehypertension) and early onset proteinuria are significant findings in patients with SCD. This underscores the importance of regular screening for proteinuria and ABPM in routine care, for early detection and prevention of progressive renal damage in SCD.

Women with OSA have higher chances of having metabolic syndrome than men: effect of gender on syndrome Z in cross sectional study

STUDY OBJECTIVES

This study was done to find out prevalence of Metabolic syndrome (MS) in patients with Obstructive Sleep Apnea (OSA) and whether there is any difference in prevalence of syndrome Z in male and female.

METHODOLOGY

All consecutive diagnosed patients with OSA between June 2015 and Oct 2019 were screened for metabolic syndrome and factors associated with metabolic syndrome in OSA were analyzed.

RESULTS

During study period, 502 patients (357 males; 145 females) were diagnosed with OSA. Mean age was 51.88 ± 12.18 years (females and males:55.91 ± 9.74 and 50.24 ± 12.70 years, respectively). Mean BMI was 31.60 ± 11.09 kg/m² (female: 35.29 ± 7.19 and male: 30.1 ± 12.0 kg/m²) (p < 0.001). Mean AHI was 62.67 ± 35.22. Mild, moderate and severe category of OSA constituted 7.3%, 15.3% and 77.4% respectively. MS was found in 72.7% (365 out of 502) individuals with OSA. MS was found in 75.8%, 68.4 and 48.7% in severe, moderate and mild OSA patients respectively (p < 0.001). Females OSA patients had significantly high percentage (88.27%) of metabolic syndrome compared to males OSA patients (66.38%) {p < 0.001}. Female patients with SZ had higher metabolic score (p = 0.019) and were older (p < 0.001).

CONCLUSION

Metabolic syndrome is highly prevalent in OSA population (72.7%) and is much more common in female OSA patients (88%) than males OSA (68%). All OSA patients should be screened for MS so that early intervention can be done in these patients so as to prevent cardiovascular complications.

Development of competitive inhibition ELISA as an effective potency test to analyze human rabies vaccines and assessment of the antigenic epitope of rabies glycoprotein

The potency of all modern tissue culture human rabies vaccines is measured based on the National Institute of Health (NIH) potency test that is laborious, time-consuming, involves large test variations and requires sacrifice of large number of animals. To circumvent these limitations, several researchers and WHO expert working groups have discussed development of alternative in vitro methods to replace the NIH potency test. Although several immunochemical methods have been proposed to quantify rabies glycoprotein (G-protein) using multiple murine monoclonal antibodies, we report an In vitro competitive inhibition ELISA (CIA) method based on the use of a neutralizing rabies glycoprotein site III directed novel therapeutic human rabies monoclonal antibody (RAB1) that shows equivalence to the mice NIH potency test in recognition of neutralization site of the glycoprotein. In vitro potency testing of WHO 7th International Standard for rabies vaccine (IS) by CIA using RAB1 and In-house reference standard (IHRS) as a standard to assess its suitability for the assessment of validation parameters showed accurate and precise values with <15% coefficient variance. The method was validated using 5PL standard curve with linearity r² > 0.98 and LLOQ of 0.125 IU/mL indicating sensitivity of the method. The method was found to be precise, robust and accurate to quantitate intact rabies glycoprotein in final vaccine and showed a strong correlation (Pearson's r = 0.81) with the NIH potency values of licensed Vero cell rabies vaccine. The CIA test using RAB1 was able to accurately quantitate degradation of rabies vaccine and assess loss in antigenicity of lyophilized and reconstituted liquid rabies vaccine under thermal stress conditions. The method was able to differentiate between potent and reduced potency vaccine samples. The new in vitro competitive inhibition ELISA method using RAB1 thus can be a valid alternative to the NIH test.

Evaluation of MTBDRsl for detecting resistance in Mycobacterium tuberculosis to second-line drugs

SETTING: Patients with presumed multidrug-resistant tuberculosis (MDR-TB) and undergoing MDR-TB treatment from Rajasthan, India.OBJECTIVE: To compare the GenoType^® MTBDRsl v.1.0 (MTBDRsl) assay capacity to detect resistance to ofloxacin, amikacin, capreomycin, kanamycin and ethambutol in Mycobacterium tuberculosis with phenotypic drug susceptibility testing (DST) using MGIT^™960™ in sputum samples and isolates.DESIGN: Fifty-three smear-positive sputum samples were tested directly by MTBDRsl and 205 MDR-TB isolates were processed using MTBDRsl and DST for five drugs on MGIT960. DNA sequencing was performed in isolates with discordance in the results between the two methods for the gyrA, gyrB and rrs genes.RESULT: Sensitivity and specificity of MTBDRsl was found to be respectively 93.1% and 100% for fluoroquinoline, respectively 75-78% and 100% for aminoglycosides/cyclopeptides, respectively 70% and 92% for ethambutol and respectively 92.3% and 100% for extensively drug-resistant (XDR) TB detection. On sequencing eight discordant isolates for quinolones, mutations were seen in 12.5% of the gyrB gene and among 20 discordant isolates for aminoglycosides/cyclopeptides in the rrs gene in 15% isolates. The turnaround time was 2 days for MTBDRsl vs. 10 days for MGIT960.CONCLUSIONS: MTBDRsl can be used as an initial rapid test for detecting XDR-TB, resistance to quinolones and aminogycosides/cyclopeptides in smear-positive sputum samples.

Occupational health hazards of trichloroethylene among workers in relation to altered mRNA expression of cell cycle regulating genes (p53, p21, bax and bcl-2) and PPARA

Trichloroethylene (TCE) is widely used as a metal degreaser in industrial processes. The present study reports on the effects of TCE exposure on workers employed in the lock industries. To ensure exposure of the workers to TCE, its toxic metabolites, trichloroacetic acid (TCA), dichloroacetic acid (DCA) and trichloroethanol (TCEOH) were detected in the plasma of the subjects through solid phase microextraction-gas chromatography-electron capture detection. TCA, DCA and TCEOH were detected in the range of 0.004–2.494 μg/mL, 0.01–3.612 μg/mL and 0.002–0.617 μg/mL, respectively. Quantitative reverse transcription polymerase chain reaction analysis revealed up-regulated expression of p53 (2.4-fold; p < 0.05), p21 (2-fold; p < 0.01), bax (2.9-fold; p < 0.01) mRNAs and down-regulated expression of bcl-2 (67%; p < 0.05) mRNAs, indicating DNA damaging potential of these metabolites. No effects were observed on the levels of p16 and c-myc mRNAs. Further, as TCA and DCA, the ligand of peroxisome proliferator activated receptor alpha (PPARA), are involved in the process of hepatocarcinogenesis in rodents, we examined expression of PPARA mRNA and let-7c miRNA in the workers. No statistically significant differences in expression of PPARA mRNA and let-7c miRNA in patients were observed as compared to values in controls. Dehydroepiandosterone sulfate (DHEAS) is a reported endogenous ligand of PPARA so its competitive role was also studied. We observed decreased levels of DHEAS hormone in the subjects. Hence, its involvement in mediation of the observed changes in the levels of various mRNAs analyzed in this study appears unlikely.

In vitro cytogenetic assessment of trichloroacetic acid in human peripheral blood lymphocytes

Trichloroacetic acid (TCA), a common water disinfection byproduct and a persistent metabolite of trichloroethylene (TCE), has been examined for its genotoxic potential in human lymphocytes. Chromosomal aberration (CA) and cytokinesis-block micronucleus (CBMN) assay were employed to assess the toxicity of TCA. Lymphocytes obtained from three healthy donors were exposed to 25, 50, and 100 μg/ml concentration of TCA separately. TCA exposure resulted in chromosomal anomalies and the formation of micronuclei in lymphocytes. Chromosome analysis revealed the dose-dependent and significant induction of CA. Chromatid break/chromosome break, fragments, and chromatid exchanges were commonly observed. Exposure of higher concentration (50 and 100 μg/ml) significantly inhibited mitotic index. Data obtained with CBMN assay indicated that the induction of micronucleus (MN) formation was greater than that of CA. At 25 μg/ml, TCA induced significant frequencies of MN as compared to control cells. Significant induction of MN at the lowest concentration indicates TCA may also interact with mitotic spindles. Lower percentage of CA and MN at 100 μg/ml as compared to 50 μg/ml indicates occurrence of severe cytotoxicity on exposure of 100 μg/ml TCA in lymphocytes. Collectively, results of both cytogenetic assays indicate that exposure of TCA can induce significant genotoxic and cytotoxic effects.

Antibody response to purified chick embryo cell vaccine in equines for production of equine rabies immune globulin

Rabies is endemic in India. The post exposure treatment of class three bite cases, as recommended by the World Health Organization, must involve the use of rabies immunoglobulin as soon as possible and up to the seventh day of start of anti rabies vaccination. The annual requirement in India as projected by the Ministry of Health, Government of India is about 1500 liters of purified anti rabies serum (ERIG). Central Research Institute (CRI), Kasauli, being the sole producer of ERIG in India, an effort was made to increase the production of ERIG by the use of tissue culture vaccine (Human) for primary immunization of equines. It also involved changing the vaccine from horse brain suspension to tissue culture vaccine by eliminating horse sacrifice for antigen preparation. A better immune response was obtained.

Application of the PCR technique for a rapid, specific and sensitive detection of Salmonella spp. in foods

We report here the use of a PCR based assay modified by us for the detection of Salmonella spp. in foods, based on amplification of a 236 bp Salmonella specific hin/H2 region [Way et al. (1993) Applied and Environmental Microbiology 59, 1473-1479], using Ampli Taq Gold polymerase. Using this assay we were able to detect all the Salmonella serovars tested. The limit of detection was 1 fg of purified target DNA or N x 10(0) (1-3 cells) cfu ml(-1) of pure bacterial culture. This assay could detect N x 10(0) cfu Salmonella cells g(-1) of the food sample unambiguously in presence of endogenous microflora following 6 h enrichment, thus requires a duration of approximately 10 h for the full processing from DNA template preparation, PCR and visualization of DNA product on agarose gel. The main advantage of this PCR detection method is its sensitivity, and specificity. We also tried to adopt DNA template isolation method simply by boiling the bacterial cells thereby reducing the possibility of contamination, cutting the processing time and cost considerably. This can be an added advantage for the use of this system in simple lab setups.

Critical Phenomena in the Clouding Behavior of Nonionic Surfactants Induced by Additives

Effects of anionic surfactants, hydrotropes, and electrolytes on the cloud point of Triton X-100 have been studied over six decades of additives concentrations. A comprehensive look at all the data reveals significant new learnings. While anionic surfactants and hydrotropes affect the cloud point of non-ionics at ultra low (monomeric) concentrations, electrolytes exhibit a minimum critical concentration above which they cast their effect. This suggests that the former work by modifying the surface charge of non-ionic micelles (i.e., by affecting the solute), whereas the latter work by modifying the properties of the bulk medium. Above their respective critical concentrations, salting-out electrolytes decrease the cloud point while salting-in electrolytes increase it, the trends being linear with additive concentration in either case. The magnitude of the effect of anionic surfactants and hydrotropes increases gradually with increasing concentration till their respective cmc's are reached and then there is a sharp rise in the cloud point. Copyright 1999 Academic Press.

Absolute Doubly Differential Cross Section for Bremsstrahlung Spectra Produced in 7.0 keV e<formula>^-</formula>--Ag and Au Collisions

The first experimental data are presented for the absolute doubly differential cross section (DDCS) for non-characteristics (bremsstrahlung) X-ray spectra produced by 7.0 keV electron bombardment of (semi-thick) targets of silver and gold at a photon detection angle of 90 degree. The bremsstrahlung spectra are corrected for detector's efficiency as well as for target effects; namely, electron energy loss, backscattering and photon-attenuation in the target. The DDCS values so obtained are compared with the predictions of a thin target bremsstrahlung theory. The agreement between experiment and theory for DDCS both in magnitude and shape is found to be satisfactory within the systematic experimental uncertainty of about 27%. penetrating electrons into the thick targets and the depth distribution of photons generated inside the targets are expected to be also present in the interaction. However, the contributions of these effects to the DDCS have not been taken into consideration. Various possible reasons for the existing discrepancy between experiment and theory are pointed out.

Trichloroethylene toxicity in mice: a biochemical, hematological and pathological assessment

Oral administration of trichloroethylene (TCE; 0, 500, 1000 and 2000 mg/kg/day) to male mice once daily, 5 days a week for a period of 28 days, caused a significant increase in liver weight, degeneration/necrosis of hepatocytes and characteristics proliferation of endothelial cells of hepatic sinusoids. Increase in kidney weight, glomerular nephrosis, degeneration/desquamation of tubular epithelium and characteristic amyloid deposition in glomeruli were observed only in the group of mice treated with 2000 mg/kg TCE. These changes occurred concurrently with a significant increase in total protein and free sulphydryl contents, elevated activities of acid phosphatase and catalase and decreased activity of delta-aminolevulinic acid dehydratase (delta-ALAD) indicating the sensitivity of liver and kidney as target tissues in TCE-toxicity. Hematological studies showed a significant increase in RBC counts and a reduction in WBC counts without any statistically significant change in the hemoglobin, urea nitrogen, creatinine and uric acid levels in the blood of TCE-exposed mice. A dose-related increase in cell density and acid phosphatase activity with a parallel significant decrease in the activity of delta-ALAD were observed in the bone marrow, which appear to be responsible for hematological alterations in TCE-exposed mice. The results suggest that early metabolic, pathological and hematological perturbations following a short-term exposure of TCE in mice, can provide the basis for its documented potential for chronic effects like blood dyscrasia and cancer.

Influence of trichloroethylene treatment on phosphoinositides in rat brain

The effect of oral administration of trichloroethylene, a neurotoxic solvent, on the levels of phosphoinositides in rat brain was studied. Two hours after administration of a single dose of trichloroethylene (1000 mg/kg body wt.), the levels of phosphatidylinositol (PI) and phosphatidylinositol 4,5-biphosphate (PIP2) were reduced by 24 and 17%, respectively, without any significant change in that of phosphatidylinositol-4-phosphate (PIP). Twenty hours after treatment, the levels of PI and PIP2 were increased by 22 and 38%, respectively. Repeated administration of the same dose of trichloroethylene for 1 year markedly reduced the levels of PI (52%), PIP (23%) and PIP2 (45%). These results for the first time suggest the involvement of a phosphoinositide messenger system in trichloroethylene neurotoxicity.

Hepatotoxic effects elicited by n-hexane or n-heptane

Hepatotoxic effects of n-hexane and n-heptane administered i.p. (1 ml/kg body wt) were studied in albino rats after 1, 2, 7 and 45 days of treatment. Hepatic protein content decreased with n-heptane and total sulphydryl content showed a significant decrease in the rats exposed to either solvent. A significant increase in lipid peroxidation was observed after 24 h and 48 h exposure to n-hexane or n-heptane. A marked decrease in drug metabolizing activity and an increase in pentabarbitone sleeping time was also observed. Hepatic glucose-6-phosphatase, a microsomal marker enzyme, showed a significant decrease.

Toxicity of n-hexane and 2,5-hexanediol to the haemopoietic system: a preliminary report

The effect of n-hexane and its metabolite, 2,5-hexanediol, on the haemopoietic system has been investigated in the rat. 59Fe uptake was decreased in the bone marrow of n-hexane-treated animals. Spleen and bone marrow were the target sites for the metabolite 2,5-hexanediol, whereas n-hexane as such does not affect these organs.

Peroxisome proliferation and lipid peroxidation in rat liver

Male F344 rats were fed a diet containing the peroxisome proliferators 2-[4-(2,2-dichlorocyclopropyl)phenoxy]-2-methylpropionic acid [ciprofibrate (0.025%)] or [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio]acetic acid [Wy-14643 (0.1%)] for up to 14 months to determine whether hepatic peroxisome proliferation caused by these agents results in the induction of membrane lipid peroxidation in the liver. Peroxidative damage of membrane lipids from whole liver, postnuclear, heavy-particle, microsomal, and nuclear membranes was evaluated by determining the extent of formation of conjugated dienes (ultraviolet absorption, 233 nm). Increased generation of diene conjugates was noted in whole-liver, postnuclear, and heavy-particle membrane lipids of rats fed peroxisome proliferators for 6 months or longer when compared to controls. An additional, more intense absorption profile in the ultraviolet absorption range of approximately 276 nm was noted in the membrane lipids derived from whole liver, postnuclear, and heavy particle pellets, but not in the nuclear and microsomal membrane lipids of livers with peroxisome proliferation. Although the exact chemical nature of this delta 276 nm peak is not clear, it is attributed to the formation of ketone dienes and/or conjugated trienes. The excess lipid peroxidation correlates with the previous observation of accumulation of abundant quantities of lipofuscin in hepatocytes of rats chronically exposed to peroxisome proliferators. The generation of conjugated dienes and ketone dienes and/or trienes together with increased levels of H2O2 generation by peroxisomal enzymes, and decreased levels of hepatic glutathione peroxidase, glutathione reductase, and glutathione-S-transferases, enzymes responsible for the defense against H2O2 damage, suggest the occurrence of membrane lipid peroxidation and oxidative stress in livers of rats treated with carcinogenic peroxisome proliferators.

Transcription regulation of peroxisomal fatty acyl-CoA oxidase and enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase in rat liver by peroxisome proliferators

The structurally diverse peroxisome proliferators ciprofibrate, clofibrate, and bis(2-ethylhexyl) phthalate [(EtHx)2 greater than Pht] increase the activities of hepatic catalase and peroxisomal fatty acid beta-oxidation enzymes in conjunction with profound proliferation of peroxisomes in hepatocytes. In order to delineate the level at which these enzymes are induced in the liver, the transcriptional activity of specific genes for fatty acyl-CoA oxidase (FAOxase) and enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase bifunctional enzyme (PBE), the first two enzymes of the peroxisomal beta-oxidation system, and for catalase were measured in isolated hepatocyte nuclei obtained from male rats following a single intragastric dose of ciprofibrate, clofibrate, or (EtHx)2 greater than Pht. All three peroxisome proliferators rapidly increased the rate of FAOxase and PBE gene transcription in liver, with near maximal rates (9-15 times control) reached by 1 hr and persisting until at least 16 hr after administration of the compound. FAOxase and PBE mRNA levels, measured by blot-hybridization analysis and FAOxase and PBE protein content, analyzed by immunoblotting, increased concurrently up to at least 16 hr following a single dose of peroxisome proliferator. The catalase mRNA level increased about 1.4-fold, but the transcription rate of the catalase gene was not significantly affected. The results show that the peroxisome proliferators clofibrate, ciprofibrate, and (EtHx)2 greater than Pht selectively increase the rate of transcription of peroxisomal fatty acid beta-oxidation enzyme genes. Whether the transcriptional effects are mediated by peroxisome proliferator-receptor complexes remains to be elucidated.

32P-postlabeling analysis of peroxisome proliferator-DNA adduct formation in rat liver in vivo and hepatocytes in vitro

Hepatocarcinogenic peroxisome proliferators, clofibrate, ciprofibrate, Wy-14643 or di(2-ethylhexyl)phthalate, were administered once daily by gavage to groups of three male F344 rats for 3 days and the rats were killed 2 h after the last dose. The DNA isolated from the livers was analyzed for possible carcinogen-DNA adducts, by a most sensitive 32P-postlabeling technique which can detect one adduct in 10(10) nucleotides. No adducts were detected by this assay in the DNA isolated from the livers of rats treated with any of the peroxisome proliferators. Adducts were also not found in the DNA of hepatocytes exposed in vitro to these peroxisome proliferators for 4 h in primary suspension cultures. Failure to detect peroxisome proliferator DNA adducts in hepatocytes under in vivo and in vitro conditions supports the contention that formation of a peroxisome proliferator-DNA adduct is not an essential step in the carcinogenesis by this novel class of carcinogens.

Lack of covalent binding of peroxisome proliferators nafenopin and Wy-14 643 to DNA in vivo and in vitro

[3H][2-methyl-2-p-(1,2,3,4-tetrahydro-naphthyl)phenoxy] propionic acid (nafenopin), a hepatocarcinogenic peroxisome proliferator, when administered p.o. to normal intact and partially hepatectomized male F344 rats did not show any significant binding to DNA and RNA, but bound to proteins. The in vitro incubation of [3H]nafenopin and [3H]4-chloro-[6-(2,3-xylidino)pyrimidinylthio]acetic acid (Wy-14643), another peroxisome proliferator, with hepatic microsomes and calf thymus DNA also showed no significant binding of these chemicals to DNA.

DNA damage related to increased hydrogen peroxide generation by hypolipidemic drug-induced liver peroxisomes

Several hypolipidemic drugs and certain industrial plasticizers induce proliferation of peroxisomes, enhance the activity of peroxisome-associated beta-oxidation of fatty acids, and produce hepatocellular carcinomas in the livers of rodents. Because these chemicals themselves are not mutagens and do not covalently modify DNA, unlike the majority of chemical carcinogens, we proposed that the persistent proliferation of peroxisomes, and the induction of associated peroxisomal oxidases, caused a sustained increase in intracellular H2O2 or other reduced oxygen species, which would then introduce mutagenic DNA damage. In the present study, we investigated the ability of peroxisomes purified from the livers of normal and hypolipidemic drug-treated rats to induce DNA strand scission in vitro. Gradient-purified peroxisomes from livers of hypolipidemic drug-treated rats produced a 30- to 70-fold increase in H2O2 generation when compared to controls. The levels of H2O2 generated in incubations containing control or hypolipidemic drug-induced peroxisomes correlated well with the induction of single strand breaks in supercoiled simian virus 40 DNA molecules that were included in these reconstituted peroxisome incubations. Addition of excess catalase to peroxisome incubations failed to prevent strand breaks, suggesting that other reduced oxygen species may be rapidly generated from H2O2. These experimental results are consistent with a mechanism of hepatocarcinogenesis in which hepatocellular genetic damage is introduced by the by-products of peroxisomal fatty acid beta-oxidation, an oxidative pathway that is dramatically increased in hypolipidemic drug-treated livers.

Subcutaneous kerosene toxicity in albino rats

Biochemical, histopathological, and hematological parameters were studied in male Wistar rats after repeated subcutaneous administration of commercial kerosene (0.5 ml/kg body wt, 6 days a week) for a period of 35 days. At necropsy, treatment-related increases in the weights of liver, spleen, and peripheral lymph nodes were noted. Correspondingly, there was an increase in DNA, RNA, protein, and lipid contents of liver and spleen. Histopathological examination of liver, spleen, thymus, kidney, adrenal, and lymph nodes revealed treatment-related lesions. Similarly, biochemical indices studied in liver revealed an increase in alkaline phosphatase and a decrease in benzo[a]pyrene hydroxylase levels. Furthermore serum cholinesterase, carboxylesterase, and albumin levels were significantly diminished while serum alkaline phosphatase levels were found to be greatly enhanced. The findings might be related as the likely systemic effects in workers upon percutaneous kerosene exposure during work.

Irreversible inhibition of hepatic glutathione S-transferase by ciprofibrate, a peroxisome proliferator

Ciprofibrate (2-[4-(2,2-dichlorocyclopropyl) phenoxy]2-methyl propionic acid) which is a hypolipidemic agent and has been shown to cause peroxisome proliferation, non-competitively inhibits glutathione S-transferase activity of rat liver, both in vivo and in vitro. Among all the glutathione S-transferases of rat liver, ligandin is maximally inhibited by ciprofibrate. Studies with the purified glutathione S-transferases of rat liver indicate that the affinities of different subunits of liver enzymes for ciprofibrate are in the order Ya greater than Yb, Yb' greater than Yc.

Toxicity of n-hexane and n-heptane: some biochemical changes in liver and serum

The toxic effects of i.p. administered n-hexane and n-heptane on biochemical processes in rat liver, as indicated by the increase in alkaline phosphatase activity and decrease in FDP aldolase activity, and their reflection on blood chemistry, were studied. Serum cholinesterase activity and albumin and cholesterol content showed statistically significant decreases with the increase in FDP aldolase activity. The significance of the findings is discussed.

Estimation of temperature and fraction of superthermal electrons in laser-produced plasmas

A simple method for the estimation of temperature and fraction of superthermal electrons in laser-produced plasmas is discussed.