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1.
J Appl Microbiol ; 127(6): 1635-1645, 2019 Dec.
Article in English | MEDLINE | ID: mdl-31517421

ABSTRACT

AIM: To study the association of opportunistic infection due to Myroides odoratimimus in piglets immunocompromised by porcine circovirus type 2 (PCV2) infection. METHODS AND RESULTS: The clinical samples (n = 101) were analysed bacteriologically. The isolates were identified by their phenotypes and MALDI TOF-MS analysis as Myroides species. The phylogram constructed based on nucleotide sequences of the 16S rRNA gene showed identity (~99%) with the M. odoratimimus isolates. The minimum inhibitory concentration values for antibiotics revealed M. odoratimimus to be resistant against carbapenem, cephalosporins, aminoglycosides and fluoroquinolones. The presence of PCV2 in affected tissue samples was confirmed by amplification of the 565 bp region of ORF2 of the PCV2 genome. The topology of the phylogenetic tree grouped the PCV2 with cluster-2d. CONCLUSIONS: PCV2 being immunosuppressive in nature might have impaired the immunity thereby increasing the susceptibility of immunocompromised piglets to opportunistic pathogens such as M. odoratimimus leading to disease severity and high mortality. The M. odoratimimus isolates were found to be multidrug resistant and evidenced for uncertain clinical relevance and hence could act as hidden source of public health hazard. SIGNIFICANCE AND IMPACT OF THE STUDY: Myroides odoratimimus is a rarely reported human pathogen. We reported the incidence of infection due to seemingly rare isolates of M. odoratimimus causing an outbreak of pneumonia in piglets. This appears, to the best of authors' knowledge, to be the first outbreak due to Myroides recorded in animal clinical cases described in the literature.


Subject(s)
Flavobacteriaceae Infections/immunology , Flavobacteriaceae Infections/microbiology , Flavobacteriaceae/isolation & purification , Porcine Postweaning Multisystemic Wasting Syndrome/immunology , Porcine Postweaning Multisystemic Wasting Syndrome/microbiology , Animals , Anti-Bacterial Agents/pharmacology , Circovirus/classification , Circovirus/genetics , Circovirus/isolation & purification , Flavobacteriaceae/classification , Flavobacteriaceae/drug effects , Flavobacteriaceae/genetics , Immunocompromised Host , Microbial Sensitivity Tests , Phylogeny , RNA, Ribosomal, 16S/genetics , Swine , Weaning
2.
Prostate Cancer Prostatic Dis ; 20(4): 418-423, 2017 12.
Article in English | MEDLINE | ID: mdl-28653675

ABSTRACT

BACKGROUND: Obesity, a cause of subclinical inflammation, is associated with increased risk of high-grade prostate cancer (PC) and poor outcomes. Whether inflammation occurs in periprostatic white adipose tissue (WAT), and contributes to the negative impact of obesity on PC aggressiveness, is unknown. METHODS: In a single-center, cross-sectional design, men with newly diagnosed PC undergoing radical prostatectomy were eligible for study participation. The primary objective was to examine the prevalence of periprostatic WAT inflammation defined by the presence of crown-like structures (CLS-P) as detected by CD68 immunohistochemistry. Secondary objectives were to explore the clinical and systemic correlates of periprostatic WAT inflammation. Tumor characteristics and host factors including BMI, adipocyte diameter, and circulating levels of lipids, adipokines, and other metabolic factors were measured. Wilcoxon rank-sum, Chi-square, or Fisher's exact tests, and generalized linear regression were used to examine the association between WAT inflammation and tumor and host characteristics. RESULTS: Periprostatic fat was collected from 169 men (median age 62 years; median BMI 28.3). Periprostatic WAT inflammation was identified in 49.7% of patients and associated with higher BMI (P=0.02), larger adipocyte size (P=0.004) and Gleason grade groups IV/V tumors (P=0.02). The relationship between WAT inflammation and high Gleason grade remained significant after adjusting for BMI (P=0.04). WAT inflammation correlated with higher circulating levels of insulin, triglycerides, and leptin/adiponectin ratio, and lower high density lipoprotein cholesterol, compared to those without WAT inflammation (P's <0.05). CONCLUSION: Periprostatic WAT inflammation is common in this cohort of men with PC and is associated with high-grade PC.


Subject(s)
Adipose Tissue, White/pathology , Inflammation/pathology , Obesity/pathology , Prostatic Neoplasms/pathology , Adipose Tissue, White/metabolism , Aged , Body Mass Index , Humans , Inflammation/complications , Inflammation/metabolism , Inflammation/surgery , Male , Middle Aged , Neoplasm Grading , Obesity/complications , Obesity/metabolism , Obesity/surgery , Prostate/metabolism , Prostate/pathology , Prostate/surgery , Prostatectomy , Prostatic Neoplasms/complications , Prostatic Neoplasms/metabolism , Prostatic Neoplasms/surgery
3.
Oncogene ; 36(16): 2255-2264, 2017 04 20.
Article in English | MEDLINE | ID: mdl-27748766

ABSTRACT

Dysregulated activation of the CDK4/6 kinases is a hallmark of most mammary-derived carcinomas. ATP-competitive inhibitors against this complex have been recently advanced in the clinic and have shown significant activity, particularly against tumors driven by the estrogen receptor (ER). However, resistance to these compounds has begun to emerge often months to years after their initiation. We investigated potential mechanisms of resistance using cell line models that are highly sensitive to this class of drugs. After prolonged exposure to the selective and potent CDK4/6 inhibitor LY2835219, clones emerged and several were found to harbor amplification of the CDK6 kinase. Amplification of CDK6 resulted in a marked increase in CDK6 expression and reduced response of the CDK4/6 target, phospho-Rb (pRb), to CDK4/6 inhibitors. Knockdown of CDK6 restored drug sensitivity, while enforced overexpression of CDK6 was sufficient to mediate drug resistance. Not only did CDK6 overexpression mediate resistance to CDK4/6 inhibitors but it also led to reduced expression of the ER and progesterone receptor (PR), and diminished responsiveness to ER antagonism. The reduced ER/PR expression after CDK4/6 inhibitor resistance was additionally observed in tumor biopsy specimens from patients treated with these drugs. Alternative mechanisms of resistance to CDK4/6 inhibitors such as loss of pRb and cyclin E1 overexpression also exhibited decreased hormone responsiveness, suggesting that the clinical paradigm of sequential endocrine-based therapy may be ineffective in some settings of acquired CDK4/6 resistance.


Subject(s)
Breast Neoplasms/enzymology , Cyclin-Dependent Kinase 4/antagonists & inhibitors , Cyclin-Dependent Kinase 6/antagonists & inhibitors , Drug Resistance, Neoplasm , Protein Kinase Inhibitors/pharmacology , Receptors, Estrogen/metabolism , Aminopyridines/pharmacology , Benzimidazoles/pharmacology , Breast Neoplasms/diet therapy , Breast Neoplasms/metabolism , Cell Line, Tumor , Cyclin-Dependent Kinase 6/genetics , Female , Gene Amplification , Humans , MCF-7 Cells , Signal Transduction/drug effects
4.
3 Biotech ; 6(1): 60, 2016 Jun.
Article in English | MEDLINE | ID: mdl-28330130

ABSTRACT

Fourteen endophytic bacterial isolates were isolated from the rhizome of Curcuma longa L. were characterized on the basis of morphology, biochemical characteristics and 16S rRNA gene sequence analysis. The isolates were identified to six strains namely Bacillus cereus (ECL1), Bacillus thuringiensis (ECL2), Bacillus sp. (ECL3), Bacillus pumilis (ECL4), Pseudomonas putida (ECL5), and Clavibacter michiganensis (ECL6). All the strains produced IAA and solubilized phosphate and only two strains produced siderophore (ECL3 and ECL5) during plant growth promoting trait analysis. All the endophytic strains utilized glucose, sucrose and yeast extract as a carbon source where as glycine, alanine, cystine and glutamine as nitrogen source. The strains were mostly sensitive to antibiotic chloramphenicol followed by erythromycin while resistant to polymixin B. The endophytic strains effectively inhibit the growth of Escherichia coli, Klebsiella pneumoniae and some of the fungal strain like Fusarium solani and Alterneria alternata. The strain ECL2 and ECL4 tolerated maximum 8 % of NaCl concentration where as strains ECL5 and ECL6 6 % in salinity tolerance.

5.
J Chem Phys ; 142(17): 174910, 2015 May 07.
Article in English | MEDLINE | ID: mdl-25956123

ABSTRACT

Using Langevin dynamics simulations, we study effects of the shear force on the rupture of a double stranded DNA molecule. The model studied here contains two single diblock copolymers interacting with each other. The elastic constants of individual segments of diblock copolymer are considered to be different. We showed that the magnitude of the rupture force depends on whether the force is applied at 3' - 3' - ends or 5' - 5' - ends. Distributions of extension in hydrogen bonds and covalent bonds along the chain show the striking differences. Motivated by recent experiments, we have also calculated the variation of rupture force for different chain lengths. Results obtained from simulations have been validated with the analytical calculation based on the ladder model of DNA.


Subject(s)
DNA/chemistry , Models, Genetic , Models, Molecular , Nucleic Acid Conformation , Computer Simulation , Elasticity , Hydrogen Bonding , Polymers/chemistry
6.
Arch Dis Child ; 100(10): 994-9, 2015 Oct.
Article in English | MEDLINE | ID: mdl-25854874

ABSTRACT

The identification of the genetic causes of the multiple endocrine neoplasia (MEN) syndromes 1 and 2, and associated genotype-phenotype relationships, has revolutionised the clinical care of affected patients. A genetic diagnosis can be made during infancy and careful clinical surveillance, coupled with early intervention, has the potential to improve both morbidity and mortality. These developments have seen the management of patients with MEN move into the arena of paediatric medicine. In this review article, we consider the genetic causes of MEN together with the clinical manifestations and management of these syndromes.


Subject(s)
Multiple Endocrine Neoplasia/genetics , Adolescent , Child , Genetic Testing , Humans , Multiple Endocrine Neoplasia/diagnosis , Multiple Endocrine Neoplasia/therapy , Mutation
7.
Oncogene ; 34(17): 2189-203, 2015 Apr 23.
Article in English | MEDLINE | ID: mdl-24931164

ABSTRACT

Metastasis is the primary cause of cancer-related death in oncology patients. A comprehensive understanding of the molecular mechanisms that cancer cells usurp to promote metastatic dissemination is critical for the development and implementation of novel diagnostic and treatment strategies. Here we show that the membrane protein RECK (Reversion-inducing cysteine-rich protein with kazal motifs) controls breast cancer metastasis by modulating a novel, non-canonical and convergent signal transducer and activator of transcription factor 3 (STAT3)-dependent angiogenic program. Neoangiogenesis and STAT3 hyperactivation are known to be fundamentally important for metastasis, but the root molecular initiators of these phenotypes are poorly understood. Our study identifies loss of RECK as a critical and previously unknown trigger for these hallmarks of metastasis. Using multiple xenograft mouse models, we comprehensively show that RECK inhibits metastasis, concomitant with a suppression of neoangiogenesis at secondary sites, while leaving primary tumor growth unaffected. Further, with functional genomics and biochemical dissection we demonstrate that RECK controls this angiogenic rheostat through a novel complex with cell surface receptors to regulate STAT3 activation, cytokine signaling, and the induction of both vascular endothelial growth factor and urokinase plasminogen activator. In accordance with these findings, inhibition of STAT3 can rescue this phenotype both in vitro and in vivo. Taken together, our study uncovers, for the first time, that RECK is a novel regulator of multiple well-established and robust mediators of metastasis; thus, RECK is a keystone protein that may be exploited in a clinical setting to target metastatic disease from multiple angles.


Subject(s)
Breast Neoplasms/metabolism , GPI-Linked Proteins/metabolism , Neoplasm Proteins/metabolism , Neovascularization, Pathologic/metabolism , Animals , Breast Neoplasms/blood supply , Breast Neoplasms/genetics , Breast Neoplasms/pathology , Female , GPI-Linked Proteins/genetics , Humans , Mice , Mice, Nude , Neoplasm Metastasis , Neoplasm Proteins/genetics , Neovascularization, Pathologic/genetics , Neovascularization, Pathologic/pathology , STAT3 Transcription Factor , Urokinase-Type Plasminogen Activator/genetics , Urokinase-Type Plasminogen Activator/metabolism , Vascular Endothelial Growth Factor A/genetics , Vascular Endothelial Growth Factor A/metabolism
8.
Article in English | MEDLINE | ID: mdl-24329389

ABSTRACT

We study the effect of a gradient of solvent quality on the coil-globule transition for a polymer in a narrow pore. A simple self-attracting, self-avoiding walk model of a polymer in solution shows that the variation in the strength of the interaction across the pore leads the system to go from one regime (good solvent) to the other (poor solvent) across the channel. This may be thought to be analogous to thermophoresis, where the polymer goes from the hot region to the cold region under the temperature gradient. The behavior of short chains is studied using exact enumeration while the behavior of long chains is studied using transfer matrix techniques. The distribution of the monomer density across the layer suggests that a gatelike effect can be created, with potential applications as a sensor.

9.
J Chem Phys ; 139(16): 165101, 2013 Oct 28.
Article in English | MEDLINE | ID: mdl-24182082

ABSTRACT

We study the effects of the shear force on the rupture mechanism on a double stranded DNA. Motivated by recent experiments, we perform the atomistic simulations with explicit solvent to obtain the distributions of extension in hydrogen and covalent bonds below the rupture force. We obtain a significant difference between the atomistic simulations and the existing results in the literature based on the coarse-grained models (theory and simulations). We discuss the possible reasons and improve the coarse-grained model by incorporating the consequences of semi-microscopic details of the nucleotides in its description. The distributions obtained by the modified model (simulations and theoretical) are qualitatively similar to the one obtained using atomistic simulations.


Subject(s)
DNA/chemistry , Models, Molecular , Nucleic Acid Conformation , Hydrogen Bonding , Software
10.
World J Microbiol Biotechnol ; 29(4): 635-43, 2013 Apr.
Article in English | MEDLINE | ID: mdl-23184579

ABSTRACT

We analyzed methylotrophs in Bina natural vegetation (BNV), and revegetated overburden dump of four (ROBD4) and 12 years (ROBD12), at Bina coal mine in Sonbhadra district. The cultured strains identified as Pseudomonas, Acinetobacter, Stenotrophomonas and Cellvibrio (γ-Proteobacteria), Methylophilus, Ralstonia, Burkholderia (α-Proteobacteria) Methylobacterium and Inquilinus (ß-Proteobacteria), Bacillus (Firmicutes) and Flexibacter (Sphingobacteria) in their 16s rRNA gene sequence similarity. The strains differed in citrate, lactose, formate, urea and xylose utilization. Methanol utilization by Stenotrophomonas, Inquilinus, Cellvibrio and Flexibacter is for first time. The preferred N- sources were proline, glutamate and nitrate for most of the strains. All strains tolerated (2.5 % NaCl) and SDS (0.2 %); 16 strains survived in crystal violet (0.01 %) and nine strains in sodium azide (0.02 %. Methylotrophic population trend was BNV > ROBD12 > ROBD4. The presence of majority of strain of BNV at ROBD12 and ROBD4 indicated restoration of soil methylotrophic functional diversity in revegetated dumps.


Subject(s)
Bacteria/classification , Bacteria/isolation & purification , Biodiversity , Organic Chemicals/metabolism , Soil Microbiology , Soil Pollutants/metabolism , Bacteria/metabolism , Bacterial Typing Techniques , Cluster Analysis , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , DNA, Ribosomal/chemistry , DNA, Ribosomal/genetics , Molecular Sequence Data , Phylogeny , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNA
11.
Nepal J Ophthalmol ; 3(2): 193-5, 2011.
Article in English | MEDLINE | ID: mdl-21876597

ABSTRACT

BACKGROUND: Ophthalmomyiasis in humans is a rare phenomenon. OBJECTIVES: To create awareness among the ophthalmologists regarding larval conjunctivitis. CASES: We report two cases of ophthalmomyiasis, which came to a tertiary care centre with features of unilateral acute catarrhal conjunctivitis. OBSERVATIONS: Fly larvae were detected on slit-lamp examination and removed after immobilizing them with topical 4 % lignocaine. Topical antibiotics and steroid drops were prescribed for 2 weeks. The samples were identified as Oestrous ovis by the entomology department of the Institute of Tropical Medicine, Kolkata. The signs and symptoms regressed within 48 hours. CONCLUSION: The ocular myiasis can manifest as a unilateral catarrhal conjunctivitis.


Subject(s)
Conjunctivitis/diagnosis , Conjunctivitis/parasitology , Eye Infections, Parasitic/diagnosis , Myiasis/diagnosis , Adult , Animals , Conjunctivitis/drug therapy , Diptera/growth & development , Eye Infections, Parasitic/drug therapy , Humans , India , Larva/growth & development , Male , Myiasis/drug therapy , Young Adult
12.
Avian Pathol ; 40(2): 207-11, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21500041

ABSTRACT

Disseminated histoplasmosis caused by Histoplasma capsulatum, a zoonotic fungal organism, is an important disease in animals and humans, particularly those with compromised immune systems. Reports of disseminated histoplasmosis in an avian species are not available within the current literature. Candida albicans, another fungal agent with zoonotic importance, is a commensal of the avian digestive tract that is often associated with opportunistic infections particularly in young or immunocompromised birds. This report describes a case of concomitant histoplasmosis and candidiasis in an Eclectus parrot (Eclectus roratus) characterized by severe granulomatous glossitis, blepharitis and osteomyelitis with numerous intrahistiocytic and extracellular yeasts (H. capsulatum) as well as intralesional hyphae, pseudohyphae and conidia (C. albicans). To our knowledge, co-infection with H. capsulatum and C. albicans has not been reported in an avian species.


Subject(s)
Bird Diseases/microbiology , Candidiasis, Oral/veterinary , Histoplasmosis/veterinary , Parrots/microbiology , Animals , Bird Diseases/pathology , Blepharitis/microbiology , Blepharitis/pathology , Blepharitis/veterinary , Candida albicans/pathogenicity , Candidiasis, Oral/complications , Candidiasis, Oral/microbiology , Candidiasis, Oral/pathology , Euthanasia, Animal , Eyelids/microbiology , Eyelids/pathology , Fatal Outcome , Female , Glossitis/microbiology , Glossitis/pathology , Glossitis/veterinary , Histoplasma/pathogenicity , Histoplasmosis/complications , Histoplasmosis/microbiology , Histoplasmosis/pathology , Humans , Immunocompromised Host , Osteomyelitis/microbiology , Osteomyelitis/pathology , Osteomyelitis/veterinary , Tongue/microbiology , Tongue/pathology , Zoonoses/microbiology
13.
J Comp Pathol ; 144(4): 324-7, 2011 May.
Article in English | MEDLINE | ID: mdl-21146179

ABSTRACT

A 6-year-old, neutered female Pembroke Welsh corgi was presented with a 1-month history of ataxia and panting. The clinical signs progressed until the dog became anorexic, obtunded and exhibited circling to the left. At necropsy examination, a mass was detected in the left forebrain, impinging on the cribriform plate. Microscopically, the mass was composed of sheets of round to pleomorphic neoplastic cells with vacuolated cytoplasm. Nuclear atypia, anisocytosis and anisokaryosis were common. Numerous bizarre, multinucleated giant cells containing 60 or more nuclei and giant mononuclear cells were present. The matrix contained abundant reticulin. Immunohistochemistry revealed the neoplastic cells uniformly to express vimentin, and a small number of neoplastic cells expressed glial fibrillary acid protein. A diagnosis of giant cell glioblastoma was made. Although well recognized in man, this tumour has been documented rarely in the veterinary literature.


Subject(s)
Brain Neoplasms/veterinary , Cerebrum/pathology , Dog Diseases/pathology , Glioblastoma/veterinary , Animals , Biomarkers, Tumor/metabolism , Brain Neoplasms/metabolism , Brain Neoplasms/pathology , Cerebrum/metabolism , Dog Diseases/metabolism , Dogs , Fatal Outcome , Female , Glioblastoma/metabolism , Glioblastoma/pathology , Immunohistochemistry/veterinary , Vimentin/metabolism
14.
Vet Pathol ; 48(3): 754-7, 2011 May.
Article in English | MEDLINE | ID: mdl-20574070

ABSTRACT

Mycotic meningoencephalitis in dogs may manifest as a primary disease of the central nervous system or as a part of disseminated infection. Fungi belonging to the genus Bipolaris are saprophytic plant pathogens and can cause disease in humans. The authors report a case of Bipolaris infection in a dog with granulomatous meningoencephalitis, nephritis, and vasculitis. The clinical and histological features resembled those of the more common aspergillosis, thus warranting confirmation by molecular methods. Polymerase chain reaction and sequence analysis identified Bipolaris from the brain lesion, indicating its involvement in the disease. To the authors' knowledge, this is the first reported case of meningoencephalitis caused by this fungus in a domestic animal.


Subject(s)
Ascomycota/isolation & purification , Dog Diseases/microbiology , Kidney Diseases/veterinary , Meningoencephalitis/veterinary , Mycoses/veterinary , Animals , Dog Diseases/pathology , Dogs , Female , Kidney Diseases/microbiology , Kidney Diseases/pathology , Meningoencephalitis/microbiology , Meningoencephalitis/pathology , Mycoses/microbiology , Mycoses/pathology
15.
J Chem Phys ; 132(23): 235105, 2010 Jun 21.
Article in English | MEDLINE | ID: mdl-20572742

ABSTRACT

We develop a simple model to study the effects of the applied force on the melting of a double stranded DNA (dsDNA). Using this model, we could study the stretching, unzipping, rupture and slippagelike transition in a dsDNA. We show that in absence of an applied force, the melting temperature and the melting profile of dsDNA strongly depend on the constrained imposed on the ends of dsDNA. The nature of the phase boundary of the force-temperature diagram, which separates the zipped and the open state for the shearinglike transition is remarkably different than the DNA unzipping.


Subject(s)
DNA/chemistry , Models, Molecular , Transition Temperature , Biomechanical Phenomena , Movement , Nucleic Acid Conformation , Nucleic Acid Denaturation , Thermodynamics
16.
Vet Pathol ; 47(4): 654-7, 2010 Jul.
Article in English | MEDLINE | ID: mdl-20466864

ABSTRACT

A 5-day-old quarter horse colt with a history of hypothermia, agonal breathing, and diarrhea was euthanized. At necropsy, numerous slightly raised, discrete, closely approximated submucosal nodules were observed in the colon and small intestine. Histologically, these nodules were composed of expanded submucosal mesenchyme that contained numerous neurons either individually or in ganglia. Thirty-two percent of these ganglia included 8 or more neurons, in contrast to 6% in an age-matched foal. Some nodules had necrosuppurative inflammation with vasculitis, thrombosis, and bacterial colonization. A few heterotopic neurons were randomly distributed in the mucosa and the muscularis mucosa. Histologic changes were most consistent with intestinal neuronal dysplasia, a disease of the submucosal plexus described in humans.


Subject(s)
Colitis/veterinary , Horse Diseases/pathology , Animals , Animals, Newborn , Colitis/pathology , Diagnosis, Differential , Fatal Outcome , Horses
17.
J Clin Microbiol ; 47(4): 1264-8, 2009 Apr.
Article in English | MEDLINE | ID: mdl-19109465

ABSTRACT

Isolation and characterization of the new species Chrysosporium ophiodiicola from a mycotic granuloma of a black rat snake (Elaphe obsoleta obsoleta) are reported. Analysis of the sequences of different fragments of the ribosomal genes demonstrated that this species belongs to the Onygenales and that this species is genetically different from other morphologically similar species of Chrysosporium. This new species is unique in having both narrow and cylindrical-to-slightly clavate conidia and a strong, pungent odor.


Subject(s)
Chrysosporium/classification , Chrysosporium/isolation & purification , Colubridae/microbiology , Granuloma/veterinary , Mycoses/veterinary , Animals , Chrysosporium/cytology , Chrysosporium/genetics , DNA, Fungal/chemistry , DNA, Fungal/genetics , DNA, Ribosomal/chemistry , DNA, Ribosomal/genetics , DNA, Ribosomal Spacer/chemistry , DNA, Ribosomal Spacer/genetics , Genes, rRNA , Granuloma/microbiology , Molecular Sequence Data , Mycoses/diagnosis , Mycoses/microbiology , Phylogeny , RNA, Fungal/genetics , RNA, Ribosomal/genetics , Sequence Analysis, DNA
18.
Phys Rev E Stat Nonlin Soft Matter Phys ; 78(2 Pt 1): 021905, 2008 Aug.
Article in English | MEDLINE | ID: mdl-18850863

ABSTRACT

Single-molecule force spectroscopy provide details of the underlying energy surfaces of proteins which are essential to the understanding of their unfolding process. Recently, it has been observed experimentally that by pulling proteins in different directions relative to their secondary structure, one can gain a better understanding of the shape of the energy landscape. We consider simple lattice models which are anisotropic in nature to study the response of a force in unfolding of a polymer. Our analytical solution of the model, supported by extensive numerical calculations, reveal that the force temperature diagrams are very different depending on the direction of the applied force. We find that either unzipping or shearing kind transitions dominate the dynamics of the unfolding process depending solely on the direction of the applied force.


Subject(s)
Models, Chemical , Protein Folding , Proteins/chemistry , Thermodynamics
19.
Cell Mol Biol (Noisy-le-grand) ; 50(5): 575-84, 2004 Jul.
Article in English | MEDLINE | ID: mdl-15559974

ABSTRACT

Cyanobacterial species composition of fresh water and terrestrial ecosystems and chemical environment of water in Schirmacher Oasis in Continental Antarctica was investigated. Over 35 species of cyanobacteria were recorded. Diazotrophic species both heterocystous and unicellular contributed more than half to the count except in lake ecosystem. The species composition varied among the fresh water as well as terrestrial ecosystems. The physico-chemical analyses of water revealed its poor nurient content which might have supported the growth of diazotrophic cyanobacteria in an Antarctic environment. Among the cyanobacteria Oscillatoria, Phormidium and Nostoc commune were the dominant flora in most of the habitats. The physiological characteristics of isolated cyanobacteria strains indicated that N2-fixation, nitrate uptake, nitrate-reduction, ammonium-uptake, GS-transferase activity and photosynthesis was unaffected at low temperature (5 degrees C) which indicated low temperature adaptation for Antarctic cyanobacteria. This phenomenon was not evident in different strains of tropical origin. The temperature optima for N2-fixation for the different Antarctic cyanobacterial strains was in the range of 15-25 degrees C, nearly 10 degrees C lower than their respective reference strains of tropical origin. Similar results were obtained for cyanobacteria-moss association. The low endergonic activation energy exhibited by the above metabolic activities supported the view that cyanobacteria were adapted to Antarctic ecosystem.


Subject(s)
Cyanobacteria/physiology , Ecology , Antarctic Regions , Cold Climate , Nitrate Reductase , Nitrate Reductases/metabolism , Nitrates , Nitrogen Fixation/physiology , Photosynthesis/physiology , Quaternary Ammonium Compounds/metabolism , Sodium Chloride/metabolism
20.
J Natl Cancer Inst ; 93(23): 1783-90, 2001 Dec 05.
Article in English | MEDLINE | ID: mdl-11734594

ABSTRACT

BACKGROUND: Expression of fibroblast growth factors (FGFs) is increased in a substantial fraction of human prostate cancers in vivo and in prostate cancer cell lines. Altered FGF signaling can potentially have a variety of effects, including stimulating cell proliferation and inhibiting cell death. To determine the biologic significance of altered FGF signaling in human prostate cancer, we disrupted signaling by expression of a dominant-negative (DN) FGF receptor in prostate cancer cell lines. METHODS: PC-3, LNCaP, and DU145 prostate cancer cells were stably transfected with DN FGFR constructs, and LNCaP and DU145 cells were infected with a recombinant adenovirus expressing DN FGFR-1. The effect of DN FGFR-1 expression was assessed by colony-formation assays, cell proliferation assays, flow cytometry, and cytogenetic analysis. Key regulators involved in the G(2)-to-M cell cycle transition were assessed by western blotting to examine cyclin B1 expression and by in vitro kinase assay to assess cdc2 kinase activity. RESULTS: Stable transfection of the DN FGFR-1 construct inhibited colony formation by more than 99% in all three cell lines. Infection of LNCaP and DU145 prostate cancer cells with adenovirus expressing DN FGFR-1 led to extensive cell death within 48 hours. Flow cytometry and cytogenetic analysis revealed that the DN FGFR-1 receptor led to arrest in the G(2) phase of the cell cycle before cell death. Cyclin B1 accumulated in DN FGFR-1-infected LNCaP cells, but cdc2 kinase activity was decreased. CONCLUSIONS: These findings reveal an unexpected dependence of prostate cancer cells on FGF receptor signal transduction to traverse the G(2)/M checkpoint. The mechanism for the G(2) arrest is not clear. Our results raise the possibility that FGF-signaling antagonists might enhance the cell death induced by other prostate cancer therapies.


Subject(s)
Prostatic Neoplasms/metabolism , Receptors, Fibroblast Growth Factor/metabolism , Receptors, Fibroblast Growth Factor/physiology , Signal Transduction , Adenoviridae/genetics , Blotting, Western , CDC2 Protein Kinase/metabolism , Cell Cycle , Cell Death , Cell Division , Cell Survival , Chromosomes , Cyclin B/biosynthesis , Cyclin B1 , Cytogenetics , Flow Cytometry , Genes, Dominant , Humans , Lac Operon , Male , Precipitin Tests , Time Factors , Transfection , Tumor Cells, Cultured
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