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At least 253 records · Page 14Linked to original sources
PubMed1988

Treatment of breast cancer among elderly women with segmental mastectomy or segmental mastectomy plus postoperative radiotherapy.

Elderly women with cancer are often treated non-aggressively. Between January 1972 and March 1984, 128 women greater than 60 years were treated for Stage I or II breast cancer with segmental mastectomy (SGM) plus/minus postoperative radiation at one of our four area hospitals. Whereas 82% of similar patients less than 60 years were referred for postop radiation, only 39.8% of patients greater than 60 were so referred. Referral rates progressively diminished with increasing patient age above 60. Thus, we reviewed the outcome of 77 elderly women treated with SGM and 51 treated with SGM+RT. Treatment groups were similar with regard to prognostic clinical and histologic parameters. Mean follow-up is 51.4 months. Among SGM patients, 45.5% of patients between 60-70 years, 37.9% of those greater than 70, and 20% of those greater than 80 years experienced loco/regional failure prior to death. Conversely, only two local failures occurred among all elderly women treated with SGM+RT. Distant failure was approximately 11% and was unaffected by treatment. Complications of SGM+RT were modest. These data suggest that SGM+RT can be safely and effectively applied to the elderly. Moreover, the data suggests that postop radiation may be more beneficial when extended to elderly patients post segmental mastectomy than among younger women. Referring surgeons should focus upon their patients' physiologic and not chronologic age as a basis for treatment allocation decisions.

Age Factors↗
PubMed2001

Insect segmentation: Genes, stripes and segments in "Hoppers".

Recent work has revealed that orthologues of several segmentation genes are expressed in the grasshopper embryo, in patterns resembling those shown in Drosophila. This suggests that, despite great differences between the embryos, a hierarchy of gap/pair-rule/segment polarity gene function may be a shared and ancestral feature of insect segmentation.

Animals↗
PubMed1978

Amino acid sequences of alpha-helical segments from S-carboxymethylkerateine-A. Complete sequence of a type-II segment.

1. The helical fragments obtained by partial chymotryptic digestion of S-carboxymethylkeratine-A, the low-sulphur fraction from wool, were fractionated into type-I and type-II helical segments in aqueous urea under conditions limiting carbamoylation. 2. The amino acid sequence of a 109-residue type-II segment was completed by using the sequenator. 3. When the data were incorporated into a helical model of 3.6 residues per turn the hydrophobic residues generated a band aligned at a slight angle to the helical axis. This result is in accord with the postulated coiled-coil structure of the crystalline regions of alpha-keratin.

Amino Acid Sequence↗
PubMed2001

Clinical consequences of ST-segment changes caused by body position mimicking transient myocardial ischemia: hazards of ST-segment monitoring?

A case is described in which an acute ST-segment change, presumably due to a change in body position, is erroneously interpreted as an acute ischemic event. Positional ST-segment changes during continuous, multi-lead electrocardiographic (ECG) monitoring are particularly challenging to distinguish from transient myocardial ischemia because 1) positional ECG templates are often not feasible to record at the beginning of monitoring in unstable patients; 2) positional ECG templates, if recorded, are often not readily accessible to clinicians for later comparison; 3) body position cannot be correlated with ST events because patients are out of the direct view of nurses during the event or clinicians review ST trends at a later time; 4) ST monitors typically do not store ECGs frequently enough to be able to observe on the ST trend the gradual ("ramp-like") onset of ST changes that is characteristic of transient ischemia; and 5) absence of chest pain with a ST event does not help clinicians identify false alarms because it is well understood that the majority of ischemic events are clinically silent.

Angioplasty, Balloon, Coronary↗
PubMed1995

Invariant chain made in Escherichia coli has an exposed N-terminal segment that blocks antigen binding to HLA-DR1 and a trimeric C-terminal segment that binds empty HLA-DR1.

Invariant chain (Ii), a membrane glycoprotein, binds class II major histocompatibility complex (MHC) glycoproteins, probably via its class II-associated Ii peptide (CLIP) segment, and escorts them toward antigen-containing endosomal compartments. We find that a soluble, trimeric ectodomain of Ii expressed and purified from Escherichia coli blocks peptide binding to soluble HLA-DR1. Proteolysis indicates that Ii contains two structural domains. The C-terminal two-thirds forms an alpha-helical domain that trimerizes and interacts with empty HLA-DR1 molecules, augmenting rather than blocking peptide binding. The N-terminal one-third, which inhibits peptide binding, is proteolytically susceptible over its entire length. In the trimer, the N-terminal domains act independently with each CLIP segment exposed and free to bind an MHC class II molecule, while the C-terminal domains act as a trimeric unit.

Amino Acid Sequence↗
PubMed2004

Val133 and Cys137 in transmembrane segment 2 are close to Arg935 and Gly939 in transmembrane segment 11 of human P-glycoprotein.

P-glycoprotein (P-gp; ABCB1) transports a wide variety of structurally diverse compounds out of the cell. The protein has two homologous halves joined by a linker region. Each half consists of a transmembrane (TM) domain with six TM segments and a nucleotide-binding domain. The drug substrate-binding pocket is at the interface between the TM segments in each half of the protein. Preliminary studies suggested that the arrangement of the two halves of P-gp shows rotational symmetry (i.e. "head-to-tail" arrangement). Here, we tested this model by determining whether the cytoplasmic ends of TM2 and TM3 in the N-terminal half are in close contact with TM11 in the C-terminal half. Mutants containing a pair of cysteines in TM2/TM11 or TM3/TM11 were subjected to oxidative cross-linking with copper phenanthroline. Two of the 110 TM2/TM11 mutants, V133C(TM2)/G939C(TM11) and C137C(TM2)/A935C (TM11), were cross-linked at 4 degrees C, when thermal motion is reduced. Cross-linking was specific since no cross-linked product was detected in the 100 double Cys TM3/TM11 mutants. Vanadate trapping of nucleotide or the presence of some drug substrates inhibited cross-linking of mutants V133C(TM2)/G939C(TM11) and C137C(TM2)/A935C(TM11). Cross-linking of TM2 and TM11 also blocked drug-stimulated ATPase activity. The close proximity of TM2/TM11 and TM5/TM8 (Loo, T. W., Bartlett, M. C., and Clarke, D. M. (2004) J. Biol. Chem. 279, 7692-7697) indicates that these regions between the two halves must enclose the drug-binding pocket at the cytoplasmic side of P-gp. They may form the "hinges" required for conformational changes during the transport cycle.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMedDate not supplied

Recordings of the movement at the intervertebral segment L5-S1: a technique for the determination of the movement in the L5-S1 spinal segment by using three specified postural positions.

The pathomechanism of low-back pain generation is not understood very well. Functional disturbances of motion at the individual segmental level appear to play a role in many cases. In this study a technique of numeric analysis of radiographic observations of the lumbar spine is developed by which the authors are able to assess the displacement of the two components of the L5-S1 motion segment in the sagittal plane when the subject assumes three specified standard postural positions.

Adolescent↗
PubMed2005

Posterior fixation of thoracolumbar burst fracture: short-segment pedicle fixation versus long-segment instrumentation.

OBJECTIVE: The treatment of thoracolumbar burst fracture is a controversial issue. Short-segment (SS) pedicle fixation has become a popular treatment option. However, there are several studies regarding the high rate of failure. The aim of this prospective study was to compare SS versus long-segment (LS) instrumentation. METHODS: For this purpose, 18 consecutive patients were assigned to two groups. Group 1 included nine patients treated by SS pedicle fixation, whereas group 2 included nine patients treated by LS instrumentation. SS instrumentation was pedicle fixation one level above and below the fractured vertebra. LS instrumentation was hook fixation (claw hooks attached to second upper vertebra and infralaminar hooks attached to first upper vertebra) above and pedicle fixation (pedicle screws attached to first and second lower vertebrae) below the fractured vertebra. RESULTS: As a result, measurements of local kyphosis, sagittal index, and anterior vertebral height compression showed that the LS group had a better outcome at final follow-up (P < 0.05). Also, the SS group had a 55% failure rate, whereas the LS group had prolonged operative time and increased blood loss. However, there was no difference between the two groups according to Low Back Outcome Score. CONCLUSIONS: In conclusion, radiographic parameters demonstrated that LS instrumentation is a more effective management of thoracolumbar burst fractures. Nevertheless, clinical outcome was the same between the two groups. However, our conclusions were based on posterior-only surgery. Anterior column support would negate the need for LS fixation. Also, SS would have been more successful if two above and two below pedicle screws were used.

Adolescent↗
PubMed2007

Baculovirus expression of the 11 mycoreovirus-1 genome segments and identification of the guanylyltransferase-encoding segment.

The type member Mycoreovirus 1 (MyRV-1) of a newly described genus, Mycoreovirus, isolated from a hypovirulent strain 9B21 of the chestnut blight fungus, has a genome composed of 11 dsRNA segments (S1-S11). All of the segments have single ORFs on their capped, positive-sense strands. Infection of insect cells by baculovirus recombinants carrying full-length cDNAs of S1-S11 resulted in overexpression of protein products of the expected sizes, based on their deduced amino acid sequences. This expression system was utilized to identify the S3-encoded protein (VP3) as a guanylyltransferase by an autoguanylylation assay, in which only VP3 was radiolabelled with [alpha-(32)P]GTP. A series of progressive N-terminal and C-terminal deletion mutants was made to localize the autoguanylylation-active site of VP3 to aa residues 133-667. Within this region, a sequence stretch (aa 170-250) with relatively high sequence similarity to homologues of two other mycoreoviruses and two coltiviruses was identified. Site-directed mutagenesis of conserved aa residues revealed that H233, H242, Y243, F244 and F246, but not K172 or K202, play critical roles in guanylyltransferase activities. Together with broader sequence alignments of 'turreted' reoviruses, these results supported the a/vxxHx(8)Hyf/lvf motif, originally noted for orthoreovirus and aquareoviruses, as an active site for guanylyltransferases of viruses within the Orthoreovirus, Aquareovirus, Cypovirus, Oryzavirus, Fijivirus, Coltivirus and Mycoreovirus genera, as well as for the proposed Dinovernavirus genus.

Animals↗
PubMed1983

Gene mapping of rotavirus double-stranded RNA segments by northern blot hybridization: application to segments 7, 8, and 9.

Cloned DNA copies of double-stranded RNA segments 7, 8, and 9 of UK bovine rotavirus were nick-translated with [alpha-(32)P]ATP and hybridized to double-stranded RNA of various rotavirus strains which had been separated on long polyacrylamide gels and then transferred to o-aminophenylthioether paper. Specific hybridization of the UK calf clones to the separated RNA segments allowed the corresponding genes of four different rotaviruses to be rapidly determined.

DNA↗
PubMed1997

Segment-specific noncoding sequences of the influenza virus genome RNA are involved in the specific competition between defective interfering RNA and its progenitor RNA segment at the virion assembly step.

The generation of influenza A virus defective interfering (DI) particles was studied by using an NS2 mutant which produces, in a single cycle of virus replication, a large amount of DI particles lacking the PA polymerase gene. The decrease in PA gene replication has been shown to occur primarily at the cRNA synthesis step, with preferential amplification of PA DI RNA species present in a marginal amount in the virus stock. In addition, at the assembly step the PA DI RNAs were preferentially incorporated into virions, resulting in selective reduction in the packaging of the PA gene into virions. Similarly, in cells dually infected with the NS2 mutant and wild-type viruses, packaging of the wild-type PA gene was also greatly suppressed. In contrast, incorporation of other RNA segments, i.e., the PB2 and NS genes, was not affected, suggesting that the PA DI RNAs competed only with the PA gene in a segment-specific manner. Experiments involving rescue of recombinant chloramphenicol acetyltransferase (CAT) RNA flanked by the noncoding regions of the PA (PA/CAT RNA) and PB2 (PB2/CAT RNA) genes into viral particles showed that only PA/CAT RNA was not rescued by infection with the NS2 mutant virus containing the PA DI RNAs. However, recombinant PA/CAT RNA in which either the 3' or 5' noncoding region was replaced with that of the PB2 gene was rescued by the NS2 mutant. These results suggest that the noncoding regions of the PA gene are responsible for the competition with PA DI RNA species at the virus assembly step and that coexistence of the both noncoding regions would be a prerequisite for this phenomenon. Decreased packaging of the progenitor RNA by the DI RNA, in addition to the suppression of cRNA synthesis, is likely involved in the production of DI particles.

Animals↗
PubMed2004

New support for clarifying the relation between ST segment resolution and microvascular function: degree of ST segment resolution correlates with the pressure derived collateral flow index.

OBJECTIVE: To investigate the relation between the degree of ST segment resolution (STR) after thrombolysis and the pressure derived collateral flow index (CFIp), determined using an intracoronary pressure measurement technique in patients with recent myocardial infarction. METHODS: 33 patients were studied. TIMI grade III flow was achieved in the infarct related artery by thrombolysis. A surface ECG was obtained on admission and 90 minutes later. The sum of ST segment elevations was measured by summing all leads with ST elevation on the baseline ECG and on the 90 minute ECG (after thrombolysis) and calculating the percentage recovery. The study population was divided into two groups, with good STR (> or = 50%; group 1) or poor STR (< 50%; group 2). After angiography, a fibreoptic pressure monitoring guidewire was advanced to the stenosis to be dilated. The CFIp was determined as the ratio [coronary wedge pressure - central venous pressure]/[mean aortic pressure - central venous pressure]. RESULTS: The mean STR on the surface ECG was 54.6% and mean (SD) CFIp was 0.25 (0.12) (range 0.10-0.41). There was an inverse correlation between the individually calculated percentage of STR and CFIp (r = -0.64, p < 0.01). The mean CFIp was lower in patients with a good STR than in those with a poor STR (0.18 (0.07) v 0.27 (0.10), p < 0.02). CONCLUSIONS: Although TIMI grade III flow was achieved after thrombolysis, a worse STR on the surface ECG was associated with higher CFIp measured in the infarct related artery. CFIp appears to reflect the degree of microvascular obstruction by quantifying impedance of the microvasculature.

Blood Pressure↗
PubMed1986

ST segment response to acute coronary occlusion: coronary hemodynamic and angiographic determinants of direction of ST segment shift.

To assess the relationship between the direction of ST segment response to transient coronary occlusion and collateral function, we studied 25 patients with diagnostic ST segment changes during transient occlusion of the proximal left anterior descending artery (LAD). Electrocardiographic leads I, II, V2, and V5; left ventricular filling, aortic, and distal coronary pressures; and great cardiac vein flow were measured during percutaneous transluminal coronary angioplasty (PTCA) of the LAD. During a 1 min LAD balloon occlusion, 16 patients had reversible ST elevation (group I) and nine patients had ST depression (group II). The ST responses in individual patients were consistent during repeated occlusions, and ST depression never preceded ST elevation. Angiography before PTCA showed less severe LAD stenosis in group I (69 +/- 15%) than in group II (88 +/- 10%; p less than .01) and collateral filling of the LAD in no group I patient but in six of nine patients in group II (p less than .01). During LAD occlusion, determinants of myocardial oxygen demand (left ventricular filling pressure, aortic pressure, heart rate, and double product) were similar in both groups. Group I patients, however, had lower distal coronary pressure (25 +/- 8 vs 41 +/- 16 mm Hg) and residual great cardiac vein flow (33 +/- 14 vs 51 +/- 22 ml/min) and higher coronary collateral resistance (3.1 +/- 2.1 vs 1.5 +/- 0.8 mm Hg/ml/min) than group II patients (all p less than .05). In patients with ST elevation during LAD occlusion, stenosis before PTCA was less severe, visible collaterals were not present, and hemodynamic variables during LAD occlusion reflected poorer collateral function.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1983

Magnetic measurement of S-T and T-Q segment shifts in humans. Part II: Exercise-induced S-T segment depression.

The direct-current magnetocardiogram, which shows the T-Q (baseline) shift, is used to clarify the cause of S-T depression induced by stress testing in the human heart. Measurements are made of the amount of baseline shift associated with the S-T depression. Results are presented of a well-documented patient, with typical coronary artery disease, undergoing a two-step exercise test. Before exercise, there was no S-T or baseline shift. During exercise, the S-T segment became depressed and the baseline segment was simultaneously elevated, at about 70% of the S-T amplitude. After termination of exercise, the baseline elevation disappeared somewhat more rapidly than the S-T depression. These results were consistent in repeated tests of this patient. Because the baseline shift is a reflection of an injury current, these results confirm the belief that exercise-induced S-T depression is mostly due to an injury current which is interrupted during the S-T interval. The baseline shift seen here is the first non-invasive measurement of an injury current in the human heart, and its presence and time-course generally agree with measurements in the animal heart. This work also confirms that the direct-current magnetocardiogram, although not practical for clinical purposes, is useful as a research tool.

Heart↗
PubMed1989

Surface molecular mobility and platelet reactivity of segmented poly(etherurethaneureas) with hydrophilic and hydrophobic soft segment components.

Segmented poly(etherurethaneureas) (SPUUs) with hydrophilic and hydrophobic polyether components were prepared. The surface chemical composition of SPUUs in various environments was investigated by means of X-ray photoelectron spectroscopic and dynamic contact angle measurements. These measurements revealed that in a hydrated state, the higher surface free energy component is enriched on the surface of the SPUU in order to minimize the interfacial free energy between water and the solid surface. The surface molecular mobility showed a strong correlation with bulk molecular motion. Platelet adhesion tests and dynamic contact angle measurements after adsorption of bovine serum albumin revealed that the surface of SPUUs with hydrophilic soft segments has a non-adhesive nature. The platelet reactivity of hydrophobic SPUUs is influenced by microphase separation at the surface.

Biocompatible Materials↗
PubMed1998

Beat-to-beat variation of the ST segment in a patient with right bundle branch block, persistent ST segment elevation, and ventricular fibrillation: a case report.

The authors describe a patient with ventricular fibrillation associated with right bundle branch block-like QRS morphology and persisting ST segment elevation in the precordial leads, in whom the morphology of the ST segment changed from the coved type to the saddle-back type or vice versa on a beat-to-beat basis. Such an observation has never been reported in the previous literature.

Adult↗
PubMed1990

Cell patterning in the Drosophila segment: spatial regulation of the segment polarity gene patched.

Intrasegmental patterning in the Drosophila embryo requires the activity of the segment polarity genes. The acquisition of positional information by cells during embryogenesis is reflected in the dynamic patterns of expression of several of these genes. In the case of patched, early ubiquitous expression is followed by its repression in the anterior portion of each parasegment; subsequently each broad band of expression splits into two narrow stripes. In this study we analyse the contribution of other segment polarity gene functions to the evolution of this pattern; we find that the first step in patched regulation is under the control of engrailed whereas the second requires the activity of both cubitus interruptusD and patched itself. Furthermore, the products of engrailed, wingless and hedgehog are essential for maintaining the normal pattern of expression of patched.

Animals↗
PubMed1993

Segmental migration of the hindbrain neural crest does not arise from its segmental generation.

The proposed pathways of chick cranial neural crest migration and their relationship to the rhombomeres of the hindbrain have been somewhat controversial, with differing results emerging from grafting and DiI-labelling analyses. To resolve this discrepancy, we have examined cranial neural crest migratory pathways using the combination of neurofilament immunocytochemistry, which recognizes early hindbrain neural crest cells, and labelling with the vital dye, DiI. Neurofilament-positive cells with the appearance of premigratory and early-migrating neural crest cells were noted at all axial levels of the hindbrain. At slightly later stages, neural crest cell migration in this region appeared segmented, with no neural crest cells obvious in the mesenchyme lateral to rhombomere 3 (r3) and between the neural tube and the otic vesicle lateral to r5. Focal injections of DiI at the levels of r3 and r5 demonstrated that both of these rhombomeres generated neural crest cells. The segmental distribution of neural crest cells resulted from the DiI-labelled cells that originated in r3 and r5 deviating rostrally or caudally and failing to enter the adjacent preotic mesoderm or otic vesicle region. The observation that neural crest cells originating from r3 and r5 avoided specific neighboring domains raises the intriguing possibility that, as in the trunk, extrinsic factors play a major role in the axial patterning of the cranial neural crest and the neural crest-derived peripheral nervous system.

Actin Cytoskeleton↗