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Biomedical subjects

A Kolchinsky

Publications and source records attributed to A Kolchinsky.

At least 19 recordsLinked to original sources
PubMed2002

Specificity of mammalian Y-box binding protein p50 in interaction with ss and ds DNA analyzed with generic oligonucleotide microchip.

p50 protein is a member of the Y-box binding transcription factor family and is a counterpart of YB-1 protein. The generic microchip was used to analyze the sequence specificity of p50 binding to single (ss) and double-stranded (ds) oligodeoxyribonucleotides. The generic microchip contained 4,096 single-stranded octadeoxyribonucleotides in which all possible core 6-mers (4(6)=4,096) were flanked at their 3' and 5'-ends with degenerated nucleotides. The oligonucleotides were chemically immobilized within polyacrylamide gel pads fixed on a glass slide. The binding of p50 to the generic microchip was shown to be the most specific to ss GGGG motif and then to ss CACC and CATC motifs. GC-rich ds oligonucleotides of the generic microchip, and particularly those containing GGTG/CACC, GATG/CATC, and GTGG/CCAC heterogeneous motifs, were most efficiently destabilized due to interaction with p50. Gel-shift electrophoresis has shown that the protein exhibits much higher binding specificity to 24-mer oligoA-TGGGGG-oligoA containing G-rich 6-mer, in comparison with 24-mer oligoA-AAATAT-oligoA carrying A,T-rich 6-mer in full correspondence with the data obtained with the microchip. Studies of DNA-binding proteins using gel-immobilized ss and ds DNA fragments provide a unique possibility to detect low-affinity complexes of these proteins with short sequence motifs and assess the role of these motifs in sequence-specific interactions with long recognition sites.

Animals↗
PubMed2001

Neurosurgical intervention for Parkinson's disease: an update.

For patients with advanced Parkinson's disease who do not respond to levodopa anymore, neurosurgical intervention is the only option. Cell transplantation has not met expectations as yet. Deep brain stimulation is gaining ground and currently seems to be the most efficient, flexible, and safe procedure.

Cell Transplantation↗
PubMed2000

Evaded bioethics.

Explore the source record for details and available documents.

Altruism↗
PubMed1998

X-ray-induced P-selectin localization to the lumen of tumor blood vessels.

P-selectin is a cell adhesion molecule that is sequestered in Weibel-Palade storage reservoirs within the vascular endothelium and alpha granules in platelets. P-selectin is rapidly translocated to the vascular lumen after tissue injury to initiate the adhesion and activation of platelets and leukocytes. We studied the histological pattern of P-selectin expression in irradiated tumor blood vessels. We observed that P-selectin was localized within the endothelium of tumor vessels prior to treatment. At 1-6 h following irradiation, P-selectin was mobilized to the lumen of blood vessels. To determine whether radiation-induced vascular lumen localization of P-selectin was tumor type specific or species specific, we studied tumors in rats, C3H mice, C57BL6 mice, and nude mice. P-selectin localization to the vascular lumen was present in all tumors and all species studied. Irradiated intracranial gliomas showed P-selectin localization to the vascular lumen within 1 h, whereas blood vessels in normal brain showed no P-selectin staining in the endothelium and no localization to the irradiated vascular lumen. Radiation-induced P-selectin localization to the vascular lumen increased in time-dependent manner, until 24 h after irradiation. P-selectin in platelets may account for the time-dependent increase in staining within the vascular lumen after irradiation. We therefore used immunohistochemistry for platelet antigen GP-IIIa to differentiate between endothelial and platelet localization of P-selectin. We found that GP-IIIa staining was not present at 1 h after irradiation, but it increased at 6 and 24 h. P-selectin localization to the vascular lumen at 6-24 h was, in part, associated with platelet aggregation. These findings indicate that radiation-induced P-selectin staining in the vascular lumen of neoplasms is associated with aggregation of platelets. Radiation-induced localization of P-selectin to the vascular lumen is specific to the microvasculature of malignant gliomas and is not present in the blood vessels of the irradiated normal brain.

Animals↗
PubMed1997

Map order and linkage distances of molecular markers close to the supernodulation (nts-1) locus of soybean.

The molecular characteristics of markers in the chromosome region surrounding the supernodulation gene (nts-1) of soybean (Glycine max L. Merr.) were investigated in 187 F2 plants from a cross of G. max cv. Bragg (nts) and G. soja PI468.397 (wild-type nodulation). RFLP marker pUTG-132a, linked tightly (0.7+/-0.5 cM) to nts-1, was converted to a PCR marker. The polymorphism resides within a 1.72 kb PstI fragment and consists of an 832 bp insertion in G. max relative to the wild progenitor G. soja. The insertion is flanked by a 35 bp direct duplication that was found only once in G. soja. Data suggest that the pUTG-132a sequence exists only once in the genome, which is compatible with the recessive nature of nts-1. Accordingly, pUTG-132a is a valuable marker for map-based cloning. Another RFLP marker, pA-381, was mapped 4.8 cM distal to nts-1. Marker order, established by Maximum Likelihood Analysis, placed nts-1 between pUTG-132a and pA-381. To generate additional molecular markers, a segregating F2 population was analysed using bulked segregant analysis (BSA) and single oligonucleotide primer-based PCR (DNA amplification fingerprinting; DAF). PCR marker pcr5-4L was mapped to soybean linkage group H and sequenced. The data revealed (i) recombination events and marker order in the nts-1 region; (ii) the molecular nature and cause of polymorphisms in linked molecular markers; (iii) a low density of polymorphisms around nts-1, and (iv) diploidy of the distal region of linkage group H of soybean.

Chromosome Mapping↗
PubMed1993

Physical mapping of a region in the soybean (Glycine max) genome containing duplicated sequences.

Pulsed-field gel electrophoresis (PFGE) was used to study a cluster of molecular markers in the soybean genome. There were 550 kb per centimorgan (cM) in the cluster, which is close to the calculated average for the whole genome. The analysis was complicated by the presence of duplicated sequences, and some ambiguities arising from this were resolved by using second-dimension conventional electrophoresis to relate physical maps to the RFLP map of soybean. The results show that there is a high degree of conservation of 'rare cutter' sites between homoeologous regions. Finally, PFGE can confirm physical linkage of monomorphic copies of markers, which can aid in the study and comparison of homoeologous regions that are invisible to RFLP analysis.

Chromosome Mapping↗
PubMed1993

Direct end labelling of telomeres.

A novel approach of direct end labelling of telomeres is presented. Chromosome-sized, agarose-embedded DNA was treated with T4 DNA polymerase to remove protruding 3' end of telomeres and to generate single-stranded 5' ends. The DNA was then labelled by the same enzyme in the presence of [alpha-32P]dGTP and cold dATP and dTTP. Labelled yeast chromosomes separated by pulsed field gel electrophoresis maintained their integrity. Digestion of yeast chromosomes separated in pulsed field gels with a restriction nuclease (HinfI), followed by conventional electrophoresis in the second dimension, resulted in a fingerprint-like pattern of labelled telomeres. This was very similar to the hybridization pattern of a similar two-dimensional gel probed with cloned yeast telomeric sequence. The same approach enabled us to label telomeres in soybean, determine their size, and to reveal polymorphisms in the length of telomeres between the closely related subspecies Glycine max (soybean) and Glycine soja.

Arabidopsis↗
PubMed1991

"Portraying" of plant genomes using polymerase chain reaction amplification of ribosomal 5S genes.

Nontranscribed spacers of plant genes coding for ribosomal 5S RNA were amplified using the polymerase chain reaction. Primers were synthesized that were complementary to 3' (direct) and 5' (reverse) ends of the coding region and that are universal for higher plants. The patterns of polymerase chain reaction products are species and, sometimes, variety specific. The use of this approach for identification of barley 5S genes in chromosome-addition lines of wheat is discussed. This principle can be applied for the "portraying" of other tandem repetitive genes containing divergent regions.

Base Sequence↗
PubMedDate not supplied

Drug resistance conferred by MDR1 expression in spheroids formed by glioblastoma cell lines.

Three-dimensional cell cultures (spheroids) provide an in vitro approximation of solid tumors in vivo. Some mechanisms of drug resistance were reported to differ in their effects on monolayer and spheroid cells. We have compared the effect on the expression of P-glycoprotein (Pgp), the MDR1 gene product, on vinblastine resistance in two glioblastoma lines, U87 and U251, grown as either monolayers or spheroids. U87 cells form spheroids spontaneously and the spheroids continue to grow, while U251 cells form spheroids only when plated over agarose and do not proliferate in spheroids. U87 cells are equally resistant to vinblastine in monolayer and in spheroids, while U251 cells are 4.5 times more resistant in spheroids than in monolayers. The distribution of a fluorescent vinblastine derivative in cells of spheroids was more heterogeneous than in monolayers. MDR1-expressing U87 cells increased their resistance 9-fold in monolayer and 50-fold in spheroids, while MDR1 transduction of U251 cells made them 20-fold more resistant in monolayer and 160-fold more resistant in spheroids. MDR1 expression in both cell lines decreased the accumulation of 3H-vinblastine and fluorescent vinblastine derivative. These results indicate that MDR1 is more efficient in conferring drug resistance in spheroids than in monolayer cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗