172 research outputs found
Physiological roles and regulation of the cryptic prophage-encoded small protein DicB and small RNA DicF in Escherichia coli
No full textBacterial adaptation to stress conditions is vital for their survival in different environments. In the past decade, the important roles that small RNAs (sRNAs) and small proteins perform in regulating the stress response in bacteria has become evident. While the roles of numerous sRNAs and small proteins encoded on the bacterial core genome have been characterized, very few that are phage or prophage-encoded have been studied. This dissertation describes the roles and regulation of the sRNA DicF and small protein DicB encoded on the Qin cryptic prophage of Escherichia coli K12. Bacterial genomes harbor cryptic prophages that have lost genes required for induction, excision from host chromosomes, or production of phage progeny. DicB and DicF are encoded on the dicBF operon, which is located in the immunity region of the cryptic prophage Qin. DicB and DicF have previously been implicated in inhibiting cell division of the host bacterium. In this study, we show that the small protein DicB protects the host cells from phage infection. DicB specifically inhibits infection by λ and other phages that use ManYZ inner membrane proteins to inject their DNA into the host cell. DicB also inhibits the canonical function of ManYZ, which is mannose sugar transport. We demonstrated that the previously known interaction between DicB and MinC, a host protein involved in proper positioning of the Z ring during cell division, is necessary for the DicB-dependent phenotypes involving ManYZ identified in this study. The sRNA DicF is widely conserved is many E. coli strains and inhibits ftsZ mRNA translation in E. coli. In this study, we establish the mechanism of this regulation by characterizing the base pairing interaction between DicF and ftsZ, and delineate the roles of other host factors involved in this regulation. Additionally, we identify new mRNA targets of the sRNA DicF, that are primarily involved in host cell metabolism. The final part of this thesis work describes the genetic mechanisms defining the regulation of the dicBF operon. The dicBF operon is constantly repressed under laboratory conditions by the repressor DicA. In this work, we identified that the protein Rem impairs DicA repression of the dicBF operon and is the antirepressor of DicA. We show that Rem induces expression of dicB and dicF, which leads to the concomitant cell filamentation phenotype as DicB and DicF are cell division inhibitors. In the absence of the dicBF gene products, the promoter of the dicBF operon was found to undergo spontaneous induction in a subset of cells, reminiscent of the λ phage bistable genetic switch. Lastly, urea and high temperature were identified as strong inducers of the dicBF promoter in strains deleted for the dicBF operon. Our results suggest that expression of the dicBF operon is regulated in multiple ways in E. coli K12, indicative of the complex relationship that exists between the host cell and cryptic prophages.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2023-05-01The student, Preethi Narayani Thattai Ragunathan, accepted the attached license on 2020-12-22 at 15:01.The student, Preethi Narayani Thattai Ragunathan, submitted this Dissertation for approval on 2020-12-22 at 16:38.This Dissertation was approved for publication on 2020-12-23 at 13:10.DSpace SAF Submission Ingestion Package generated from Vireo submission #16136 on 2021-09-16 at 17:01:29Made available in DSpace on 2021-09-17T02:34:10Z (GMT). No. of bitstreams: 2
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Segmentation of Carpal Bones: Based on Statistical Shape Models using Spherical Harmonics
No full textA study has been conducted on the application of Spherical Harmonics based Statistical Shape Modelling for Image Segmentation. This study is focused on the segmentation of Wrist bones using the above mentioned technique.Mechanical Engineering | BioMechanical Desig
Effect of γ-aminopropyltriethoxy silane (γ-APS) coupling agent on mechanical and morphological properties of high density polyethylene (HDPE)/acrylonitrile butadiene rubber (NBR)/palm pressed fibre (PPF) composites
No full textA Study of Electrolyte Disturbances in HIV Infected Patients
No full textINTRODUCTION:
AIDS was first recognized in the United States in the
summer of 1981, when the U.S. Centers for Disease Control and Prevention
(CDC) reported the unexplained occurrence of Pneumocystis jiroveci
(formerly P. carinii) pneumonia in five previously healthy homosexual men
in Los Angeles and of Kaposi's sarcoma (KS) with or without P. jiroveci
pneumonia in 26 previously healthy homosexual men in New York and Los
Angeles. Within months, the disease became recognized in male and female
injection drug users (IDUs) and soon thereafter in recipients of blood
transfusions and in hemophiliacs. As the epidemiologic pattern of the
disease unfolded, it became clear that an infectious agent transmissible by
sexual (homosexual and heterosexual) contact and blood or blood products
was the most likely etiologic cause of the epidemic.
In 1983, human immunodeficiency virus (HIV) was isolated
from a patient with lymphadenopathy, and by 1984 it was demonstrated
clearly to be the causative agent of AIDS. In 1985, a sensitive enzymelinked
immunosorbent assay (ELISA) was developed, which led to an
appreciation of the scope and evolution of the HIV epidemic at first in the
United States and other developed nations and ultimately among developing
nations throughout the world.
Luc Montaineger from Pasteur Institute, France, discovered the
causative agent in 1983,and labelled it as LAV -2 lymphadenopathy
associated virus.[2]. Robert Gallo from USA also isolated the virus in 1984,
and named it HTLV-III, Human T Lymphotropic Virus-III. The
International committee on Taxonomy of Viruses re designated both the
viruses and named it as Human Immunodeficiency Virus.
Acquired immunodeficiency syndrome (AIDS) is caused by human immunodeficiency virus (HIV) which can be contracted
through sexual contact, exposure to blood including sharing contaminated
needles and syringes and by certain blood products or other body fluids.
Human immunodeficiency virus/acquired immunodeficiency syndrome has
been the leading cause of death among young adults in the United state and
has a devastating impact on people in the developing countries. The clinical
presentation of this disease include pneumonia, fever/pyrexia loss of vision,
night sweats, chronic diarrhoea, weight loss, lymphadenopathy, cough, and
itchy maculopapular generalized skin rash, blue discolouration, anaemia and
hairy leukoplakia.
AIMS OF THE STUDY:
1 To find out the prevalence of electrolyte disturbances in HIV infected
Patients.
2. And their correlation with CD4+ counts.
MATERIAL AND METHODS:
Study design : Cross sectional study.
Study Population:
The cross sectional study included all 150 patients
admitted in medicine and STD wards, GRH. Both male and female patients
were included in this study.
Place : Medicine Dept., Govt. Rajaji Hospital, Madurai Medical College,
Madurai.
Collaborative Departments: 1) Department of Bio-Chemistry,
Govt. Rajaji Hospital, Madurai Medical College, Madurai and
2) Department of STD, Govt. Rajaji Hospital, Madurai Medical College,
Madurai.
Period of study: 6 months (Nov 1, 2008 to April 30, 2009).
Sample size: 150 patients.
Selection of the study subjects:
150 patients admitted with HIV infection in
the medical and STD wards, Govt. Rajaji Hospital from July to December
2008 formed the study group.
All patient’s with HIV infection, admitted in both
medical and dept. of STD are included in this study which includes both
AIDS related complex and AIDS. Since only symptomatic patients and
patients with opportunistic infections(eg. T.B meningitis, chronic diarrhea,
etc., ) are getting admitted in wards, asymptomatic patients were not
included in this study.
111 male and 39 female patients were included in this
study. Sex distribution is shown in table 1.
RESULTS: It indicate the mean age is 30.85 ± 4.78 (±1SD). The minimum and maximum CD4+ counts are 75, 349/micro litre respectively.
The mean CD4 count is 209.45±80.88/micro litre (±1SD).The mean serum
sodium level is 136.65±6.00(±1SD)Meq/litre. The minimum and maximum
serum sodium level are 125 Meq/litre,146 Meq/litre respectively (Figure 6)
(Table 1).The mean serum potassium levels is4.01±0.95 Meq/litre (±1SD).
The minimum and maximum serum potassium levels observed are 2.5
Meq/litre, 7.4 Meq/litre respectively (table 2) (Figure 7).
Among 150 pt’s, 52 pt’s had hyponatremia and 98 patients had normal sodium levels (Figure2). The percentage of hyponatremia is 34.7%. Among the 52 patients, female patients are 32 and males are 20 . And the percentage of hyponatremia for both males and females are 14.7%, 20.0% respectively (table 3) (Figure 4).
CONCLUSION:
Hyponatremia, hypokalemia and hyperkalemia are common
electrolyte disorders with HIV infected patients. Because of the high
incidence of the electrolyte disturbances with HIV infected patients, close
monitoring and aggressive management are mandatory
The horse has bolted: revisiting the market reaction to going concern modifications of audit reports
No full textThis paper examines what value is added by an audit report through an investigation of the information content for first-time going concern modifications (GCMs). Consistent with prior research, we find no evidence of a short-term market reaction to the public announcement of a first-time GCM. We document a significant adverse medium-term market reaction in the 12 months prior to a first-time GCM announcement, but find no evidence of a persistent market underreaction in the 12 months following the announcement. These results are consistent with an audit opinion fulfilling an attestation function and confirming the deteriorating financial condition of a firm. Copyright (c) The Authors Journal compilation (c) 2007 AFAANZ.
Effect of polypropylene maleic anhydride (PPMAH) on mechanical and morphological properties of polypropylene (PP)/recycled acrylonitrile butadiene rubber (NBRr)/empty fruit bunch (EFB) composites
No full textA study on clinico-immunological profile and treatment outcome of psoriatic arthritis
No full textINTRODUCTION:
Robert Willan, the British dermatologist described psoriasis as an independent disease in 18-th century. The French Physician Baron Jean Louis Alibert first described the association between the psoriasis and psoriatic arthritis in 1918. Initial clinical features of PsA were described first by Wright V et al in 1959 and along with Moll they published the first classification criteria in 1973. Psoriatic arthritis was included as a distinct arthritis in the classification of rheumatic diseases in 1964 by American Rheumatism Association.
Psoriatic arthritis is one of the diseases of SpA family and defined as inflammatory arthritis occurring in patients with psoriasis and negative test for rheumatoid factor commonly. It is a progressive and disabling disease and often associated with increased morbidity.
According to one prospective study by Kane D [et. Al.], psoriatic arthritis constituted 13% of new patients attending early arthritis clinic and progressive erosive change occurs in around 50% of patients in the first few years.
The exact prevalence of psoriasis and psoriatic arthritis is not known and the prevalence of psoriasis in general population is around 1 to 3 %. The incidence of arthritis in patients with psoriasis is between 5 and 7 %. There are only few studies in psoriatic arthritis in India especially the immunological profile like anti -CCP antibodies in psoriatic arthritis, correlation of skin and arthritis. So we took this study to correlate the skin disease and arthritis as well as to study the immunological profile of patients with psoriatic arthritis.
AIMS AND OBJECTIVES:
1) To study the clinical profile of patients with psoriatic arthritis.
2) To assess the correlation between skin disease and arthritis in patients with psoriatic arthritis.
3) To study the immunological profile of patients with psoriatic arthritis.
4) To assess the outcome of patients with psoriatic arthritis.
MATERIALS AND METHODS:
PLACE OF THE STUDY:
Department of Rheumatology, Rajiv Gandhi Government General Hospital & Madras Medical College, Chennai-3.
DESIGN OF THE STUDY:
Prospective analytical study.
PERIOD OF THE STUDY:
2 years -From January 2011 to December 2012.
ETHICS COMMITTEE APPROVAL:
Approval from hospital ethics committee was obtained before starting the study.
CONSENT:
A clearly written informed consent on their own language was taken from all patients and from their parents in case juvenile PsA.
INCLUSION CRITERIA:
1) Adults who are fulfilling CASPAR classificat ion criteria for psoriatic arthritis.
2) Children fulfilling ILAR criteria for Juvenile psoriatic arthritis.
EXCLUSION CRITERIA:
1) Reactive arthritis,
2) Rheumatiod arthritis,
3) Enteropathic arthritis,
4) Crystal arthritides.
RESULTS:
Totally 110 patients were included for the study over two years period. Out of these 61 (55.5 %) were males and 49 (44.5 %) were females. Lowest age of the patient in our study was 9 years and highest was 70 years. Mean age of the patient was 39.55 years. Majority of the patients were in between 3rd to 5th decade.
CONCLUSION:
1) The mean age of the patients in our study was 39.5 years.
2) Slight male preponderance was observed (1.2 : 1 ).
3) Skin disease preceding arthritis was noted in majority of patients (56%) and simultaneous onset was found in 19 % of patients.
4) Onset of arthritis after 10 years of psoriasis is uncommon (9%).
5) Psoriasis vulgaris was the commonest skin pattern and symmetric polyarthritis was the commonest subtype of arthritis noted in our study.
6) The prevalence of ANA, anti-CCP and RF positivity in our patients were 14.2%, 9.7 %, 6.3% respectively.
7) Anterior uveitis was observed in3.6 % of our patients.
8) Positive correlation between skin and joint disease activity was noticed although statistically not significant.
9) Anti-CCP positive psoriatic arthritis patients had higher number swollen, tender joints and more radiographic damage.
10) At the end of one year follow-up, 57.5% of patients showed PsARC improvement response.
11) At the end of two years follow-up, 48.7% of patients showed PsARC response and 2.7% showed Minimal Disease Activity response
Single molecule fret study on the mechanism of RecA mediated strand exchange
No full textRecA plays a critical role during double strand break repair via homologous recombination. During the strand exchange reaction, RecA forms a helical filament on single stranded (ss) DNA that searches for homology and exchanges complementary base pairs with a homologous double strand (ds) DNA to form a new heteroduplex. The study of strand exchange in ensemble assays is limited by the diffusion limited homology search process which masks the subsequent strand exchange reaction. We developed a single molecule fluorescence assay with a few basepair and milliseconds resolution which can separate initial docking from the subsequent propagation of joint molecule formation. Our data suggests that propagation occurs in 3 bp increments with destabilization of the incoming dsDNA and concomitant pairing with the reference ssDNA. Our model for strand exchange links structural models of RecA to its catalytic function.
Next, we investigated the mechanism of RecA mediated homology search. Using tools with high spatiotemporal resolution to observe the encounter complex between the RecA filament and dsDNA, we present evidence in support of the “sliding model” wherein a RecA filament diffuses on a dsDNA track. Our results suggest that the sliding of the dsDNA relative to the RecA filament can explain the rapid changes in FRET which we have observed upon the docking of non-homologous dsDNA to the RecA filament. We further show that homology can be identified during such sliding. Sliding is thermally driven and occurs in the absence of ATP hydrolysis. Furthermore, homology recognition and basepairing can involve as few as 6 bp of complementarity. Our observation presents an example of how a multi-protein complex bound to DNA can serve as a vehicle enabling homology search processes via 1-D sliding.
Finally, we demonstrate how an extension of the two color FRET assay to measure four colors simultaneously allows us to measure the correlation of reaction completion between the two ends of a single synaptic complex. We expect that this method will enable a multi dimensional analysis of independent reaction coordinates with broad applications in measuring the correlated dynamics of more complex biological systemsItem withdrawn by Mark Zulauf ([email protected]) on 2012-04-02T14:25:15Z
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ChemInform Abstract: Studies of Phthalazine-5,8-quinone, a Ring Contraction, and Some Novel and Potentially Useful Fluorescent Phthalimides.
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