Impact of phosphate and other medium components on physiological regulation of bacterial laccase production

Laccases are multicopper oxidases known to catalyze the transformation of a wide range of phenolic and non-phenolic substrates using oxygen as electron acceptor and forming water as the only by product. Their potential relevance in several industries requires the constant search for novel laccases. Positive outcome of the isolation of laccase producing bacteria depends on the nature and concentration of media constituents. Several attempts to isolate laccase producing bacteria failed when the phosphate-containing M9 minimal medium was used. Shift to phosphate-less M162 medium led to successful isolations. Seven bacterial isolates belonging to genera Bacillus, Lysinibacillus, Bhargavaea and Rheinheimera were used to study the effect of medium constituents on laccase production. Inorganic phosphate (≥50 mM) was found to regulate laccase synthesis negatively though no inhibitory effect of phosphate (10-500 mM) was seen on laccase activity. All isolates ceased laccase synthesis when grown in the presence of tryptone (0.2-1%), with R. tangshanensis as an exception, or yeast extract (1.5-2%) as the only C/N source in M162 medium. Supplementation upto 0.1% of glucose in basal M162 medium increased laccase production in five isolates but decreased at higher concentrations. The influence of medium components on laccase synthesis was further affirmed by zymographic studies. These observations offer possibilities of isolating promising laccase producers from diverse environmental sources. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:541-548, 2017.

ASSESSMENT OF INHALATION DOSE FROM THE INDOOR 222Rn AND 220Rn USING RAD7 AND PINHOLE CUP DOSEMETERS

Radon is the most important source of natural radiation and is responsible for approximately half of the received dose from all sources. Most of this dose is from inhalation of the radon progeny, especially in closed atmospheres. Concentration of radon (²²²Rn) and thoron (²²⁰Rn) in the different villages of Jalandhar and Kapurthala district of Punjab has been calculated by pinhole cup dosemeters and RAD7. On an average, it has been observed from the study that the values of all the parameters calculated are higher in case of active monitoring than the passive monitoring. The calculated equilibrium equivalent ²²²Rn concentration (EEC_Rn) and equilibrium equivalent ²²⁰Rn concentration (EEC_Th) fluctuate in the range from 5.58 to 34.29 and from 0.35 to 2.7 Bq m^-3 as estimated by active technique, respectively. Similarly, the observed mean value of the potential alpha energy concentration of ²²²Rn (PAEC_Rn) and ²²⁰Rn (PAEC_Th) is 4.55 and 4.34 mWL, respectively. The dose rate to the soft tissues and lung from indoor ²²²Rn varies from 0.06 to 0.38 and from 0.50 to 3.05 nGy h^-1, respectively. The total annual effective dose for the residents of the study area is less than 10 mSv.

Nanomechanical sandwich assay for multiple cancer biomarkers in breast cancer cell-derived exosomes

The use of exosomes as cancer diagnostic biomarkers is technically limited by their size, heterogeneity and the need for extensive purification and labelling. We report the use of cantilever arrays for simultaneous detection of multiple exosomal surface-antigens with high sensitivity and selectivity. Exosomes from breast cancer were selectively identified by detecting over-expressed membrane-proteins CD24, CD63, and EGFR. Excellent selectivity however, was achieved when targeting the cell-surface proteoglycan, Glypican-1 at extraordinary limits (∼200 exosomes per mL, ∼0.1 pg mL(-1)).

G9a histone methyltransferase inhibitor BIX01294 promotes expansion of adult cardiac progenitor cells without changing their phenotype or differentiation potential

OBJECTIVES

As a follow-up to our previous reports showing that the G9a histone methyltransferase-specific inhibitor BIX01294 enhances bone marrow cell cardiac potential, this drug was examined for its effects on cardiomyocytes and mouse cardiac progenitor cells (CPCs).

MATERIALS AND METHODS

Cardiomyocytes and cardiac explants were cultured ± BIX01294, and examined for changes in cardiac function, protein and gene expression. Additionally, enriched populations of CPCs, contained in the 'phase bright cell' component of explants, were harvested from non-treated and BIX01294-treated cardiac tissue, and assayed for differences in cell phenotype and differentiation potential. Mouse CPCs were cultured with rat cardiomyocytes to allow differentiation of the progenitors to be assayed using species-specific PCR primers.

RESULTS

While BIX01294 had no discernible effect on myocyte function and sarcomeric organization, treatment with this drug significantly increased CPC proliferation, as indicated by enhanced MTT metabolization and BrdUrd incorporation (4.1- and 2.0-fold, respectively, P < 0.001) after 48 h labelling, and increased Ki67 expression (4.8-fold, P < 0.001) after 7 days culture. Heart explants exposed to BIX01294 generated 3.6-fold (P < 0.005) greater yields of CPCs by 2 weeks culture. Importantly, CPCs obtained from non-treated and BIX01294-treated cultures did not differ in phenotype or differentiation potential.

CONCLUSIONS

These data indicate that BIX01294 can expand CPCs without undermining their capacity as cardiac progenitors, and suggest that this drug may have utility for generating large numbers of CPCs for cardiac repair.

Critical factors affecting laccase-mediated biobleaching of pulp in paper industry

Next to xylanases, laccases from fungi and alkali-tolerant bacteria are the most important biocatalysts that can be employed for eco-friendly biobleaching of hard and soft wood pulps in the paper industry. Laccases offer a potential alternative to conventional, environmental-polluting chlorine and chlorine-based bleaching and has no reductive effect on the final yield of pulp as compared to hemicellulases (xylanases and mannanases). In the last decade, reports on biobleaching with laccases are based on laboratory observations only. There are several critical challenges before this enzyme can be implemented for pulp bleaching at the industrial scale. This review discusses significant factors like redox potential, laccase mediator system (LMS)-synthetic or natural, pH, temperature, stability of enzyme, unwanted grafting reactions of laccase, and cost-intensive production at large scale which constitute a great hitch for the successful implementation of laccases at industrial level.

Exploitation of sperm-Escherichia coli interaction at the receptor-ligand level for the development of anti-receptor antibodies as the vaginal contraceptive

In an earlier work performed in our laboratory, we have been able to isolate a sperm receptor (SR) from human spermatozoa playing critical role in fertilization using sperm--E. coli interactions at the receptor-ligand level. It has been hypothesized that for the development of an immunocontraceptive, antibodies generated against the SR should have the ability to impair sperm parameters. In this league, an attempt was made to generate anti-SR antibodies and their effect on sperm parameters such as motility, viability, Mg(2+) -dependent ATPase activity, acrosome status, and apoptotic index was examined. Loss of sperm motility was observed with 100% agglutination. Interaction of anti-SR antibodies with spermatozoa resulted in reduced Mg(2+) -dependent ATPase activity (1020 ± 0.53%), premature acrosomal loss (61.5 ± 0.67%) as well as induced apoptosis (58.76 ± 2.5%). The induction of sperm damage was specifically because of anti-SR polyclonal antibodies as it could be mitigated by the addition of purified SR. Further, when in vivo efficacy of anti-SR antibodies was checked, results showed that a single intravaginal administration with anti-SR antibodies in female BALB/c mice led to the failure of conception. However, simultaneous administration of SR with anti-SR polyclonal antibodies resulted in sustenance of fertility. Infertility induced by anti-SR antibodies did not show any other tissue pathology; hence the present work highlights the potential of anti-SR polyclonal antibodies to be used as a vaginal contraceptive.

Alterations in mitochondrial DNA copy number and the activities of electron transport chain complexes and pyruvate dehydrogenase in the frontal cortex from subjects with autism

Autism is a neurodevelopmental disorder associated with social deficits and behavioral abnormalities. Recent evidence suggests that mitochondrial dysfunction and oxidative stress may contribute to the etiology of autism. This is the first study to compare the activities of mitochondrial electron transport chain (ETC) complexes (I-V) and pyruvate dehydrogenase (PDH), as well as mitochondrial DNA (mtDNA) copy number in the frontal cortex tissues from autistic and age-matched control subjects. The activities of complexes I, V and PDH were most affected in autism (n=14) being significantly reduced by 31%, 36% and 35%, respectively. When 99% confidence interval (CI) of control group was taken as a reference range, impaired activities of complexes I, III and V were observed in 43%, 29% and 43% of autistic subjects, respectively. Reduced activities of all five ETC complexes were observed in 14% of autistic cases, and the activities of multiple complexes were decreased in 29% of autistic subjects. These results suggest that defects in complexes I and III (sites of mitochondrial free radical generation) and complex V (adenosine triphosphate synthase) are more prevalent in autism. PDH activity was also reduced in 57% of autistic subjects. The ratios of mtDNA of three mitochondrial genes ND1, ND4 and Cyt B (that encode for subunits of complexes I and III) to nuclear DNA were significantly increased in autism, suggesting a higher mtDNA copy number in autism. Compared with the 95% CI of the control group, 44% of autistic children showed higher copy numbers of all three mitochondrial genes examined. Furthermore, ND4 and Cyt B deletions were observed in 44% and 33% of autistic children, respectively. This study indicates that autism is associated with mitochondrial dysfunction in the brain.

Atypical phenotype associated with reported GCK exon 10 deletions: Clinical judgement is needed alongside appropriate genetic investigations

BACKGROUND

Maturity-onset diabetes of the young (MODY) caused by heterozygous mutations in the glucokinase (GCK) gene typically presents with lifelong, stable, mild fasting hyperglycaemia. With the exception of pregnancy, patients with GCK-MODY usually do not require pharmacological therapy. We report two unrelated patients whose initial genetic test results indicated a deletion of GCK exon 10, but whose clinical phenotypes were not typical of GCK-MODY.

CASE REPORTS

In case 1, the patient was hyperglycaemic at diagnosis (glucose > 30 mmol/l) and elevated glucose levels > 10 mmol/l persisted after withdrawal of insulin therapy. The patient in case 2 was also hyperglycaemic at diagnosis [HbA1c > 86 mmol/mol (10%)], which improved with the introduction of oral hypoglycaemic agents. These clinical features were not consistent with GCK-MODY. Both patients had a single nucleotide variant that prevented multiplex ligation-dependent probe analysis, which generated a false positive result of a GCK exon 10 deletion.

CONCLUSION

False positive genetic results in these two unrelated cases were attributable to the presence of a rare single nucleotide variant that prevented ligation of the probe in the multiplex ligation-dependent probe analysis kit used and falsely indicated deletion of exon 10 within GCK. Both cases had clinical features that did not tally with the typical GCK-MODY phenotype. These cases emphasize the need to interpret the results of definitive genetic tests within the specific clinical context. Increased medical sequencing is likely to lead to more reports of novel mutations of uncertain significance. If genetic investigations do not agree with the clinical picture, clinicians should exercise caution when making therapeutic changes based on these results.

Abstract P1-06-01: Upregulation of metabolism as a potential resistance mechanism to bevacizumab in primary breast cancer

Background: Recently the FDA has withdrawn the indication for bevacizumab in metastatic breast cancer after several clinical studies failed to demonstrate an overall survival benefit. These studies however did report an increase in response rates to chemotherapy and improvement in progression free survival, suggesting a pattern of response to the drug followed by the development of resistance. We have little knowledge of the molecular mechanisms driving the development of resistance to bevacizumab. To better understand these mechanisms, we have conducted a window of opportunity study using a single cycle of bevacizumab with detailed pharmacodynamic assessments using gene expression arrays and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).

Methods: After ethical approval, 47 newly diagnosed locally advanced breast cancer patients were prospectively enrolled in this trial. Patients received single dose bevacizumab (15mg/ kg) 2 weeks prior to neoadjuvant chemotherapy and underwent core biopsies for gene expression and immunohistochemistry analysis and DCE-MRI scans before and 2 weeks after bevacizumab. 35 patients who had invasive ductal carcinoma together with good quality MRI scans and core biopsies before and after bevacizumab were included in this analysis. Pharmacokinetic (PK) modelling techniques were used to quantify PK parameters (Ktrans, kep, ve) from the DCE-MRI data. Gene expression profiling was performed using the Affymetrix Human Exon 1.0 ST arrays.

Results: The majority of patients (28/35) showed a significant reduction in vessel permeability and blood flow of at least 30% following bevacizumab, with a mean decrease in the forward transfer constant (P &lt; 0.0001) and the reverse rate constant kep (P &lt; 0.0001). From gene expression and immunohistochemistry analyses, we identified several key metabolism-related genes that are significantly up-regulated after bevacizumab treatment, including pyruvate dehydrogenase kinase isozyme 1 (PDK1) (fig.1) and carbonic anhydrase 9 (CA9). In addition, we found a number of interesting genes that are down-regulated after bevacizumab treatment, including sulfatase-1 (SULF1), and cyclin E1 (CCNE1).

Discussion: This study highlights that the combination of DCE-MRI and gene expression arrays can lead to an improved understanding of the molecular mechanisms governing response and resistance to anti-angiogenic therapy. Heterogeneity of response to bevacizumab was demonstrated, with some tumours showing increases or no change in Ktrans and others marked reductions, which may be of value in early stratification for therapy maintenance. Furthermore, the gene expression analysis showed activation of pathways, which could contribute to the development of resistance. For example, we observed significant up regulation of genes involved in regulating the switch from mitochondrial metabolism to glycolysis, such as PDK1. This suggests that using bevacizumab with the other targeted agents such as Dichloroacetate, a PDK1 inhibitor might be helpful in overcoming the development of resistance and ultimately lead to improved patient survival. Our preclinical studies strongly support this possibility.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-06-01.

Effect of felodipine on the serum lipid profile of patients with hypertension

Forty patients suffering from mild to moderate degree of hypertension were put on felodipine. Their lipid profile was analysed before the start of their therapy and consecutively at two and four months after starting felodipine. There was a statistically significant fall in the levels of serum cholesterol, serum triglycerides and serum total lipids; though no appreciable variation was observed in HDL and LDL cholesterol levels. At baseline there were a few patients who had higher than the normal range of the serum lipid profile. Analysis of these patients showed a highly significant fall in the levels of serum cholesterol, serum triglycerides, serum LDL-cholesterol and serum total lipids i.e. felodipine modified the lipid profiles of hypertensive patients in a positive way.