Serum DHEA-S levels could be used as a comparable diagnostic test to assess the pubertal growth spurt in dentofacial orthopedics

Background

Pubertal growth spurt assessment guides the timing of intervention for correcting the skeletal discrepancies in dentofacial orthopedics. Serum hormones are being studied for the skeletal age assessment to avoid unnecessary radiographic exposure. The present study is to evaluate the relationship of serum hormones dehydroepiandrosterone-sulfate (DHEA-S), insulin-like growth factor (IGF-1), and cervical vertebral stages (CS stages) in the skeletal age assessment of orthodontics patients around the circumpubertal age.

Methods

A total of ninety subjects with age ranging from 7 to 21 years were selected and divided into two groups based on the sex (45 males, 45 females). They were further distributed in each group based on the six CS stages determined from the lateral cephalogram. Blood samples from each subject were collected to evaluate the serum DHEA-S and IGF-1 levels by using the enzyme-linked immunosorbent assay (ELISA). Collected data were analyzed in SPSS software with a test of normalcy, unpaired t test, and one-way analysis of variance (ANOVA) followed by the least significant difference (LSD) post hoc comparison test and univariate regression analysis.

Results

The highest mean serum hormone levels were found in CS 4 in group A (male) and CS 3 in group B (female). ANOVA results showed that there was a significant difference in the serum hormone levels among the different CS stages in both the groups for both the hormones. Statistically, a significant difference was found between each CS stages for both the hormones except in the DHEA-S levels between CS 5 and CS 6.

Conclusions

The mean serum DHEA-S levels followed a typical pattern from the CS 1 till CS 6 which was comparable and similar to the mean serum IGF-1 levels in respect to CS stages. Thus, serum DHEA-S levels could be used as a possible diagnostic test for the assessment of the skeletal pubertal growth spurt in dentofacial orthopedics.

Combinatorial effect of curcumin and tumor necrosis factor-α-related apoptosis-inducing ligand (TRAIL) in induction of apoptosis via inhibition of nuclear factor kappa activity and enhancement of caspase-3 activity in chronic myeloid cells: An In-vitro study

Background

Nuclear factor kappa B (NFkB-light-chain-enhancer of activated B-cells) expression and its regulation is a key role in the development of number of malignancies, as NFkB mediates the balance between cell death and its survival. Therefore, NFkB regulation constitutes an attractive target to overcome the resistance to chemotherapeutic agents in anticancer therapy. Curcumin, as a chemopreventive agent, has a potential role in inhibiting cell growth in a variety of malignancies. Thus, this study was aimed to investigate the efficacy of curcumin along with tumor necrosis factor-α-related apoptosis-inducing ligand (TRAIL) in KCL-22 myeloid cells along with an investigation of the mechanism by which both the agents exert their effects.

Materials and Methods

KCL-22 cells were exposed to different doses of curcumin and TRAIL alone and in combination. Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, caspase activity by fluorescent method, protein expression by western Blot, and NFkB activity by electrophoretic mobility shift assays, respectively.

Results

Cell viability assay revealed that when both the agents, curcumin and TRAIL, were used together, there was reduced cell viability in dose- and time-dependent manner as compared to each agent alone. Curcumin and TRAIL enhanced the caspase-3 activity as compared to caspase-8 and caspase-9. Both the agents induced apoptosis in KCL-22 cells by suppressing the IκB kinase and NFkB activity.

Conclusion

Our results conclude that curcumin and TRAIL effectively induce the apoptosis through the inhibition of NFkB activity and by enhancing the caspase-3 activity. Thus, curcumin may prove as a potent inhibitor of NFkB by representing its role in cancer pathogenesis, especially in chronic myeloid leukemia cells.

Assessment of liver function in pregnant anemic women upon oral iron and folic acid supplementation

Oral iron therapy is the most widely prescribed treatment for iron deficiency anemia. However, oral iron supplementation may also lead to various health problems. The recognition of these physiological variations is essential for the diagnosis of liver diseases during the course of pregnancy. Therefore, the objective of this study was to assess the variations in levels of routine liver function tests (LFTs) in pregnant women before and after iron and folic acid treatment. Iron and folic acid was supplemented to 500 normal pregnant anemic women (mild=200, moderate=200 and severe=100) and 100 age matched normal pregnant non-anemic as controls daily for 100 days. Blood index values and liver function parameters were precisely monitored. Hemoglobin (Hb), total protein (TP), iron (Fe), albumin and alkaline phosphatase (ALP) levels were found increased (P<0.001; P<0.01; P<0.05) after treatment in mild, moderate, severe and control, respectively. Lipid peroxidation (LPx), aspartate transaminase (AST) and alanine transaminase (ALT) were increased in pretreated mild, moderate and severe groups and further increased after all treated subjects. Moreover, gamma-glutamyl transpeptidase (GGT) was found to decrease in pre and posttreated subjects. Treatment with iron and folic acid although has remarkable efficacy for Hb and body iron stores although for the cost of increasing the associated compartment of total bilirubin, AST and ALT concomitant with decreased GGT levels. Data obtained from the present study provide new insights into the mandatory application of liver function tests likely to be monitored at regular and specific intervals during the course of pregnancy.

Leptin as a Predictive Marker in Unexplained Infertility in North Indian Population

INTRODUCTION

According to WHO, the primary infertility in India is about 3.9% (age-standardized to 25-49 year) and 16.8% (age-standardized to 15-49 year), using the "age but no birth" definition. Several factors which affect fertility include low sperm production in men, poor egg quality and blocked fallopian tubes in women and also hormonal imbalances. Leptin plays a critical role in women's reproduction and neuroendocrine health. It is used for treating exercise-induced bone loss, eating disorders and infertility.

AIM

To evaluate the serum leptin levels in Indians and to ascertain the relationship between serum leptin levels, Unexplained Infertility (UI) and related variables [height, weight, Waist Hip Ratio (WHR), Body Mass Index (BMI)] between obese infertile, non-obese infertile and healthy subjects.

MATERIALS AND METHODS

The present case-control study was conducted at the Department of Obstetrics and Gynaecology, King George's Medical University (KGMU), Lucknow, India and funded by Department of Science and Technology, New Delhi, India. The study included 229 female participants in the age group of 18-40 years (120 cases and 109 controls) who were randomly selected. The blood samples were collected from the Infertility Clinic, Queen Mary's Hospital, KGMU, Lucknow, India. All the participants underwent complete physical examination. Initially, the participants were categorized into fertile and infertile groups, they were further divided on the basis of BMI, normal (BMI- 18.5-24.5) and overweight or obese (BMI≥25). Leptin level was measured by Active Human Leptin ELISA kit and BMI of all subjects was calculated in kg/m² (weight in kg and height in m).

RESULTS

A highly positive linear correlation (R=0.754, p<0.001) was found between BMI and serum leptin in unexplained infertile women, which indicates a strong relationship between BMI and serum leptin. The variation in serum leptin is explained by the independent variable, BMI. There was a partial positive linear correlation between BMI and serum leptin in the control group. Statistically there was no significant correlation (R=0.109, p=0.258) between BMI and serum leptin in the control group.

CONCLUSION

The present study clearly demonstrates that level of leptin is higher in unexplained infertile than in the fertile group, and also shows that a strong relationship exists between BMI and serum leptin in the obese group. Serum leptin level was significantly higher in obese than non-obese subjects. Thus, leptin is an important factor for normal reproductive function. Obesity, the main cause of infertility may be controlled by regulating the leptin concentration.

Oxidative stress and antioxidative parameters in patients with spinal cord injury: implications in the pathogenesis of disease

STUDY DESIGN

Oxygen-derived free radicals have been implicated in the pathogenesis of spinal cord injury (SCI) after trauma.

OBJECTIVE

In this review we will elucidate the importance of oxidative stress and antioxidants and its possible relationship with SCI.

METHODS

Literature analysis of oxidative stress, antioxidative parameters based on its implications in the pathogenesis along with devastating effect of oxidative stress parameters on SCI patients and its suggested proposed treatment by antioxidants have been performed.

RESULTS

SCI remains a major health problem despite advances in neurotechnology. Previous studies have reported oxidative stress in SCI patients, but the results were inconsistent. Furthermore, increased free radical levels are reported in SCI. Moreover, we have also mentioned in this review that oxidative stress is supposed to be increased in patients with SCI, which is related to the severity of SCI pain.

CONCLUSION

Oxidative stress was commonly seen in SCI patients, which may provide useful information to augment the understanding of pathophysiology of SCI patients. However, complete understanding of the biochemical events occurring at a cellular level that influence oxidative damage is required to guide future therapeutic advances. Furthermore, supplementation of antioxidants may also be considered in these patients.

Biochemical alteration of hepatic functions by histamine H3-receptor agonist and antagonist in immunized rabbits

AIM

The aim of our study was to investigate the functional roles of H3R agonist and antagonist in the development of hepatic functions impairment in immunized rabbits.

METHODS

The study comprised of six groups containing 18 rabbits in each. Group-I (negative control) and group-II (positive control) received sterile distilled water intramuscularly while Group III-VI received histamine (100 µgkg-1, s.c.), R-[-]-α-methylhistamine (H3R-agonist, 10 µgkg-1, s.c.), iodophenpropit (H3R-antagonist, 1 µgkg-1, i.m.), and the combination of iodophenpropit (1 µgkg-1, i.m.) plus histamine (100 µgkg-1, s.c.), respectively, b.i.d. (12 hours [8 am and 8 pm]) for 10 days. Groups II-VI were immunized on day 3 with intravenous injection of sheep red blood cells (1×109 cells/ml).

RESULTS

On each experimental day, the mean values of serum enzymes and bilirubin in group-I and group-II showed no changes while in groups III, IV, V, and VI, these enzymes and bilirubin levels showed significant changes (p<0.05), when compared with their values within the group. Profile of ALT and AST production revealed that ALT and AST levels moderately were changed due to degeneration of the liver.

CONCLUSION

Our results suggest that R-[-]-α-methylhistamine showed moderate, and histamine and iodophenpropit showed mild degeneration of liver functions; while iodophenpropit plus histamine showed hepatic functions similar to control group. This study suggests that H3R antagonist in combination with histamine may be a non-toxic therapeutic target for histamine research (Fig. 7, Ref. 28). Text in PDF www.elis.sk.

NMR-based metabonomics study of sub-acute hepatotoxicity induced by silica nanoparticles in rats after intranasal exposure

Silica nanoparticles (SiO(2) NPs) are widely used commercially; however, their potential toxicity on human health has attracted particular attention. In the present study, the intranasal toxicological effect of 10nm and 80nm SiO(2) NPs (dosed at 150μg for 90 days) on rats was investigated using conventional approaches and metabonomics analysis of serum. Oxidative stress was measured by assessing Lipid peroxide (LPO) levels and enzymatic activities of Superoxide dismutase (SOD), Catalase (CAT), and Glutathione (GSH) levels in liver tissue homogenate. These biochemical observations were supplemented by histological examination of liver sections. SiO(2) NPs enhanced lipid peroxidation with concomitant reduction in SOD, CAT, and GSH content. In addition, SiO(2) NPs also produced alterations in hepatic histopathology. We also evaluated the effect of SiO(2) NPs on the activities of hepatic enzymes such as aminotransferases (ALT/AST) and alkaline phosphatase (ALP) which revealed significant increase in their activity when compared with control. Metabonomic profile of 90 days SiO(2) NPs treated rat sera exhibited significant increase in lactate, alanine, acetate, creatine and choline coupled with a considerable decrease in glucose level. These perturbations, on the whole, implicate impairment in tricarboxylic acid cycle and liver metabolism, which suggests that silica nanoparticles may have a potential to induce hepatotoxicity in rats.

Assessment of association of exposure to polycyclic aromatic hydrocarbons with bronchial asthma and oxidative stress in children: A case control study

Background:

Polycyclic aromatic hydrocarbons (PAH) originate from the incomplete combustion of organic matter and ambient air pollution by these is increasing. There is also an increase in the global prevalence of asthma, for which environmental pollution has been recognized as one of the important factors. Exposure to pollutants and other allergens induces chronic airway inflammation by generation of reactive oxygen species, causing oxidative stress. Therefore, the objective of the present study was to assess association, if any, between exposure to PAH and asthma as well as oxidative stress in children.

Method:

In this hospital-based case control study, cases of bronchial asthma aged 1–14 years and healthy matched controls were included. Oxidative stress was measured by assessing the levels of enzymes catalase, superoxide dismutase, malondialdehyde (MDA), and reduced glutathione (GSH).

Results:

Forty-two cases and 20 controls were enrolled. Mean blood level of phenanthrene, a PAH, was 63.11 ppb ± 115.62 and 4.20 ppb ± 10.68 ppb in cases and controls, respectively (P = 0.02). Mean blood levels of GSH was significantly lower in cases and controls (27.39 μg/ml ± 11.09 versus 47.39 g/ml ± 13.83; P-value = 0.001). Likewise, mean blood level of MDA in nanomole/ml was significantly higher in asthma as compared with controls (12.85 ± 5.40 versus 8.19 ± 5.16; P-value = 0.002), suggestive of increased oxidative stress.

Conclusions:

Because elevated blood level of phenanthrene is associated with bronchial asthma as well as with oxidative stress, measures to reduce exposure to PAH may possibly lead to reduced incidence and severity of bronchial asthma.

Protective potential of Bacopa monniera (Brahmi) extract on aluminum induced cerebellar toxicity and associated neuromuscular status in aged rats

The present study attempts to assess the comparative effects of Bacopa monniera, (40 mg/kg body weight) and donepezil (2.5 mg/kg b. wt) on aluminum (100 mg / kg b. wt. of AlCl3) mediated oxidative damage in the cerebellum of aged rats (24 months) along with the associated dysfunctioning of neuromuscular coordination and motor activity. A significant decrease in the activities of antioxidant enzymes and increased total reacting oxygen species, lipid and protein peroxidation products observed in aluminum exposed rats. We observed that treatment with B. monniera extract restored the altered antioxidant enzyme activities more, when compared with donepezil. However, acetylcholinesterase showed similar effect both in donepezil and B. monniera treated groups. The content of aluminum was increased in all experimental groups, however, iron content was found increased in all groups except the B. monniera treated groups. Moreover, aluminum treated groups of rats exhibited significant changes in behavioral profiles but these changes were in both B. monniera and donepezil treated groups. The light microscopic and ultrastructural studies revealed damaged Purkinje's neurons and altered granular cell layer along with the increased accumulation of lipofuscin granules in aluminum treated animals. These changes were quite less pronounced in B. monniera group than that of donepezil and this may be due to the reduction of excess iron content by B. monniera. On the basis of our results it may be concluded that Al may be linked with cerebellar degeneration and neuromuscular disorders while Bacopa monniera extract helps in reversing these changes.

1H NMR spectroscopy in the diagnosis of Klebsiella pneumoniae-induced urinary tract infection

The (1)H NMR spectroscopic method is suggested and its utility is demonstrated for the diagnosis of Klebsiella pneumoniae (K. pneumoniae) in urinary tract infection (UTI). K. pneumoniae have the specific property of metabolizing glycerol to 1,3-propanediol (1,3-PD), acetate, ethanol and succinate. The quantity of 1,3-PD produced correlates well with the viable bacterial count. Other common bacteria causing UTI (except for Citrobacter frundii), such as Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), Enterobacter aerogenes, Acinetobacter baumanii, Proteus mirabilis, Enterococcus faecalis, Streptococcus gp B and Staphylococcus aureus do not metabolize glycerol under similar conditions. Citrobacter frundii (C. frundii) also gives the same NMR results but is easily differentiated as being motile on direct microscopic examination of urine and it is not common nosocomial infectious agent in urinary tract infection. The method provides a single-step documentation of K. pneumoniae (and C. frundii) qualitatively as well as quantitatively. Out of the total 614 subjects considered, clinical diagnosis of UTI was obtained in 516 cases (84%). The NMR-based screening had a sensitivity of 90%, a specificity of 100% and a false negativity of 10% relative to the conventional quantitative culture method. In the present authors' experience, the results of NMR spectroscopy based screening show a very good correlation with the diagnosis of urinary tract infected patients.

(1)H NMR spectroscopy in the diagnosis of Pseudomonas aeruginosa-induced urinary tract infection

The utility of (1)H NMR spectroscopy is suggested and demonstrated for the diagnosis of Pseudomonas aeruginosa in urinary tract infection (UTI). The specific property of P. aeruginosa of metabolizing nicotinic acid to 6-hydroxynicotinic acid (6-OHNA) is exploited. The quantity of 6-OHNA produced correlates well with the viable bacterial count. Other common bacteria causing UTI such as Escherichia coli, Klebsiella pneumonia, Enterobacter aerogenes, Acinetobacter baumanii, Proteus mirabilis, Citrobacter frundii, Enterococcus faecalis, Streptococcus gp B and Staphylococcus aureus do not metabolize nicotinic acid under similar conditions. The method provides a single-step documentation of P. aeruginosa qualitatively as well as quantitatively. The NMR method is demonstrated on urine samples from 30 patients with UTI caused by P. aeruginosa.

Crystallization of E. coli RuvA gives insights into the symmetry of a Holliday junction/protein complex

The E. coli protein RuvA (resistance to ultraviolet light) has been overexpressed in E. coli, purified and crystallized using the hanging-drop vapour-diffusion method with sodium chloride as the precipitant. The crystals, which diffract to beyond 1.9 A, belong to the tetragonal system, space group P4 with unit-cell dimensions of a = 83.7, c = 33.1 A with a monomer in the asymmetric unit. RuvA is known to be a tetramer and thus the crystal symmetry implies that its quaternary structure will be based on fourfold rotation symmetry rather than 222 symmetry. This is consistent with electron microscopy data on Holliday junction DNA complexes and implies that the arms of the four DNA duplexes involved in recombination adopt fourfold rotation symmetry.

Circadian periodicity of plasma lipid peroxides and other anti-oxidants as putative markers in gynecological malignancies

BACKGROUND

The chronome (from chronos, time, and nomos, rule), or time structure, of lipid peroxidation and anti-oxidant defense mechanisms may relate to prevention and curative chronochemotherapeutic efficacy and management.

PATIENTS AND METHODS

Newly diagnosed women with gynecological malignancies (N = 30), 30-60 years of age, and age-matched clinically healthy women (N = 35) provided blood samples every 6 hours for 24 hours under standardized conditions. Plasma malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) activities, and serum ascorbate, urate and high-density lipoprotein cholesterol (HDL-C) concentrations were determined.

RESULTS

Each variable underwent circadian variation (p < or = 0.002). Patients differed from controls by their overall chronome-adjusted mean value (MESOR) and by the circadian dynamics in the spectral element of their chronome.

CONCLUSION

Chronomes of putative anti- and pro-oxidants should be mapped to explore their putative chemotherapeutic role as markers in cancer chronoprevention and management of established disease.

Characterisation of the catalytically active form of RecG helicase

Replication of DNA is fraught with difficulty and chromosomes contain many lesions which may block movement of the replicative machinery. However, several mechanisms to overcome such problems are beginning to emerge from studies with Escherichia coli. An important enzyme in one or more of these mechanisms is the RecG helicase, which may target stalled replication forks to generate a four-stranded (Holliday) junction, thus facilitating repair and/or bypass of the original lesion. To begin to understand how RecG might catalyse regression of fork structures, we have analysed what the catalytically active form of the enzyme may be. We have found that RecG exists as a monomer in solution as measured by gel filtration but when bound to junction DNA the enzyme forms two distinct protein-DNA complexes that contain one and two protein molecules. However, mutant inhibition studies failed to provide any evidence that RecG acts as a multimer in vitro. Additionally, there was no evidence for cooperativity in the junction DNA-stimulated hydrolysis of ATP. These data suggest that RecG functions as a monomer to unwind junction DNA, which supports an 'inchworm' rather than an 'active rolling' mechanism of DNA unwinding. The observed in vivo inhibition of wild-type RecG by mutant forms of the enzyme was attributed to occlusion of the DNA target and correlates with the very low abundance of replication forks within an E.COLI: cell, even during rapid growth.

Circadian periodicity of urinary volume, creatinine and 5-hydroxyindole acetic acid excretion in healthy Indians

The circadian periodicity of urinary output, creatinine (Cr) and 5-hydroxyindole acetic acid (5-HIAA) excretion was studied under near-tropical conditions in 130 healthy volunteers (65 men and 65 women, 16-75 years of age) with a diurnal activity from about 06:30 to about 22:00 and nocturnal rest. These volunteers were divided into 4 groups, 16-30, 31-45, 46-60 and 61-75 years of age, comprising 20, 20, 15 and 10 participants of each gender, respectively. A marked circadian rhythm was recorded for urine volume, Cr and 5-HIAA excretion in healthy Indians of different ages. The acrophase tended to be delayed in the older age group. The relative amplitude decreased with advancing age, notably in women. Overall, men produced a larger urine volume as compared to women. Excretions of Cr and 5-HIAA in healthy Indian volunteers of different ages may be influenced by diet, societal relations, climate and/or geographic location. The contribution of such factors in metabolism and degradation warrants further study.

Studies on circadian periodicity of urinary corticoids in carcinoma of the breast

The circadian periodicity of urinary 17-ketogenic steroids (17-KGS), 17-ketosteroids (17-KS) and creatinine (Cr) was studied preoperatively and on the 9th postoperative day in 25 histopathologically proved breast cancer patients and in 15 healthy Indian women under tropical conditions. A statistically significant rhythm was observed in healthy participants for all three variables. Urinary corticoids were markedly elevated in breast cancer patients irrespective of the stage of the disease in comparison with healthy controls. The degree of elevation was more pronounced preoperatively in advanced stage breast cancer in comparison with other groups. After mastectomy, the values of all three variables declined markedly, approaching usual values with a circadian rhythm resembling the pattern found in clinical health.

DNA binding and helicase domains of the Escherichia coli recombination protein RecG

The Escherichia coli RecG protein is a unique junction-specific helicase involved in DNA repair and recombination. The C-terminus of RecG contains motifs conserved throughout a wide range of DNA and RNA helicases and it is thought that this C-terminal half of RecG contains the helicase active site. However, the regions of RecG which confer junction DNA specificity are unknown. To begin to assign structure-function relationships within RecG, a series of N- and C-terminal deletions have been engineered into the protein, together with an N-terminal histidine tag fusion peptide for purification purposes. Junction DNA binding, unwinding and ATP hydrolysis were disrupted by mutagenesis of the N-terminus. In contrast, C-terminal deletions moderately reduced junction DNA binding but almost abolished unwinding. These data suggest that the C-terminus does contain the helicase active site whereas the N-terminus confers junction DNA specificity.

The RecG branch migration protein of Escherichia coli dissociates R-loops

The RuvAB and RecG proteins of Escherichia coli promote branch migration of Holliday junction intermediates in genetic recombination. Both are structure-specific helicases that unwind and rewind DNA at the junction point. The helicase activities of these proteins were investigated using RNA:DNA hybrid molecules. RuvAB catalyses the unwinding of RNA:DNA partial duplexes of at least 218 bp in a reaction that requires both RuvA and RuvB, ATP and Mg2+. RecG failed to unwind these substrates even when the duplex region was reduced to 35 bp. In contrast, RecG rapidly removes a 218 nt RNA from an R-loop substrate, whereas RuvAB does not. RecG's ability to dissociate R-loops is correlated with an ability to reduce the copy number of pUC plasmids and other constructs based on the ColE1 replicon. Copy number is reduced severely when the plasmid carries recG+. RecG is assumed to reduce copy number by interfering with RNA II's ability to form an R-loop at the plasmid origin of replication and prime DNA synthesis. The dissociation of R-loops by RecG is discussed in terms of the functions needed to promote recombination and to prime DNA replication at D-loops formed during the early stages of RecA-mediated recombination.

Modulation of recombination and DNA repair by the RecG and PriA helicases of Escherichia coli K-12

The RecG protein of Escherichia coli is a structure-specific DNA helicase that targets strand exchange intermediates in genetic recombination and drives their branch migration along the DNA. Strains carrying null mutations in recG show reduced recombination and DNA repair. Suppressors of this phenotype, called srgA, were located close to metB and shown to be alleles of priA. Suppression depends on the RecA, RecBCD, RecF, RuvAB, and RuvC recombination proteins. Nine srgA mutations were sequenced and shown to specify mutant PriA proteins with single amino acid substitutions located in or close to one of the conserved helicase motifs. The mutant proteins retain the ability to catalyze primosome assembly, as judged by the viability of recG srgA and srgA strains and their ability to support replication of plasmids based on the ColE1 replicon. Multicopy priA+ plasmids increase substantially the recombination- and repair-deficient phenotype of recG strains and confer similar phenotypes on recG srgA double mutants but not on ruvAB or wild-type strains. The multicopy effect is eliminated by K230R, C446G, and C477G substitutions in PriA. It is concluded that the 3'-5' DNA helicase/translocase activity of PriA inhibits recombination and that this effect is normally countered by RecG.

Crystal structure of DNA recombination protein RuvA and a model for its binding to the Holliday junction

The Escherichia coli DNA binding protein RuvA acts in concert with the helicase RuvB to drive branch migration of Holliday intermediates during recombination and DNA repair. The atomic structure of RuvA was determined at a resolution of 1.9 angstroms. Four monomers of RuvA are related by fourfold symmetry in a manner reminiscent of a four-petaled flower. The four DNA duplex arms of a Holliday junction can be modeled in a square planar configuration and docked into grooves on the concave surface of the protein around a central pin that may facilitate strand separation during the migration reaction. The model presented reveals how a RuvAB-junction complex may also accommodate the resolvase RuvC.

Holliday junction resolvases encoded by homologous rusA genes in Escherichia coli K-12 and phage 82

The RusA protein of Escherichia coli is an endonuclease that can resolve Holliday intermediates and correct the defects in genetic recombination and DNA repair associated with inactivation of RuvAB or RuvC. The structure of the rusA gene, its organisation in the genome, and its interaction with the Ruv and RecG proteins have been investigated. Recombinant plasmids carrying rusA were identified by their ability to make ruv mutants resistant to UV light. The gene was located to an open reading frame encoding a polypeptide of 120 amino acids. It forms the fifth gene in an operon containing a chain of short, interlinked open reading frames. A similar arrangement was found in the genome of the lambdoid bacteriophage, 82. The two rusA genes show 95% sequence identity. The E. coli operon forms part of the defective lambdoid prophage, DLP12, and is probably derived from a phage related to 82 and PA-2. rusA appears to be very poorly expressed in E. coli, but can be activated by insertion of IS2 or IS10 upstream of the coding sequence to promote transcription. These insertions arise spontaneously in ruv strains as suppressors of the mutant phenotype. Deletion of rusA from the chromosome of either wild-type or ruv mutant strains has no obvious effect on recombination or sensitivity to UV light. Multicopy plasmids expressing RusA alone make ruvA, ruvB, and ruvC mutants resistant to UV light. Suppression depends critically on RecG.

Studies on circadian periodicity of plasma 17-hydroxycorticosteroids (17-OHCS) in carcinoma of the breast

Circadian periodicity of plasma 17-hydroxycorticosteroids (17-OHCS) was studied in 25 histopathologically proved breast cancer patients pre operatively and on the 9th postoperative day and in 15 healthy women under tropical conditions. A marked rhythm in plasma 17-OHCS concentration was noticed in healthy controls. The maximal concentration occurred at 06:00 followed by a consistent decline throughout the daytime, reaching a minimum at 00:00 with an amplitude statistically significantly different from zero and an acrophase around 08:56. The plasma 17-OHCS concentration was found to be elevated at all sampling hours in breast cancer patients, irrespective of the stage of the disease. However, the degree of elevation and disruption of rhythm was more pronounced in advanced sages, preoperatively, in comparison to other groups. Moreover, the values declined markedly at all collection hours after mastectomy, approaching usual values and rhythm characteristics on the 9th postoperative day.

Processing of intermediates in recombination and DNA repair: identification of a new endonuclease that specifically cleaves Holliday junctions

The formation and subsequent resolution of Holliday junctions are critical stages in recombination. We describe a new Escherichia coli endonuclease that resolves Holliday intermediates by junction cleavage. The 14 kDa Rus protein binds DNA containing a synthetic four-way junction (X-DNA) and introduces symmetrical cuts in two strands to give nicked duplex products. Rus also processes Holliday intermediates made by RecA into products that are characteristic of junction resolution. The cleavage activity on X-DNA is remarkably similar to that of RuvC. Both proteins preferentially cut the same two strands at the same location. Increased expression of Rus suppresses the DNA repair and recombination defects of ruvA, ruvB and ruvC mutants. We conclude that all ruv strains are defective in junction cleavage, and discuss pathways for Holliday junction resolution by RuvAB, RuvC, RecG and Rus.

Resolution of Holliday intermediates in recombination and DNA repair: indirect suppression of ruvA, ruvB, and ruvC mutations

The ruvA, ruvB, and ruvC genes of Escherichia coli provide activities that catalyze branch migration and resolution of Holliday junction intermediates in recombination. Mutation of any one of these genes interferes with recombination and reduces the ability of the cell to repair damage to DNA. A suppressor of ruv mutations was identified on the basis of its ability to restore resistance to mitomycin and UV light and to allow normal levels of recombination in a recBC sbcBC strain carrying a Tn10 insertion in ruvA. The mutation responsible was located at 12.5 min on the genetic map and defines a new locus which has been designated rus. The rus suppressor works just as well in recBC sbcA and rec+ sbc+ backgrounds and is not allele specific. Mutations in ruvB and ruvC are suppressed to an intermediate level, except when ruvA is also inactive, in which case suppression is complete. In all cases, suppression depends on RecG protein, a DNA-dependent ATPase that catalyzes branch migration of Holliday junctions. The rus mutation activates an additional factor that probably works with RecG to process Holliday junction intermediates independently of the RuvAB and RuvC proteins. The possibility that this additional factor is a junction-specific resolvase is discussed.

Circadian periodicity of urinary inhibitor of calcium oxalate crystallization in healthy Indians and renal stone formers

The inhibitory activity (IA) of calcium oxalate crystallization was investigated in healthy Indians and renal stone formers. A marked circadian rhythm was observed in men and women of both groups. The rhythm pattern was similar on the basis of sex; however, it was different in stone formers as compared to normals. The acrophase for crystallization of calcium oxalate was observed, respectively, at 05.43 and 05.52 h in healthy men and women, and at 09.52 and 09.23 h in male and female renal stone formers. Moreover, the acrophase of percent inhibition by IA was observed at 17.44 and 17.52 h in healthy participants and at 21.52 and 21.27 h in male and female stone formers, respectively. Therefore, the acrophase suggests a highest risk of crystallization during the morning hours and a minimum one during the evening hours. The day-night rhythmic pattern of urinary calcium, magnesium and phosphorus is discussed in relation to the rhythm of IA.

Role of free radicals in Plasmodium berghei infected Mastomys natalensis brain

Lipid peroxide, lipid hydroperoxide, reduced glutathione, oxidised glutathione, lipofuscin contents and the activity of the enzyme superoxide dismutase were assessed in P. berghei infected M. natalensis brain. The results showed significant increase in the levels of lipid peroxides, lipid hydroperoxides and lipofuscin in brain subcellular fractions of P. berghei infected M. natalensis. Furthermore, a depressed superoxide dismutase activity was observed along with regulation in glutathione content. An elevated level of lipid peroxidation products along with depressed activity of scavengers in brain during malaria highlights the role of free radicals in malarial pathology.

Biochemical studies on mouse liver following Plasmodium berghei infection

The lipid composition of mouse liver following infection with P. berghei was investigated. The liver lipid contents of infected animals were greatly increased mainly due to the accumulation of triacylglycerides. There was enhanced lipid concentration (85.29%). Significantly (23.7%) depleted liver cholesterol was also found in the mice. Similarly, phospholipid contents of liver were also decreased by 19.90 per cent. The liver from P. berghei infected mouse produced more lipid peroxide, as compared to control animals (314%). Significant depletion was also observed in carbohydrate, glycogen and glucose (79.1, 86.26 and 78.6% respectively) contents of liver at high parasitaemia. The lower contents of nucleic acid in the infected hosts observed in the study may be partly due to the absorption of nucleic acids by the parasites from the host cells.

Vaccination of rhesus monkeys against Plasmodium knowlesi with aqueous suspension of MDP as an adjuvant

In these investigations two types of antigen preparations were used: (i) Whole Antigen (WAg), and (ii) Soluble Antigen (SAg). For immunization, Muramyl Dipeptide (MDP) was employed as an adjuvant. Highest reciprocal antibody titre values were recorded in ELISA and IHA tests from animals immunized by WAg-MDP. Skin reactions in animals sensitized with WAg-MDP combination showed a well developed zone of erythema with induration after 24 hours of intradermal injection. Animals immunized with WAg-MDP showed a maximum leukocyte migration inhibition. All the animals in experimental and control groups showed patent infection following challenge with live parasites. Animals belonging to the control groups showed 100% mortality. On the basis of these experiments it could be concluded that MDP preparation afforded some protection to the test animals.

Pathogenesis of cerebral malaria

Plasmodium knowlesi infected rhesus monkeys were employed for investigating brain tissue damage in experimentally induced cerebral malaria. Light microscopic studies revealed parasitic infiltration of virtually all the regions of CNS. Electron microscopic observations confirmed the light microscopic findings. These studies further revealed the presence of macrophages in the blood vessels of infected monkeys. In conclusion, the pathogenesis of cerebral malaria seems to be an outcome of a typical triad consisting of: (1) mechanical obstruction of the blood capillaries by parasitized RBCs; (2) biochemical events, involving free radicals, and (3) immunological dysfunction.

The recR locus of Escherichia coli K-12: molecular cloning, DNA sequencing and identification of the gene product

The recR gene of Escherichia coli, which is associated with recBC-independent mechanisms of recombination and DNA repair, has been located between dnaZX and htpG on a 6.4 kb EcoRI fragment of DNA that has been cloned and analysed in lambda and plasmid vectors. Nucleotide sequencing of this interval revealed two open reading frames that constitute an operon lying immediately downstream of dnaZX. The second of these two reading frames was identified as recR. It encodes a polypeptide with a predicted molecular weight of 21,965 Daltons that migrates on SDS gels as a 26 kDa protein. The first gene of the operon encodes a polypeptide of 12,015 daltons. Its function is not known.

Identification of the recR locus of Escherichia coli K-12 and analysis of its role in recombination and DNA repair

A new recombination gene called recR has been identified and located near dnaZ at minute 11 on the current linkage map of Escherichia coli. The gene was detected after transposon mutagenesis of a recB sbcB strain and screening for insertion mutants that had a reduced efficiency of recombination in Hfr crosses. The recR insertions obtained conferred a recombination deficient and extremely UV sensitive phenotype in both recB recC sbcA and recB recC sbcB sbcC genetic backgrounds. recR derivatives of recBC+ sbc+ strains were proficient in conjugational and transductional recombination but deficient in plasmid recombination and sensitive to UV light. Strains carrying recR insertions combined with mutations in uvrA and other rec genes revealed that the gene is involved in a recombinational process of DNA repair that relies also on recF and recO, and possibly recJ, but which is independent of recB, recC and recD. The properties of two other insertions, one located near pyrE and the other near guaA, are discussed in relation to their proximity to recG and xse (the gene for exonuclease VII), respectively.

Protective effect of L. donovani antigens using glucan as an adjuvant

Golden hamsters were immunized with various antigen fractions of Leishmania donovani promastigotes. Beta 1,3-glucan was used as an adjuvant in these vaccination experiments. The results indicate that immunization of animals with the microsomal fraction (subcellular fraction III) in combination with glucan confers considerable immune protection against L. donovani infection. The immune protection was confirmed by correspondingly lower parasite burden in the livers and spleens of test animals compared to controls. Additionally, the vaccinated animals showed positive skin test responsiveness after challenge, along with increased antibody titres. Immunization of animals with whole and particulate antigen fractions was also found to afford a high degree of resistance. The other subcellular and soluble antigen fractions conferred very little protection. In these experiments, glucan was found to be a potent adjuvant when injected, intraperitoneally, with Leishmania antigens. Similar doses of parasite extracts given without an adjuvant were able to confer only very little or no protection.

Entamoeba histolytica antigens as possible vaccinogens? A short review

A few key papers which have recently been published on the characterization of amoeba antigens are reviewed. Immunofluorescence tests and immunoelectron microscopy have demonstrated the localization of certain surface antigens on axenically cultured trophozoites. Most of the surface antigens have largely been shown to elicit a humoral response. The elicitation of cellular response has not been well illustrated. The localization of a large number of antigens in cytoplasmic vacuoles and plasma membrane indicates that a greater stimulus to the host would be provided by intracellular antigens than by those located on the surface of amoeba trophozoites. In a few inoculation studies, amoeba antigens, in combination with several adjuvants, have been successfully employed for inducing protective immunity in various animal model systems. These and other results clearly demonstrate that amoeba antigens are fully capable of generating humoral and as well as CMI responses. A combination of these two effector limbs of immunity can be fully exploited through effective use of future vaccines.