PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Molecular characterization”

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 73 records · Page 4Linked to original sources

[Molecular characterization of cutaneous neuroendocrine (Merkel cell) carcinoma. Review of the literature and presentation of a caseload].

Molecular characterization of neuroendocrine (Merkel cell) carcinoma of the skin. Review of the literature and report of three cases. Although neuroendocrine carcinoma of the skin (NECS) is comparatively a rare clinical-histological entity, numerous morphological and ultrastructural studies have been carried out since the tumor was identificated by Toker (1972). Recently immunocytochemistry has allowed a better molecular characterization (immunophenotype) of this tumor and a more exact diagnosis. The main problem for the pathologist is the differential diagnosis between NECS and skin neoplasms--both primitive and metastatic--which require a more aggressive treatment. Often the classical morphological criteria do not distinguish NECS from non-Hodgkin's lymphoma, amelanotic melanomas, cutaneous metastases of lung small cell carcinoma or of neuroblastoma. The co-expression of cytokeratins and neurofilaments constantly found in NECS, is surely the best differential criterion from non-neuroendocrine carcinomas. Furthermore, the typical paranuclear location of both the intermediate filaments in NECS is a distinctive peculiarity as opposed to lung microcytoma, where cytokeratins and neurofilaments, when present, show widespread perinuclear positivity. Chromogranin A is found only in a small percentage of tumor cells, whilst synthesis of calcitonin, somatostatin, gastrin, ACTH, is very rare. Finally, the lack of common leukocyte antigen (CLA), S-100 protein and vimentin in NECS rules out the diagnoses of lymphoma, melanoma and sarcoma respectively.

Aged↗

Molecular characterization of uptake hydrogenase in Frankia.

A molecular characterization of uptake hydrogenase in Frankia was performed by using two-dimensional gel electrophoresis, matrix-assisted laser-desorption ionization-time-of-flight mass spectrometry, PCR amplification and Southern blotting. A polypeptide of approx. 60 kDa was recognized in Frankia UGL011102, AVCI1 and KB5 on the two-dimensional gel by blotting with Ralstonia eutropha (Hox G) antibody. Further analysis by MS resulted in a peptide 'fingerprint', which was similar to the membrane-bound hydrogenase 2 large subunit (HYD2) in Escherichia coli. In addition, a 127 bp PCR fragment could also be amplified from Frankia AVCI1, which gave a 76% similarity with the large subunit of hydrogenase in, e.g., Azotobacter chrococcum, Bradyrhizobium japonicum and Rhizobium leguminosarum. Although immunological similarity between the small subunit of Frankia hydrogenase and that of other organisms has not yet been found, a PCR product of 500 bp could be amplified from the local source of Frankia, the analysis of which gave 69 and 67% identity with the small subunit of hydrogenases in B. japonicum and R. leguminosarum respectively. A Southern-blot analysis further indicated evidence for the presence of the small hydrogenase subunit in other Frankia strains, i.e. KB5, AvcI1 and CcI3.

Amino Acid Sequence↗

Microvirus of chlamydia psittaci strain guinea pig inclusion conjunctivitis: isolation and molecular characterization.

The authors report the isolation and molecular characterization of a bacteriophage, φCPG1, which infects CHLAMYDIA: psittaci strain Guinea pig Inclusion Conjunctivitis. Purified virion preparations contained isometric particles of 25 nm diameter, superficially similar to spike-less members of the φX174 family of bacteriophages. The single-stranded circular DNA genome of φCPG1 included five large ORFs, which were similar to ORFs in the genome of a previously described CHLAMYDIA: bacteriophage (Chp1) that infects avian C. psittaci. Three of the ORFs encoded polypeptides that were similar to those in a phage infecting the mollicute Spiroplasma melliferum, a pathogen of honeybees. Lesser sequence similarities were seen between two ORF products and the major capsid protein of the φX174 coliphage family and proteins mediating rolling circle replication initiation in phages, phagemids and plasmids. Phage φCPG1 is the second member of the genus CHLAMYDIAMICROVIRUS:, the first to infect a member of a CHLAMYDIA: species infecting mammals. Similarity searches of the nucleotide sequence further revealed a highly conserved (75% identity) 375 base sequence integrated into the genome of the human pathogen Chlamydia pneumoniae. This genomic segment encodes a truncated 113 residue polypeptide, the sequence of which is 72% identical to the amino-terminal end of the putative replication initiation protein of φCPG1. This finding suggests that C. pneumoniae has been infected by a phage related to φCPG1 and that infection resulted in integration of some of the phage genome into the C. pneumoniae genome.

Amino Acid Sequence↗

Molecular characterization of a ring chromosome 14 showing that the PI locus is centromeric to the D14S1 and IGH loci.

Molecular characterization of a ring chromosome 14 was carried out in a patient with the 46,XX,r(14) karyotype. The breakpoints shown by chromosome banding were within bands p11 and q32. Using molecular probes for the immunoglobulin heavy chain (IGH), D14S1 and PI loci located at 14q32, we showed that the IGH and D14S1 loci, located at 14q32.3 and 14q32.2 respectively, were deleted on the ring chromosome 14, but that the PI locus was not. Therefore, the chromosomal break lies between PI and D14S1. These results show that the order of these chromosome 14 markers is cen-PI-D14S1-IGH, in keeping with multipoint linkage data. Further molecular characterization of ring 14 chromosomes should lead to a detailed understanding of the molecular events and clinical consequences of the gene deletion associated with such chromosomal aberrations.

Blotting, Southern↗

Molecular characterization of higher plant NAD-dependent isocitrate dehydrogenase: evidence for a heteromeric structure by the complementation of yeast mutants.

NAD-dependent isocitrate dehydrogenase (IDH) is a key enzyme controlling the activity of the citric acid cycle. Despite more than 30 years of work, the plant enzyme remains poorly characterized. In this paper, a molecular characterization of the plant IDH is presented. Starting from probes defined according to sequence comparisons, three full-length cDNAs named Ntidha, Ntidhb and Ntidhc encoding different IDH subunits have been isolated from a Nicotiana tabacum cell suspension library. Sequence comparisons of the tobacco IDH subunits with the E. coli NADP-dependent enzyme, and the yeast IDH1 and IDH2 subunits suggested that only IDHa had the capacity to be catalytic as IDHb and IDHc were lacking certain residues implied in catalysis. The ability of antibodies raised against the recombinant IDHa protein to preferentially cross-react with IDH2 indicated that IDHa was more closely related to IDH2 than to IDH1. Complementation of yeast single IDH mutants showed that IDHb and IDHc could replace the function of the yeast regulatory IDH1 subunit. Although IDHa was unable to complement the IDH2 mutant, its catalytic function was revealed by the ability of two heteromeric enzymes, composed of either IDHa with IDHb or IDHa with IDHc, to replace IDH function in a yeast double mutant lacking both subunits. Expression studies at the protein and mRNA levels show that each subunit is present in both root and leaf tissues and that the three IDH genes respond in the same way to nitrate addition. Taken together, such observations suggest that the physiologically active enzyme is composed of the three different subunits. These results show for the first time that the plant IDH is heteromeric and that IDH subunit composition appears to be conserved between plant and animal kingdoms.

Amino Acid Sequence↗

Molecular characterization of human healthy and neoplastic cerebral and renal tissues by in vitro (1)H NMR spectroscopy (review).

The clinical impact of (1)H NMR spectroscopy in the study of human organs, brain and kidney in particular, is well demonstrated. The in vitro (1)H NMR technique is a powerful tool for monitoring changes in intracellular metabolites of human normal and neoplastic cerebral and renal tissues. Healthy and tumoral tissues of different histologic types have been fully characterized from a biochemical standpoint. Molecular characterization is performed on both the aqueous and lipid extracts of surgically removed tissue biopsies yielding a full picture of tissue biochemistry. These analyses have disclosed markers of healthy brain and kidney and of their respective neoplastic lesions. Moreover, some biochemical features can differentiate neoplasms within the same histological type. In particular, lipidic components, like cholesteryl esters (namely oleate), detected in highest grade tumors, warrant further investigation. A better understanding of the biochemistry of diseased human tissues could open the way to new diagnostic and treatment strategies.

Brain Neoplasms↗

The use of fine-needle aspiration cytology in the molecular characterization of neuroblastoma in children.

BACKGROUND: The utility of fine-needle aspiration (FNA) material in the molecular characterization of a group of neuroblastic tumors (NT) in children is presented. METHODS: A recent study showed a high accuracy rate for FNA cytology (FNAC) in combination with immunostaining as a diagnostic method in 26 children with NT. In the current study FNA smears from 18 children were analyzed, either at the time of diagnosis or retrospectively, on available stored smears for cellular DNA content (DNA ploidy) by means of image cytometry (ICM) and 1p deletion and N-myc amplification by interphase fluorescent in situ hybridization (FISH). RESULTS: A total 62 analyses (DNA ploidy, 20 analyses; chromosome 1 or 2 number, 11 analyses; 1p deletion, 16 analyses; and N-myc, 15 analyses) resulted in clear information in 60 cases, whereas 2 tests for N-myc amplification failed. The results were compared with each other and with cytometric DNA analyses on tumor touch imprints (n = 12) and N-myc analyses on material from surgical specimens (Southern blot analysis, n = 12). The results were concordant in all but seven analyses (all with clear informative results) in six children. These discrepancies may be explained as an effect of either chemotherapy or tumor heterogeneity. CONCLUSIONS: FNA is a fast and noninvasive diagnostic technique that yields sufficient material for the molecular characterization of neuroblastic tumors by means of FISH and ICM. Such analyses are of prognostic significance because they predict tumor behavior and response to therapy according to International Neuroblastoma Staging System/International Neuroblastoma Risk Groups criteria. In the majority of cases it also is possible to obtain material for storage and future investigations.

Biopsy, Needle↗

Molecular characterization of cDNAs encoding low-molecular-weight heat shock proteins of soybean.

Three cDNA clones (GmHSP23.9, GmHSP22.3, and GmHSP22.5) representing three different members of the low-molecular-weight (LMW) heat shock protein (HSP) gene superfamily were isolated and characterized. A fourth cDNA clone, pFS2033, was partially characterized previously as a full-length genomic clone GmHSP22.0. The deduced amino acid sequences of all four cDNA clones have the conserved carboxyl-terminal LMW HSP domain. Sequence and hydropathy analyses of GmHSP22, GmHSP22.3, and GmHSP22.5, representing HSPs in the 20 to 24 kDa range, indicate they contain amino-terminal signal peptides. The mRNAs from GmHSP22, GmHSP22.3, and GmHSP22.5 were preferentially associated in vivo with endoplasmic reticulum (ER)-bound polysomes. GmHSP22 and GmHSP22.5 encode strikingly similar proteins; they are 78% identical and 90% conserved at the amino acid sequence level, and both possess the C-terminal tetrapeptide KDEL which is similar to the consensus ER retention motif KDEL; the encoded polypeptides can be clearly resolved from each other by two-dimensional gel analysis of their hybrid-arrest translation products. GmHSP22.3 is less closely related to GmHSP22 (48% identical and 70% conserved) and GmHSP22.5 (47% identical and 65% conserved). The fourth cDNA clone, GmHSP23.9, encodes a HSP of ca. 24 kDa with an amino terminus that has characteristics of some mitochondrial transit sequences, and in contrast to GmHSP22, GmHSP22.3, and GmHSP22.5, the corresponding mRNA is preferentially associated in vivo with free polysomes. It is proposed that the LMW HSP gene superfamily be expanded to at least six classes to include a mitochondrial class and an additional endomembrane class of LMW HSPs.

Amino Acid Sequence↗

Epidemiological studies on American leishmaniasis in Ceará State, Brazil. Molecular characterization of the Leishmania isolates.

Two methods of molecular characterization, using monoclonal antibodies and enzyme electrophoresis, were employed in the identification of 36 stocks of Leishmania isolated from human and canine cases of American visceral (AVL) and cutaneous (ACL) leishmaniases in the northern part of Ceará State, Brazil. Molecular homogeneous strains of Leishmania donovani (chagasi) isolated from both human and canine hosts were detected in 14 municipalities. Two more parasite species, L. braziliensis braziliensis and L. mexicana amazonensis, were also detected in the state. The implication of these results with respect to both the clinical and epidemiological data are discussed.

Animals↗

Molecular characterization of HbH disease in the Cuban population.

Molecular characterization of the alpha-thalassemia mutations present in nine HbH subjects from Cuba was achieved by digestion with Bam HI, Bgl II, and Apa I and hybridization with alpha- and zeta-specific probes. The results show that the molecular basis of the genetic defect is quite homogeneous, all the subjects carrying the - alpha 3.7 type I/--SEA genotype. Variations are observed in the size of the zeta polymorphic fragments.

Cuba↗

Mild beta-thalassemia intermedia caused by compound heterozygosity for (G)gamma((A)gammadeltabeta)(o)/beta-thalassemia and molecular characterization of the defect in four Chinese families.

Molecular characterization of the compound heterozygous condition - (G)gamma((A)gammadeltabeta)(o)/beta-thalassemia - in four families showing mild beta-thalassemia intermedia was carried out using DNA amplification techniques. Using the Amplification Refractory Mutation System (ARMS) to confirm the beta-mutations and DNA amplification to detect the 100-kb Chinese-specific (G)gamma((A)gammadeltabeta)(o)-deletion, ()two families were confirmed to possess (G)gamma((A)gammadeltabeta)(o)/beta-thalassemia with the IVSII No. 654 beta(+)-allele. In the third family, the (G)gamma((A)gammadeltabeta)(o)-deletion was confirmed in the father and the mother was a beta-thalassemia carrier with the cd 41-42 beta(o)-allele. Their affected child with (G)gamma((A)gammadeltabeta)(o)/beta-thalassemia was found to be transfusion dependent. The same (G)gamma((A)gammadeltabeta)(o)-deletion and beta-thalassemia (cd 41-42) was also confirmed in a fourth family. In addition, the mother was also diagnosed with Hb H disease (genotype -alpha(3.7)/-(SEA)). Both the children were found to possess (G)gamma((A)gammadeltabeta)(o)/beta-thalassemia but they were not transfusion dependent and this could be due to co-inheritance of alpha-thalassemia-2 (genotype-alpha(3.7)/alphaalpha) in the children together with their compound heterozygous condition.

Adult↗

[Molecular characterization of thalassemias in the Valencia community and its relationship with the hematological phenotype].

PURPOSE: The aim of the study is to present the first results of molecular characterization of thalassaemias in Valencian Community and their relationship with the haematological parameters. PATIENTS AND METHODS: The study includes 87 thalassemic patients: 30 alpha-thalassaemias, 40 beta-thalassaemias and 17 delta beta-thalassaemias. The molecular alterations were studied in white cell blood DNA, either following different PCR methods or by testing the digestion of the amplified PCR products with selective restriction enzymes. RESULTS: The molecular characterization of beta-thalassaemias was achieved in 94% of the subjects, being the transition C-->T in CD-39 the most frequent (44%) of the mutations studied. 94% of the delta beta-thalassaemias studied corresponded to the delta beta-Spanish type. All the alpha thalassaemias characterized (64%) corresponded to the -alpha 3.7 deletion. The reamining 36% were negative for the alpha 0 deletions --MED, --20.5, or the non deletional mutations Hph I and NocI. DISCUSSION: In the Valencian Community, like what has been described for the beta-thalassaemias in other Mediterranean regions of Spain (Barcelona, Granada and Mallorca), a high incidence in C-->T transition in CD-39 was observed, in contrast with central and south-western regions of Spain, where the G-->A IVS-I-1 is the most frequent mutation. Our study supports that the IVS-I-6 mutations is the one with lower repercussions on the haematological parameters. Our study confirms the Spanish type of delta beta-thalassaemia as the most frequent in the Valencian Community, and that the 3.7 kb alpha deletion is the most frequent mutation for the alpha-thalassaemia, although alpha thalassaemia is also the poorly characterized form of thalassaemia.

DNA Mutational Analysis↗

Molecular characterization of alpha-thalassemia in the Mexican population.

BACKGROUND: alpha-Thalassemia (alpha-Thal) has been poorly characterized at the molecular level in Mexico. METHODS: 106 consecutive individuals identified in Laboratorios Clínicos de Puebla, with either hypochromia (MCH < 24 pg) and/or microcytosis (MCV < 75 fl in women or < 80 fl in man), without iron deficiency, with or without anemia were investigated in this study, along a 16 month-period. alpha and beta-Thal were looked for, the former were characterized at the molecular level. RESULTS: Out of the 106 consecutive cases with hypochromia and/or microcytosis and normal levels of protoporphyrin zinc complex, 48 cases (45.3%) had thalassemia (37 cases of betaThal and 11 cases of alphaThal), whereas in 58 cases (54.7%) a definite diagnosis could not be established. Of the alpha-Thal cases, 8 were heterozygous and two were homozygous for the -alpha3.7 deletion, whereas one case was heterozygous for the alpha2Hph allele. CONCLUSIONS: Only few of the alpha-Thal alleles tested were found, thus the alpha-thalassemic mutations, present in the studied population, seem to be rather heterogeneous.

Anemia, Hypochromic↗

Molecular characterization of glucose-6-phosphate dehydrogenase deficiency in Brazil.

Molecular characterization of glucose-6-phosphate dehydrogenase (G6PD) variants was carried out in 150 unrelated G6PD deficient blood donors from the region of Campinas, Brazil. By allele specific oligomer hybridization or digestion of exon 4 of the G6PD gene with the restriction endonuclease NlaII, we detected the 202 G-->A mutation in 146 individuals. This mutation was associated with the 376 G-->A substitution and only one haplotype was observed in these individuals. Digestion of exon 6 with the restriction enzyme MboII showed the presence of the Mediterranean variant in three individuals. Haplotype analysis showed, in all three samples, a T at nt 1311 and the C at nt 13 in intron 11, suggesting a European origin of this variant. By SSCP analysis and direct sequencing we detected the mutation nt 1003 G-->A (335 Ala-->Thr) in one blood donor. This mutation was previously described in a boy of Indian ancestry and the variant was denominated G6PD Chatam. The case described here has no Indian ancestry; thus, we presume that the mutations have arisen independently, although we do not know the haplotype of the Indian patient. The haplotype of our case was the most common observed in our population (PvuII, BspHI+, PstI+, 1311C, NlaIII-). Thus, our data indicate that G6PD A- with the 202 G-->A mutation is the most frequent G6PD deficiency in the population of southeastern Brazil. The remaining variants had a Mediterranean origin. These results are in agreement with the origin of the Brazilian population.

Brazil↗

Molecular characterization of the first avian LDL receptor: role in sterol metabolism of ovarian follicular cells.

Low levels of expression and sluggish sterol-mediated regulation have been likely reasons for the failure to molecularly characterize a bona fide LDL receptor (LDLR) in egg-laying species to date. The overall structure of the chicken LDLR, delineated here by cDNA cloning, has been conserved in evolution, since hallmark properties of mammalian LDLRs are already present in the avian protein. The chicken receptor appears to prefer LDL over VLDL as ligand, in compliance with its main role in providing lipoprotein-derived cholesterol for steroid production in ovarian follicular cells. This is also compatible with the fact that estrogen administration increased hepatic LDLR expression in roosters despite dramatically stimulated VLDL production. In cultured chicken embryo fibroblasts, expression of the receptor was induced by incubation with cholesterol synthesis inhibitors such as a statin. Furthermore, preincubation of induced cells with a specific anti-receptor antibody blocks LDL endocytosis, demonstrating that the receptor is ligand-endocytosis competent. Finally, the distribution of LDLRs among the extraoocytic cell populations lends support to a three-cell model for estrogen production within the ovarian follicle. In summary, the molecular characterization of the first avian LDLR reveals novel information about evolutionary, structural, and functional aspects of members of the supergene family of LDLR-related proteins.

Amino Acid Sequence↗

Molecular characterization and delineation of subtle deletions in de novo "balanced" chromosomal rearrangements.

To test the hypothesis that the phenotypic abnormalities seen in cases with apparently balanced chromosomal rearrangements are the result of the presence of cryptic deletions or duplications of chromosomal material near the breakpoints, we analyzed three cases with apparently balanced chromosomal rearrangements and phenotypic abnormalities. We characterized the breakpoints in these cases by using microsatellite analysis by polymerase chain reaction and fluorescence in situ hybridization analysis of yeast artificial chromosome clones selected from the breakpoint regions. Molecular characterization of the translocation breakpoint in patient 1 [46,XY,t(2;6)(p22.2;q23.1)] showed the presence of a 4- to 6-Mb cryptic deletion between markers D6S412 and D6S1705 near the 6q23.1 breakpoint. Molecular characterization of the proximal inversion 7q22.1 breakpoint in patient 2 [46,XY,inv(7)(q22.1q32.1)] revealed the presence of a 4-Mb cryptic deletion between D7S651 and D7S515 markers. No deletion or duplication of chromosomal material was found near the breakpoints in patient 3 [46,XX,t(2;6)(q33.1;p12.2)]. Our study suggests that a systematic molecular study of breakpoints should be carried out in cases with apparently balanced chromosomal rearrangements and phenotypic abnormalities, because cryptic deletions near the breakpoints may explain the phenotypic abnormalities in these cases.

Abnormalities, Multiple↗

[Molecular characterization of ABO*O alleles at the ABO group locus in three chilean populations].

BACKGROUND: Among the allelic variants of blood groups, the molecular characterization of ABO blood group has clinical and anthropological importance. AIM: To perform a characterization of the molecular variants of the allele ABO*O of the ABO blood group. MATERIAL AND METHODS: Eighty four subjects of Aymara origin, living in Northern Chile, 75 individuals of Huilliche origin, living in Southern Chile and 82 subjects living in Santiago (Central Chile), were studied. All individuals were of group O, homozygotes for G261- deletion, that defines O1 alleles. Mutations G188A, G261-, G542A, T646A and C771T, described for alleles O1, O1variant and G542A were determined by PCR-RFLP (polymerase chain reaction-restriction fragment lenght polymorphism). RESULTS: Allele O1variant has frequencies of 0.65, 0.81 and 0.6 in Aymara, Huilliche and Santiago subjects, respectively. The figures for allele O1 are 0.35, 0.19 and 0.4, respectively and those for the allele with G542A mutation are 0.119, 0.113 and 0.079, respectively. CONCLUSIONS: These results are concordant with the reported higher frequency of allele O1variant in South American aboriginal populations. The frequencies of G542A allele in these Chilean individuals are lower than those described for Amazon aborigines.

ABO Blood-Group System↗

Molecular characterization of clinical Streptococcus pneumoniae isolates with reduced susceptibility to fluoroquinolones emerging in Italy.

Fifteen Streptococcus pneumoniae clinical isolates with reduced fluoroquinolone susceptibility (defined as a ciprofloxacin MIC of > or = 4 microg/ml), all collected in Italy in 2000-2003, were typed and subjected to extensive molecular characterization to define the contribution of drug target alterations and efflux mechanisms to their resistance. Serotyping and pulsed-field gel electrophoresis analysis indicated substantial genetic unrelatedness among the 15 isolates, suggesting that the new resistance traits arise in multiple indigenous strains rather than through clonal dissemination. Sequencing of the quinolone resistance-determining regions of gyrA, gyrB, parC, and parE demonstrated that point mutations producing single amino acid changes were more frequent in topoisomerase IV (parC mutations in 14 isolates and parE mutations in 13) than in DNA gyrase subunits (gyrA mutations in 7 isolates and no gyrB mutations observed). No isolate displayed a quinolone efflux system susceptible to carbonyl cyanide m-chlorophenylhydrazone; conversely, four-fold or greater MIC reductions in the presence of reserpine were observed in all 15 isolates with ethidium bromide, in 13 with ulifloxacin, in 9 with ciprofloxacin, in 5 with norfloxacin, and in none with five other fluoroquinolones. The effect of efflux pump activity on the level and profile of fluoroquinolone resistance in our strains was minor compared with that of target site modifications. DNA mutations and/or efflux systems other than those established so far might contribute to the fluoroquinolone resistance expressed by our strains. Susceptibility profiles to nonquinolone class antibiotics and resistance-associated phenotypic and genotypic characteristics were also determined and correlated with fluoroquinolone resistance. A unique penicillin-binding protein profile was observed in all five penicillin-resistant isolates, whereas the same PBP profile as S. pneumoniae R6 was exhibited by all six penicillin-susceptible isolates. This is the first attempt to molecularly characterize clinical isolates of S. pneumoniae with reduced susceptibility to fluoroquinolones emerging in Italy.

Anti-Bacterial Agents↗