121 research outputs found
Chiral Perturbation to One Loop Including the Meson
We formulate the chiral perturbation theory at the one loop level in the
effective lagrangian including the meson as a dynamical gauge boson of a
hidden local symmetry(HLS). The size of radiative correction to the
phenomenological parameter of HLS is estimated to be about \%. The
complete list of terms is given and the one loop counter terms
are determined explicitly in the flavor model. We also obtain matching
conditions to the conventional chiral perturbation of Gasser and Leutwyler in
the chiral limit in a renormalization scale independent manner. We find that
Gasser--Leutwyler's estimates for are saturated by and its
one loop contributions without introducing non-minimal couplings of
- system, suggesting the absence of the tree level meson
contributions.Comment: 14pages, KEK-TH-349/KEK preprint 92-16
Effective mass of phi mesons at finite temperature
The effective mass of phi meson at non-zero temperature is re-examined with
an effective chiral Lagrangian. We find that the phi mass decreases with
temperature but the effect is small compared to the result obtained from
calculations using QCD sum rules. The leading contributions come from kaon loop
corrections but vector meson contributions are also important as temperature
increases. We discuss consequences of these changes to the phenomena of chiral
phase transition in hot hadronic matter.Comment: 11 pages with two figures (not included), LaTe
Transplantation of the cadaver heart harvested one hour after hypoxic cardiac arrest using the core-cooling technique in dogs.
A shortage of donor organs in clinical transplantation prompted us to study whether resuscitated dead hearts could be utilized for successful orthotopic heart transplantation. After 60 min of hypoxic cardiac arrest, one group of canine hearts was resuscitated (Res group, n = 6). The other group was harvested directly (Non-Res group, n = 6). In the Res group, cardiopulmonary bypass was utilized for resuscitation at 37 degrees C and the animals were then core-cooled to 15 degrees C. The hearts then were preserved in University of Wisconsin solution and orthotopically transplanted. Stable prostacyclin analogue (OP2507) and verapamil, a calcium antagonist, were added to the cardioplegia, and substrate-enriched warm blood cardioplegia and a hydroxy radical scavenger (EPC) were administered at the time of reperfusion of the transplanted heart. All animals in each group were successfully weaned from cardiopulmonary bypass with dopamine (5 micrograms/kg/min). Cardiac function without dopamine was better preserved in the Res group than the Non-Res group (Emax: 130.6 +/- 41.5% vs. 47.1 +/- 24.7%; mean +/- SD, as percent of postbrain death values, P < 0.01 by unpaired t-test). Cadaver hearts 60 min after anoxic arrest can be successfully re-animated and orthotopically engrafted. In addition, the core-cooling technique is useful. We believe this study serves as the key step in the clinical application of dead hearts to successful cardiac transplantation.</p
A prospective randomized trial of fk506 versus cyclosporine after human pulmonary transplantation
We have conducted a unique prospective randomized study to compare the effect of PK506 and cyclosporine (CsA) as the principal immunosuppressive agents after pulmonary transplantation. Between October 1991 and March 1993, 74 lung transplants (35 single lung transplants [SLT], 39 bilateral lung transplant [BLT]) were performed on 74 recipients who were randomly assigned to receive either FK or CsA. Thirty-eight recipients (19 SLT, 19 BLT) received FK and 36 recipients (16 SLT, 20 BLT) received CsA. Recipients receiving FK or CsA were similar in age, gender, preoperative New York Heart Association functional class, and underlying disease. Acute rejection (ACR) was assessed by clinical, radiographic, and histologic criteria. ACR was treated with methylprednisolone, 1 g i.v./day, for three days or rabbit antithymocyte globulin if steroid-resistant.During the first 30 days after transplant, one patient in the FK group died of cerebral edema, while two recipients treated with CsA died of bacterial pneumonia (1) and cardiac arrest (1) (P=NS). Although one-year survival was similar between the groups, the number of recipients free from ACR in the FK group was significantly higher as compared with the CsA group (P<0.05). Bacterial and viral pneumonias were the major causes of late graft failure in both groups. The mean number of episodes of ACR/ 100 patient days was significantly fewer in the FK group (1.2) as compared with the CsA group (2.0) (P<0.05). While only one recipient (1/36=3%) in the group treated with CsA remained free from ACR within 120 days of transplantation, 13% (5/38) of the group treated with FK remained free from ACR during this interval (P<0.05). The prevalence of bacterial infection in the CsA group was 1.5 episodes/100 patient days and 0.6 episodes/100 patient days in the FK group. The prevalence of cytomegaloviral and fungal infection was similar in both groups.Although the presence of bacterial, fungal, and viral infections was similar in the two groups, ACR occurred less frequently in the FK-treated group as compared with the CsA-treated group in the early postoperative period (<90 days). Early graft survival at 30 days was similar in the two groups, but intermediate graft survival at 6 months was better in the FK group as compared with the CsA group. © 1994 by Williams and Wilkins
Thermal effects on dilepton production from annihilation
We study finite temperature effects on dilepton production from pion-pion
annihilation in hot hadronic matter. The softening of the pion dispersion
relation in a medium is found to enhance the production rate of dileptons with
invariant masses in the region of . On the other hand,
the reduction of the pion electromagnetic form factor at finite temperature
leads to a suppression of the dilepton production rate. Including both effects,
we have found that the dilepton yield is slightly enhanced in the invariant
mass region MeV but is suppressed around the vector meson
resonance. We further discuss the relevance of our results to recent
experimental data from the S+Au collisions at CERN/SPS energies by the CERES
collaboration.Comment: 11 pages + 3 figures (figures are not included but available on
request), revte
Detection of G119S ace-1 R mutation in field-collected Anopheles gambiae mosquitoes using allele-specific loop-mediated isothermal amplification (AS-LAMP) method
Background
Malaria vectors have developed resistance to the four families of insecticides available for public health purposes. For example, the kdr mutation is associated with organochlorines and pyrethroids resistance. It is of particular concern that organophosphate and carbamate resistance associated with the G119S ace-1 R mutation has recently increased in West Africa in extent and frequency, and is now spreading through the Anopheles gambiae malaria vector population. There is an urgent need to improve resistance management using existing insecticides and new tools to quickly assess resistance level for rapid decision-making.
Methods
DNA extracted from field-collected mosquitoes was used to develop the method. Specific primers were designed manually to match the mutation region and an additional mismatched nucleotide in the penultimate position to increase specificity. Other primers used are common to both wild and mutant types. The allele specific (AS)-LAMP method was compared to the PCR restriction fragment length polymorphism (PCR-RFLP) and real-time PCR (RT-PCR) methods using the genomic DNA of 104 field-collected mosquitoes.
Results
The primers designed for LAMP were able to distinguish between the wild type (ace-1 S ) and mutated type allele (ace-1 R ). Detection time was 50 min for the wild type homozygous and 64 min for the heterozygous. No amplification of the resistant allele took place within the 75-min test period when using the wild type primers. For the ace-1 R resistant type, detection time was 51 min for the resistant homozygous and 55 min for the heterozygous. No amplification of the wild type allele took place within the 75-min test period when using the resistant type primers. Gel electrophoresis of LAMP products confirmed that amplification was primer-DNA specific, i.e., primers could only amplify their target specific DNA. AS-LAMP, PCR-RFLP, and RT-PCR showed no significant difference in the sensitivity and specificity of their ace-1 R detection ability.
Conclusions
The AS-LAMP method could detect the ace-1 R mutation within 60 min, which is faster than conventional PCR-RFLP. This method may be used to quickly detect the ace-1 R mutation for rapid decision-making, even in less well-equipped laboratories
Activity and stability of recombinant human superoxide dismutase in buffer solutions and hypothermic perfusates.
The stability of recombinant human superoxide dismutase (r-hSOD) in buffer solutions was studied in solutions at various pH and temperatures. Additionally, we studied the effects of incubation with proteases, serum and two types of hypothermic perfusates. R-hSOD was stable in the pH range of 6-11 and at temperatures up to 80 degrees C for 30 min. R-hSOD activity was not affected by incubation with trypsin, aminopeptidase M or serum for 2 h. R-hSOD activity determined at various temperatures (4-37 degrees C) did not vary remarkably. R-hSOD in hypothermic perfusates was stable at 4-37 degrees C for 24 h.</p
Urinary Titin Is Increased in Patients After Cardiac Surgery
Background: Few non-invasive biomarkers have been used to detect myocardial injury in patients with heart diseases. Recently, the N-terminal fragment (N-titin) of titin, a giant sarcomeric protein, which is involved in muscular passive tension and viscoelasticity, has been reported to detect muscle damage in patients with cardiomyopathy as well as in patients with skeletal muscle dystrophy and in healthy volunteers with endurance exercise. In the present study, we evaluated whether urinary N-titin is changed during a perioperative period and whether its increase reflects myocardial damage.Materials and Methods: In 18 patients who underwent cardiac surgery, blood and urine samples were obtained before and after surgery. We measured the urinary levels of N-titin with a highly sensitive ELISA system.Results: Urinary N-titin to creatinine (N-titin/Cr) was significantly increased in all patients postoperatively (43.3 ± 39.5 pmol/mg/dL on the day of operation) and remained significantly high for at least 4 days postoperatively. Urinary N-titin/Cr was positively correlated with serum cardiac troponin T (r = 0.36, p = 0.0006, n = 90) but not creatine kinase-MB (CK-MB). We also found that urinary N-titin/Cr in patients after a coronary artery bypass grafting operation was higher by day 2 postoperatively than in patients following open cardiac surgeries.Conclusion: The cleaved N-titin was significantly increased in urine after cardiac surgery. Urinary N-titin may be useful for detecting the risk of latent postoperative cardiac damage
Eta absorption by mesons
Using the chiral Lagrangian with hidden local
symmetry, we evaluate the cross sections for the absorption of eta meson () by pion (), rho (), omega (), kaon (), and kaon
star () in the tree-level approximation. With empirical masses and
coupling constants as well as reasonable values for the cutoff parameter in the
form factors at interaction vertices, we find that most cross sections are less
than 1 mb, except the reactions ,
, , and , which are a few mb, and the reactions and , which are more than 10 mb. Including these reactions in a kinetic model
based on a schematic hydrodynamic description of relativistic heavy ion
collisions, we find that the abundance of eta mesons likely reaches chemical
equilibrium with other hadrons in nuclear collisions at the Relativistic Heavy
Ion Collider.Comment: 29 pages, 10 figures, version to appear in Nucl. Phys.
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