Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.3.1.51 (HDR)
605 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanism of physiologic alteration by high (HDR) or low dose rate (LDR) (5 or 120 cGy/min) irradiation of plateau-phase bone marrow stromal cell cultures was investigated using a technique of in vitro bone marrow transplantation. Purified stromal cell cultures from C57BL/6J, C3H/HeJ, or (C57BL/6J X DBA2/J)F1 (B6D2F1) mouse marrow were irradiated to doses of 2.5 to 10 Gy at LDR or 10-100 Gy at HDR and were then engrafted in vitro with nonadherent hematopoietic cells from murine continuous bone marrow cultures. Parameters of engraftment quantitated included: (1) numbers of adherent proliferating hematopoietic cell colonies, "cobblestone islands" (2) cumulative production of nonadherent hematopoietic cells over 8 weeks after engraftment, (3) M-CSF, GM-CSF and multi-CSF (IL-3) dependent hematopoietic progenitor cells forming greater than or equal to 50 cell colonies in semisolid medium, (4) cumulative production of CFUs, and (5) number of adherent stromal cells positive for detectable extracellular laminin or collagen type IV (markers of endothelial cells, reticular adventitial cells, or sinus lining cells). There was a decrease in cobblestone island formation between 5 and 10 Gy and this parameter possibly increased at doses of 50 and 100 Gy. There was no difference between HDR and LDR irradiation to 10 Gy. Irradiation to doses above 10 Gy decreased support of engrafted cells forming CFU-GM and CFU-GEMM. Measures of CFUs after 10 Gy were variable but indicated a possible increase with HDR and no effect of LDR at 1 week and a decrease in both HDR and LDR groups at 3 weeks after engraftment. Thus, LDR and HDR irradiation in vitro alter several specific parameters of marrow stromal cell support for engrafted hematopoietic stem cells.
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PMID:Alteration in hematopoietic stem cell seeding and proliferation by both high and low dose rate irradiation of bone marrow stromal cells in vitro. 289 57

The ingestion of monosodium glutamate in sensitive individuals has been reported to cause severe asthma. We therefore studied the effects of L-glu on airway function and histamine (H) responsiveness in the rabbit. Histamine dose response curves (HDR's) were performed by measuring total lung resistance (RL) after inhalation of saline and increasing concentrations of H (1-30 mg/ml). The concentration of H producing a 20% increase in RL (PC20H) was obtained by interpolation. To assess the effects of L-glu, 8 rabbits were infused with L-glu (0.2 g/kg/hr) or saline in random order (14 days apart) for 4 hours followed by an HDRC. To look at possible late effects, a repeat HDRC was also performed in 6 rabbits 12 hours after completion of the L-glu infusion. In order to see whether rabbits rendered hyperresponsive responded to L-glu, the above protocol was performed in 7 rabbits following the inhalation of 3 micrograms of the activated complement fragment C5a des Arg. The L-glu infusions increased the plasma levels approx. ten-fold (mean +/- SEM 0.119 +/- 0.012 base-line, 1.272 +/- 0.061 mmol/l post infusion). L-glu did not increase the PC20H or baseline RL in either the normal rabbits at 4 or 12 hours or in the C5a des Arg treated rabbits at 4 hours. It is concluded that L-glu does not cause bronchoconstriction or an increase in airway responsiveness to H in the rabbit.
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PMID:The effect of L-glutamic acid on airway function and reactivity in the rabbit. 290 65

In continuation of our long-term afterloading method applied in the treatment of patients with inoperable cervix carcinomas, we have introduced the ring and pin applicator system into the short term afterloading proceeding. The benefit of a standardized treatment method is especially relevant in HDR afterloading therapy. A time-consuming brachytherapy planning is not necessary because of the constant source distribution within the rigidly shaped ring and pin applicator and the unchanged dose to point A according to Manchester. Percutaneous radiotherapy planning is further facilitated by fixing a metal clip in the cervix at the first HDR insertion. With the aid of anterior-posterior localization radiography, the centre of the circular absorber used by us can be located on the metal clip. In case of an asymmetric position of the cervix, this allows to avoid a dose excess at one pelvis wall caused by superimposing target volumes of brachytherapy and percutaneous therapy as well as an insufficient dose at the opposite wall of the pelvis.
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PMID:[Simplified HDR-afterloading and high-voltage therapy of cervical carcinoma]. 312 47

This multicenter, double-blind, randomized, parallel study compared the efficacy and safety of two dosages of naproxen sodium (NS) in 100 patients with bone pain due to metastatic cancer. Patients were asked to rate their pain on a scale of 0-99; those patients with pain scores of 40 or more (indicating moderate to severe pain) were enrolled. Patients receiving the high-dosage regimen (HDR; n = 51) received NS 550 mg every 8 h for 3 days. Those receiving the low-dosage regimen (LDR; n = 49) received on day 1 an initial dose of NS 550 mg followed by NS 275 mg capsules every 8 h through day 3. Patients evaluated pain intensity 8 times/day. During use of NS, pain intensity scores decreased by approximately one-third in each treatment group. Among patients who responded to NS, pain relief with the HDR was significantly greater than with the LDR. Differences between regimens in adverse events during treatment were non-significant; complaints were mainly gastrointestinal and mild.
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PMID:Naproxen sodium in treatment of bone pain due to metastatic cancer. 322 54

The effect of high-dose cyclophosphamide (Cy), either alone or in combination with irradiation, upon the development of interstitial pneumonitis (IP) after bone marrow transplantation (BMT) was investigated in a Brown Norway rat model. The parameters that were examined included ventilation rate, mortality, and histopathology. No damage to the lungs was observed in rats given Cy alone in supralethal dosages plus BMT, and mortality resulted from severe aplasia of hemopoietic and lymphoid tissues with multifocal hemorrhages, secondary infections, and sepsis. Two separate periods of mortality were observed within the first 180 days following whole thorax irradiation with a high dose rate (HDR; 0.8 Gy/min) or a low dose rate (LDR; 0.05 Gy/min). The addition of Cy prior to irradiation resulted in an increased mortality in the first period (before day 100) in all experimental groups. The influence of Cy on mortality at 180 days however, was different for the HDR and LDR experiments. The LD50-180 after HDR irradiation, dose range 8 to 18 Gy, was not significantly altered by the addition of Cy (100 mg/kg) 1 day prior to irradiation, whereas Cy (100 mg/kg) 1 day prior to LDR irradiation, dose range: 16 to 24 Gy, caused an enhancement of radiation damage with a decrease of the LD50-180 by 1.33 Gy. The dose modification factor (DMF) was 1.07. This enhancement was no longer significant after splitting up the dose of Cy in two dosages of 50 mg/kg given on 2 consecutive days prior to irradiation with a LDR. The extrapolation of the data in this rat model to available dose-response curves on IP after BMT and radiation pneumonitis in humans, implied that non-infectious IP is a radiation pneumonitis that is only slightly enhanced by Cy.
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PMID:Lung damage following bone marrow transplantation: II. The contribution of cyclophosphamide. 330 44

In order to decrease the morbidity rate after combined radiotherapy of the cervix carcinoma, a tungsten shield 3 and 5 mm thick for the rectum has been developed by the authors which is applied with the ring and pin applicator of the Selectron unit (LDR- and HDR-afterloading). The isodose curves were measured in a plexiglas phantom, and the radiation dose at the reference points was determined by means of a ionization dosimeter. The phantom measurements were performed with the same arrangement of sources as applied in radiotherapy. The measurements showed a dose reduction at point Rmax of 33% (HDR) and 44% (LDR) with the tungsten shield 5 mm thick.
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PMID:[Rectal shielding for a Selectron-ring applicator system (HDR- and LDR-afterloading)]. 342 77

Mice were given cyclophosphamide 30 mg/kg intraperitoneally before thoracic irradiation at high dose-rate (HDR, 100 cGy/min) or low dose-rate (LDR, 5 cGy/min). The development of pneumonitis was monitored by regular measurement of breathing rate. Peak rises in breathing rate occurred around 4-9 weeks in those given cyclophosphamide before irradiation, and around 14-16 weeks in those given radiation alone, regardless of dose-rate. The dose reduction factor (DRF = LDR/HDR ratio) for LDR irradiation was congruent to 1.8 but LDR sparing was abolished (DRF congruent to 1.0) when cyclophosphamide was given before irradiation.
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PMID:The effect of low dose-rate and cyclophosphamide on the radiation tolerance of the mouse lung. 375 69

High dose whole body irradiation is commonly included in conditioning regimens for bone marrow transplantation for treatment of patients with hematological malignancies. Interstitial pneumonitis is a major complication after BMT. About one-fourth of all BMT patients die from IP. In about half of these cases, an infectious agent, particularly cytomegalovirus, is involved. When no infectious cause is found, it is classified as idiopathic IP (IIP). Total body irradiation is often associated with the induction of IIP; however, extrapolation of animal data from the experiments presented indicates that this is not the only factor contributing to IIP in man. Brown Norway (BN/Bi) rats were bilaterally irradiated to the lungs with 300 kV X rays at a high dose rate (HDR; 0.8 Gy/min) and at a low dose rate (LDR; 0.05 Gy/min). The dose-response curves found were very steep. In the LDR group, lung function studies were performed. There was a strong correlation between the increase in ventilation rate and the death pattern. The LD50 at 180 days was 13.3 Gy for HDR and 22.7 Gy for LDR. The ratios of LD50/180 at 0.05 Gy/min to that at 0.8 Gy/min is 1.7, which indicates a great repair capacity of the lungs. Extrapolation of animal data to patient data leads to an estimated dose of about 15-16 Gy at a 50% radiation pneumonitis induction for low dose rate TBI. As the absorbed dose in the lungs of BMT patients rarely exceeds 10 Gy, additional factors such as remission-induction chemotherapy, cyclophosphamide, methotrexate, cyclosporin A, graft-versus-host disease, etc., might be involved in the high incidence of IIP in man after BMT.
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PMID:Lung damage following bone marrow transplantation: I. The contribution of irradiation. 388 9

Since April 1983 patients with gynecologic tumors have been irradiated with the HDR afterloading method at the University Hospital of Cologne. The therapy scheme for the carcinoma of the cervix consists of a combination of intracavitary contact irradiation and external radiotherapy. Brachytherapy is preponderant in an early stage of tumor extension, whereas teletherapy contributes more to the total dose in advanced stages. At first, the pelvis is totally exposed to a homogenous irradiation, so the shrunken tumor can more easily be arrived by curietherapy. The therapy scheme is described for the different tumor stages with its dosages, fractionations, and treatment pauses. Besides the use of special multiple-way applicators, the risk organs are protected by collimating with a block the middle part of the external irradiation field as soon as the maximum permissible dose is reached. A special block shape minimizes the dose irregularities at the field borders. The total physical dose at point A is about 60 Gy. The high dose rate of HDR afterloading has to be considered when calculating the biologic efficient dose. Here the dose rate factor furnishes a rough relation to the established radium dosage.
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PMID:[Presentation of a therapy scheme and irradiation technic for short-term contact irradiation of cervical cancer]. 392 63

The anticoagulant effect of heparin was studied in 20 patients undergoing aortocoronary bypass surgery. The protamine dose necessary to reverse heparin after extracorporeal circulation (ECC) was assessed in ten patients from individual heparin dose-response curves (HDR group). The other ten patients received protamine according to a routine protocol (control group). The protamine administration was followed in both groups by injection of 3-5 g tranexamic acid (Cyklokapron). A wide range of sensitivity to heparin was shown by the patients. Although almost twice as much protamine was given to the control group as to the HDR group, the effect on heparin reversal was similar. The variability of protamine dose did not influence the post-bypass levels of fibrinogen, AT-III, activated coagulation time (ACT) or Cephotest, and fibrinolysis was not observed in either of the groups. During ECC there was poor correlation between ACT and plasma heparin levels, and the use of heparin dose-response curves was grossly misleading in regard to true heparin concentration. The postoperative bleeding was not related to the levels of heparin or coagulation parameters after heparin reversal. The concentrations of fibrinogen and AT-III showed variations dependent on the changes in haematocrit. A number of factors other than heparin that influence ACT are discussed.
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PMID:The value of activated coagulation time in monitoring heparin therapy during extracorporeal circulation. 661 86


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