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At least 19 recordsLinked to original sources
PubMed1977

Histocompatibility antigens controlled by the I region of the murine H-2 complex. II. K/D region compatibility is not required for I-region cell-mediated lymphocytotoxicity.

In the cell-mediated lymphocytotoxicity assay, A.TH effector cells sensitized to A.TL lymphocytes lyse not only A.B10.AQR effector cells lyse B10.BR and B10.BYR target cells in addition to B10.AQR cells. These findings indicate that for CML to occur across the IA region barrier, compatibility at K or D regions is not required.

Animals↗
PubMedDate not supplied

Loco-regional renewal of malignant skin melanomas. II. Regional lymph node metastases and regional recurrence.

The strategy of surgical therapy to treat regional disease in melanoma remains still controversial. The author analyzed 154 of 183 melanoma patients, who could be studied for the usefulness of surgery directed against regional tumour spread. Radical tumour excision combined with elective lymph node dissection (E+eRND) in medium or high risk tumour patients was found superior to therapeutic dissection (tRND) inasmuch 5-year-survival rates were significantly different (p < 0.001). Life expectancy seemed to be further impaired when postdissectional renewal appeared following tRND (5-year-survival rates 31.8 per cent --> 12.7 per cent) or tRND was incomplete.

Humans↗
PubMed1992

Regional left ventricular wall thickening. Relation to regional uptake of 18fluorodeoxyglucose and 201Tl in patients with chronic coronary artery disease and left ventricular dysfunction.

BACKGROUND: In previous studies comparing regional 201Tl (201Tl) and 18fluorodeoxyglucose (FDG) activity in patients with chronic coronary artery disease and left ventricular dysfunction, we hypothesized that regions with mild-to-moderate reduction in FDG activity and regions with mild-to-moderate irreversible 201Tl defects after 3- to 4-hour redistribution represent viable myocardium. In the present study, regional FDG and 201Tl activities were compared with regional systolic wall thickening by gated magnetic resonance imaging (MRI) to confirm the presence of viable myocardium in these territories. METHODS AND RESULTS: Twenty-five patients with chronic stable coronary artery disease and left ventricular dysfunction (ejection fraction, 28 +/- 10) underwent exercise 201Tl tomographic imaging (SPECT), using a reinjection protocol, positron emission tomography (PET) with FDG and H2(15)O, and gated MRI. Matched SPECT, PET, and MRI tomograms were analyzed. From the PET data, 105 regions had matched reduction in FDG and blood flow, of which 69 regions had moderately reduced FDG uptake (50-79% uptake relative to a normal reference region) and 36 had severely reduced FDG uptake (less than 50% of normal activity). Regions with moderately reduced as compared with severely reduced FDG activity had greater end-diastolic wall thickness (9.4 +/- 2.6 versus 8.0 +/- 3.7 mm; p less than 0.05) and regional systolic wall thickening (1.7 +/- 2.7 versus -0.7 +/- 2.1 mm; p less than 0.01). From the SPECT data, 169 irreversible 201Tl defects after 3-4 hour redistribution were identified, of which 70 were mild (greater than 65 to less than 85% of maximal 201Tl activity), 52 were moderate (50-65% of maximal activity), and 47 were severe (less than 50% of maximal activity). Regional systolic wall thickening was greater in regions with normal 201Tl uptake (3.3 +/- 2.3 mm) as compared with all other regions. Regions showing only mild or moderate irreversible defects at redistribution, however, showed wall thickening (2.4 +/- 2.4 and 2.2 +/- 2.5 mm, respectively), which was similar to that observed in regions with reversible 201Tl defects (2.1 +/- 2.2 mm). Only regions with severe irreversible defects at redistribution showed absence of thickening (-0.1 +/- 2.9 mm, p less than 0.01 versus all other groups). After 201Tl reinjection, 12 of 47 (26%) regions with severe irreversible defects showed enhanced 201Tl uptake. The impairment in regional systolic wall thickening was not significantly different between 201Tl defects with and without enhanced 201Tl uptake after reinjection. FDG activity, however, was present in all 12 regions (100%) with enhanced 201Tl uptake after reinjection as compared with only five of 35 (14%) that were unchanged after reinjection (p less than 0.01). CONCLUSIONS: Therefore, preserved wall thickness and systolic wall thickening in regions with moderate reduction in blood flow and FDG activity, and in irreversible 201Tl defects that are only mild-to-moderate, provide additional evidence that such regions represent viable myocardium. Moreover, the finding of metabolic activity and 201Tl uptake in regions with reduced blood flow and absent wall thickening provides clinical evidence of hibernating myocardium in humans.

Adult↗
PubMed1979

Regional ejection fraction: a quantative radionuclide index of regional left ventricular performance.

Radionuclide measurements of regional left ventricular ejection fraction were evaluated as a quantitative index of regional left ventricular function. Left ventricular regional ejection fractions were derived from background-corrected, time-activity curves in 43 patients assessed by both gated equilibrium radionuclide angiocardiography and left ventricular contrast angiography. From a single, modified left anterior oblique projection, the regional change in background corrected counts was determined in each of three anatomic regions. The normal range for regional radionuclide ejection fraction was determined in 10 patients with normal contrast ventriculograms and without obstructive coronary artery disease at coronary arteriography. Regional ejection fraction was compared with percent segmental axis shortening and extent of akinetic segments in corresponding regions of the contrast ventriculogram. Radionuclide and roentgenographic methods were in agreement as to the presence or absence of abnormal wall motion in 83 of 99 left ventricular regions (84%) in 33 patients evaluated prospectively. Comparison of regional ejection fraction demonstrated significant differences between regions with roentgenographically determined normokinesis (75 +/- 3%, mean +/- SEM), hypokinesis (44 +/- 3%, p less than 0.0005) and akinesis (24 +/- 5%, p less than 0.005). We conclude that the left ventricular regional ejection provides a reliable quantitative assessment of regional left ventricular performance.

Adult↗
PubMed1977

Early changes in regional and global left ventricular function induced by graded reductions in regional coronary perfusion.

To determine the sequence of changes in segmental myocardial function, regional lactate metabolism and global left ventricular function induced by mild regional ischemia, blood flow in the left anterior descending coronary artery of 10 dogs was reduced by 10 percent decrements with use of a screw clamp. At each level of flow, segmental mechanical function and regional metabolism were assessed, the former with use of a mercury-in-Silastic length gauge and the latter with transmyocardial lactate balance measurements obtained with sampling from the anterior interventricular vein. Coronary arterial flow at the onset of regional lactate production was 48 +/- 4 percent (mean +/- standard error of the mean) of the control value. The onset of segmental mechanical dysfunction coincided with the onset of lactate production. Epicardial S-T segment abnormalities over the ischemic zone usually could not be detected until coronary flow was further reduced. After the onset of regional ischemia there was a linear correlation between coronary arterial flow and regional lactate production. At the onset of mild regional ischemia, defined as the onset of regional lactate production, no significant or directionally consistent changes were noted in standard measurements of global left ventricular performance, including heart rate, mean aortic pressure, left ventricular end-diastolic pressure, cardiac output, stroke volume, stroke work and peak positive dP/dt (maximal rate of rise of pressure). However, peak negative dP/dt (maximal rate of pressure decrease) decreased from 99 +/- 2 to 89 +/- 3 percent of the control value (P less than 0.0005) coincident with the onset of ischemia. It is hypothesized that dyssynchronous wall motion in the ischemic zone during isometric relaxation accounts for this decrease in peak negative dP/dt.

Animals↗
PubMed1992

Human platelet glycoprotein IIIb binds to thrombospondin fragments bearing the C-terminal region, and/or the type I repeats (CSVTCG motif), but not to the N-terminal heparin-binding region.

Major blood membrane platelet glycoprotein IIIb (GPIIIb), also termed GPIV or CD365, has been identified as a receptor for thrombospondin (TSP), collagen and Plasmodium falciparum-infected erythrocytes. The aim of the present study was to identify region(s) of TSP involved in binding of GPIIIb. Proteolytic fragments of TSP (M(r) 140 kDa, 120-18 kDa and 27 kDa on SDS/PAGE under reducing conditions) were purified by f.p.l.c. and identified by N-terminal gas-phase sequencing, e.l.i.s.a. and Western blots using monoclonal antibodies directed against defined domains of TSP. The 140 kDa and 120-18 kDa fragments (C-terminal region), but not the 27 kDa fragment (N-terminal region), were shown to bind to GPIIIb by using e.l.i.s.a. and affinity-chromatography systems. TSP binding to a GPIIIb-affinity column was Ca(2+)-dependent and reduced by 45% in the presence of EDTA. Moreover, TSP was only partially eluted with EDTA from a Ca(2+)-equilibrated GPIIIb column. A fragment of 68 kDa, obtained by further digestion of the 140 kDa fragment, bound to the GPIIIb-Sepharose affinity column. This fragment, or stalk-like region, bears the TSP type I repeats that show sequence similarity to regions on properdin, Plasmodium falciparum proteins and antistasin. Peptides (CSVTCG or SVTCGGGV) representing these repeats bound isolated GPIIIb in a Ca(2+)-independent way, but did not completely inhibit the GPIIIb and TSP interaction. These studies indicate that GPIIIb binds to the TSP via the C-terminal region and/or the CSVTCG motif, but not to the N-terminal region. Interaction between GPIIIb and the TSP C-terminal region or the CSVTCG motif is respectively Ca(2+)-dependent and -independent.

Amino Acid Sequence↗
PubMed1978

Regional myocardial blood flow in regions of prior myocardial infarction before and after revascularization.

In 30 patients who received 102 saphenous vein bypass grafts, 91 were patent. Preoperative intracoronary injection of 99mTc-labeled albumin particles suspended in contrast revealed 81 regions of perfusion deficit which subsequently received successful revascularization. With postoperative graft injection of isotope, 48 of these regions no longer showed a perfusion deficit (59%), while 33 showed no change (41%). In these 30 patients, 16 of 17 (94%) revealed perfusion defects in regions of prior transmural myocardial infarction. Conversely, only 55 of 96 regions distal to coronary artery stenosis of greater than 50% revealed perfusion defects (57%). Thus, 99mTc-labeled microsphere studies seem to be valuable in detecting regions of prior infarction. After angiographically documented revascularization, the method continued to reveal perfusion deficits in 41% of abnormal regions noted preoperatively, even though almost half of these same specific regions showed improved postoperative regional contractility after postextrasystolic potentiation.

Cardiac Catheterization↗
PubMed1992

The multi-locus H-2Dw16 region has an organization distinct from the Dd region.

Genomic DNA blot analyses using probes derived from the BALB/c 3' flanking region of the Ld gene (Ld 3' fl-C) and from near the BALB/c D3d gene (50.2A) indicate that the B10.GAA37 mouse strain has a multi-locus D (Dw16) region distinct from the five-gene organization observed in the Dd and Dq regions. To isolate the Dw16 region class I genes, a genomic B10. GAA37-lambda EMBL3 library was generated and screened with probes that preferentially hybridize to K and D region class I genes. Hybridization analyses of the isolated lambda clones with Ld derived oligonucleotide probes suggested that one of the lambda clones contained the Lw16 gene, whereas several other lambda clones contained the Dw16 gene. The sequence of the Dw16 gene is most similar to that of the Dp gene, particularly in the 3' half. Furthermore, the Lw16 gene is quite similar in the 5' half and virtually identical in the 3' half to the Ld gene, indicating that Lw16, but not Dw16, is a member of the Ld gene family. Collectively, these data suggest that, through a D region recombination event, the novel Dw16 region may have been assembled from primordial counterparts of the Dp and Ld genes.

Amino Acid Sequence↗
PubMed1975

Effect of graded reductions in regional coronary perfusion on regional and total cardiac function.

This study examines the effects of graded reduction in regional coronary perfusion and changes in arterial oxygen concentration upon regional myocardial function and left ventricular function. In 14 open chest dogs, the distal left anterior descending coronary artery was cannulated and perfused at different pressures with blood equilibrated with either 21 or 95 percent oxygen, and regional function in the perfused myocardial segment was determined by use of the pressure-length loop. The mass of perfused left ventricular myocardium was determined by injection of sodium fluorescein at a constant pressure of 100 mm Hg. Regional function decreased minimally as coronary perfusion pressure and flow were reduced to 50 to 65 mm Hg and 25 to 55 ml/min per 100 g, respectively. When pressure and flow were reduced below these critical ranges, regional function decreased sharply. Changes in left ventricular function were comparable but of lesser magnitude. The relations between regional function or left ventricular function and coronary perfusion were not affected by changing arterial oxygen concentration, except at the low range of coronary perfusion pressures (22 plus or minus 6 mm Hg), at which pressure regional function was significantly lower (P less than 0.025) in the experiments with 95 percent oxygen. Thus, the sensitivity of myocardial performance to a decrease in effective coronary perfusion pressure and flow is remarkably dependent upon whether pressure and flow are above a critical level.

Animals↗
PubMed1976

The binding site of protein L1 ON 23-S ribosomal RNA of Escherichia coli. 2. Identification of the rna region contained in the L1 ribonucleoproteins and determination of the order of the RNA subfragments within this region.

Ribonucleoproteins were obtained by T1 ribonuclease digestion of reconstitued complexes of ribosomal protein L1 AND 23-S RNA from Escherichia coli. The RNA region of the main ribonucleoprotein 2 was totally digested with T1 ribonuclease. The oligonucleotide products were characterised and they showed that this region comprises 148 nucleotides located between the 550th and 1000th necleotides from the 3' end of the 23-S RNA. Of the other two ribonucleoproteins, the largest ribonucleoprotein 1 contained an extra RNA sequence, of at least 15 nucleotides, that was located at the 5' end of the RNA region. The smallest ribonucleoprotein 3 lacked an RNA section towards the 3' end of the region. The order of the RNA subfragments and the enzymic cutting positions in the whole RNA region are given for the ribonucleoproteins. It is shown that protein L1 most strongly protects a continuous section of 115 nucleotides at the 5' end of the main RNA region. Finally, evidence is presented for a methylated base, and for two sequence heterogeneities, in this region of the 23-S RNA.

Alkaline Phosphatase↗
PubMed1992

The oriT region of the Agrobacterium tumefaciens Ti plasmid pTiC58 shares DNA sequence identity with the transfer origins of RSF1010 and RK2/RP4 and with T-region borders.

Ti plasmids of Agrobacterium tumefaciens are conjugal elements whose transfer is induced by certain opines secreted from crown galls. On transmissible plasmids, DNA transfer initiates within a cis-acting site, the origin of conjugal transfer, or oriT. We have localized an oriT on the A. tumefaciens plasmid pTiC58 to a region containing the conjugal transfer loci traI and traII and acc, which is the locus encoding catabolism of the two conjugal opines, agrocinopines A and B. The smallest functional oriT clone, a 65-bp BamHI-ApaI fragment in the recombinant plasmid pDCBA60-11, mapped within the traII locus. The nucleotide sequence for a 665-bp KpnI-EcoRI fragment with oriT activity was determined. DNA sequence alignments showed identities between the pTiC58 oriT and the transfer origins of RSF1010, pTF1, and RK2/RP4 and with the pTiC58 T-region borders. The RSF1010-like sequence on pTiC58 is located in the smallest active oriT clone of pTiC58, while the sequence showing identities with the oriT regions of RK2/RP4 and with T-region borders maps outside this region. Despite their sequence similarities, pTiC58 oriT clones were not mobilized by RP4; nor could vectors containing the RK2/RP4 oriT region or the oriT-mob region from RSF1010 be mobilized by pTiC58. In contrast, other Ti plasmids and a conjugally active Agrobacterium opine catabolic plasmid, pAtK84b, efficiently mobilized pTiC58 oriT clones. In addition, the RSF1010 derivative, pDSK519, was mobilized at moderate frequencies by an Agrobacterium strain harboring only the cryptic plasmid pAtC58 and at very low frequencies by an Agrobacterium host that does not contain any detectable plasmids.

Agrobacterium tumefaciens↗
PubMed1978

Guinea pig immunoglobulin light chain isotypes. II. The preferential expression of lambda chain-bearing anti-phenyltrimethylammonium antibodies is associated with restricted variable region expression, but not with any alteration in the proportion of lambda chain constant region isotypes, relative to normal immunoglobulins.

The inbred strain 13 guinea pig expresses at least three isotypes of immunoglobulin (Ig) lambda chain. The proportion of these isotypes in normal Ig can be estimated by isolating a constant (C) region cyanogen bromide peptide from lambda chains and quantitatively analyzing its component tryptic peptides. Anti-phenyltrimethylammonium antibody, when analyzed in this way, was found to contain the same proportion of each lambda chain C region isotype as did normal Ig. The specific antibody light (L) chain pools were found to contain predominantly lambda chains, although these are the minority type in guinea pig normal Ig L chain pools. Moreover, amino-terminal, 5-pyrrolidone-2-carboxylic acid-containing peptides isolated from antibody lambda chains show no demonstrable sequence heterogeneity, while their homologs isolated from normal lambda chains are markedly heterogeneous. That a restriction in heterogeneity of variable region framework residue positions is not associated with any alteration in the proportion of C region isotypes in these antibody lambda chains, implies that translocation of all guinea pig lambda chain variable region genes to the isotypic C region genes occurs in a random way.

Animals↗
PubMed1979

Mass spectral characterization of the K-region and non K-region dihydrodiols of 7,12-dimethylbenz (a) anthracene.

Dihydrodiols are derived from intermediary arene oxides during the metabolism of polycyclic aromatic hydrocarbons. In this study, the mass spectra of the trimethylsilyl ether derivatives obtained from the 5,6-dihydrodiol and 8,9-dihydrodiol of 7,12-dimethylbenz [a] anthracene were compared. The mass spectral fragmentation patterns indicate some key features in distinguishing a K-region dihydrodiol from its non K-region isomer. The 8,9-dihydrodiol, a non K-region metabolite, exhibits a greater tendency to undergo a ring contraction fragmentation process while the K-region 5,6-dihydrodiol participates preferably in other fragmentation pathways. The data presented in this report will be useful in charcterizing K-region and nonK-region metabolic epoxidation of polycyclic aromatic hydrocarbons.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1992

The oriT region of the conjugative transfer system of plasmid pCU1 and specificity between it and the mob region of other N tra plasmids.

The oriT region of the conjugative IncN plasmid pCU1 has been localized to a 669-bp sequence extending from pCU1 coordinates 8.48 to 9.15 kb. The nucleotide sequence of this region was determined. The region is AT-rich (69% AT residues), with one 19-bp and one 81-bp sequence containing 79% or more AT residues. Prominent sequence features include one set of thirteen 11-bp direct repeats, a second set of two 14-bp direct repeats, six different inverted repeat sequences ranging from 6 to 10 bp in size, and two sequences showing 12 of 13 nucleotides identical to the consensus integration host factor binding sequence. Specificity between this oriT and mobilization (mob) functions encoded by the N tra system was demonstrated. This specificity is encoded by the region lying clockwise of the BglII site at coordinate 3.3 on the pCU1 map. Two N tra plasmids isolated in the preantibiotic era were unable to mobilize recombinant plasmids carrying the oriT region of pCU1 or to complement transposon Tn5 mutations in the mob region of the closely related plasmid pKM101.

Base Sequence↗
PubMed2026

Transcription Start Regions in PTU-intergenic regions drive cell cycle-dependent transcriptional activation events in Leishmania donovani.

Leishmania displays an unconventional mode of transcription, with long clusters of genes being transcribed polycistronically from Transcription Start Regions (TSRs), being processed into monocistronic units prior to translation. It has long been believed that transcription is constitutive: failure to identify consensus sequences across TSRs (except a GT-rich motif supporting transcription in Trypanosoma brucei) and absence of canonical eukaryotic transcription factors led to the conclusion that regulation is primarily post-transcriptional, with epigenetics playing a role in triggering transcription initiation. This study stems from our previous findings identifying a few genes to be activated in a cell cycle-dependent manner. Using nuclear run-on assays to analyze nascent transcripts of two chromosomes, chromosomes 2 and 14, we find that while most genes are constitutively transcribed, a subset of genes gets activated at specific cell cycle stages. Reporter assays reveal that this transcriptional activation is driven by the regions immediately upstream of the genes. Sequence analyses of these TSRs lying in polycistronic intergenic regions (PIRs) uncovered a 10-mer GT-rich motif, in synchrony with earlier findings in T. brucei identifying a GT-rich motif at bidirectional TSRs. We also identify a second 25-mer motif at these TSRs, and deletion analyses find this motif to be critical for regulating gene expression. The findings of this study reveal that transcriptional events in these unicellular parasites are more complex than believed thus far: not all transcriptional events are constitutive, polycistronic transcription is not the only mode of transcription, and cis-acting sequence elements regulate at least some transcriptional events in these parasites.IMPORTANCEEndemic to 90 countries, Leishmania parasites cause a spectrum of diseases called Leishmaniases. No vaccines for human use are available to date, and the drugs currently used to treat the disease are expensive, have toxic side effects, and have complex administration regimens, with emerging drug resistance compounding problems. Researchers continue to investigate Leishmania cellular processes, with the hope of uncovering new therapeutic target sites. Gene regulation in these parasites is unusual, being modulated by various mechanisms, including epigenetic modifications, gene dosage, and post-transcriptional processing. Transcription is typically polycistronic and constitutive, initiating from Transcription Start Regions (TSRs) lying upstream of the first gene in the polycistronic transcription unit (PTU). The work presented here reveals that a subset of genes is transcribed monocistronically in a cell cycle-dependent manner from Transcription Start Regions lying in the PTU-intergenic regions (PIRs), underscoring the complexities of gene regulation in these parasites.

Leishmania donovani↗