Quercetin's antibiofilm effectiveness against drug resistant Staphylococcus aureus and its validation by in silico modeling

Staphylococcus aureus is typically treated with antibiotics, however, due to its widespread and unselective usage, resistant strains of S. aureus have increased to a great extent. Treatment failure and recurring staphylococcal infections are also brought on by biofilm development, which boosts an organism's ability to withstand antibiotics and is thought to be a virulence factor in patients. The present study investigates the antibiofilm activity of naturally available polyphenol Quercetin against drug-resistant S. aureus. Micro dilution plating and tube adhesion methods were performed to evaluate the antibiofilm activity of quercetin against S. aureus. Quercetin treatment resulted in remarkably reduction of biofilm in S. aureus cells. Further we performed a study to investigate binding efficacies of quercetin with genes icaB and icaC from ica locus involved in biofilm formation. 3D structure of icaB, icaC and quercetin were retrieved from Protein data bank and PubChem chemical compound database, respectively. All computational simulation were carried out using AutoDock Vina and AutoDockTools (ADT) v 1.5.4. In silico study demonstrated a strong complex formation, large binding constants (Kb) and low free binding energy (ΔG) between quercetin and icaB (Kb = 1.63 × 10-5, ΔG = -7.2 k cal/mol) and icaC (Kb = 1.98 × 10-6, ΔG = -8.7 kcal/mol). This in silico analysis indicates that quercetin is capable of targeting icaB and icaC proteins which are essential for biofilm formation in S. aureus. Our study highlighted the antibiofilm activity of quercetin against drug resistant pathogen S.aureus.

Anticancer Drug Discovery Based on Natural Products: From Computational Approaches to Clinical Studies

Globally, malignancies cause one out of six mortalities, which is a serious health problem. Cancer therapy has always been challenging, apart from major advances in immunotherapies, stem cell transplantation, targeted therapies, hormonal therapies, precision medicine, and palliative care, and traditional therapies such as surgery, radiation therapy, and chemotherapy. Natural products are integral to the development of innovative anticancer drugs in cancer research, offering the scientific community the possibility of exploring novel natural compounds against cancers. The role of natural products like Vincristine and Vinblastine has been thoroughly implicated in the management of leukemia and Hodgkin's disease. The computational method is the initial key approach in drug discovery, among various approaches. This review investigates the synergy between natural products and computational techniques, and highlights their significance in the drug discovery process. The transition from computational to experimental validation has been highlighted through in vitro and in vivo studies, with examples such as betulinic acid and withaferin A. The path toward therapeutic applications have been demonstrated through clinical studies of compounds such as silvestrol and artemisinin, from preclinical investigations to clinical trials. This article also addresses the challenges and limitations in the development of natural products as potential anti-cancer drugs. Moreover, the integration of deep learning and artificial intelligence with traditional computational drug discovery methods may be useful for enhancing the anticancer potential of natural products.

CRISPR/Cas9 as a therapeutic tool for triple negative breast cancer: from bench to clinics

Clustered regularly interspaced short palindromic repeats (CRISPR) is a third-generation genome editing method that has revolutionized the world with its high throughput results. It has been used in the treatment of various biological diseases and infections. Various bacteria and other prokaryotes such as archaea also have CRISPR/Cas9 systems to guard themselves against bacteriophage. Reportedly, CRISPR/Cas9-based strategy may inhibit the growth and development of triple-negative breast cancer (TNBC) via targeting the potentially altered resistance genes, transcription, and epigenetic regulation. These therapeutic activities could help with the complex issues such as drug resistance which is observed even in TNBC. Currently, various methods have been utilized for the delivery of CRISPR/Cas9 into the targeted cell such as physical (microinjection, electroporation, and hydrodynamic mode), viral (adeno-associated virus and lentivirus), and non-viral (liposomes and lipid nano-particles). Although different models have been developed to investigate the molecular causes of TNBC, but the lack of sensitive and targeted delivery methods for in-vivo genome editing tools limits their clinical application. Therefore, based on the available evidences, this review comprehensively highlighted the advancement, challenges limitations, and prospects of CRISPR/Cas9 for the treatment of TNBC. We also underscored how integrating artificial intelligence and machine learning could improve CRISPR/Cas9 strategies in TNBC therapy.

Transcriptomic Profiling Unravels Novel Deregulated Gene Signatures Associated with Acute Myocardial Infarction: A Bioinformatics Approach

Acute myocardial infarction (AMI) is a severe disease with elevated morbidity and mortality rate worldwide. This is attributed to great losses of cardiomyocytes, which can trigger the alteration of gene expression patterns. Although several attempts have been made to assess the AMI biomarkers, to date their role in rescuing myocardial injury remains unclear. Therefore, the current study investigated three independent microarray-based gene expression datasets from AMI patients (n = 85) and their age-sex-matched healthy controls (n = 70), to identify novel gene signatures that might be involved in cardioprotection. The differentially expressed genes (DEGs) were analyzed using 'GEO2R', and weighted gene correlation network analysis (WGCNA) was performed to identify biomarkers/modules. We found 91 DEGs, of which the number of upregulated and downregulated genes were 22 and 5, respectively. Specifically, we found that the deregulated genes such as ADOR-A3, BMP6, VPS8, and GPx3, may be associated with AMI. WGCNA revealed four highly preserved modules among all datasets. The 'Enrichr' unveiled the presence of miR-660 and STAT1, which is known to affect AMI severity. Conclusively, these genes and miRNA might play a crucial role the rescue of cardiomyocytes from severe damage, which could be helpful in developing appropriate therapeutic strategies for the management of AMI.

CRISPR/Cas9 system in breast cancer therapy: advancement, limitations and future scope

Cancer is one of the major causes of mortality worldwide, therefore it is considered a major health concern. Breast cancer is the most frequent type of cancer which affects women on a global scale. Various current treatment strategies have been implicated for breast cancer therapy that includes surgical removal, radiation therapy, hormonal therapy, chemotherapy, and targeted biological therapy. However, constant effort is being made to introduce novel therapies with minimal toxicity. Gene therapy is one of the promising tools, to rectify defective genes and cure various cancers. In recent years, a novel genome engineering technology, namely the clustered regularly interspaced short palindromic repeat (CRISPR)-associated protein-9 (Cas9) has emerged as a gene-editing tool and transformed genome-editing techniques in a wide range of biological domains including human cancer research and gene therapy. This could be attributed to its versatile characteristics such as high specificity, precision, time-saving and cost-effective methodologies with minimal risk. In the present review, we highlight the role of CRISPR/Cas9 as a targeted therapy to tackle drug resistance, improve immunotherapy for breast cancer.

Genome-wide expression reveals potential biomarkers in breast cancer bone metastasis

Breast cancer metastases are most commonly found in bone, an indication of poor prognosis. Pathway-based biomarkers identification may help elucidate the cellular signature of breast cancer metastasis in bone, further characterizing the etiology and promoting new therapeutic approaches. We extracted gene expression profiles from mouse macrophages from the GEO dataset, GSE152795 using the GEO2R webtool. The differentially expressed genes (DEGs) were filtered by log2 fold-change with threshold 1.5 (FDR < 0.05). STRING database and Enrichr were used for GO-term analysis, miRNA and TF analysis associated with DEGs. Autodock Vienna was exploited to investigate interaction of anti-cancer drugs, Actinomycin-D and Adriamycin. Sensitivity and specificity of DEGs was assessed using receiver operating characteristic (ROC) analyses. A total of 61 DEGs, included 27 down-regulated and 34 up-regulated, were found to be significant in breast cancer bone metastasis. Major DEGs were associated with lipid metabolism and immunological response of tumor tissue. Crucial DEGs, Bcl3, ADGRG7, FABP4, VCAN, and IRF4 were regulated by miRNAs, miR-497, miR-574, miR-138 and TFs, CCDN1, STAT6, IRF8. Docking analysis showed that these genes possessed strong binding with the drugs. ROC analysis demonstrated Bcl3 is specific to metastasis. DEGs Bcl3, ADGRG7, FABP4, IRF4, their regulating miRNAs and TFs have strong impact on proliferation and metastasis of breast cancer in bone tissues. In conclusion, present study revealed that DEGs are directly involved in of breast tumor metastasis in bone tissues. Identified genes, miRNAs, and TFs can be possible drug targets that may be used for the therapeutics. However, further experimental validation is necessary.

Systematic review and meta-analysis of candidate gene association studies of benign prostate hyperplasia

BACKGROUND

Benign prostate hyperplasia (BPH) is the most common urological problem in elderly males. Recent studies have reported polymorphism in various metabolic genes in BPH. However, their association with the susceptibility of BPH is still inconsistent. Here, we systematically reviewed and performed a meta-analysis of CYP17, VDR, and ACE genes to determine their precise association with the risk of BPH.

METHODS

A comprehensive literature search for published studies on candidate gene associations involving vitamin D receptor (VDR), angiotensin-converting enzyme (ACE), and CYP17 genes with the risk of BPH was done up to April 2020 in PubMed, Scopus, Cochrane Central Register of Controlled Trials (CENTRAL), and Google Scholar databases. Fixed/random effects models were used to estimate the odd's ratio (OR) and 95% confidence intervals (CIs). Begg's funnel plot was used to assess the potential for publication bias.

RESULTS

We found a total of 23 studies containing 3461 cases and 3833 controls for these gene polymorphisms. A significant association of ACE gene polymorphism was observed under the recessive (II vs. ID + DD) model for BPH susceptibility compared to control subjects (overall OR = 1.67, 95% CI = 1.03-2.73). Similar trends were observed for ACE gene polymorphism in Caucasian (OR = 6.18, 95% CI = 1.38-27.68) and Asian (OR = 1.42, 95% CI = 0.99-2.03) populations under study. No significant association was observed in VDR and CYP17 gene polymorphisms in any dominant or recessive models.

CONCLUSION

Significant OR demonstrated the implication of ACE gene polymorphism in the proliferation of prostate tissue, which in turn is associated with BPH susceptibility. However, prospective studies at large scale and sample size are needed to confirm the current findings.

Deregulated Protein Kinases: Friend and Foe in Ischemic Stroke

Ischemic stroke is the third leading cause of mortality worldwide, but its medical management is still limited to the use of thrombolytics as a lifesaving option. Multiple molecular deregulations of the protein kinase family occur during the period of ischemia/reperfusion. However, experimental studies have shown that alterations in the expression of essential protein kinases and their pharmacological modulation can modify the neuropathological milieu and hasten neurophysiological recovery. This review highlights the role of key protein kinase members and their implications in the evolution of stroke pathophysiology. Activation of ROCK-, MAPK-, and GSK-3β-mediated pathways following neuronal ischemia/reperfusion injury in experimental conditions aggravate the neuropathology and delays recovery. Targeting ROCK, MAPK, and GSK-3β will potentially enhance myelin regeneration, improve blood-brain barrier (BBB) function, and suppress inflammation, which ameliorates neuronal survival. Conversely, protein kinases such as PKA, Akt, PKCα, PKCε, Trk, and PERK salvage neurons post-ischemia by mechanisms including enhanced toxin metabolism, restoring BBB integrity, neurotrophic effects, and apoptosis suppression. Certain protein kinases such as ERK1/2, JNK, and AMPK have favourable and unfavourable effects in salvaging ischemia-injured neurons. Targeting multiple protein kinase-mediated pathways simultaneously may improve neuronal recovery post-ischemia.

Differentially Expressed Genes and Their Clinical Significance in Ischaemic Stroke: An In-Silico Study

Background

Ischaemic stroke (IS), a multifactorial neurological disorder, is mediated by interplay between genes and the environment and, thus, blood-based IS biomarkers are of significant clinical value. Therefore, this study aimed to find global differentially expressed genes (DEGs) in-silico, to identify key enriched genes via gene set enrichment analysis (GSEA) and to determine the clinical significance of these genes in IS.

Methods

Microarray expression dataset GSE22255 was retrieved from the Gene Expression Omnibus (GEO) database. It includes messenger ribonucleic acid (mRNA) expression data for the peripheral blood mononuclear cells of 20 controls and 20 IS patients. The bioconductor-package ‘affy’ was used to calculate expression and a pairwise t-test was applied to screen DEGs (P < 0.01). Further, GSEA was used to determine the enrichment of DEGs specific to gene ontology (GO) annotations.

Results

GSEA analysis revealed 21 genes to be significantly plausible gene markers, enriched in multiple pathways among all the DEGs (n = 881). Ten gene sets were found to be core enriched in specific GO annotations. JunD, NCX3 and fibroblast growth factor receptor 4 (FGFR4) were under-represented and glycoprotein M6-B (GPM6B) was persistently over-represented.

Conclusion

The identified genes are either associated with the pathophysiology of IS or they affect post-IS neuronal regeneration, thereby influencing clinical outcome. These genes should, therefore, be evaluated for their utility as suitable markers for predicting IS in clinical scenarios.

Effect of internet use on medical students before and after 4g internet service in india: A comparative study

BACKGROUND

Internet is being used extensively throughout the world from last decade. In India internet service has entered into new generation called 4G. Medical students are particularly vulnerable group for problematic internet use on account of the time they spend online. This might have negative effects on their physical, psychological and social health. Hence they are more prone to internet addiction.

AIMS

To compare use and effect of internet service among medical students before and after the availability of 4G service.

STUDY DESIGN

Institution based cross sectional study.

METHODS AND MATERIAL

Predesigned validated questionnaires were provided to the medical students in the year 2014. The questionnaire included demographics, pattern of internet use and Young's internet addiction test. Again in the year 2018 the similar procedure was carried out after introduction of 4G service. The data was collected and compared. Analysis was done using SPSS 25.

STATISTICAL ANALYSIS

Descriptive statistics, Chi² test and Mann-Whitney test was applied.

RESULTS

Among 424 medical students 207 students were assessed in the year 2014 and 217 students in 2018.There was a significant change of pattern of use. Also significant increase in number of female users and severity of internet addiction in 2018. The ill effect of internet was on rise after availability of 4G service.

CONCLUSIONS

The prevalence of internet addiction and its ill effect on behavior among medical students was higher after availability of 4G service in same college. So appropriate preventive and interventional strategies need to be developed in professional institutions.

No changes in heme synthesis in human Friedreich´s ataxia erythroid progenitor cells

Friedreich's ataxia (FRDA) is a neurodegenerative disease caused by reduced expression of the protein frataxin. Frataxin is thought to play a role in iron-sulfur cluster biogenesis and heme synthesis. In this study, we used erythroid progenitor stem cells obtained from FRDA patients and healthy donors to investigate the putative role, if any, of frataxin deficiency in heme synthesis. We used electrochemiluminescence and qRT-PCR for frataxin protein and mRNA quantification. We used atomic absorption spectrophotometry for iron levels and a photometric assay for hemoglobin levels. Protoporphyrin IX and Ferrochelatase were analyzed using auto-fluorescence. An "IronChip" microarray analysis followed by a protein-protein interaction analysis was performed. FRDA patient cells showed no significant changes in iron levels, hemoglobin synthesis, protoporphyrin IX levels, and ferrochelatase activity. Microarray analysis presented 11 genes that were significantly changed in all patients compared to controls. The genes are especially involved in oxidative stress, iron homeostasis and angiogenesis. The mystery about the involvement of frataxin on iron metabolism raises the question why frataxin deficiency in primary FRDA cells did not lead to changes in biochemical parameters of heme synthesis. It seems that alternative pathways can circumvent the impact of frataxin deficiency on heme synthesis. We show for the first time in primary FRDA patient cells that reduced frataxin levels are still sufficient for heme synthesis and possibly other mechanisms can overcome reduced frataxin levels in this process. Our data strongly support the fact that so far no anemia in FRDA patients was reported.

Gene regulation by long purine tracks in brain related diseases

Purine repeats are randomly distributed in the human genome, however, they show potential role in the transcriptional deregulation of genes. Presence of long tracks of purine repeats in the genome can disturb its integrity and interfere with the cellular behavior by introducing mutations and/or triple stranded structure formation in DNA. Our data revealed interesting finding that a majority of genes carrying purine repeats, of length n≥200, were down regulated and found to be linked with several brain related diseases [1]. The unique feature of the purine repeats found in the present study clearly manifests their significant application in developing therapeutics for neurological diseases.

Identification of genes containing expanded purine repeats in the human genome and their apparent protective role against cancer

Purine repeat sequences present in a gene are unique as they have high propensity to form unusual DNA-triple helix structures. Friedreich's ataxia is the only human disease that is well known to be associated with DNA-triplexes formed by purine repeats. The purpose of this study was to recognize the expanded purine repeats (EPRs) in human genome and find their correlation with cancer pathogenesis. We developed "PuRepeatFinder.pl" algorithm to identify non-overlapping EPRs without pyrimidine interruptions in the human genome and customized for searching repeat lengths, n ≥ 200. A total of 1158 EPRs were identified in the genome which followed Wakeby distribution. Two hundred and ninety-six EPRs were found in geneic regions of 282 genes (EPR-genes). Gene clustering of EPR-genes was done based on their cellular function and a large number of EPR-genes were found to be enzymes/enzyme modulators. Meta-analysis of 282 EPR-genes identified only 63 EPR-genes in association with cancer, mostly in breast, lung, and blood cancers. Protein-protein interaction network analysis of all 282 EPR-genes identified proteins including those in cadherins and VEGF. The two observations, that EPRs can induce mutations under malignant conditions and that identification of some EPR-gene products in vital cell signaling-mediated pathways, together suggest the crucial role of EPRs in carcinogenesis. The new link between EPR-genes and their functionally interacting proteins throws a new dimension in the present understanding of cancer pathogenesis and can help in planning therapeutic strategies. Validation of present results using techniques like NGS is required to establish the role of the EPR genes in cancer pathology.

First Report of Wet Rot of Withania somnifera Caused by Choanephora cucurbitarum in India

Withania somnifera (Ashwagandha) is native to India and commercially cultivated for the production of root withanolides that have anticarcinogenic properties. A disease appeared on plantings of W. somnifera during the 2010 monsoon at the CIMAP and in adjoining areas of northern India. Symptoms first appeared as water-soaked lesions on leaves and stems that progressed to a wet rot. Mature lesions harbored black fructifications of the suspect pathogen. Pathogen isolations were done by placing pieces of infected tissues on potato dextrose agar. A fungus tentatively identified as a Choanephora sp. that produced white aerial mycelia that later turned pale yellow was consistently isolated from infected plant parts. Mycelia were hyaline and nonseptate. Sporangiophores bearing sporangiola were erect, hyaline, unbranched, apically dilated to form a clavate vesicle from which arose dichotomously branched distally clavate secondary vesicles. Sporangiola were indehiscent, ellipsoid, brown to dark brown with distinct longitudinal striations, and measured 12 to 20 × 6 to 12 μm. Sporangia were multispored, spherical, initially white to yellow and pale brown to dark brown at maturity, and measured 40 to 160 μm. Sporangiospores from sporangia were ellipsoid to broadly ellipsoid, brown to dark brown, indistinctly striate with fine hyaline polar appendages, and measured 16 to 20 × 8 to 12 μm. On the basis of the cultural as well as morphological characteristics and description in the monograph by Kirk (2), the fungus was identified as a Choanephora sp. The identification was also confirmed by IMTECH, Chandigarh, India with Accession No. MTCC-10731. The species was later characterized as Choanephora cucurbitarum (Berk. & Ravenel) Thaxt (GenBank Accession No. AB470642) by using universal primers ITS-1 and ITS-4. Its sequence comprising of 18S rRNA partial, complete ITS 1, 5.8S rRNA, ITS 2, and 28S rRNA partial was submitted to NCBI GenBank with Accession No. JN639861. Pathogenicity of the fungus was established on five healthy plants by artificial inoculation with spray of an aqueous spore suspension containing 10⁶ spores/ml. Plants sprayed with sterile distilled water were used as controls. Both inoculated and control plants were kept in a humidity chamber (96%) for 3 days and thereafter placed in the glasshouse at 28 ± 2°C. Initial symptoms developed in 2 to 3 days while typical disease symptoms appeared on all the inoculated plants after 7 to 10 days. Control plants were free from infection. The reisolation from artificially infected plants again yielded a Choanephora sp., thus fulfilling Koch's postulates. W. somnifera cultivation has been affected by root rot and wilt caused by Fusarium solani and leaf spot caused by Alternaria dianthicola (3). The occurrence of a Choanephora sp. was reported on periwinkle, petunia (1), and Boerhavia diffusa (4). However, to our knowledge, incidence of this pathogen on W. somnifera has not been reported so far. Thus, wet rot of W. somnifera caused by C. cucurbitarum is a new report from India and worldwide. References: (1) G. E. Holcomb. Plant Dis. 87:751, 2003. (2) P. M. Kirk. Mycol. Pap. 152:1, 1984. (3) C. K. Maiti et al. Plant Dis. 91:467, 2007. (4) N. Singh et al. New Dis. Rep. 23:29, 2011.

Death certification in a teaching hospital--a one year review

Death certification is believed to be very poor and inaccurate in most of the health institutions in India. A hospital based study on assessing the accuracy in completing the medical certificates of cause of death was conducted in Regional Institute of Medical Sciences (RIMS), Imphal during September to December 2007. Medical Certification of Cause of Death (MCCD) from the Medical Record Section for the period from 1st January up to 31st December, 2006 were audited for errors committed in completing the certificates. Data extracted using a proforma--age, sex, date of death, causes of death as recorded, department. Major error was observed in 38.3% and minor error was observed in 77.6% of the MCCD. Mechanism of death was listed as the cause of death in 21.9% of the certificates. The most prevalent type of error was the absence of time intervals (65.3%).

Distribution patterns of natural radioactivity and delineation of anomalous radioactive zones using in situ radiation observations in Southern Tamil Nadu, India

In situ radiation measurements in the beach sectors and adjacent hinterlands and along rivers in the interiors of southern peninsular India were carried out using a portable radiation survey meter. A very high intrinsic anomalous radioactivity >26microGy/h has been observed in the hinterlands within a fresh quarry and weathered boulders in the syenite rock body around Puttetti in the western Kanyakumari district of southern Tamil Nadu. Over the weathered hillocks in the hinterlands adjacent to the coast around Inayam, Kurumpanai and Midalam, the in situ radiation measurements have also exhibited high radioactivity ranging from 4 to 22microGy/h which is significantly higher than the radiation exposure rates (RER) observed along the beach sectors at various locations from Chavara to Tuticorin (1-14microGy/h). The observed radiation levels are presumably the highest concentration in southern India and it is the first time that such a high intrinsic radiogenic source in the hinterlands is reported in southwest coast of India. It is also observed based on the laboratory analysis of samples and in situ radiation data that the rivers/channels in this region contain insignificant level of radioactivity concentration and hence they do not contribute much to the placer deposits on the beaches. The placer deposits associated with significant RER (both in situ observations as well as laboratory estimates from samples) in the beach sectors from Kadiapattanam to Inayam are inferred to be derived through the country rocks/weathered hillocks in the immediate hinterlands.

Analysis of normal electrocardiograms of Jamunapari goats

In the present study, the normal electrocardiographic (ECG) values in the adult male Jamunapari breed of the goats were described. The mean heart rate in the goats was 127 +/- 3.46 per minute and ranged 107 and 168. The amplitudes and duration of various waveforms of ECG for six standard limb leads (I, II, III, aVL, aVR and aVF) were estimated. The overall P, QRS and T amplitudes (millivolts) were 0.065 +/- 0.01, 0.47 +/- 0.06 and 0.20 +/- 0.014 respectively. The duration (seconds) of these wave forms were 0.042 +/- 0.005, 0.033 +/- 0.002 and 0.10 +/- 0.014, respectively. The P-R interval and R-R intervals ranged between 0.06- 0.14 and 0.40-0.58 respectively. The average Q-T interval was 0.24 +/- 0.01 second, indicating the time for which the caprine ventricle remained depolarized. The corrected QT interval was also calculated which was found to vary from 0.24 to 0.57. The mean frontal plane vectors for the wave forms P, QRS and T wave forms were +49.99 +/- 6.02, +37.34 +/- 4.05 and +52.26 +/- 6.79 degrees respectively.

Aspiration vs nonaspiration technique of cytodiagnosis--a critical evaluation in 160 cases

The two sampling techniques were studied in 160 randomly selected cases of superficial swellings in various sites of the body. They were sampled by fine needle aspiration (FNA) and by non-aspiration (NA) (a needle without application of aspiration pressure). Cell samples were cytologically assessed and critically evaluated using five objective parameters. Contamination with blood was more in lymphnode, thyroid and liver lesions in aspiration smears than NA smears and values were statistically significant. Similarly when compared for the degree of cellular trauma and cellular degeneration statistically significant better results were obtained by nonaspiration technique for lymphnode lesions. Regarding amount of cellular material obtained by FNA, statistical significant better results were found for breast lesions only. Statistically significant better maintenance of architecture was observed only for thyroid lesions by NA technique. Better average scores were observed by NA technique for lymphnode and thyroid only. Categorizing all the smears obtained by FNA & NA on the basis of their scores according to predetermined criteria, greater number of diagnostically adequate specimens were obtained by FNA than by NA but the number of diagnostically superior specimens obtained by NA technique was found to be more than that by FNA. The difference was found to be statistically significant. However the number of inadequate smears was also more by NA technique than by FNA technique.

Common nitrogen control of caesium uptake, caesium toxicity and ammonium (methylammonium) uptake in the cyanobacterium Nostoc muscorum

Studies were carried out to examine the role of ammonium transport activity in the control of caesium uptake and toxicity in Nostoc muscorum. The results showed a definite specific role of the ammonium-repressible/derepressible ammonium transport system of the cyanobacterium in caesium uptake, accumulation and toxicity. Furthermore, the results showed that N. muscorum can acquire resistance against diazotrophically-associated caesium toxicity when supplied with ammonium as a nitrogen source. In addition, alternatively, a mutant strain was Cs-resistant in the absence of any effect on NH(+4)-transport, suggesting that Cs+ resistance may be determined at more than one cellular site.

Mutational analysis of the NH4+-nitrogen controls that regulate ammonium transport activity, heterocyst differentiation, nitrogenase activity and the heterocyst-spacing pattern in the cyanobacterium Nostoc muscorum

Mutational analysis of the genetic determinants mediating NH(4+)-nitrogen regulating effects on NH(4+)-transport activity, heterocyst differentiation, nitrogenase activity and heterocyst pattern formation was carried out in Nostoc muscorum. Evidence suggested the operation of three separate genetic determinants in such nitrogen control; one mediating NH(4+)-repression control on both heterocyst formation and NH(4+)-transport activity, a second (Nif-R) mediating NH(4+)-repression control on nitrogenase synthesis/activity and a third (Pat-R) essential for intercalary heterocyst formation/distribution. Ammonia itself functioned as repressor signal of heterocyst formation and nitrogenase synthesis/activity and the glutamine synthetase enzyme played no role in the repression/derepression control of heterocyst development and functional nitrogenase formation.

Mutational replacement of molybdenum by vanadium in assimilation of N2 or NO3- as nitrogen source in the cyanobacterium Nostoc muscorum

Tungsten resistant (Wr) mutants of Het+Nif+Nia+, Het+Nif-Nia+ and Het+Nif+Nia- strains of Nostoc muscorum were isolated with severely defective molybdate transport activity. All such mutants showed vanadium (V)-dependent nitrogenase activity and/or nitrate reductase activity and V-dependent growth on N2-nitrogen and/or NO3(-)-nitrogen and V-dependent NO3(-)-repression of heterocyst formation and nitrogenase activity. None of them grew with molybdenum (Mo) under parallel growth condition. Results strongly suggest the ability of V to replace Mo in N2-assimilation or NO3(-)-assimilation under Mo-deficiency.

Dopaminergic regulation of luteinizing hormone-releasing hormone release at the median eminence level: immunocytochemical and physiological evidence in hens

Theoretically, the most effective inhibitory control of hypophysiotropic luteinizing hormone-releasing hormone (LHRH) release might occur through a presynaptic inhibition of LHRH neuronal terminals at the median eminence (ME) level. Since: (a) we have recently reported the existence of synaptic contacts between dopamine- and LHRH-containing processes in the ewe ME, and (b) nutritional deprivation induces an ovulatory failure in both birds and mammals, we have assessed the possibility that the anovulatory state induced by feed withdrawal (FW) in laying hens, might be caused by a dopaminergic inhibition of LHRH release at the ME level. Laying hens at the start (35 weeks old) and end (75 weeks old) of their commercial egg-laying life were killed at 0, 1, 2 and 4 days after FW. Serum luteinizing hormone (LH) and progesterone (P4), in vitro release of LHRH by isolated ME, and LHRH content in ME and preoptic area (POA) were determined by RIA. ME content of dopamine (DA) and its main metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) were assessed by LCED. The distribution of LHRH and tyrosine hydroxylase (TH)-containing processes at the ME level of the hen was determined immunocytochemically. In the hen, LHRH-containing cell bodies are localized in the anterior hypothalamus and medial POA. LHRH-containing axons project toward the ME and infundibulum through the ventral-lateral hypothalamus. TH-containing perikarya are concentrated in the arcuate nucleus and in the adjacent part of the periventricular nucleus, dorsal to the arcuate. TH-containing axons converge toward the ME and descend into the infundibulum. Dense concentrations of TH- and LHRH-containing processes are located in the lateral and mediobasal portions of the external layer of the ME, providing opportunities for synaptic interactions between them. Ovulatory failure and regression of the ovary and reproductive tract occurred 2-3 days after FW at the end, but not at the beginning of the hen's commercial egg-laying life. After FW, hens at the end of their productive life had higher (p less than 0.01) tuberoinfundibular DA turnover, produced less LHRH, and had lower serum LH and P4 than hens undergoing FW at the beginning of their productive life. In addition, in vitro release of HRH from denervated ME tissue of hens undergoing FW at the end of their commercial egg-laying life was higher and was reversed in a dose-dependent fashion by DA, but not by serotonin. Thus, the ovulatory failure associated with FW in laying hens might be caused by a presynaptic inhibition of in vivo LHRH release at the level of ME hypothalamic neuronal terminals.

Evidence for a role of glutamine synthetase in assimilation of amino acids as nitrogen source in the cyanobacterium Nostoc muscorum

Methylammonium/ammonium ion, glutamine, glutamate, arginine and proline uptake, and their assimilation as nitrogen sources, was studied in Nostoc muscorum and its glutamine synthetase-deficient mutant. Glutamine served as nitrogen source independent of glutamine synthetase activity. Glutamate was not metabolised as a nitrogen source but still inhibited nitrogenase activity and diazotrophic growth. Glutamine synthetase activity was essential for the assimilation of N2, ammonia, arginine and proline as nitrogen sources but not for the control of their transport, heterocyst formation, and production of ammonia or aminoacid dependent repressor signal for N2-fixing heterocysts. These results also suggest that glutamine synthetase serves as the sole route of ammonia assimilation and glutamine synthesis, and ammonia per se as the repressor signal for N2-fixing heterocysts and methylammonium (ammonium) transport.

Evidence for energy-dependent copper efflux as a mechanism of Cu2+ resistance in the cyanobacterium Nostoc calcicola

Wild-type Nostoc calcicola carried out oxygenic photosynthesis extremely sensitive to copper. A Cu(2+)-resistant mutant (Cu-R1) of the cyanobacterium grew normally at high concentrations of Cu2+. Its ability to grow under such conditions was found to be due to mutational acquisition of an energy-dependent efficient system of Cu(2+)-efflux, which rendered Cu(2+)-inhibited oxygenic photosynthesis fully reversible.

Relationship of blood markers to disease severity and drug efficacy in rat adjuvant arthritis

Rat adjuvant arthritis (AA) was used as a model to evaluate several blood markers as possible predictive indicators of drug efficacy. AA was induced in Sprague-Dawley rats by the injection of complete Freund's adjuvant into the right hind foot pad. The rats were dosed p.o. from day 18 to day 31 with levamisole (10 mg/kg), indomethacin (1 mg/kg), diclofenac sodium (0.5 & 1 mg/kg), and prinomide (10 & 20 mg/kg). Disease severity was assessed by paw circumference on day 31. The following blood markers were analyzed: hyaluronate by ELISA, prostaglandin E2 by RIA, ESR by micro-dispette, total PMN by Technicon H-1, and albumin by BCG dye. Blood marker correlation (r) to disease severity was: hyaluronate (0.71), prostaglandin E2 (0.58), ESR (0.52), PMN (0.58), and albumin (-0.71). The relative rank order of drug efficacy (indomethacin, diclofenac sodium, and prinomide) did not differ using the change in paw circumference (day 31-day 17) or blood markers. Levamisole exacerbated the disease as measured by all the above parameters. Thus, these blood markers provide additional information for the statistical evaluation of drugs in rat adjuvant arthritis.

Pharmacological modulation of rat monocytes: in vivo effects on Ia expression and interleukin-1 production

We have shown that during the developing phase of adjuvant disease (AD) in rats the expression of MHC class II (Ia) antigens on blood monocytes (BM) was enhanced. The results of a study in established AD are reported now. Four agents were tested: indomethacin and diclofenac-sodium (1 mg/kg/day); levamisole and prinomide (10 mg/kg/day), administered orally from day 18-31 after induction of AD. We assessed the following BM parameters: Ia expression, interleukin-1 (sIL-1) production, and membrane bound IL-1 (mIL-1). In AD Ia expression was enhanced, no changes occurred in mIL-1 or sIL-1. Indomethacin treatment reduced sIL-1 production, levamisole Ia expression and mIL-1 activity, prinomide all three parameters measured and diclofenac, though clinically effective, none.

Influence of different forms of nitrogen on uptake of ammonium, glutamate and glutamine in the cyanobacterium Nostoc muscorum

Effect of various types of nitrogen nutrition was studied on the uptake of ammonium, glutamate and glutamine by Nostoc muscorum and its Het-Nif- mutant. Ammonium nitrogen acted as a potent inhibitor/repressor of ammonium, glutamate and glutamine transport. Nitrate nitrogen was found to be a strong inhibitor/repressor of ammonium transport, a partial inhibitor/repressor of glutamate transport but, caused a partial stimulation of glutamine transport.

Genetic transformation of glutamine auxotrophy to prototrophy in the cyanobacterium Nostoc muscorum

Glutamine auxotrophic (Gln-) and L-methionine D,L-sulfoximine (MSX) resistant (MSXr) mutants of N. muscorum were isolated and characterized for nitrogen nutrition, nitrogenase activity, glutamine synthetase (GS) activity and glutamine amide, alpha-keto-glutarate amido transferase (GOGAT) activity. The glutamine auxotroph was found to the GOGAT-containing GS-defective, incapable of growth with N2 or NH4+ but capable of growth with glutamine as nitrogen source, thus, suggesting GS to be the primary enzyme of both ammonia assimilation and glutamine formation in the cyanobacterium. The results of transformation and reversion studies suggests that glutamine auxotrophy is the result of a mutation in the gln A gene and that gln A gene can be transferred from one strain to another by transformation.

EVIDENCE FOR INTERGENERIC TRANSFORMATION IN FILAMENTOUS, DIAZOTROPHIC CYANOBACTERIA

A clonal population of a mutant Nostoc muscorum, with the ability to assimilate azide as a fixed nitrogen source, was used as a source of donor DNA for transforming Anabaena doliolum from an azide-sensitive to an azide-assimilating phenotype. The donor DNA. transformed A. doliolum efficiently and the transformation process was sensitive to DNAase, resistant to RNAase A, dependent on photosynthetic light and required a specific contact period between donor DNA and recipient cells. The gene(s) responsible for azide assimilation appear to be located on chromosomal DNA and not on plasmid DNA. The transformants of A. doliolum resemble the azide assimilating mutant strain of N. muscorum in respect of (1) azide repression of heterocyst and nitrogenase formation, (2) azide-dependent increase in phycocyanin to chlorophyll ratio. These results suggest that the chromosomal DNA of mutant N. muscorum, and not its plasmid DNA, is the carrier of genetic information for its azide assimilatory phenotype and that this can be transferred efficiently to A. doliolum.

CARBON NUTRITION AND THE REGULATION OF UPTAKE HYDROGENASE ACTIVITY IN FREE-LIVING AND SYMBIOTIC ANABAENA CYCADEAE

Anabaena cycadeae was grown with N₂ as nitrogen source, either photoautotrophically in light or with glucose as carbon source in darkness. The rate of growth was much slower in darkness but the heterocyst frequency was much the same; nitrogenase activity (on a chlorophyll basis) was about half that of light-grown cells. Light-grown organisms contained uptake hydrogenase activity but dark-grown organisms did not. The addition of glucose to light-grown organisms was followed by the disappearance of uptake hydrogenase activity over the following 48 hours and the disappearance was independent of light. Heterocyst frequency and nitrogenase activity were much less affected by glucose addition. A. cycadeae growing symbiotically in cycad roots had much higher heterocyst frequency and nitrogenase activity than the free-living form but no detectable uptake hydrogenase activity. It is suggested that the rate of supply of carbohydrate to the heterocyst controls the development of uptake hydrogenase activity and that the absence of this activity in the symbiotic cyanobacteria indicates that the organisms in the cycad roots have an ample supply of carbohydrate.

REGULATION BY AZIDE OF HETEROCYST AND NITROGENASE IN AZIDE-RESISTANT MUTANTS OF THE CYANOBACTERIUM, NOSTOC MUSCORUM

A novel class of azide-resistant mutants of N, muscorum is described in which azide caused inhibition of heterocyst differentiation and nitrogen fixation without causing inhibition of growth. The results indicate the utilization of azide, as a fixed nitrogen source, by the mutant strain. An increase in the ability to take up azide and in the phycocyanin/chlorophyll ratio following growth of the mutant in azide-containing medium are additional findings which support the conclusion that the mutant utilizes azide as a source of nitrogen. In the parental strain, Ca²⁺ -dependent and Mg²⁺ -dependent ATPases, and cellular nitrate reductase were inhibited by azide. The corresponding ATPases from the mutant strain were not inhibited by azide. There was evidence, in cell-free extracts, for an enzyme system which utilized azide as an electron acceptor and NADPH-ferredoxin as electron donor. The activity of this system was significantly higher (on a protein basis) in cells of the mutant grown on azide than in cells of either the parent or the mutant when grown on nitrate. It is suggested that the azide resistance of this class of mutant is due to a mutation which leads to azide resistant Ca²⁺ - and Mg²⁺ - ATPases. Such a mutation may allow an azide utilizing system, inherently present in both parent and mutant strains, to be expressed.

Loss of aerobic nitrogen fixation associated with kasugamycin resistance in the heterocystous nitrogen-fixing, streptomycin resistant blue-green alga Nostoc muscorum

Heterocystous N2-fixing, Streptomycin resistant (Het (+)Nif(+)Str-R) Nostoc muscorum produces two groups of Kasugamycin resistant (Kas-R) phenotypes: one group showing normal heterocyst frequency and normal aerobic growth with N2 as a nitrogen source, the other group showing loss of growth with N2 as nitrogen source under aerobic growth conditions. Examination of strains showing Kas-R associated loss of aerobic N2 growth shows them to comprise three classes: Class A showing loss of both heterocyst and nitrogenase activity, class B showing formation of heterocyst but no nitrogenase activity and class C lacking heterocyst but containing microaerobic nitrogenase activity. The three classes of mutants revert to aerobic prototrophy with almost similar frequency of about 10(-6) suggesting them to have arisen as a result of single mutational events. Their reversion to prototrophy is simultaneously accompanied by the loss of Kas-R phenotype. All the phenotypic revertants in general appear more or less similar to the parental strain in respect to heterocyst formation, aerobic N2 growth and Kasugamycin sensitivity (Kas-S).

Evidence for ammonia as an inhibitor of heterocyst and nitrogenase formation in the cyanobacterium Anabaena cycadeae

Growth and regulation of heterocyst and nitrogenase by fixed nitrogen sources were studied comparatively in parent and glutamine auxotrophic mutant of Anabaena cycadeae. The parent strain grew well on N2, NH+4 or glutamine while the mutant strain grew on glutamine but not on N2 or NH+4. The total lack of active glutamine synthetase in the mutant strain thus appears to be the reason for its observed lack of growth in N2 or NH+4, which explains why it is a glutamine auxotroph and at the same time shows glutamine synthetase to be the sole primary ammonia assimilating enzyme. NH+4 repression of heterocyst and nitrogenase in the mutant and the parental strains and their derepression by L-methionine-DL-sulfoximine suggest that NH+4 per se and not glutamine synthetase mediated pathway of ammonia assimilation is the initial repressor signal of heterocyst and nitrogenase in A. cycadeae.

Inhibition of photosystem II of nitrogen-fixing blue-green alga Nostoc linckia by the rice-field herbicide benthiocarb

Effects of rice-field herbicide benthiocarb (S(4-chlorobenzyl)-N,N-diethyl thiolcarbamate) was studied on the nitrogen-fixing blue-green alga Nostoc linckia. The herbicide caused inhibition of growth and heterocyst formation, an increase in intensity of photoacoustic signals, and a four-fold reduction in oxygen evolution, but did not affect dark O2-uptake. The inhibition of growth and heterocyst formation was relieved by 500 micrograms/ml glucose. A Het-Nif- mutant of Nostoc muscorum failed to show an increase in reversion, frequency after treatment with 10 micrograms/ml benthiocarb for 1 hr.

Studies on Claviceps parasitic on Panicum species in India

Panicum repens and P. antidotale were found to be infected with Claviceps sp. This is the first report of ergot on P. repens. The pyrenomycete produced abundant sclerotia on the host plants. The sclerotia contained 0.71 and 0.68% alkaloids, respectively, which predominantly consisted of chanoclavine, festuclavine and agroclavine. The infected grasses were possibly mycotoxic. Submerged cultures of Claviceps strain isolated from Panicum spp. produced significant amount of chanoclavine, festuclavine and agroclavine. No pharmaceutically important alkaloid was found in sclerotia or in submerged culture.