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1.
J Affect Disord ; 355: 157-166, 2024 Jun 15.
Article in English | MEDLINE | ID: mdl-38527529

ABSTRACT

BACKGROUND: Diet largely impacts the gut microbiota, and may affect mental and somatic health via the gut-brain axis. As such, the relationship between diet and the microbiota in Bipolar Disorder (BD) could be of importance, but has not been studied before. The aim was therefore to assess whether dietary quality is associated with the gut microbiota diversity in patients with recently diagnosed BD, and whether changes occur in dietary quality and microbiota diversity during their first year of treatment. METHODS: Seventy recently (<1 year) diagnosed patients with BD were included in the "Bipolar Netherlands Cohort" (BINCO), and a total of 45 participants were assessed after one year. A 203-item Food Frequency Questionnaire (FFQ) data yielded the Dutch Healthy index (DHD-15), and the microbiota composition and diversity of fecal samples were characterized by 16S rRNA gene amplicon sequencing at baseline and 1-year follow-up. Associations and changes over time were analyzed using multivariate regression analyses and t-tests for paired samples. RESULTS: Included patients had a mean age of 34.9 years (SD ± 11.2), and 58.6 % was female. Alpha diversity (Shannon diversity index), richness (Chao1 index) and evenness (Pielou's Evenness Index) were positively associated with the DHD-15 total score, after adjustment for sex, age and educational level (beta = 0.55; P < 0.001, beta = 0.39; P = 0.024, beta = 0.54; P = 0.001 respectively). The positive correlations were largely driven by the combined positive effect of fish, beans, fruits and nuts, and inverse correlations with alcohol and processed meats. No significant changes were found in DHD-15 total score, nor in microbiota diversity, richness and evenness indexes during one year follow-up and regular treatment. CONCLUSION: A healthy and varied diet is associated with the diversity of the microbiota in BD patients. Its potential consequences for maintaining mood stability and overall health should be studied further.


Subject(s)
Bipolar Disorder , Gastrointestinal Microbiome , Humans , Female , Adult , Dietary Patterns , Netherlands , RNA, Ribosomal, 16S/genetics , Diet , Gastrointestinal Microbiome/genetics
2.
J Clin Microbiol ; 60(2): e0173721, 2022 02 16.
Article in English | MEDLINE | ID: mdl-34911367

ABSTRACT

Clostridioides difficile is the most common cause of antibiotic-associated gastrointestinal infections. Capillary electrophoresis (CE)-PCR ribotyping is currently the gold standard for C. difficile typing but lacks the discriminatory power to study transmission and outbreaks in detail. New molecular methods have the capacity to differentiate better and provide standardized and interlaboratory exchangeable data. Using a well-characterized collection of diverse strains (N = 630; 100 unique ribotypes [RTs]), we compared the discriminatory power of core genome multilocus sequence typing (cgMLST) (SeqSphere and EnteroBase), whole-genome MLST (wgMLST) (EnteroBase), and single-nucleotide polymorphism (SNP) analysis. A unique cgMLST profile (more than six allele differences) was observed in 82 of 100 RTs, indicating that cgMLST could distinguish most, but not all, RTs. Application of cgMLST in two outbreak settings with RT078 and RT181 (known to have low intra-RT allele differences) showed no distinction between outbreak and nonoutbreak strains in contrast to wgMLST and SNP analysis. We conclude that cgMLST has the potential to be an alternative to CE-PCR ribotyping. The method is reproducible, easy to standardize, and offers higher discrimination. However, adjusted cutoff thresholds and epidemiological data are necessary to recognize outbreaks of some specific RTs. We propose to use an allelic threshold of three alleles to identify outbreaks.


Subject(s)
Clostridioides difficile , Clostridioides , Clostridioides difficile/genetics , Genome, Bacterial/genetics , Humans , Multilocus Sequence Typing/methods , Polymerase Chain Reaction , Ribotyping
4.
FEMS Microbiol Lett ; 366(11)2019 06 01.
Article in English | MEDLINE | ID: mdl-31253991

ABSTRACT

Twitter is one of the most popular social media networks that, in recent years, has been increasingly used by researchers as a platform to share science and discuss ongoing work. Despite its popularity, Twitter is not commonly used as a medium to teach science. Here, we summarize the results of #EUROmicroMOOC: the first worldwide Microbiology Massive Open Online Course taught in English using Twitter. Content analytics indicated that more than 3 million users saw posts with the hashtag #EUROmicroMOOC, which resulted in over 42 million Twitter impressions worldwide. These analyses demonstrate that free Microbiology MOOCs shared on Twitter are valuable educational tools that reach broad audiences throughout the world. We also describe our experience teaching an entire Microbiology course using Twitter and provide recommendations when using social media to communicate science to a broad audience.


Subject(s)
Microbiology , Social Media , Communication , Information Dissemination/methods , Social Networking
5.
Leukemia ; 30(9): 1832-43, 2016 09.
Article in English | MEDLINE | ID: mdl-27174491

ABSTRACT

We identified mutations in the IL7Ra gene or in genes encoding the downstream signaling molecules JAK1, JAK3, STAT5B, N-RAS, K-RAS, NF1, AKT and PTEN in 49% of patients with pediatric T-cell acute lymphoblastic leukemia (T-ALL). Strikingly, these mutations (except RAS/NF1) were mutually exclusive, suggesting that they each cause the aberrant activation of a common downstream target. Expressing these mutant signaling molecules-but not their wild-type counterparts-rendered Ba/F3 cells independent of IL3 by activating the RAS-MEK-ERK and PI3K-AKT pathways. Interestingly, cells expressing either IL7Ra or JAK mutants are sensitive to JAK inhibitors, but respond less robustly to inhibitors of the downstream RAS-MEK-ERK and PI3K-AKT-mTOR pathways, indicating that inhibiting only one downstream pathway is not sufficient. Here, we show that inhibiting both the MEK and PI3K-AKT pathways synergistically prevents the proliferation of BaF3 cells expressing mutant IL7Ra, JAK and RAS. Furthermore, combined inhibition of MEK and PI3K/AKT was cytotoxic to samples obtained from 6 out of 11 primary T-ALL patients, including 1 patient who had no mutations in the IL7R signaling pathway. Taken together, these results suggest that the potent cytotoxic effects of inhibiting both MEK and PI3K/AKT should be investigated further as a therapeutic option using leukemia xenograft models.


Subject(s)
Mitogen-Activated Protein Kinase Kinases/antagonists & inhibitors , Phosphoinositide-3 Kinase Inhibitors , Precursor T-Cell Lymphoblastic Leukemia-Lymphoma/metabolism , Proto-Oncogene Proteins c-akt/antagonists & inhibitors , Receptors, Interleukin-7/metabolism , Signal Transduction/drug effects , Animals , Cell Proliferation/drug effects , Humans , Mice , Precursor T-Cell Lymphoblastic Leukemia-Lymphoma/pathology , Protein Kinase Inhibitors/pharmacology , Receptors, Interleukin-7/antagonists & inhibitors , Transfection , Tumor Cells, Cultured
6.
Leukemia ; 24(12): 2014-22, 2010 Dec.
Article in English | MEDLINE | ID: mdl-20861909

ABSTRACT

Aberrant activation of the NOTCH1 pathway by inactivating and activating mutations in NOTCH1 or FBXW7 is a frequent phenomenon in T-cell acute lymphoblastic leukemia (T-ALL). We retrospectively investigated the relevance of NOTCH1/FBXW7 mutations for pediatric T-ALL patients enrolled on Dutch Childhood Oncology Group (DCOG) ALL7/8 or ALL9 or the German Co-Operative Study Group for Childhood Acute Lymphoblastic Leukemia study (COALL-97) protocols. NOTCH1-activating mutations were identified in 63% of patients. NOTCH1 mutations affected the heterodimerization, the juxtamembrane and/or the PEST domains, but not the RBP-J-κ-associated module, the ankyrin repeats or the transactivation domain. Reverse-phase protein microarray data confirmed that NOTCH1 and FBXW7 mutations resulted in increased intracellular NOTCH1 levels in primary T-ALL biopsies. Based on microarray expression analysis, NOTCH1/FBXW7 mutations were associated with activation of NOTCH1 direct target genes including HES1, DTX1, NOTCH3, PTCRA but not cMYC. NOTCH1/FBXW7 mutations were associated with TLX3 rearrangements, but were less frequently identified in TAL1- or LMO2-rearranged cases. NOTCH1-activating mutations were less frequently associated with mature T-cell developmental stage. Mutations were associated with a good initial in vivo prednisone response, but were not associated with a superior outcome in the DCOG and COALL cohorts. Comparing our data with other studies, we conclude that the prognostic significance for NOTCH1/FBXW7 mutations is not consistent and may depend on the treatment protocol given.


Subject(s)
Cell Cycle Proteins/genetics , F-Box Proteins/genetics , Mutation , Precursor T-Cell Lymphoblastic Leukemia-Lymphoma/drug therapy , Precursor T-Cell Lymphoblastic Leukemia-Lymphoma/genetics , Prednisone/therapeutic use , Receptor, Notch1/genetics , Ubiquitin-Protein Ligases/genetics , Child , F-Box-WD Repeat-Containing Protein 7 , Female , Gene Rearrangement , Homeodomain Proteins/genetics , Humans , Male , Treatment Outcome
7.
J Appl Microbiol ; 101(3): 531-41, 2006 Sep.
Article in English | MEDLINE | ID: mdl-16907804

ABSTRACT

AIM: Understanding the basis for the heterogeneous (or bistable) expression patterns of competence development and sporulation in Bacillus subtilis. METHODS AND RESULTS: Using flow cytometric analyses of various promoter-GFP fusions, we have determined the single-cell gene expression patterns of competence development and initiation of sporulation in a chemically defined medium (CDM) and in biofilms. CONCLUSIONS: We show that competence development and initiation of sporulation in a CDM are still initiated in a bistable manner, as is the case in complex media, but are sequential in their timing. Furthermore, we provide experimental proof that competence and sporulation can develop under conditions that normally do not trigger these processes. SIGNIFICANCE AND IMPACT OF THE STUDY: Some pathogens are able to develop natural competence, which is a serious medical problem with the increased acquired multi-drug resistance of these organisms. Another adaptive microbial response is spore formation. Because of their heat resistance and hydrophobicity, spores of a variety of species are of major concern for the food industry. Using the model organism B. subtilis, we show that competence development and sporulation are initiated in a bistable and sequential manner. We furthermore show that both processes may be noise-based, which has major implications for the control of unwanted differentiation processes in pathogenic and food-spoilage micro-organisms.


Subject(s)
Bacillus subtilis/physiology , Gene Expression Regulation, Bacterial/physiology , Bacillus subtilis/genetics , Bacterial Proteins/genetics , Biofilms , Cell Count , Culture Media , DNA, Bacterial/genetics , Flow Cytometry/methods , Gene Expression Regulation, Bacterial/genetics , Green Fluorescent Proteins/genetics , Mutation/genetics , Plasmids , Promoter Regions, Genetic/genetics , Spores, Bacterial/genetics , Spores, Bacterial/physiology , Transcription Factors/genetics
8.
Vaccine ; 18(18): 1920-4, 2000 Mar 17.
Article in English | MEDLINE | ID: mdl-10699341

ABSTRACT

Oligonucleotides containing immunostimulatory CpG motifs (CpG ODN) have been shown to be potent Th1-type adjuvants for augmenting antigen-specific responses in mice against hepatitis B surface antigen (HBsAg). The hepatitis B virus (HBV) infects only humans and great apes and appears to exist among wild chimpanzees and orangutans. An outbreak of HBV among orangutans being rehabilitated for re-introduction to the jungle caused the death of several animals. A prophylactic vaccination program revealed that orangutans are quite hypo-responsive to a current commercial vaccine compared to results obtained previously in humans and chimpanzees. Addition of CpG ODN to hepatitis B vaccine greatly increased the seroconversion rate and the titers of antibody against HBsAg (anti-HBs). This is the first demonstration of CpG DNA in a great ape and the results have important implications for the vaccination of humans against HBV and other diseases.


Subject(s)
Adjuvants, Immunologic/therapeutic use , Ape Diseases/immunology , CpG Islands/immunology , DNA/immunology , DNA/therapeutic use , Hepatitis B Vaccines/immunology , Hepatitis B/immunology , Immune Tolerance/drug effects , Animals , Ape Diseases/prevention & control , Hepatitis Antibodies/biosynthesis , Hepatitis B/prevention & control , Hepatitis B/veterinary , Hepatitis B Surface Antigens/immunology , Oligodeoxyribonucleotides/immunology , Oligodeoxyribonucleotides/therapeutic use , Pongo pygmaeus
9.
Support Care Cancer ; 8(1): 59-64, 2000 Jan.
Article in English | MEDLINE | ID: mdl-10650900

ABSTRACT

Factors determining the place of palliative care and death were studied by interviewing 40 patients using a semi-structured questionnaire. The 86 interviews assessed showed that both emotional and somatic factors played a part in the determination of whether patients were transferred and of their place of death. Emotional factors were mentioned in 41% as being of importance, and physical factors in 32%. Material and financial factors are probably underestimated owing to the methodology.


Subject(s)
Attitude to Death , Neoplasms/psychology , Palliative Care , Patient Transfer , Adult , Aged , Aged, 80 and over , Cancer Care Facilities , Chi-Square Distribution , Female , Home Care Services , Hospices , Humans , Male , Middle Aged , Odds Ratio , Retrospective Studies , Surveys and Questionnaires , Terminal Care
10.
Ann Allergy Asthma Immunol ; 77(6): 488-90, 1996 Dec.
Article in English | MEDLINE | ID: mdl-8970440

ABSTRACT

BACKGROUND: Elevations of creatine kinase have been described, but have been associated with high doses of albuterol given by oral or intravenous routes. Most reports have described an elevation of MB isoenzyme fraction from the heart. Elevation of creatine kinase-MM isoenzyme from skeletal muscle rarely appears to be associated with the use of inhaled albuterol. OBJECTIVE: A patient is discussed who presented with severe myalgias and was found to have elevated creatine kinase-MM from albuterol metered dose inhaler. METHODS: Clinical status, creatine kinase levels, electromyography, enzyme stains, histopathologic and lactate challenge studies were done to evaluate the status of the patient. RESULTS: Without exercise or use of albuterol, creatine kinase-MM levels were normal. With the use of albuterol, whether inhaled or by oral therapy, the creatine kinase-MM level increased. When combined with exercise, higher levels occurred. Workup was normal except histopathology revealed a myopathy. CONCLUSION: Patients with myalgias from albuterol with elevated creatine kinase-MM fraction should be investigated for possible myopathy.


Subject(s)
Albuterol/administration & dosage , Bronchodilator Agents/administration & dosage , Creatine Kinase/metabolism , Muscle, Skeletal/enzymology , Administration, Inhalation , Albuterol/adverse effects , Albuterol/pharmacology , Ammonia/blood , Biopsy, Needle , Bronchodilator Agents/pharmacology , Electromyography , Exercise/physiology , Humans , Isoenzymes , Lactates/blood , Male , Middle Aged , Muscle, Skeletal/pathology , Muscular Diseases/chemically induced , Paraffin Embedding , Respiratory Function Tests
11.
Pediatr Pulmonol ; 20(2): 63-70, 1995 Aug.
Article in English | MEDLINE | ID: mdl-8570304

ABSTRACT

We examined the relationship of pulmonary infection and inflammation in cystic fibrosis (CF) by performing 31 bronchoalveolar lavages (BAL) in 14 young children with minimal lung disease from CF. While 10 of the 14 patients had elevated polymorphonuclear leukocyte (PMN) counts initially, only 4 had bacteria generally regarded as pathogenic in the recovered BAL fluid. Three of these 4 and 6 of the others had follow-up bronchoscopies at 6 months intervals. PMN counts remained normal for only one patient. However, pathogenic bacteria were recovered during the repeat BALs only in those patients who were colonized initially. Proinflammatory cytokines and proteinases were generally elevated, and interleukin-8 (IL-8) concentration correlated inversely with oxygen saturation (SaO2). No complications of the procedure occurred. We conclude that BAL identifies inflammation and the presence of bacteria in the lower airway at an early stage of the disease. This information may be used to guide therapy in patients too young or otherwise unable to produce sputum. These data also suggest that inflammation is present early in the course of CF lung disease before colonization and infection of the lungs with potentially pathogenic bacteria occurs. Since inflammation appears to be the earliest detectable evidence of lung disease in CF, monitoring of inflammation with BAL may serve as a useful marker of clinical benefits from new treatments in patients with minimal lung disease.


Subject(s)
Cystic Fibrosis/complications , Pneumonia, Bacterial/complications , Bacteria/isolation & purification , Bronchoalveolar Lavage , Bronchoalveolar Lavage Fluid/microbiology , Child , Child, Preschool , Cystic Fibrosis/metabolism , Cytokines/metabolism , Endopeptidases/metabolism , Female , Follow-Up Studies , Humans , Infant , Inflammation/etiology , Inflammation/metabolism , Leukocyte Count , Male , Pneumonia, Bacterial/microbiology
12.
Ann Otol Rhinol Laryngol ; 104(7): 537-41, 1995 Jul.
Article in English | MEDLINE | ID: mdl-7598366

ABSTRACT

Exercise-induced laryngomalacia (EIL) is characterized by severe dyspnea, stridor, and mild wheezing unresponsive to prophylactic treatment with beta-agonists and cromolyn sodium. Symptoms develop with extreme exertion, but resolve quickly as the degree of exercise is decreased. Diagnosis requires flexible fiberoptic laryngoscopy before, during, and after exercise. If the diagnosis of EIL is confirmed by laryngoscopy during maximal exercise, laser epiglottoplasty is effective in alleviating symptoms and improving the airway. However, because symptoms develop only during maximal exertion, EIL is unlikely to produce symptoms or functional disability in persons who lead relatively sedentary lives.


Subject(s)
Exercise , Laryngeal Diseases/etiology , Child , Dyspnea/etiology , Female , Humans , Laryngeal Diseases/diagnosis , Laryngeal Diseases/surgery , Laryngoscopy , Laser Therapy
13.
Infect Immun ; 63(5): 2026-32, 1995 May.
Article in English | MEDLINE | ID: mdl-7729917

ABSTRACT

The role of the mrkD gene in attachment by a type 3 fimbriate Klebsiella pneumoniae strain was further characterized. A clinical isolate, K. pneumoniae IA565, was found to contain two copies of the gene encoding the fimbrial subunit, mrkA, and one copy of the gene encoding the adhesin subunit, mrkD. One copy of mrkA was located on the bacterial chromosome, and the other copy was associated with mrkD and located on a plasmid. The plasmid-borne mrk gene cluster was lost when K. pneumoniae IA565 was subcultured serially in broth at 44 degrees C. The resulting mrkD-negative strain, designated K. pneumoniae IApc35, did not exhibit the following adherence characteristics associated with K. pneumoniae possessing MrkD-positive fimbriae: agglutination of tannic acid-treated human erythrocytes and attachment to trypsinized human buccal cells. However, K. pneumoniae IApc35 produced type 3 fimbriae that were composed of the characteristic 21.5-kDa major fimbrial subunit, were reactive with specific serum, and were visualized specifically by immunoelectron microscopy. K. pneumoniae IApc35 retained a copy of the mrkA gene on its chromosome. This mrkA-containing gene cluster could be complemented by a recombinant plasmid carrying only the mrkD gene, resulting in restoration of the K. pneumoniae IA565-like adhesive phenotype and demonstration of type 3 filament-associated MrkD subunits by using colloidal gold labeling and immunoelectron microscopy. These data indicate that K. pneumoniae may contain multiple copies of the mrk genes which may be present simultaneously on both plasmid and chromosomal DNAs and which may encode fimbriae with different binding specificities.


Subject(s)
Adhesins, Bacterial , Bacterial Adhesion/genetics , Bacterial Proteins/genetics , Fimbriae Proteins , Fimbriae, Bacterial/genetics , Klebsiella pneumoniae/genetics , Bacterial Proteins/immunology , Bacterial Proteins/isolation & purification , Bronchi/cytology , Cells, Cultured , Epithelial Cells , Fimbriae, Bacterial/immunology , Hemagglutination Tests , Humans , Klebsiella pneumoniae/immunology , Microscopy, Immunoelectron , Mouth/cytology , Mutation , Plasmids/genetics
14.
Semin Respir Infect ; 7(3): 218-26, 1992 Sep.
Article in English | MEDLINE | ID: mdl-1475545

ABSTRACT

Progressive pulmonary disease is the primary cause of morbidity and mortality in adult patients with cystic fibrosis (CF). The decrease in lung function associated with infection with Pseudomonas aeruginosa has been related to the severity of pulmonary inflammation. Thus therapies that reduce pulmonary inflammation may prove to be clinically efficacious. Therapeutic interventions that target pulmonary inflammation may be directed either at the infecting organism, especially P aeruginosa, or at host responses. Eradication of P aeruginosa from the airways of patients with CF has not been accomplished. However, reduction of the burden of P aeruginosa or modification of virulence factors are practical goals. Normalization of the host response ultimately depends on correction of the molecular defect. Until then, therapies are being investigated that may modulate pulmonary inflammation. These include therapies aimed at compensating for the defect in ion transport, down-regulating inflammatory cell responses, inhibiting host inflammatory products, or altering airway secretions. Preliminary data suggest that each of these approaches may have clinical efficacy. Large, multicenter trials addressing these issues are presently ongoing and hold the promise for continued improvement in the clinical course of patients with CF.


Subject(s)
Cystic Fibrosis/therapy , Immunotherapy/methods , Pseudomonas Infections/therapy , Respiratory Tract Infections/therapy , Anti-Bacterial Agents/therapeutic use , Cystic Fibrosis/complications , Expectorants/therapeutic use , Humans , Ibuprofen/therapeutic use , Interferon-gamma/therapeutic use , Prednisone/therapeutic use , Protease Inhibitors/therapeutic use , Pseudomonas Infections/etiology , Pulmonary Surfactants/therapeutic use , Respiratory Tract Infections/etiology
15.
16.
Tijdschr Diergeneeskd ; 101(12): 649-57, 1976 Jun 15.
Article in Dutch | MEDLINE | ID: mdl-179162

ABSTRACT

In a part of the broiler flocks vaccinated against Newcastle disease (N.C.D) and infectious bronchitis (I.B.), disease symptoms of lingering nature have been observed, generally in the second half of the rearing period. In a practical investigation with weekly examinations of chickens, supplemented by a serological examination of twenty-four animals per flock at the age of six weeks, it was hoped to establish the factors responsible for this "vaccination reaction". In the district under notice the vaccination reaction syndrome had been responsible for widspread abandoning of twice spraying against N.C.D. in the first and fourth week in favour of drinking-water vaccination (generally combined with I.B. vaccination) in the second week and spray-vaccination in the fourth week or of combined drinking-water vaccination in the second week, either with or without N.C.D. drinking-water vaccination in the fourth week. Admittedly the incidence of vaccination reaction in flocks vaccinated exclusively via the drinking water was less frequent (32%) than in flocks in which the second vaccination was administered as a spray (48%), but this difference was largely accounted for by infection with Mycoplasma gallisepticum and/or Mycoplasma synoviae, complicated by infection with Escherichia coli. Of the thirty-three flocks free of mycoplasmosis, 24% exhibited the vaccination reaction, while the incidence to the fifteen infected flocks was 73.4%. In flocks infected with mycoplasmosis the course of E. coli infections was serious in 46.7% of the birds, while this figure was 18.2% in flocks free of mycoplasmosis. In flocks free of mycoplasmosis, the percentage of serious E. coli infections was lower after spray vaccination (14.3%) than after drinking-water vaccination (21%). The strains of E. coli brought in by one-day chicks from the hatchery disappear rapidly and play no role of any significance in the problem of colibacillosis observed at an age of three weeks or older. Of the 310 isolated strains of E. coli, 52 could not be typed and the others belonged to eighty different serotypes. With respect to the effect of infectious bronchitis the investigation does not provide sufficient evidence to permit of drawing conclusions. A significant role in the occurrence of the syndrome was played by coccidiosis and Gumboro's disease. With respect to environmental factors the available data did not allow of drawing conclusions. The authors recommend continuing with all available means to free the breeding animals from M. gallisepticum and M. synoviae, undertaking scientifically based research into the role of infectious bronchitis in the "vaccination reaction" syndrome, an effective programme of hygiene to control E...


Subject(s)
Bronchitis/veterinary , Newcastle Disease/prevention & control , Poultry Diseases/prevention & control , Vaccination/veterinary , Viral Vaccines/adverse effects , Aerosols , Animal Feed , Animal Husbandry , Animals , Coccidiosis/veterinary , Escherichia coli Infections/veterinary , Infectious bursal disease virus/isolation & purification , Mycoplasma Infections/veterinary , Poultry , Vaccination/methods , Water
17.
Eur J Biochem ; 58(2): 269-72, 1975 Oct 15.
Article in English | MEDLINE | ID: mdl-1102302

ABSTRACT

The dissociation and association behaviour of 70-S ribosomes of Escherichia coli has been studied. It has been shown that the dissociation-association reaction can be both a real dynamic equilibrium and a non-equilibrium reaction, dependent upon the ionic conditions of the solvent. At relatively high ionic strength (I = 0.15 M or more) the dissociation-association reaction is an equilibrium reaction, whereas at lower ionic strength (I = 0.1 M or less) there is no dynamic equilibrium between 70-S ribosomes and its subunits. In the latter case a hysteresis in the dissociation-association reaction is observed. Whether there is a dynamic equilibrium or not can be demonstrated by a single centrifugation experiment, using the analytical ultracentrifuge.


Subject(s)
Escherichia coli/ultrastructure , Ribosomes , Macromolecular Substances , Magnesium , Osmolar Concentration , Ultracentrifugation
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