			Home About us Contact

Molecular Heterogeneity (molecular + heterogeneity)

Distribution by Scientific Domains

Medical Sciences	76%
Chemistry	11%

Selected Abstracts

Molecular heterogeneity in Yersinia enterocolitica and ,Y. enterocolitica -like' species , Implications for epidemiology, typing and taxonomy

FEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 1 2005
Jugsharan S. Virdi
Abstract Yersinia enterocolitica is an extremely heterogeneous species. Serotyping and biotyping have been used extensively, in the past, to study its heterogeneity and epidemiology. Application of methods like ribotyping, pulsed-field gel electrophoresis and a host of other genomic techniques have further revealed molecular heterogeneity in this species. Furthermore, these methods may be used effectively to supplement serotyping and biotyping schema for studying epidemiology of Y. enterocolitica. This is evident from the ability of some of these methods to subtype strains belonging to serogroups O:3, O:9 and O:8 , which are most commonly encountered in human Yersiniosis. Multilocus enzyme electrophoresis and nucleotide sequencing have reiterated the taxonomic relationships of this organism. However there is paucity of information about the molecular heterogeneity of ,Y. enterocolitica -like' species, which need to be addressed in the future. Also, newer techniques such as amplified fragment length polymorphism, VNTR-based typing and multilocus sequence typing should be applied to further understand epidemiology, population structure and evolutionary genetics of Y. enterocolitica and ,Y. enterocolitica -like' species. [source]

Molecular heterogeneity of the A3 subgroup

INTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 2 2000
M.L. Barjas-Castro
Summary The molecular characterization of the subgroup A3 remains unclear. Four unrelated A3 blood donors were studied. Family studies were possible in three of them. The A3 subgroup was defined by immunohaematological evaluation with four different commercially available serums. Exons VI and VII of the ABO gene, responsible for 91% of the catalytic active part of the glycosyltransferase, were amplified and subjected to direct sequencing. The results in all samples showed heterozygosity for the G261 deletion. In the A3 allele, the following associations were found: C467T mutation and 1060C deletion in one A3 blood donor and in another G829A and 1060C. In one case, only the 1060C deletion was demonstrated in the A3 allele. One blood donor presented the T646A and the G829A mutations in homozygosity. It was concluded that the A3 blood group is very heterogeneous at the molecular level. [source]

Molecular heterogeneity of familial porphyria cutanea tarda in Spain: characterization of 10 novel mutations in the UROD gene

BRITISH JOURNAL OF DERMATOLOGY, Issue 3 2007
M. Méndez
Summary Background, Porphyria cutanea tarda (PCT) results from decreased hepatic uroporphyrinogen decarboxylase (UROD) activity. In the majority of patients, the disease is sporadic (S-PCT or type I) and the enzyme deficiency is limited to the liver. Familial PCT (F-PCT or type II) is observed in 20,30% of patients in whom mutations on one allele of the UROD gene reduce UROD activity by approximately 50% in all tissues. Another variant of PCT (type III) is characterized by family history of the disease although it is biochemically indistinguishable from S-PCT. Objectives, To investigate the molecular basis of PCT in Spain and to compare enzymatic and molecular analysis for the identification of patients with F-PCT. Methods, Erythrocyte UROD activity measurement and mutation analysis of the UROD gene were carried out in a cohort of 61 unrelated Spanish patients with PCT and 50 control individuals. Furthermore, each novel missense mutation identified was characterized by prokaryotic expression studies. Results, Of these 61 patients, 40 (66%) were classified as having S-PCT, 16 (26%) as having F-PCT and five (8%) as having type III PCT. Discordant results between enzymatic and molecular analysis were observed in two patients with F-PCT. In total, 14 distinct mutations were found, including 10 novel mutations: five missense, one nonsense, three deletions and an insertion. Prokaryotic expression of the novel missense mutations demonstrated that each results in decreased enzyme activity or stability. Conclusions, These results confirm the high degree of molecular heterogeneity of F-PCT in Spain and emphasize the usefulness of molecular genetic analysis to distinguish between F-PCT and S-PCT. [source]

Characterization of Ethylene Copolymers with Liquid Chromatography and Melt Rheology Methods

MACROMOLECULAR SYMPOSIA, Issue 1 2009
Yefim Brun
Abstract Summary: Melt rheology and polymer chromatography methods were applied to characterize molecular heterogeneities in products of free radical copolymerization of ethylene with methyl acrylate and vinyl acetate comonomers performed in continuously stirred tank and tubular reactors. We found that the ethylene,vinyl acetate copolymers made in both reactors had similar linear viscoelastic properties typical to branched products of the high pressure process. But the ethylene,methyl acrylate copolymers obtained in the tubular reactor had unusually high melt viscosity at low shear rate and much lower onset of shear thinning despite the narrower molecular weight distribution and the lower overall amount of long-chain branches compare to their autoclave counterparts with similar average molecular weight and chemical composition. Using interaction polymer chromatography method called gradient elution at critical point of adsorption we found that ethylene-acrylate copolymers from the tubular reactor had very broad chemical composition distribution, which was consistent with a significant difference in reactivity ratios between ethylene and acrylate comonomers. Such chemical composition heterogeneity can be a reason for the observed unusual rheological properties of these copolymers. [source]

Commercial manufacturing scale formulation and analytical characterization of therapeutic recombinant antibodies

DRUG DEVELOPMENT RESEARCH, Issue 3 2004
Reed J. Harris
Abstract Stable therapeutic antibody dosage forms present production technology challenges, particularly when high-concentration formulations are needed to meet the elevated dose requirements that are generally required for successful antibody therapy. Solid dosage forms, such as lyophilized powders, are generally more stable than liquid formulations. High-concentration drug products can be achieved by reconstitution of the lyophilisate in a smaller volume than its initial (pre-lyophilization) volume, but requires a significant vial overfill. High-concentration liquid formulations are becoming feasible as new techniques and technologies become available. Analytical methods to detect subtle molecular variations have been developed to demonstrate manufacturing consistency. Some molecular heterogeneity is contributed by conserved sites, such as Asn297 glycosylation and the loss of heavy chain C-terminal Lys residues. Characteristics that affect potency, stability, or immunogenicity must be elucidated for each therapeutic antibody. Drug Dev. Res. 61:137,154, 2004. © 2004 Wiley-Liss, Inc. [source]

Molecular heterogeneity in Yersinia enterocolitica and ,Y. enterocolitica -like' species , Implications for epidemiology, typing and taxonomy

Relevance of Ras gene mutations in the context of the molecular heterogeneity of multiple myeloma

HEMATOLOGICAL ONCOLOGY, Issue 1 2007
Daniela Intini
Abstract Ras gene mutations are a recurrent genetic lesion in multiple myeloma (MM). Here, we report a mutation analysis of N- and K- Ras genes in purified plasma cell populations from a panel of 81 newly diagnosed MM patients stratified according to the most frequent genetic and molecular features associated with the neoplasia. Ras gene mutations, mostly involving the N- Ras gene, were detected in 20% of the patients. Ras mutations did not correlate with the presence of chromosome 13q deletion, trisomy of chromosome 11, 1q amplification or hyperdiploidy. In addition, despite an appreciable association with tumours overexpressing Cyclin D1, Ras mutations did not correlate at significant levels with any of the proposed groups in the TC classification, based on the presence of the major IgH chromosomal translocations and expression of Cyclin D genes. Finally, transcription analyses revealed the presence of differentially expressed transcripts in human multiple myeloma cell lines carrying the Ras gene mutations but not in primary tumours. Overall, these data suggest that Ras gene mutations are not likely to represent a master lesion in MM but its relevance needs to be considered in the context of other genetic abnormalities. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Molecular pathology of NEU1 gene in sialidosis,

HUMAN MUTATION, Issue 5 2003
Volkan Seyrantepe
Abstract Lysosomal sialidase (EC 3.2.1.18) has a dual physiological function; it participates in intralysosomal catabolism of sialylated glycoconjugates and is involved in cellular immune response. Mutations in the sialidase gene NEU1, located on chromosome 6p21.3, result in autosomal recessive disorder, sialidosis, which is characterized by the progressive lysosomal storage of sialylated glycopeptides and oligosaccharides. Sialidosis type I is a milder, late-onset, normosomatic form of the disorder. Type I patients develop visual defects, myoclonus syndrome, cherry-red macular spots, ataxia, hyperreflexia, and seizures. The severe early-onset form, sialidosis type II, is also associated with dysostosis multiplex, Hurler-like phenotype, mental retardation, and hepatosplenomegaly. We summarize information on the 34 unique mutations determined so far in the sialidase gene, including four novel missense and one novel nonsense mutations found in two Czech and two French sialidosis patients. The analysis of sialidase mutations in sialidosis revealed considerable molecular heterogeneity, reflecting the diversity of clinical phenotypes that make molecular diagnosis difficult. The majority of sialidosis patients have had missense mutations, many of which have been expressed; their effects on activity, stability, intracellular localization, and supramolecular organization of sialidase were studied. A structural model of sialidase allowed us to localize mutations in the sialidase molecule and to predict their impact on the tertiary structure and biochemical properties of the enzyme. Hum Mutat 22:343,352, 2003. © 2003 Wiley-Liss, Inc. [source]

Faecal screening of colorectal cancer

INTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 3 2008
A. Loganayagam
Summary Aims:, Screening and prevention of colorectal cancer (CRC) is a public health priority. Recent progress in understanding the biology of CRC has lead to possible new approaches to screening. In particular, assay of faecal molecular markers represents a promising non-invasive approach to screening, with improved safety, accuracy and patient compliance. Methods:, MEDLINE/PubMed searches were used to identify key articles relating to faecal-based screening with secondary review of cited publications. Results:, Faecal markers of CRC can be broadly divided into DNA based and non-DNA based. Conclusions:, Faecal occult blood testing for CRC screening has been advocated for decades for its non-invasiveness and low cost. It has exhibited a 15,33% decrease in mortality, despite drawbacks with sensitivity and compliance. Other non-DNA markers have the adequate sensitivity for inflammatory lesions but do not have the required specificity for screening average-risk populations. Faecal DNA testing has the potential to enhance the performance characteristics of stool testing. Because of molecular heterogeneity of cancer, no single DNA marker has yielded adequate sensitivity. Analysis of several combinations of markers in studies have produced high detection rates of both CRC and advanced adenomas in selected patient groups. However, the currently available markers, both non-DNA and DNA, have not yet been validated in large-scale studies screening average -risk population nor have they so far shown the necessary sensitivity and specificity required for large-scale screening programmes. Another major drawback with the DNA-based markers is the cost-effectiveness. Issues regarding implementation and compliance remain unanswered. These critical problems have to be rectified before these techniques can be recommended for large-scale CRC screening. [source]

Characterization of N -palmitoylated human growth hormone by in situ liquid,liquid extraction and MALDI tandem mass spectrometry

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 6 2007
Emmanuelle Sachon
Abstract Acylation is a common post-translational modification found in secreted proteins and membrane-associated proteins, including signal transducing and regulatory proteins. Acylation is also explored in the pharmaceutical and biotechnology industry to increase the stability and lifetime of protein-based products. The presence of acyl moieties in proteins and peptides affects the physico-chemical properties of these species, thereby modulating protein stability, function, localization and molecular interactions. Characterization of protein acylation is a challenging analytical task, which includes the precise definition of the acylation sites in proteins and determination of the identity and molecular heterogeneity of the acyl moiety at each individual site. In this study, we generated a chemically modified human growth hormone (hGH) by incorporation of a palmitoyl moiety on the N, group of a lysine residue. Monoacylation of the hGH protein was confirmed by determination of the intact molecular weight by mass spectrometry. Detailed analysis of protein acylation was achieved by analysis of peptides derived from hGH by protease treatment. However, peptide mass mapping by MALDI MS using trypsin and AspN proteases and standard sample preparation methods did not reveal any palmitoylated peptides. In contrast, in situ liquid,liquid extraction (LLE) performed directly on the MALDI MS metal target enabled detection of acylated peptide candidates by MALDI MS and demonstrated that hGH was N -palmitoylated at multiple lysine residues. MALDI MS and MS/MS analysis of the modified peptides mapped the N -palmitoylation sites to Lys158, Lys172 and Lys140 or Lys145. This study demonstrates the utility of LLE/MALDI MS/MS for mapping and characterization of acylation sites in proteins and peptides and the importance of optimizing sample preparation methods for mass spectrometry-based determination of substoichiometric, multi-site protein modifications. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Neoadjuvant treatment of soft-tissue sarcoma: A multimodality approach

JOURNAL OF SURGICAL ONCOLOGY, Issue 4 2010
David Reynoso BS
Abstract Unlike epithelial cancers that are both more homogeneous and easily categorized by their respective tissues of origin (e.g., breast or lung cancer), sarcomas represent a diverse class of molecularly distinct bone and soft-tissue mesenchymal neoplasms of more than 50 subtypes. This diversity, as well as the relative rarity of sarcomas as a whole, has presented challenges in conducting prospective randomized clinical trials to assess the value of neoadjuvant chemotherapy for any given subtype. Most clinical trials and meta-analyses have neglected the phenotypic and molecular heterogeneity differentiating one sarcoma subtype from another in favor of a simplified grouping that ensures timely trial completion. As the success of treating gastrointestinal stromal tumors (GISTs) with imatinib demonstrates, a decision to provide neoadjuvant chemotherapy must take into consideration both the subtype being treated and the effect such treatment would be expected to exert upon that subtype. J. Surg. Oncol. 2010; 101:327,333. © 2010 Wiley-Liss, Inc. [source]

Keratan sulfate-containing proteoglycans in sheep brain with particular reference to phosphacan and synaptic vesicle proteoglycan isoforms

BIOMEDICAL CHROMATOGRAPHY, Issue 5 2009
Efstathios A. Sinouris
Abstract Proteoglycans (PGs) are widely expressed in all areas of the brain. In this study, the keratan sulfate-containing PGs (KS-PGs) from cerebrum (CB), cerebellum (CL) and brainstem (BS) of young sheep brain were isolated, purified and characterized. The amount of KS-PGs in CL was significantly lower than that in CB and BS. KS-PGs were characterized by increased extent of glycosylation and heterogeneity of KS chains in CL. Western blot analyses demonstrated the presence of the KS-PGs phosphacan, SV2A and SV2B isoforms of synaptic vesicle proteoglycan in all three areas of the young sheep brain. Phosphacan predominated in BS and CB, showing significant molecular heterogeneity. SV2A and SV2B were found in two forms of high and low molecular sizes according to their extent of glycosylation in sheep brain. SV2A predominated in CL, where forms with very high molecular sizes were detected. Immunohistochemical examination revealed that SV2A was localized in the extracellular matrix of both gray and white matter. In contrast, phosphacan and SV2B were mainly localized in the white matter in all brain regions. The results of the present study demonstrated that KS-PGs are present in the three areas of the sheep brain, showing significant variations in their content, structure and localization among the distinct areas. These differences may be important for the physiology of the brain. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Molecular heterogeneity of familial porphyria cutanea tarda in Spain: characterization of 10 novel mutations in the UROD gene

High frequency of the 425A,G splice-site mutation and novel mutations of the COL7A1 gene in central Europe: significance for future mutation detection strategies in dystrophic epidermolysis bullosa

BRITISH JOURNAL OF DERMATOLOGY, Issue 5 2005
M. Csikós
Summary Background, Mutations in the type VII collagen gene (COL7A1) are responsible for dominant and recessive forms of dystrophic epidermolysis bullosa (DEB). These mutations are usually specific for individual families; only a few cases of recurring mutations have been identified. Objectives, Forty-three unrelated Hungarian and German patients with different DEB phenotypes were screened for novel and recurrent COL7A1 mutations. Methods, All patients were classified based on clinical and genetic findings, skin immunofluorescent antigen mapping, and electron microscopic studies. Mutation analysis was performed by amplification of genomic DNA with polymerase chain reaction using COL7A1 -specific primers, heteroduplex analysis, and direct nucleotide sequencing. Restriction endonuclease digestion was used for family screening and mutation verification. Results, In this group of patients, the splice-site mutation 425A,G was observed frequently, in 11 of 86 alleles (12·8%), once in homozygous form and in nine cases in heterozygous form. One of 100 control alleles from clinically unaffected individuals also carried the mutation. We also identified three novel mutations: the 976-3C,A splice-site mutation, and the 4929delT and 8441-15del20 deletions. Conclusions, High recurrence of the splice-site mutation 425A,G in central European patients with DEB should be taken into account when designing COL7A1 mutation detection strategies. Reporting of three novel COL7A1 mutations in this study further emphasizes the molecular heterogeneity of DEB and provides more information for studies on genotype,phenotype correlations in different DEB subtypes. [source]

Intraoperative decay profile of intact (1,84) parathyroid hormone in surgery for secondary hyperparathyroidism in a consecutive series of 50 patients on haemodialysis

BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 9 2000
J. Lokey
Background The usefulness of rapid intraoperative monitoring of intact (1,84) parathyroid hormone (PTH) is not clearly defined in the surgical management of secondary HPT in the patients on haemodialysis. The aim of this study was to define the normal pattern of decay during surgery for secondary HPT using the rapid intact (1,84) PTH assay during operation. Methods Fifty patients on haemodialysis underwent neck exploration for secondary HPT. The therapeutic goal in all patients was the subtotal resection of four or more glands and bilateral transcervical thymectomy. PTH levels were monitored using a rapid immunochemiluminometric assay. Peripheral blood samples were assayed at induction of anaesthesia, after dissection but before resection, and 20 and 40 min after resection in all patients. All patients were followed up for at least 6 months. PTH levels were expressed as absolute values, as multiples of the upper limit of normal and as the percentage decline from pre-excision values. Results Forty-eight patients (96 per cent) were considered cured after surgery. Twenty patients (40 per cent) had a PTH level less than twice normal and 20 patients (40 per cent) had a PTH level between two and four times normal at 20 min. At late follow-up, all these patients were cured. Ten patients (20 per cent) had a PTH level greater than four times normal at 20 min. Eight of these patients were cured. Seven of these eight had a PTH level at 20 min, while not less than four times normal, less than 40 per cent of the original value. In contrast, the two failures had neither a decline to less than four times normal nor a decay to less than 40 per cent of the original value. One has been reoperated with resection of a fifth gland and one awaits reoperation. Conclusion The intraoperative decay of PTH during surgery for secondary HPT in patients on haemodialysis is slower than that in patients with normal renal function. However, 20 min after resection, a decline to less than four times the upper limit of normal is predictive of cure. Variability of decay slopes in individual patients may reflect molecular heterogeneity or biphasic metabolism of the hormone. © 2000 British Journal of Surgery Society Ltd [source]

Proceedings of the Australian Physiological and Pharmacological Society Symposium: New Frontiers in Muscle Research Hybrid skeletal muscle fibres: a rare or common phenomenon?

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 8 2001
Gabriela MM Stephenson
SUMMARY 1. The main aim of the present review is to raise awareness of the molecular complexity of single skeletal muscle fibres from ,normal' and ,transforming' muscles, in recognition of the many types of hybrids that have been observed in vertebrate skeletal muscle. The data used to illustrate various points made in the review were taken from studies on mammalian (mostly rat) and amphibian muscles. 2. The review provides a brief overview of the pattern and extent of molecular heterogeneity in hybrid muscle fibres and of the methodological problems encountered when attempting to identify and characterize such fibres. Particular attention is given to four types of skeletal muscle hybrids: (i) myosin heavy chain (MHC) hybrids; (ii) mismatched MHC,myosin light chains (MLC) hybrids; (iii) mismatched MHC,regulatory protein hybrids; and (iv) hybrids containing mismatched MHC,sarcoplasmic reticulum protein isoforms. 3. Some of the current ideas regarding the functional significance, origin and cognitive value of hybrid fibres are examined critically. [source]

Application of new homologous in vitro bioassays for human lactogens to assess the actual bioactivity of human prolactin isoforms in hyperprolactinaemic patients

CLINICAL ENDOCRINOLOGY, Issue 2 2006
Alfredo Leaños-Miranda
Summary Background, ,Prolactin (PRL) plays a central role in mammary gland development and lactation. Due to its molecular heterogeneity, measurement of PRL immunoreactivity does not necessarily reflect its intrinsic bioactivity. For many years the Nb2 rat lymphoma cell bioassay has been the only reference bioassay for human lactogens. This bioassay, however, does not always correlate with the clinical features found in some patients exhibiting normal or elevated immunoreactive serum PRL concentrations. Objectives, ,(1) To determine the concentrations of bioactive PRL in serum samples from individuals with normoprolactinaemia or with different forms of hyperprolactinaemia using two recently described homologous in vitro bioassays (i.e. a transcriptional bioassay in HEK-293 cells and a proliferation assay in Ba/F3 cells); and (2) to compare these results with those generated by the classical Nb2 cell bioassay. Design, ,Cross-sectional study. Setting, ,An institutional biomedical research laboratory. Participants, ,Ten patients with symptomatic hyperprolactinaemia due to prolactinoma, 11 patients with asymptomatic hyperprolactinaemia and macroprolactinaemia, and nine normal women. Main outcome measures, ,Measurement of immunoreactive and bioactive concentrations of serum PRL. Results, ,Samples from normal women and patients with tumoral hyperprolactinaemia due to prolactinoma exhibited similar within-group concentration values of bioactive and immunoreactive serum PRL when tested by the three bioassays and the immunoradiometric assay employed. By contrast, measurement of bioactive PRL in samples from patients with macroprolactinaemia revealed that macroprolactin was poorly active in the homologous receptor bioassays, while it was more active in the Nb2 bioassay. Conclusions, ,The reduced bioactivity of PRL in patients with macroprolactinaemia may further explain the absence of clinical features of hyperprolactinaemia in these individuals. In addition, our findings indicate that species-specificity and sensitivity of the bioassays are determinant factors in the measurement of the intrinsic biological activity of circulating PRL. [source]