Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.3.1.51 (HDR)
 605 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It now appears unequivocal that three markers exist in a linkage group in chromosome 6 of man: HLA-A, HLA-B and PGM3 (Fig. 1.) Tentatively, two other HLA loci and one Ir gene have been mapped close to HLA-B. The probable map order is HLA-A - HLA-C - HLA-B - HLA-D - Ir. The biological functions of these loci are unknown. However, HLA-A, B and C are important in allograft rejection. Other closely linked loci (HDR, CML) appear to be important in the first events of the allograft rejection (first set) and in generation of killer cells. HLA-D might be important in cellular recognition and graft-versus-host reactions (matching at HLA-D decreases the incidence and severity of graft-versus-host disease), and the Ir genes in the defense against infections. HLA-B and HLA-D loci are important markers in studies of disease susceptibility. HLA-B locus antigens HLA-B27 and HLA-B8 are frequently associated with arthritic or autoimmune disorders. HLA-D determinants have been found in association with multiple sclerosis and C2 deficiency (HLA-DW2); juvenile diabetes and Addison's disease (HLA-DW3) and adult type of rheumatoid arthritis (HLA-DW4).
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PMID:Immunogenetic aspects of allotransplantation. 13 74

The high dose rate brachytherapy uses a single source os 192Ir with 10Ci of nominal activity in a remote afterloading machine. This technique allows an outpatient treatment, without the inconveniences of the conventional low dose rate brachytherapy such as use of general anesthesia, rhachianesthesia, prolonged immobilization, and personal exposition to radiation. The radiotherapy department is now studying 5 basic treatment schemes concerning carcinomas of the uterine cervix, endometrium, lung, esophagus and central nervous system tumors. With the Micro Selectron HDR, 257 treatment sessions were done in 90 patients. Mostly were treated with weekly fractions, receiving a total of three to four treatments each. No complications were observed neither during nor after the procedure. Doses, fraction and ideal associations still have to be studied, so that a higher therapeutic ratio can be reached.
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PMID:[High dose rate brachytherapy]. 134 May 84

The aim of this study was to investigate the effects of 60Co irradiation delivered at high (HDR) and low (LDR) dose-rates on rat salivary gland function. Total-body irradiation (TBI; total doses 7.5, 10 and 12.5 Gy) was applied from a 60Co source at dose-rates of 1 cGy/min (LDR) and 40 cGy/min (HDR) followed by syngeneic bone marrow rescue. Four days before and 1-30 days after TBI, submandibular and parotid saliva samples were collected in male albino Wistar rats using Lashley cups. Lag phase and flow rate were recorded, and [Na+] and [K+] were measured. The severity of salivary gland dysfunction for each dose-rate was dependent on total TBI dose in all parameters. LDR irradiation significantly enhanced the increase of lag phase, while it tended to further decrease flow rate during days 0-3. At later times the reverse effect was seen with significant LDR sparing in most cases. The changes in [Na+] and [K+] showed similar trends; LDR had an enhancing effect for early damage, while beyond day 3 it consistently produced less damage. From this dose-rate study it is concluded that the early postirradiation changes in salivary gland function are probably predominantly caused by irradiation damage to membrane structures and are less the result of reproductive failure. The later changes in salivary gland function are probably mainly dependent on repopulation of surviving stem cells.
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PMID:Contrasting dose-rate effects of gamma-irradiation on rat salivary gland function. 135 16

In a prospective, nonrandomized study 43 patients with inoperable oesophageal carcinoma were treated with a combined therapy of external and intracavitary irradiation according to the Heidelberg protocol adjusted to tumor stage, general condition and age. The proportion of external beam to afterloading doses was 2/3:1/3. The reference doses were between 50 and 75 Gy. Intracavitary radiotherapy was carried out with a HDR-afterloading device in single doses of 5 Gy. In a median follow-up of 23 months 46% had a complete remission and 42% had a partial remission. Within ten months 17 patients (39.5%) showed local tumor progression or recurrence. Presently the estimated median survival time of the whole collective is eleven months. The median survival was significantly influenced by achievement of complete remission (17.7 months in comparison to 8.7 months by missing complete remission). After completion of therapy 90% had sufficient oral nutrition. During long-term follow-up in 44% of the cases repeated measures had to be taken to eliminate initial or recurrent dysphagia. Almost all postradiogenic stenoses were caused by tumor progression. Radiogenic side-effects caused by HDR-afterloading boosts, exceeding the acceptance, were not found. The combined therapy reduces the period of hospitalisation and has the same palliative effects as an exclusively external radiotherapy.
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PMID:[The percutaneous-endocavitary irradiation of esophageal carcinomas]. 137 68

It is now well accepted that differences exist in the intrinsic radiosensitivity of human tumour cells although the molecular basis of this is still unclear. Current evidence suggests that of the lesions induced in DNA by ionising radiation, double-strand breaks (DSB) are the most closely linked to cell death. In this study, levels of DSB were measured by neutral filter elution under conditions of both repair inhibition and maximum recovery and compared with clonogenic survival curves for high (HDR) and low dose-rate (LDR) irradiation in human carcinoma lines of differing radiosensitivity. Four human lung carcinoma lines were used, two small-cell (SCLC; HC12 and HX149) and two non-small cell lines (NSCLC; HX147A7 and HX148G7). Cell survival was measured by soft agar and monolayer colony-forming assays as appropriate and a large variation in sensitivity of the cell lines was seen (alpha values of 0.06 to 0.56 Gy-1). We have previously reported that the damage induced at high dose rate does vary in these cell lines but not in a way which correlates with their cell survival response [5]. Following irradiation to 15 Gy at low dose rate essentially no DSBs were detected in any of the four lines but at 70 Gy the more sensitive SCLC showed more residual damage than in the more radioresistant NSCLC lines. The prime determinant of the difference between the LDR and HDR damage curves is likely to be repair occurring during irradiation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Differences in the level of DNA double-strand breaks in human tumour cell lines following low dose-rate irradiation. 138 73

Radiotherapy for uterine cervix carcinoma is an accepted treatment for all stages of invasive malignancy. The radiation modality is usually a combination of brachytherapy and external beam therapy for all except the most extensive tumours (stage IV--FIGO). Satisfactory results have been obtained in the Singapore General Hospital using low dose-rate radium applications in combination with cobalt teletherapy. Five year actuarial survival rates of 86.7% were obtained for FIGO stage I, 65.0% for stage II, 41.4% for stage III, 4.9% for stage IV with an overall rate of 54.0% for all stages. Corresponding 10-year rates were: 79.6%, 60.2%, 35.2%, 0% and 48.2%. Preliminary results of primary radiotherapy in 36 patients with cervical carcinoma treated by high dose-rate brachytherapy (microSelectron HDR) combined with 6MVP photons from a Siemens linear accelerator are presented. The patients were registered at the Mount Elizabeth Oncology Centre from November 1989 to December 1990 inclusive. The morbidity from high dose-rate therapy appears lower (9.1% for vaginal stenosis, 6.1% for non-severe proctitis) than for the radium series (4.1% and 20.8%) although the major complication rate appears similar (3% vs 2.8% respectively). The total failure rate is also lower at 19.4% for the HDR patients compared to 33.5% for the radium group. However, these rates are not strictly comparable as the HDR series consists of a small number of patients with limited follow-up. In the light of the data indicating acceptable morbidity with significant rate of early failure, the HDR brachytherapy doses have been increased whilst keeping within the limits set by other centres.
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PMID:Radical radiotherapy for carcinoma cervix--preliminary experience with the microSelectron high dose rate machine. 151 31

Internal methods of thermotherapy such as interstitial, endocavitary and perfusional hyperthermia in combination with high- (HDR) or low-dose rate (LDR) brachytherapy have gained increasing interest among oncologists due to the known radio- and chemosensitizing potential of heat. Interstitial techniques offer several advantages over percutaneous heating techniques: confined treatment volume with improved sparing of normal tissue; accessibility of deeper tumors in various sites; more homogeneous distribution of therapeutic temperatures; and better control and evaluation of thermal parameters, when using extensive "thermal mapping" procedures. Currently several promising techniques are investigated such as radiofrequency (RF), microwave (MW) and hot source (HS) techniques. In phase 1 to 2 studies interstitial hyperthermia (IHT) has been mostly applied in the head and neck and brain, the chest wall, the pelvic region and the extremities for primary advanced, persistent or local recurrent tumors, which have responded poorly to conventional treatment approaches. Preliminary data on 600 patients treated with interstitial thermo-radiotherapy (IHT-IRT) are extremely promising despite broad variations among the technical and clinical treatment parameters. The tumor response rate in various clinical trials ranges between 11% and 74% CR, and with respect of extensive pre-treatment approaches, the overall complication rate of 20% appears acceptable. So far several prognostic treatment factors have been identified: tumor volume; radiation dose; high minimum tumor temperatures and sufficiently good thermal quality of the hyperthermia treatment. Future technical innovations should broaden clinical implementations of interventional hyperthermia such as intraoperative hyperthermia and intracavitary hyperthermia. It would appear from these experiences, that interstitial hyperthermia is an effective and safe treatment modality, especially when combined with radiotherapy for tumor palliation. Prospective randomized multicentric studies have already been initiated to investigate its role in palliative and adjuvant tumor therapy.
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PMID:The current role of interstitial thermo-radiotherapy. 155 17

Brachytherapy is advantageous in the initial carcinomas of external auditory canal. The radiation charge of the surrounding tissues is much lower in spite of millivoltage irradiation because of its higher dosage gradient. It is stated according to the recent experiences and results on seven treated patients, that with LDR treatment of 5 x 10 Gy on consecutive days and with HDR treatment of 6 x 6 Gy on weekly interruptions (in both cases the dose means a depth of 5 mm). It is impossible to give the analysis because of the small number of cases. On base of our own patients it could be proved that lasting recovery of bone involving tumours is due to radical surgery and postoperative millivoltage irradiation.
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PMID:[The brachytherapy of carcinoma of the external auditory canal]. 155 19

CORT is a new radiosurgical treatment concept for patients with recurrent gynecologic malignancies infiltrating the pelvic wall. The operative part consists of (i) staging laparotomy; (ii) maximum debulking of the tumor from the pelvic wall and exenteration of infiltrated central pelvic organs; (iii) implantation of brachytherapy guiding tubes on the residual tumor/tumor bed at the pelvic wall; (iv) pelvic wall plasty with muscle and omentum flaps to create a protective distance between the tubes and the pelvic hollow organs and to induce therapeutic angiogenesis; and (v) surgical reconstruction of bowel, bladder, and vulvoperineovaginal functions. Radiation is given postoperatively as fractionated HDR brachytherapy via the implanted tubes. Patients without prior pelvic radiation also receive preoperative whole pelvis teletherapy. Eighteen patients with recurrent malignancies infiltrating one pelvic wall have been treated with CORT in a prospective phase I/II trial at the University of Mainz. Fourteen patients had a history of radiation therapy with midpelvic doses of 40-100 Gy (median, 65 Gy) as primary treatment. Eleven patients (61%) are without evidence of disease at 6-32 months (median, 15 months) follow-up. Four patients have died from pelvic progression and distant metastases, and two patients are alive with disease after 12 months. There was no operative mortality; however, one patient succumbed from fatal thromboembolism 6 months after therapy. Three patients with prior radiation of greater than 75 Gy had to be treated for intestinal fistulas. We conclude that CORT is feasible with encouraging preliminary results.
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PMID:The combined operative and radiotherapeutic treatment (CORT) of recurrent tumors infiltrating the pelvic wall: first experience with 18 patients. 163 36

Endobronchial intraluminal brachytherapy was conducted for 5 patients with tracheobronchial carcinoma using 192Iridium high dose-rate afterloading machine (microSelectron HDR) and guide tubes of 1.9 mm in outer diameter. Four patients with bronchial non-small cell carcinoma and one with tracheal adenocarcinoma were applied, and a dose of 6 Gy/Fr. at points 1 cm from the source once a week, and a cumulative dose of 18 Gy/3 Fr. was delivered. Guide tubes could be placed up to 3 tubes via the vocal airway, and new computer planning system could afford to calculate dose from independent lining of the source into optimization. This could be done with safety, and no remarkable acute side effects were observed attributable to this method.
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PMID:[Endobronchial intraluminal brachytherapy for patients with tracheobronchial carcinoma with high dose-rate 192-Iridium remote afterloading method]. 164 16


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