PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “molecular typing”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1977

Decomposition of molecular types of triglycerides by lipoprotein lipase in man.

1. The lipoprotein triglycerides of human plasma can be separated by gas chromatography according to their carbon number into four main groups: C48, C50, C52 and C54. We studied the decomposition of molecular types of triglycerides by posttheparin lipoprotein lipase in vitro. 2. Decomposition of the molecular type C52 does not depend on its concentration. Decomposition of the molecular types C48, C50 and C54 is in a direct correlation to their concentration. 3. The above mechanism assures stability of the triglyceride profile of human plasma, which is species specific and is expressed by the figures: C48--9%, C50--20%, C52--43%, C54--20%, remainder 8%. 4. The plasma triglyceride profile can be altered by dietetic factors. After drinking cream, the triglyceride composition is: C48--12%, C50--22%, C52--37%, C54--14%, remainder 15%. Selective decomposition of molecular types of triglycerides ensures that the profile, after a given time, returns to the original state.

Dietary Fats↗
PubMed2026

Drug-resistant genes, virulence characteristics, and molecular typing of clindamycin-resistant Streptococcus agalactiae in late pregnancy.

BACKGROUND: Streptococcus agalactiae increases the risk of adverse pregnancy outcomes and neonatal infections. Clindamycin is a key alternative for intrapartum prophylaxis in penicillin-allergic women, but the prevalence of clindamycin-resistant S. agalactiae is increasing, posing a significant clinical challenge. METHODS: A total of 178 strains isolated from tertiary hospitals in Jinan and Qingdao, Shandong Province, China, were characterized using antimicrobial susceptibility testing, whole-genome sequencing, multilocus sequence typing, serotyping, and analysis of resistance and virulence genes. RESULTS: All strains were susceptible to penicillin, ampicillin, linezolid, vancomycin, and tigecycline. In contrast, resistance rates to erythromycin, levofloxacin, and tetracycline were 95.5%, 60.1%, and 56.7%, respectively. Six serotypes and 15 sequence types belonging to eight clonal complexes were identified. Notable regional differences were observed. The Ib-ST10-CC12 lineage dominated in Jinan, whereas V-ST529-CC327 was predominant in Qingdao. The resistance gene mreA was ubiquitous (100%), followed by ermB (80.3%). The key virulence genes cylE, hylB, and pavA, were detected in all strains. fbsA (99.4%), the alpha protein family (98.9%), cfb (98.3%), the Pilus Island gene cluster (94.9%), and lmb (92.7%) were also highly prevalent. The two major clindamycin resistance genes, erm and lnuB, exhibited distinctly different enrichment patterns among S. agalactiae clonal complexes, despite a certain overlap in CC19 and CC327. Specifically, erm was significantly enriched in CC12 (serotype Ib), CC19 (III/V), and CC327 (III/V). In contrast, lnuB was predominantly restricted to CC19 and CC327, where it defined a unique phylogenetic subcluster. Significant differences in resistance and virulence gene profiles were observed across different clonal complexes. CONCLUSION: Clindamycin-resistant S. agalactiae in late-pregnancy women in Shandong Province, China exhibits a broad resistance spectrum, diverse molecular types, and significant regional heterogeneity. These findings underscore the need for continued surveillance and region-specific strategies for preventing neonatal S. agalactiae infections.

Humans↗
PubMed1978

Chaotropic resolution of high molecular weight (type I) NADH dehydrogenase, and reassociation of flavin-rich (type II) and flavin-poor subunits.

1. Type-I NADH dehydrogenase (Complex I) was solubilized and dissociated into subunits by NaClO4. NADH slows the dissociation. On subsequent stepwise addition of (NH4)2SO4 the dissociation is partly reversed, as is to be expected from the opposing effects of ClO-4 and SO-24, which are on the salting-in and salting-out sides, respectively, of the lyotropic series. 2. In consequence, the aggregates of subunits that are separated by (NH4)2-SO4 fractionation consist of randomly associated subunits as well as fragments of Type I enzyme. The fraction precipitating at 27% satd. (NH4)2SO4 is flavin-poor, that remaining soluble at 55% satd. (NH4)2SO4 flavin-rich and those separating between 27 and 55% satd. (NH4)2SO4 intermediate in composition. 3. The fraction remaining soluble at 55% satd. (NH4)2SO4 contains the purified low-molecular-weight iron-sulphur flavoprotein (Type-II dehydrogenase). It is a dimer consisting of one molecule of FMN, one 28-kilodalton and one 56-kilodalton subunit per protomer. Work of others indicates that it contains 4 Fe and 4 acid-labile S atoms per molecule of FMN. Sometimes the fraction remaining soluble at 55% satd. (NH4)2SO4 contained an additional small subunit (12 kilodaltons) and four additional Fe and acid labile S atoms per protomer. The sedimentation coefficients (s020,w) of the two preparations were 5.3 and 6.6 S, respectively, with calculated frictional ratios of 1.5 and 1.24, respectively. 4. The intermediate fractions are mixtures of the various subunits present in Complex I. Specifically a fraction separating at 55% satd. (NH4)2SO4 was found to be a mixture of two fragments, the pure iron-sulphur flavoprotein and a 26-S fragment that contained per protomer four subunits of 12 kilodaltons, one each of 28, 32, 56 and 77 kilodaltons, one molecule of FMN and 20 Fe and acid-labile S atoms. It was probably tetrameric or even larger. 5. The oxidoreductase activity of the intermediate fractions is dependent on the protein concentration, the activity with ferricyanide increasing and that with ferricytochrome c decreasing with increasing protein concentration. This is interpreted as an increased association of subunits present in the intermediate fractions. Similar results are obtained when flavin-rich and flavin-poor fractions are mixed. The association is cooperative. NADH favours the association of the subunits. 6. Association of the subunits is accompanied by a 10-fold increase in k2 (rate constant for intramolecular electron flow), a 10-fold decrease of the accessibility of ferricyanide to the reduced enzyme and a 10(4)-fold decrease of the accessibility of ferricytochrome c. The Ks (NADH) is also decreased. Although the changes are in the direction to be expected from a conversion of Type II enzyme to Type I, the value of k2 is still much less than in the latter enzyme.

Flavin Mononucleotide↗
PubMed1976

Steady-state kinetics of low molecular weight (type-II) NADH dehydrogenase.

(1) The steady-state kinetics of the NADH dehydrogenase activity of Type-II (low molecular weight) NADH dehydrogenase with the acceptors ferricyanide, cytochrome c and 2,6-dichloroindophenol are consistent with the simultaneous operation of an ordered and a ping-pong mechanism. Thus, depending on the acceptor concentration, the reduced enzyme is preferentially oxidized before or after NAD+ disociates from it. (2) The acceptors are able to oxidize the reduced enzyme and its NAD+ complex equally well. In contrast to the kinetics of the Type-I (high molecular weight) enzyme, double substrate inhibition is not found, implying that the site of oxidation of the reduced enzyme by acceptors and the NADH-binding site are remote. (3) With the indophenol, in the concentration range measured, the ordered mechanism is mainly operative. At infinite NADH and acceptor concentrations the rate constant of the reduction of enzyme by bound NADH is measured. (4) With ferricyanide and cytochrome c, in the concentration range measured, erroneous conclusions may be drawn from extrapolations owing to the fact that extrapolated lines in double-reciprocal plots of turnover number against acceptor concentration, at different NADH concentrations, intersect in the third quadrant. A method is described that allows the extrapolation of these data to zero acceptor concentrations. (5) The relation between activity and NADH concentration is sigmoidal (h = 2.0) with ferricyanide or cytochrome c as acceptor, but hyperbolic with 2,6-dichloroindophenol. The latter is also an inhibitor, competitive with respect to NADH. It is concluded that this two-electron acceptor, like ubiquinone, acts as an allosteric effector. (6) Type II is isolated from Type I without gross changes in tertiary structure, as judged by the unaltered rate constants of dissociation of NADH (k-1) and NAD+ (k4) and association of NADH (k1). (7) Type II differs from Type I in two respects, (a) The accessibility of the acceptors is greater by at least two orders of magnitude (k3). (b) The redox potential of the prosthetic group FMN is 120 mV less, as judged by a drop in the value of k2 by four orders of magnitude. It is suggested that one or more of the iron-sulphur proteins present in Type-I but lacking in Type-II dehydrogenase functions as an effector, regulating the redox potential of the FMN.

2,6-Dichloroindophenol↗
PubMed2025

Chromosomal instability by low-coverage whole-genome sequencing assay predicts prognosis in bladder cancer patients underwent radical cystectomy.

PURPOSE: To investigate chromosomal instability (CIN) in tumor tissue from radical bladder resection and to evaluate whether it can be used as a biomarker for the molecular typing of (BC). METHODS: DNA was extracted from formalin-fixed paraffin-embedded samples of 50 BC patients who were followed up to March 23 2023 using the Qiagen nucleic acid kits. We analyzed CIN in tumor of bladder by low-coverage whole genome sequencing (LC-WGS). Kaplan-Meier log-rank test was used to perform survival analysis. The association between variables and overall and progression-free survival was analyzed using the Cox proportional hazards model. RESULTS: There were 44 genome segments with statistically significant changes in copy number. CIN was significantly correlated with tumor stage, lymph node metastasis, relapse and survival status. Patients with high CIN were found to have a worse survival, with a median overall survival (OS) of 15 months. In addition, patients with high CIN were more likely to relapse, with a median progression-free survival (PFS) of 7 months. Patients with low CIN showed better OS and PFS. However, there was no significant difference in OS and PFS between T2 and T3-T4 patients. Multivariate cox regression analysis showed that high CIN was an independent predictor of OS, and high CIN and muscle invasion were independent predictors of PFS. Furthermore, patients with abnormal copy number of a single chromosome also had a poor prognosis, with a median survival of 14-30 months for OS and 5-10 months for PFS, while negative patients had a better prognosis. CONCLUSION: CIN was significantly correlated with tumor stage, lymph node metastasis, relapse and survival status of BC. Patients with high CIN or abnormal copy numbers of a single chromosome have a poor prognosis. CIN might be better than T stage in predicting the prognosis of patients with BC. Molecular typing of CIN can be used as an independent prognostic factor for BC.

Humans↗
PubMed1978

The molecular weight and character of plasma renin in SHRSP.

1. The molecular weight was 49,800 in SHRSP, quite different from the 43,300 of WK and the 49,500 and 37,700 of SHR, in females at the age of 200 days. 2. The molecular weight of plasma renin of female WK at the age of 90, 120, and 200 days ranged from 41,000 to 43,000 showing little variation. 3. The molecular weight of plasma renin varied according to the elevation of blood pressure. When blood pressure were 163, 200 to 250, and 267 mmHg, it showed 40,500, about 50,000, and about 60,000, respectively. 4. When subjected to an acid treatment, the high molecular type of SHRSP, showing molecular weights of plasma renin of about 50,000 to 60,000, increased in plasma renin activity by from 1.3 to 4.0 times.

Animals↗
PubMed1975

Characterisation of the major CNBr-Derived peptides of porcine type II collagen.

As part of a general study on the matrix macromolecules of pig cartilage, the CNBr-derived peptides of porcine type II collagen have been isolated from laryngeal cartilage and characterized. Type II was the only molecular type of collagen detected in laryngeal cartilage from 6-9 month old pigs. The major CNBr-peptides of this collagen were prepared by ion exchange and molecular sieve chromatography and characterized by SDS-polyacrylamide disc electrophoresis and amino acid analysis. Six peptides were recovered in high yield and were shown to be closely homologous to similar peptides previously recovered from bovine and human type II collagens. The largest peptide alpha1(II)CB10 appeared by SDS-disc electrophoresis to be slightly larger than previously reported. The amino acid composition of alpha1(II)CB10 supported this finding of a higher molecular weight.

Animals↗
PubMed1977

Characterization of two distinct molecular populations of type I mouse interferons.

The molecular heterogeneity of acid-stable (Type I) mouse interferons induced in C243 cells by Newcastle disease virus was analysed by SDS-polyacrylamide gel electrophoresis under non-reducing and reducing conditions, and the profiles of antiviral activities obtained were characterized biologicaly in mouse cells and in heterologous (guinea-pig) cells. Two bands of activity, A and B, were consistently present in all interferon preparations tested: under reducing conditions, the activity in all fractions of band A (with a peak of activity at about 38000 daltons) was uniformly increased, while that of band B (with a peak at about 22000 daltons) was uniformly diminished. All the active fraction in band A had only slight activity (less than 10% of homologous titres) on guinea-pig cells, whereas all those in band B were significantly more active an guinea-pig cells than on homologous L cells. Thus, mouse type I interferon preparations contain two molecular populations of interferons that can be distinguished physically (by size), biochemically (by the effect of reduction on reactivation from SDS) and biologically (by activity in heterologous cells).

Animals↗
PubMed2025

Fourier transform infrared spectroscopy enables rapid species discrimination across Malassezia and strain-level typing in M. pachydermatis.

Malassezia pachydermatis is a zoophilic yeast found on the skin and in the outer ear canal of many mammals. It normally maintains a commensal lifestyle but can cause dermatitis and otitis in predisposed hosts, particularly in atopic dogs. M. pachydermatis is genetically diverse, with strains clustering into at least three phylogroups based on molecular typing, a pattern we now confirm through whole-genome sequencing (WGS). Accurate species and strain-level identification is essential for understanding its epidemiology, pathogenic potential, and response to treatment. In this study, we established Fourier Transform Infrared (FTIR) spectroscopy as a rapid, cost-effective method for distinguishing M. pachydermatis from other Malassezia species, including M. globosa, M. furfur, M. restricta, and M. sympodialis. Within M. pachydermatis, FTIR spectroscopy resolved even closely related strains with high accuracy producing clusters congruent with WGS-based phylogeny. The incorporation of an Artificial Neural Network classifier further enhanced the discriminatory power, enabling robust and automated strain assignment. These findings demonstrate the potential of FTIR spectroscopy as a practical tool for large-scale epidemiological surveillance of M. pachydermatis and for clinical and veterinary applications where strain-level identification could inform treatment and management of Malassezia-associated diseases.

Fourier Transform Infrared (FTIR) spectroscopy↗
PubMed2026

Emergence of SCCmec variants causing false-negative MRSA results by Xpert SA Nasal Complete: a need for culture back-up?

BACKGROUND: Staphylococcus aureus (SA) is a major human pathogen and an important cause of healthcare-associated infections. Hospital-acquired methicillin-resistant S. aureus (MRSA) is associated with increased morbidity and mortality. Screening for nasal carriage of SA followed by decolonization has been shown to reduce healthcare-associated MRSA transmission and infection. Nucleic acid amplification assays (NAATs) are widely used for MRSA screening and are associated with shorter turnaround times, fewer isolation days, reduced MRSA-related infections, and improved clinical outcomes and cost savings. CASE SUMMARY: Two patients underwent preoperative nasal screening using Xpert SA Nasal Complete, and corresponding culture results were discordant with the molecular results. In both cases, the Xpert SA assay reported "SA detected and MRSA not detected," whereas culture and antimicrobial susceptibility testing (AST) demonstrated the presence of MRSA. Additional testing supported the culture-based identification of MRSA. Whole-genome sequencing and molecular typing revealed that both MRSA isolates harbored SCCmec variants that were not detected by the Xpert assay, leading to false-negative (FN) MRSA results. CONCLUSION: While NAATs remain highly sensitive and reliable tools for MRSA screening and the overall risk of FN MRSA detection may be low, our cases highlight the importance of ongoing surveillance of local MRSA epidemiology and understanding the genetic inclusivity of the molecular assays used for detection. In high-risk or targeted patients, consideration of reflex culture may be warranted.

MRSA screening↗
PubMed2026

Ribotyping for Accurate Identification of Infectious Bacteria in Animal-Derived Foods and Laboratory Samples: Implications for Human Health.

Ribotyping is a molecular typing approach based on ribosomal RNA (rRNA) gene sequences for the identification and characterization of bacterial strains. This review aims to evaluate the effectiveness of ribotyping in the identification of infectious bacteria in animal-derived foods and veterinary samples. A narrative literature review was conducted using major scientific databases, including PubMed, Scopus, Google Scholar, and Web of Science, covering studies published to 2025. Relevant articles were selected based on their focus on ribotyping methodologies (e.g., RFLP-, PCR-, and automated ribotyping) and their applications in food safety, veterinary microbiology, and zoonotic disease investigations. The findings indicate that ribotyping has been widely applied for epidemiological investigations, source tracking, and characterization of foodborne and zoonotic pathogens. These approaches have contributed to understanding bacterial diversity and monitoring antibiotic resistance patterns in animal populations and related food products. However, compared with high-resolution molecular techniques such as whole genome sequencing (WGS), ribotyping demonstrates lower discriminatory power and limited resolution for fine-scale epidemiological analysis. Despite these limitations, ribotyping remains a useful, accessible, and cost-effective tool in certain laboratory and surveillance settings, particularly where advanced genomic technologies are not readily available. Overall, integrating ribotyping with newer genomic approaches can enhance the monitoring and control of infectious bacteria, thereby supporting animal health, food safety, and public health outcomes.

animal-derived foods↗
PubMed2026

Genomic surveillance reveals escalating antimicrobial resistance and plasmid diversity in clinical Salmonella 1,4,[5],12:i:- ST34 isolates from Guizhou Province, China.

INTRODUCTION: Salmonella 1,4,[5],12:i:- ST34 has emerged as a significant public health issue due to its association with various antimicrobial resistance genes (ARGs) and transferable plasmids. However, its genomic characteristics and potential influence on public health in Guizhou have not been comprehensively assessed. METHODS: From 2019 to 2023, a 5-year surveillance was conducted in nine cities (prefectures) of Guizhou Province. We integrated phenotypic and genomic analyses of 281 clinical Salmonella 1,4,[5],12:i:- ST34 isolates to investigate the prevalence of ARGs and plasmids and to analyze the molecular epidemiology and evolution. RESULTS: The isolates exhibited resistance to first-line antibiotics, with 22.4% for ciprofloxacin, 11.4% for azithromycin, 18.5% for ceftazidime, and 39.1% for cefotaxime. ARGs showed substantial agreement with phenotypes for tetracycline, macrolides, third-generation cephalosporins (3GCs), carbapenems, and colistin (80.8-100.0% consistency; Kappa: 0.50-1.00). Plasmid analysis identified IncQ1 (84.3%) and IncHI2/IncHI2A (26.3%) as the main replicons, with the variety of plasmid replicons increasing from 7 to 21 over the 5 years. ARGs associated with resistance to critically important antibiotics (CIAs) were frequently predicted to be located on plasmid-associated contigs, with significant associations observed between IncHI2/IncHI2A plasmids and ARGs conferring resistance to fluoroquinolones, macrolides, and cephalosporins (P < 0.05). Molecular typing divided 281 isolates into 37 cgSTs, with cgST52428 being the most common. Molecular epidemiological analysis revealed that Guizhou isolates primarily clustered together, sharing close genetic ties with those from Sichuan and Guangdong, and exhibited the highest genetic similarity to pork-derived isolates. Phylogenetic analysis revealed clustering of CIA-resistant ARGs and plasmids in Clades 4 and 5, with a significant association between IncHI2/IncHI2A plasmids and CIA-resistant ARGs (&#x3c7;2 = 112.12, P < 0.001). Additionally, class 1 integron was associated with higher ARG burdens, while virulence-associated genes were conserved and predominantly chromosome-associated. Gene-content analysis revealed that isolates in Clades 4 and 5 harbored the largest mean gene complements, and cgST52428 isolates also harbored the largest among dominant cgSTs. DISCUSSION: This study presents a comprehensive genomic profile of Salmonella 1,4,[5],12:i:- ST34 in Guizhou, providing essential data for exploring the resistance characteristics and investigating the molecular epidemiology of Salmonella 1,4,[5],12:i:-.

ST34↗
PubMed1976

A possible mechanism of the generation of singlet molecular oxygen in nadph-dependent microsomal lipid peroxidation.

A simplified system, consisting of NADPH, Fe3+-ADP, EDTA, liposomes, NADPH-cytochrome c reductase and Tris - HCl buffer (pH 6.8), has been employed in studies of the generation of singlet oxygen in NADPH-dependent microsomal lipid peroxidation. The light emitted by the system involves 1deltag type molecular oxygen identifiable by its characteristic emission spectrum and its behavior with beta-carotene. The generation of another excited species (a compound in the triplet state) could be demonstrated in this system by changes of light intensity and emission spectra which arise from photosensitizer (9,10-dibromoanthracene sulfonate, eosin, Rose-Bengal)-mediated energy transfers. Chemiluminescence in the visible region was markedly quenched by various radical trappers and by an inhibitor of NADPH-cytochrome c reductase, but not by superoxide dismutase. During the early stage of lipid peroxidation, the intensity of chemiluminescence was proportional to the square of the concentration of lipid peroxide. These characteristics suggest that singlet oxygen and a compound in the triplet state (probably a carbonyl compound) are generated by a self-reaction of lipid peroxy radicals.

Animals↗
PubMed1978

Cellular and molecular studies on globin gene expression.

Globin gene expression has been studied with the use of a combination of cell and molecular biology techniques. With a somatic cell hybrid between mouse erythroleukemia (MEL) and human erythroid cells, human and mouse globin genes can be coexpressed in the same hybrid cell. Somatic cell hybridization between MEL cells and nonerythroid cells (e.g., human fibroblasts) results in hybrid cells that cannot be induced to produce hemoglobin of any type. Molecular hybridization of cellular DNA and RNA with globin cDNA indicates that the globin genes are present but that no globin mRNA is in the nonexpressing hybrid cell. This finding demonstrates that the loss of globin gene expression in the hybrid cell occurs at the level of transcription or mRNA processing. The nucleus of the nonerythroid cell is not necessary for the extinction of globin gene expression, since cybrids formed from MEL cells with enucleated nonerythroid cells also result in cells which cannot be induced to synthesize hemoglobin even after 40 or more generations. These data suggest that the cytoplasm of cells contains diffusible regulatory molecules which influence globin gene expression. In our attempt to develop an intracellular assay to test for regulatory molecules, we studied the procedure microinjection with red blood cell (RBC) ghosts. Rabbit globin mRNA (with hemin) was loaded into RBC's and then, by Sendai virus-mediated fusion, into Chinese hamster ovary (CHO) cells growing in culture; these microinjected CHO cells synthesized hemoglobin. Since this microinjection procedure appears to be effective in inserting both proteins and nucleic acids into intact cells, it should be possible to develop modifications for inserting aliquots of fractionated cytoplasm into growing cells. The procedure might then be useful as an assay for putative genetic regulatory molecules.

Animals↗
PubMed2026

Integrated bioinformatics analysis reveals cross-talking hub genes and therapeutic agents between sepsis and acute myocardial infarction.

BACKGROUND: Sepsis and acute myocardial infarction (AMI) are two significant diseases that may share overlapping etiological mechanisms. This study aims to systematically identify core genes common to both conditions and to explore their potential as therapeutic targets and drug candidates through an integrative analysis of clinical data and bioinformatics. METHODS: The AMI dataset was obtained from the GEO database, and RNA sequencing data were collected from blood samples of patients with sepsis at our hospital. Common genes were identified using differential expression gene analysis (DEG) and weighted gene co-expression network analysis (WGCNA). Functional enrichment analyses, including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, were performed. A protein-protein interaction (PPI) network was constructed, and hub genes were identified using the MCC/Degree algorithm. Diagnostic value was assessed via receiver operating characteristic curve analysis. Immune infiltration patterns, single-cell sequencing data, and molecular docking simulations were employed to evaluate immune relevance and identify potential therapeutic compounds. RESULTS: A total of 417 genes were identified between sepsis and AMI, with enrichment analysis revealing significant involvement in inflammatory responses. Three hub genes-JAK2, MYD88, and TIMP1-were selected for further investigation. ROC curves confirmed their strong diagnostic performance for both diseases. Immune infiltration analysis showed that these core genes were significantly correlated with the infiltration levels of various immune cell types. Molecular docking indicated that quercetin exhibited stable binding affinity with the proteins encoded by these genes. qPCR validation further confirmed the upregulation of these three genes, supporting the anti-inflammatory effects of quercetin as a potential targeted therapy. CONCLUSION: JAK2, MYD88, and TIMP1 were identified as shared core genes in sepsis and AMI. These genes not only serve as potential diagnostic biomarkers but also offer novel targets for developing common therapeutic strategies for both conditions. Furthermore, quercetin emerges as a promising candidate for targeted treatment.

Humans↗
PubMed2003

Evolutionary relationships among strains of Mycobacterium tuberculosis with few copies of IS6110.

Molecular typing of Mycobacterium tuberculosis by using IS6110 shows low discrimination when there are fewer than five copies of the insertion sequence. Using a collection of such isolates from a study of the epidemiology of tuberculosis in London, we have shown a substantial degree of congruence between IS6110 patterns and both spoligotype and PGRS type. This indicates that the IS6110 types mainly represent distinct families of strains rather than arising through the convergent insertion of IS6110 into favored positions. This is supported by identification of the genomic sites of the insertion of IS6110 in these strains. The combined data enable identification of the putative evolutionary relationships of these strains, comprising three lineages broadly associated with patients born in South Asia (India and Pakistan), Africa, and Europe, respectively. These lineages appear to be quite distinct from M. tuberculosis isolates with multiple copies of IS6110.

Africa↗
PubMed1978

Role of fatty acids in growth-promoting effect of serum albumin on hamster cells in vitro.

Dialyzed serum albumin had considerable growth-promoting effect on cultivated hamster cells. This effect was virtually lost on removal of the fatty acids, and it was completely restored by recombination of the fatty acid-free albumin with the isolated and purified fatty acids. The role of albumin itself appeared to be largely that of a carrier of fatty acids, protecting the cells against toxic effects of fatty acids in free solution. This conclusion was based on two observations: Fatty acids in the absence of albumin were growth-inhibitory except in extremely dilute solutions, and beta-lactoglobulin, a protein possessing, like albumin, the ability to bind and release fatty acids, could replace albumin in the presence of fatty acids with similar growth-promoting effect. Examination of individual molecular types of fatty acids showed that all unsaturated acids tested were growth-promoting, whereas the saturated acids were growth-inhibiting, with the exception of stearic acid in low concentrations. Although the possibility of a mitotic triggering effect was not excluded, the fatty acids presumably stimulated growth by providing substrate for cellular metabolism, since there was a direct relationship between the degree of growth stimulation and the duration of exposure of cells to the fatty acids.

Cell Division↗