Bacterial succession in the colon during childhood and adolescence: molecular studies in a southern Indian village

BACKGROUND

The colonic bacterial flora, largely anaerobic, is believed to establish and stabilize in the first 2 y of life.

OBJECTIVE

This study was undertaken to determine whether the bacterial flora of the colon undergoes further changes (succession) during childhood and adolescence.

DESIGN

This cross-sectional study examined fecal samples from 130 healthy children and adolescents in the age group 2-17 y and from 30 healthy adults (median age: 42 y) residing in a single village in southern India. DNA was extracted and subjected to 16S rDNA-targeted real-time polymerase chain reaction to determine the relative predominance of Bifidobacterium genus, Bacteroides-Prevotella-Porphyromonas group, Lactobacillus acidophilus group, Eubacterium rectale, and Faecalibacterium prausnitzii.

RESULTS

Bifidobacterium species and Bacteroides-Prevotella group were dominant fecal bacteria overall. E. rectale and Lactobacillus species were considerably less abundant. Clear age-related differences emerged, with a steep decline in Bifidobacterium species in adults (P < 0.0001), a steep decline of Lactobacillus species >5 y of age (P < 0.0001), an increase in Bacteroides during late adolescence and in adults (P = 0.0040), an increase in E. rectale during childhood and adolescence followed by a steep decline in adults (P < 0.0001), and a late childhood peak of F. prausnitzii with decline in adolescents and adults (P < 0.0001).

CONCLUSIONS

Changes in the bacterial flora occur during childhood and adolescence characterized by reduction in Lactobacillus and Bifidobacterium species and an increase in Bacteroides, E rectale, and F. prausnitzii peaked during late childhood in this population.

Probiotic administration alters the gut flora and attenuates colitis in mice administered dextran sodium sulfate

BACKGROUND

Probiotics are used in the therapy of inflammatory bowel disease. This study aimed to determine whether prior administration of probiotic lactobacilli and bifidobacteria would prevent disease and change gut flora in an animal model of colitis.

METHODS

Swiss albino mice received a probiotic mixture (four Lactobacillus and four Bifidobacterium species) or medium (control) for a week prior to induction of colitis by oral 4% dextran sodium sulfate (DSS) for seven days. Appropriate non-colitis controls were used. Histological damage was assessed (n = 5 per group), as was expression of mRNA for tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, transforming growth factor (TGF)-beta1 and SOCS-1 in the colonic mucosa (n = 6 per group). Secretion of TNF-alpha was measured in distal colon organ culture (n = 5-6 per group). Levels of Bacteroides, Bifidobacterium, and Lactobacillus acidophilus in feces were quantified by real time polymerase chain reaction (PCR) targeting 16S rDNA.

RESULTS

Compared to untreated DSS colitis, probiotic treatment significantly reduced weight loss (P < 0.05), shifted histological damage to lesser grades of severity (P < 0.001), reduced mRNA expression of TNF-alpha and TGF-beta1 (P < 0.05), and down-regulated production of TNF-alpha from distal colon explants (P < 0.05). Colitis induced a significant reduction in the relative proportions of Bifidobacterium, Bacteroides and Lactobacillus acidophilus group bacteria in feces, and these levels were significantly increased in probiotic-treated mice compared to DSS mice (P < 0.001).

CONCLUSION

Prior administration of probiotic bacteria reduced mucosal inflammation and damage in DSS-induced colitis. DSS colitis was associated with significant changes in the fecal anaerobic bacterial flora and these changes were modulated by administration of probiotic bacteria.

Real-time polymerase chain reaction quantification of specific butyrate-producing bacteria, Desulfovibrio and Enterococcus faecalis in the feces of patients with colorectal cancer

BACKGROUND AND AIM

Bacterial metabolites produced in the bowel are potentially related to the genesis of colorectal cancer. Butyrate is protective against cancer, whereas hydrogen sulfide and oxygen free radicals can be toxic to the epithelium. The present study was designed to quantitate Eubacterium rectale, Faecalibacterium prausnitzii (both butyrate-producing bacteria), Desulfovibrio (sulfate-reducing bacteria), and Enterococcus faecalis (that produces extracellular superoxide) in the feces of patients with colorectal cancer.

METHODS

DNA was extracted from feces of 20 patients with colorectal cancer, nine patients with upper gastrointestinal cancer and 17 healthy volunteers. Real-time polymerase chain reaction using primers aimed at 16S rDNA was used to quantitate the above bacterial species or genus, and this was expressed relative to amplification of universal sequences conserved among all bacteria.

RESULTS

Levels of E. rectale and F. prausnitzii were decreased approximately fourfold (P = 0.0088 and 0.0028, respectively) in colorectal cancer patients compared to healthy control volunteers. Levels of Desulfovibrio were not significantly different between the three groups. E. faecalis populations were significantly higher in colorectal cancer patients compared to healthy volunteers (P = 0.0294).

CONCLUSIONS

Butyrate producers were decreased and E. faecalis increased in the feces of colon cancer patients. These shifts in the colonic bacterial population could potentially lead to epithelial cell damage and increased turnover and may be a factor leading to colon cancer.

Real-time polymerase chain reaction quantification of specific butyrate-producing bacteria, Desulfovibrio and Enterococcus faecalis in the feces of patients with colorectal cancer

BACKGROUND AND AIM

Bacterial metabolites produced in the bowel are potentially related to the genesis of colorectal cancer. Butyrate is protective against cancer, whereas hydrogen sulfide and oxygen free radicals can be toxic to the epithelium. The present study was designed to quantitate Eubacterium rectale, Faecalibacterium prausnitzii (both butyrate-producing bacteria), Desulfovibrio (sulfate-reducing bacteria), and Enterococcus faecalis (that produces extracellular superoxide) in the feces of patients with colorectal cancer.

METHODS

DNA was extracted from feces of 20 patients with colorectal cancer, nine patients with upper gastrointestinal cancer and 17 healthy volunteers. Real-time polymerase chain reaction using primers aimed at 16S rDNA was used to quantitate the above bacterial species or genus, and this was expressed relative to amplification of universal sequences conserved among all bacteria.

RESULTS

Levels of E. rectale and F. prausnitzii were decreased approximately fourfold (P = 0.0088 and 0.0028, respectively) in colorectal cancer patients compared to healthy control volunteers. Levels of Desulfovibrio were not significantly different between the three groups. E. faecalis populations were significantly higher in colorectal cancer patients compared to healthy volunteers (P = 0.0294).

CONCLUSIONS

Butyrate producers were decreased and E. faecalis increased in the feces of colon cancer patients. These shifts in the colonic bacterial population could potentially lead to epithelial cell damage and increased turnover and may be a factor leading to colon cancer.

Estimation of faecal carriage of Clostridium difficile in patients with ulcerative colitis using real time polymerase chain reaction

BACKGROUND & OBJECTIVE

Ulcerative colitis (UC) is a disease of unknown aetiology in which exacerbations are sometimes linked to intestinal colonization by toxin-producing Clostridium difficile. We undertook this study to detect and quantitatively assess C. difficile in the stool of patients with UC using real time polymerase chain reaction (RT-PCR), and to compare it with healthy individuals.

METHODS

A total of 37 consecutive patients with UC (26 male, mean age 41.3 yr) and 36 healthy adult volunteers (20 male, mean age 36.4), none of whom had received antibiotics within two months prior to faecal collection, were included in the study. Faecal DNA was extracted, quantitative PCR (qPCR) carried out using primers to amplify species-specific segments of 16S rDNA of C. difficile, and expressed as relative fold difference against amplification of highly conserved (universal) segments. Toxins A and B were assayed by ELISA.

RESULTS

Quantitative PCR detected C. difficile sensitively, and spiking with increasing numbers of the organism resulted in linear increase in amplification (R(2)=0.974). C. difficile was detected by qPCR in faeces of 20 of 36 healthy volunteers and 34 of 37 patients with UC. Relatively greater amplification of C. difficile (fold difference) was noted in UC compared to controls (P<0.0001). There was no significant difference in C. difficile amplification between patients with proctitis, left sided colitis and pancolitis, or between active and quiescent colitis. Toxin was detected in the faeces of 8 of 37 patients with UC compared to 2 of 36 healthy volunteers.

INTERPRETATION & CONCLUSION

Findings of this study showed overgrowth of C. difficile in the stool of Indian patients with UC. However, its relevance to disease pathogenesis and severity in a tropical country like India needs to be investigated further.

Increased glycated hemoglobin level in non-diabetic nephrotic children is associated with oxidative stress

Glycation and lipid peroxidation are spontaneous reactions believed to contribute to the pathogenesis of nephrotic syndrome. Possible interrelations of glycated hemoglobin with reduced glutathione and malondialdehyde were evaluated in nephrotic syndrome patients. Eighteen nephrotic syndrome patients and 15 healthy controls were enrolled for this study. Glycated hemoglobin, reduced glutathione, malondialdehyde and fasting glucose were analyzed for their correlation in both the groups. In nephrotic syndrome patients, while glycated hemoglobin and malondialdehyde levels were found to be significantly increased, glutathione levels decreased significantly when compared with controls. Glycated hemoglobin was found to have a significant positive correlation with malondialdehyde and a negative correlation with glutathione. Erythrocytes depleted of glutathione, by pre-treatment with 1-chloro-2, 4-dinitrobenezene, were found to have higher glycated hemoglobin levels when compared with erythrocytes incubated with glucose alone. These data suggest that glycated hemoglobin levels are closely associated with malondialdehyde and glutathione in nephrotic syndrome patients.

PCR amplification of the IS6110 insertion element of Mycobacterium tuberculosis in fecal samples from patients with intestinal tuberculosis

PCR amplification of insertion element IS6110 of Mycobacterium tuberculosis in fecal samples was evaluated in the diagnosis of intestinal tuberculosis (ITB). The numbers of samples that tested positive by PCR with SalI digestion were 16/18 untreated-ITB samples, 0/8 treated-ITB samples, 12/14 smear-positive pulmonary tuberculosis samples, and 0/30 control samples. The sensitivity, specificity, positive predictive value, and negative predictive value of fecal PCR were 88.8%, 100%, 100%, and 93.7%, respectively.

Evaluation of private sector participation models in highway infrastructure in India – a system dynamics approach

A good and efficient road network forms the primary infrastructure that propels the development process in a country. There has been a rapid increase in the demand for highway infrastructure in India as freight traffic increased 180 times and passenger traffic increased 132 times between 1951 and 2000, whereas the total length of the road has just gone up by 8 times for the same period. Further to this, with the conventional way of depending on Government fiscal budgets for development of highway infrastructure having become impractical, Private Sector Participation (PSP) is the only effective solution to meet the rising infrastructure demands. Private sector participation in highway infrastructure projects in India has been observed presently under two major formats: BOT – Toll based and BOT – Annuity based models. BOT – Toll based model has been seen to be a failure in terms of expected returns to the concessionaire whereas the relatively newer Annuity model has been found to be attractive to the private sector. However, there exists an ambiguity whith respect to their suitability in a given case and in decision‐making. Using System Dynamics approach a framework is developed that would enable the decision maker to decide particular type of prievate sector participation (PSP) m odel for a given highway project. It is observed that the concessionaire’s desired rate of return and the traffic growth projections are the key parameters in selection of PSP model.

Safety of Arch Aortography for Assessment of Carotid Arteries

PURPOSE

To retrospectively review the safety of arch aortography and compare complication rates with published figures for selective catheter angiography.

METHODS

The medical records of patients undergoing arch aortography over the last 3 years (n=311; 180 male, 131 female; mean+/-SD age 71.0+/-9.2 years, range 42-90 years) were retrospectively reviewed. Any peri-procedural (0-48 h) complications were recorded. A certified neurologist (MSR/GSV) classified all questionable neurological events.

RESULTS

There were no focal neurological events or deaths (n=0; 0%; CI: 0-0.96%). Non-focal neurological events included mild disorientation (n=2; 0.6%; CI: 0.176-2.31) and unequal pupils (n=1; 0.3%; CI: 0.056-1.79%). Cardiovascular events included symptomatic hypotension (n=4; 1.3%; CI: 0.50-3.25%), angina (n=1; 0.3%; CI: 0.056-1.79%) and arrhythmia (n=4; 1.3%; CI: 0.50-3.25). There were 27 minor access site complications (8.7%; CI: 6.0-12.3). None of these complications extended hospital stay. None of the arch angiograms had to be followed by selective carotid angiography.

CONCLUSION

Arch aortography appears to have a lower neurological complication rate than selective carotid angiography.

Increased protein glycation in non-diabetic pediatric nephrotic syndrome: possible role of lipid peroxidation

BACKGROUND

Malondialdehyde (MDA), ascorbic acid and reduced glutathione (GSH) have been reported to play a possible role in glycation of proteins. This study was performed to evaluate this correlation in nephrotic syndrome patients by comparing the levels of fructosamine with MDA, ascorbic acid and GSH.

METHODS

Fifteen children with nephrotic syndrome during relapse and 10 age- and sex-matched healthy controls were enrolled for this study. Whole blood GSH, plasma MDA, total ascorbic acid and fasting glucose were analyzed in both the groups. Partial correlation analysis was performed to predict the independent association of MDA, ascorbic acid and GSH on fructosamine.

RESULTS

Plasma MDA and fructosamine levels were found to be increased in nephrotic syndrome patients when compared with controls. Plasma ascorbic acid and whole blood GSH were decreased in nephrotic group vs. healthy controls. Partial correlation analysis showed a significant positive correlation between fructosamine and MDA.

CONCLUSIONS

Present data point to a possible involvement of MDA in the glycation of protein in non-diabetic nephrotic syndrome patients, and provide support for the potential use of an antioxidant therapy in these patients.

pi-Facial selectivities of diastereotopic ketones: p-bromobenzoates of 4-hetero-1-decalinols

The crystal structures of the p-bromobenzoates of cis-4-oxa-1-decalinyl (C(16)H(19)BrO(3)), trans-4-oxa-1-decalinyl (C(16)H(19)BrO(3)), N-benzyl-cis-4-aza-1-decalinyl (C(23)H(26)BrNO(2)), N-benzyl-trans-4-aza-1-decalinyl (C(23)H(26)BrNO(2)) and trans-4-thia-1-decalinyl (C(16)H(19)BrO(2)S) (decalin is perhydronaphthalene) have been determined as part of a study directed at predicting and interpreting the pi-facial selectivities of diastereotopic ketones in reactions with nucleophiles. All five structures are composed of molecules that are separated by normal van der Waals distances. In all five structures, the heterocyclic and cyclohexyl rings adopt chair conformations, and the p-bromobenzoate groups are planar.

Silicon-assisted ring opening of donor-acceptor substituted cyclopropanes. An expedient entry to substituted dihydrofurans

[reaction: see text]. (tert-butyldiphenylsilyl)methylcyclopropanes undergo ring opening to furnish substituted dihydrofurans in good to excellent yields on treatment with TiCl4 in dichoromethane. The silicon that assists the regioselective ring opening is retained in the product to allow further functional group manipulations.

Trigonal planar copper(I) complex: synthesis, structure, and spectra of a redox pair of novel copper(II/I) complexes of tridentate bis(benzimidazol-2'-yl) ligand framework as models for electron-transfer copper proteins

The copper(II) and copper(I) complexes of the chelating ligands 2,6-bis(benzimidazol-2'-ylthiomethyl)pyridine (bbtmp) and N,N-bis(benzimidazol-2'-ylthioethyl)methylamine (bbtma) have been isolated and characterized by electronic and EPR spectra. The molecular structures of a redox pair of Cu(II/I) complexes, viz., [Cu(bbtmp)(NO(3))]NO(3), 1, and [Cu(bbtmp)]NO(3), 2, and of [Cu(bbtmp)Cl], 3, have been determined by single-crystal X-ray crystallography. The cation of the green complex [Cu(bbtmp)(NO(3))]NO(3) possesses an almost perfectly square planar coordination geometry in which the corners are occupied by the pyridine and two benzimidazole nitrogen atoms of the bbtmp ligand and an oxygen atom of the nitrate ion. The light-yellow complex [Cu(bbtmp)]NO(3) contains copper(I) with trigonal planar coordination geometry constituted by the pyridine and two benzimidazole nitrogen atoms of the bbtmp ligand. In the yellow chloride complex [Cu(bbtmp)Cl] the asymmetric unit consists of two complex molecules that are crystallographically independent. The coordination geometry of copper(I) in these molecules, in contrast to the nitrate, is tetrahedral, with pyridine and two benzimidazole nitrogen atoms of bbtmp ligand and the chloride ion occupying the apexes. The above coordination structures are unusual in that the thioether sulfurs are not engaged in coordination and the presence of two seven-membered chelate rings facilitates strong coordination of the benzimidazole nitrogens and discourage any distortion in Cu(II) coordination geometry. The solid-state coordination geometries are retained even in solution, as revealed by electronic, EPR, and (1)H NMR spectra. The electrochemical behavior of the present and other similar CuN(3) complexes has been examined, and the thermodynamic aspects of the electrode process are correlated to the stereochemical reorganizations accompanying the redox changes. The influence of coordinated pyridine and amine nitrogen atoms on the spectral and electrochemical properties has been discussed.