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1.
Clin Radiol ; 79(3): 213-220, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38218706

ABSTRACT

AIM: To evaluate the efficacy of using the central venous (CV) port compared with peripheral intravenous access for contrast-material injection for contrast enhancement during the portal venous phase. MATERIALS AND METHODS: Patients were divided into three groups: CV delay, CV routine, and peripheral access (PA) groups. Patients in the CV delay group underwent injection in the arm-down position with an additional delay, while those in the CV routine and PA groups underwent injections with the routine injection protocol for portal venous phase imaging. Contrast enhancement was evaluated by measuring the mean radiodensity (Hounsfield units) values for the aortic arch, abdominal aorta, inferior vena cava, portal vein, and spleen. The peak injection pressure was recorded and compared among the three groups. RESULTS: No complications related to power injection were observed during 119 contrast-material injections performed using the CV port device. The CV delay group showed significantly lower radiodensity values than the PA group (165.7 ± 20.1 versus 181 ± 19 HU [p<0.01] for the portal vein); however, no significant differences in mean radiodensity values were observed between the CV routine and PA groups (p>0.05). The median peak injection pressure was 73.5, 67, and 47 psi in the CV delay, CV routine, and PA groups, respectively (p<0.01). CONCLUSION: The CV port can be used for safe contrast-material injection while maintaining contrast enhancement on portal venous phase comparable to that achieved with peripheral intravenous access.


Subject(s)
Catheterization, Central Venous , Tomography, X-Ray Computed , Humans , Tomography, X-Ray Computed/methods , Contrast Media , Injections, Intravenous , Vena Cava, Inferior
2.
Br J Cancer ; 108(6): 1324-31, 2013 Apr 02.
Article in English | MEDLINE | ID: mdl-23422756

ABSTRACT

BACKGROUND: Several studies have demonstrated that YWHAZ (14-3-3ζ), included in the 14-3-3 family of proteins, has been implicated in the initiation and progression of cancers. We tested whether YWHAZ acted as a cancer-promoting gene through its activation/overexpression in gastric cancer (GC). METHODS: We analysed 7 GC cell lines and 141 primary tumours, which were curatively resected in our hospital between 2001 and 2003. RESULTS: Overexpression of the YWHAZ protein was frequently detected in GC cell lines (six out of seven lines, 85.7%) and primary tumour samples of GC (72 out of 141 cases, 51%), and significantly correlated with larger tumour size, venous and lymphatic invasion, deeper tumour depth, and higher pathological stage and recurrence rate. Patients with YWHAZ-overexpressing tumours had worse overall survival rates than those with non-expressing tumours in both intensity and proportion expression-dependent manner. YWHAZ positivity was independently associated with a worse outcome in multivariate analysis (P=0.0491, hazard ratio 2.3 (1.003-5.304)). Knockdown of YWHAZ expression using several specific siRNAs inhibited the proliferation, migration, and invasion of YWHAZ-overexpressing GC cells. Higher expression of the YWHAZ protein was significantly associated with the lower expression of miR-375 in primary GC tissues (P=0.0047). CONCLUSION: These findings suggest that YWHAZ has a pivotal role in tumour cell proliferation through its overexpression, and highlight its usefulness as a prognostic factor and potential therapeutic target in GC.


Subject(s)
14-3-3 Proteins/metabolism , Biomarkers, Tumor/metabolism , Cell Proliferation , Neoplasm Recurrence, Local/pathology , Stomach Neoplasms/pathology , 14-3-3 Proteins/antagonists & inhibitors , 14-3-3 Proteins/genetics , Adult , Aged , Aged, 80 and over , Apoptosis , Biomarkers, Tumor/genetics , Blotting, Western , Cell Adhesion , Cell Movement , Female , Follow-Up Studies , Gene Expression Profiling , Humans , Immunoenzyme Techniques , Lymphatic Metastasis , Male , MicroRNAs/genetics , Middle Aged , Neoplasm Recurrence, Local/genetics , Neoplasm Recurrence, Local/metabolism , Neoplasm Staging , Oligonucleotide Array Sequence Analysis , Prognosis , RNA, Messenger/genetics , RNA, Small Interfering/genetics , Real-Time Polymerase Chain Reaction , Reverse Transcriptase Polymerase Chain Reaction , Stomach Neoplasms/genetics , Stomach Neoplasms/metabolism , Survival Rate , Tumor Cells, Cultured
3.
Peptides ; 22(6): 867-72, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11390015

ABSTRACT

ONOUE, S., WAKI, Y., NAGANO, Y., SATOH, S., KASHIMOTO, K. Neuromodulatory Effects of VIP/PACAP on PC-12 Cells Are Associated with Their N-terminal Structures. PEPTIDES xx(xx) 000-000, 200x.- The current study explored whether the differences in biological activities in PC-12 cells between vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) are attributable to the sequence difference in their N-terminal portions and are correlated with the solution structures of the peptides. In the neurite outgrowth assay, N-terminal modification of VIP to PACAP-like sequences altered its effect, the activity was confirmed even at a low concentration (10(-10) M). On the contrary, N-terminal modification of PACAP 27 to VIP-like sequences reduced its activity. These relationships were also confirmed for the inhibitory effects of the peptide analogues on PC-12 cells growth at 10(-7) M. The present results combined with our previously reported data, including binding assay, support that the N-termini of VIP/PACAP plays an important role in their activities.


Subject(s)
Fluorescent Dyes/pharmacology , Neuropeptides/pharmacology , Amino Acid Sequence , Animals , Cell Division , Dimethyl Sulfoxide/pharmacology , Dose-Response Relationship, Drug , Magnetic Resonance Spectroscopy , Models, Molecular , Molecular Sequence Data , Neurons/cytology , PC12 Cells , Peptide Biosynthesis , Pituitary Adenylate Cyclase-Activating Polypeptide , Protein Structure, Tertiary , Rats , Sequence Homology, Amino Acid , Vasoactive Intestinal Peptide/chemistry
4.
Peptides ; 21(6): 821-7, 2000 Jun.
Article in English | MEDLINE | ID: mdl-10959004

ABSTRACT

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide and a member of the secretin/glucagon superfamily of peptides that include vasoactive intestinal polypeptide. PACAP is not only present in the central nervous system but also in peripheral organs, such as the gastrointestinal tract, gonads and adrenal glands, and plays various roles in mammals. Recently, we isolated and characterized PACAP, which is very similar to PACAP of mammalian origin, from the brain of a teleost, the stargazer, Uranoscopus japonicus. In the present study, the expression of PACAP mRNA was detected in the stargazer rectum using the reverse transcriptase/polymerase chain reaction (RT-PCR) method. The distribution of PACAP-like immunoreactivity in the rectum was also examined immunohistochemically, using an antiserum raised against PACAP 27, and PACAP-like immunoreactive neuronal cell bodies and fibers were found in the myenteric plexuses and the smooth muscle layers of the rectum. The present study also investigated the relaxant activity of synthesized homologous PACAP on rectal contraction. Stargazer PACAP, like that of mammalian origin, inhibited contractions stimulated by acetylcholine or potassium chloride. PACAP-induced inhibition was not affected by preincubation with atropine, propranolol, or phentolamine. These results suggest that PACAP may act directly as an inhibitory neuropeptide in the stargazer rectum.


Subject(s)
Neuropeptides/isolation & purification , Perciformes , Rectum/chemistry , Acetylcholine/pharmacology , Animals , Digestive System Physiological Phenomena/drug effects , Immunohistochemistry , In Vitro Techniques , Muscle Contraction/drug effects , Neuropeptides/genetics , Neuropeptides/pharmacology , Pituitary Adenylate Cyclase-Activating Polypeptide , Rectum/drug effects , Reverse Transcriptase Polymerase Chain Reaction
5.
Int J Radiat Oncol Biol Phys ; 44(4): 767-75, 1999 Jul 01.
Article in English | MEDLINE | ID: mdl-10386633

ABSTRACT

PURPOSE: Our aim was to study the treatment parameters that influence local control and soft tissue complications (STC) in a series of 207 Stage I and II squamous cell carcinomas of the oral tongue treated by interstitial brachytherapy (BRT) alone (127 patients), or by a combination using external beam irradiation (EBI) (80 patients) between 1980 and 1993. METHODS AND MATERIALS: The patient distribution was 93 T1, 72 T2a, and 42 T2b. The prescribed BRT dose at the plane 5 mm from the plane of the radioactive sources was 65-70 Gy in BRT alone, and 50-60 Gy in the combined treatment using EBI. Generally, an EBI dose of 30 Gy was used. No prophylactic neck treatment was performed. RESULTS: The 5-year local recurrence-free rate for T1, T2a, and T2b was 92.9%, 81.9%, and 71.8%, respectively (p < 0.05). The lesions of endophytic appearance and those located in the posterior half of the mobile tongue had a significantly lower local control rate than those of other macroscopic appearances (p = 0.02) and those in other localizations (p < 0.01). Most local recurrences (66.7%) occurred within 2 years after treatment. However, 8 of 14 recurrences of T1 and 6 of 15 recurrences among patients treated by BRT alone occurred after 5 years. Statistical analysis showed that, in BRT alone treatment, a dose rate < = 1.0 Gy/h was related to better local control (p = 0.04). There was no significant relationship between BRT dose and local control; however, the incidence of local recurrence was lowest in a BRT dose 65-70 Gy. In the combined treatment, a total dose > 85 Gy (p = 0.01), BRT dose > 55 Gy (p = 0.04), and a dose rate < 0.55 Gy/h (p = 0.03) were significantly related to better local control. The incidence of more severe STC were 11.5% and was significantly higher in T2a (p = 0.03) and T2b (p < 0.01) than in T1. Statistical analysis revealed that a dose rate > = 0.6 Gy/h was significantly related to more STC in BRT alone (p = 0.03), and that a dose rate > = 0.55 Gy/h (p < 0.03) and a BRT dose > 70 Gy ( < 0.05) and a total dose > 100 Gy (p < 0.05) were significantly related to more STC in the combined treatment. Neck metastases occurred in 25% in T1N0, 27% in T2aN0, and 31% in T2bN0 (NS). Eighty-eight percent were found within 12 months. Thirty-three secondary cancers including 12 head and neck, 8 esophageal, and 3 gastric were found after treatment. The 5-year crude survival rate for T1, T2a, and T2b was 83.4%, 66.0%, and 70.9%, respectively. CONCLUSION: To acheive better local control and fewer STC, we recommend the following relationships between dose and dose rate. In BRT alone, dose rate should be maintained at < 0.6 Gy/h with a preferable BRT dose 65-70 Gy. In the combined treatment, total dose, BRT dose and dose rate should be kept between > 85 Gy and < = 100Gy, between > 55 Gy and < = 70 Gy, and < 0.55 Gy/h, respectively. We also recommend longer follow-up periods; more than 5 years might be necessary for late local recurrences and for secondary cancers.


Subject(s)
Brachytherapy/methods , Carcinoma, Squamous Cell/radiotherapy , Tongue Neoplasms/radiotherapy , Adult , Aged , Aged, 80 and over , Analysis of Variance , Brachytherapy/adverse effects , Carcinoma, Squamous Cell/mortality , Carcinoma, Squamous Cell/pathology , Cause of Death , Female , Follow-Up Studies , Humans , Male , Middle Aged , Neoplasm Recurrence, Local/epidemiology , Neoplasm Staging , Radiation Injuries/etiology , Radiotherapy Dosage , Soft Tissue Injuries/etiology , Tongue Neoplasms/mortality , Tongue Neoplasms/pathology
7.
Eur Respir J ; 12(5): 1062-6, 1998 Nov.
Article in English | MEDLINE | ID: mdl-9863997

ABSTRACT

A recent study showed that the novel pituitary adenylate cyclase-activating peptide (PACAP)-27 analogue [Arg15,20,21,Leu17]-PACAP-27-Gly-Lys-Arg-NH2 causes sustained airway smooth muscle relaxation in vitro. This study examined whether this analogue also has bronchoprotective effects, by inhibiting muscarinic airway responsiveness in vivo. Total lung resistance was measured in anaesthetized, tracheostomized and ventilated guinea-pigs. Increasing doses of acetylcholine were given i.v. once before and thereafter repeatedly each hour after intratracheal instillation of either the PACAP-27 analogue or the clinical beta2-agonist bronchodilator salbutamol. Mean arterial blood pressure (MAP) was monitored to detect cardiovascular side-effects. Both the PACAP-27 analogue and salbutamol significantly attenuated the airway responsiveness to acetylcholine. The total inhibitory effect of the PACAP-27 analogue (350 nmol) corresponded to that of salbutamol (35 nmol). The inhibitory effect of salbutamol (35 nmol) peaked during the second hour and disappeared prior to 5 h after administration. In contrast, the corresponding effect of the analogue (350 nmol) gradually increased and peaked during the fifth hour after administration, whereas it did not fade during the observation period. Both the PACAP-27 analogue (350 nmol) and salbutamol (35 nmol) produced a transient decrease in MAP within 6 min after administration. In conclusion, the novel pituitary adenylate cyclase-activating peptide-27 analogue has bronchoprotective properties, by decreasing muscarinic airway responsiveness in guinea pigs in vivo. The time course of its effect is compatible with a more sustained duration of action compared with salbutamol.


Subject(s)
Airway Resistance/drug effects , Neuropeptides/pharmacology , Receptors, Muscarinic/physiology , Acetylcholine/pharmacology , Albuterol/pharmacology , Animals , Bronchodilator Agents/pharmacology , Dose-Response Relationship, Drug , Guinea Pigs , Male , Pituitary Adenylate Cyclase-Activating Polypeptide
8.
Peptides ; 19(9): 1489-95, 1998.
Article in English | MEDLINE | ID: mdl-9864054

ABSTRACT

Pituitary adenylate cyclase activating polypeptide (PACAP) was isolated from ovine hypothalami and found to exist as two amidated forms with 38 (PACAP 38) and 27 (PACAP 27) residues. The amino acid sequences of PACAPs isolated from the vertebrates, such as a bird, a frog and teleost fish, appear to be well conserved. In the present study, we attempted to isolate PACAP from the brain of an elasmobranch fish, Dasyatis akajei (stingray), which belongs to the Chondrichthyes (cartilaginous fish), by extraction of the acetone-dried powder with acetic acid, followed by successive high-performance liquid chromatography (HPLC) on a gel-filtration, a cation-exchange and two reverse-phase columns. Purification was monitored by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) and Western blotting analysis using an anti-PACAP 27 serum. The PACAP thus obtained consisted of 44 residues. The amino acid sequence of the comparable portion of its N-terminal 38 residues showed 92%, 89%, 89%, and 82% identity with those of mammalian, chicken, frog and teleost PACAPs with 38 residues, respectively. The extra six C-terminal residues of the stingray resembled those of tetrapod and teleost PACAP precursors which were deduced from the respective cDNAs. These results indicate that PACAP, which has an amino acid sequence showing high similarity with those of tetrapod and teleost PACAPs, is present in the elasmobranch brain.


Subject(s)
Brain Chemistry , Neuropeptides/chemistry , Skates, Fish , Amino Acid Sequence , Animals , Chromatography, High Pressure Liquid , Molecular Sequence Data , Pituitary Adenylate Cyclase-Activating Polypeptide , Sequence Analysis , Sequence Homology, Amino Acid , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
9.
Peptides ; 19(3): 593-7, 1998.
Article in English | MEDLINE | ID: mdl-9533650

ABSTRACT

The relaxant effect of a novel VIP analog, [Arg15,20,21Leu17]-VIP-Gly-Lys-Arg-NH2 was compared with that of the original VIP in the same guinea pig trachea precontracted by carbachol in vitro. The VIP analog caused significantly and concentration-dependent relaxation similarly to the original VIP. In contrast to the original VIP, the VIP analog demonstrated a slow onset and offset of action, with more than 90% of its maximum relaxation remaining 6 h after administration. Peptidase inhibition by captopril and phosphoramidon increased the relaxant effect and duration of action for original VIP but not for the VIP analog.


Subject(s)
Trachea/drug effects , Vasoactive Intestinal Peptide/analogs & derivatives , Vasoactive Intestinal Peptide/pharmacology , Albuterol/pharmacology , Amino Acid Sequence , Animals , Captopril/pharmacology , Carbachol/pharmacology , Guinea Pigs , Male , Molecular Sequence Data , Muscle Relaxation/drug effects , Structure-Activity Relationship , Time Factors , Vasoactive Intestinal Peptide/chemistry , Vasoactive Intestinal Peptide/metabolism
10.
Br J Pharmacol ; 121(8): 1730-4, 1997 Aug.
Article in English | MEDLINE | ID: mdl-9283710

ABSTRACT

1. We compared the relaxant effect of pituitary adenylate cyclase activating peptide (PACAP) 1-27 with that of a newly developed PACAP 1-27 analogue, [Arg15,20,21Leu17]-PACAP-Gly-Lys-Arg-NH2, in the guinea-pig trachea and primate bronchi in vitro (n = 4-5). 2. In the guinea-pig trachea precontracted by a submaximally effective carbachol concentration (0.1 microM), cumulative administration of PACAP 1-27 and the beta 2-adrenoceptor agonist salbutamol (3 nM-3 microM) caused significant and concentration-dependent smooth muscle relaxation, with salbutamol being approximately one log-step more potent in this model. However, in primate bronchi precontracted by carbachol (0.1 microM), cumulative administration of PACAP 1-27 and salbutamol caused concentration-dependent smooth muscle relaxation with very similar potencies and maximum relaxant effects. 3. In the guinea-pig trachea, non-cumulative administration of the PACAP 1-27 analogue and the original PACAP 1-27 (0.3-3 microM) caused concentration-dependent relaxation with a very similar maximum relaxant effect and potency. However, the onset and offset of action was markedly slower for the PACAP 1-27 analogue than for the original PACAP 1-27 (< 90% versus < 10% of peak relaxation remaining 6 h after administration). Separate experiments confirmed that the PACAP 1-27 analogue also caused significant relaxation with slower onset and offset of action than did the original PACAP 1-27 in primate bronchi. 4. Peptidase inhibition by captopril (10 microM) and phosphoramidon (1 microM) significantly increased the maximum relaxant effect and duration of action of PACAP 1-27 but not of the PACAP 1-27 analogue, during the 3 h of observation in the guinea-pig trachea. 5. We conclude that [Arg15,20,21Leu17]-PACAP-Gly-Lys-Arg-NH2 produces significant, concentration-dependent and sustained airway smooth muscle relaxation in vitro. The sustained relaxant effect is due, at least in part, to the PACAP 1-27 analogue being less susceptible to cleavage by peptidases than the original peptide PACAP 1-27.


Subject(s)
Bronchi/drug effects , Muscle Relaxation/drug effects , Neuropeptides/pharmacology , Trachea/drug effects , Albuterol/pharmacology , Animals , Bronchi/physiology , Captopril/pharmacology , Dose-Response Relationship, Drug , Glycopeptides/pharmacology , Guinea Pigs , Macaca fascicularis , Male , Pituitary Adenylate Cyclase-Activating Polypeptide , Trachea/physiology
13.
DNA Res ; 3(6): 363-77, 1996 Dec 31.
Article in English | MEDLINE | ID: mdl-9097039

ABSTRACT

The 569,750 base pair sequence corresponding to the 28.0-40.1 min region on the genetic map of Escherichia coli K-12 (W3110) was determined. This region includes the replication terminus region and contained at least 549 potential open reading frames. Among them, 160 (29%) were previously reported, 174 (32%) were homologous to other known genes, 102 (18%) were identical or similar to hypothetical genes registered in databases, and the remaining 113 (21%) did not show a significant similarity to any other gene. Of interest was the finding of a large number of genes and gene clusters in and near the replication termination region which had been thought to be genetically silent. Those included a cluster of genes for fatty acid beta-oxidation, the third copy of the pot (spermidine/putrescine transport system) gene cluster, the second dpp (dipeptide transport system) operon, the second dsm (anaerobic dimethyl sulfoxide reductase) operon, a cluster of fim (fimbrial) genes and a DNA helicase-like gene with a high molecular weight. In addition, we found the dnaC- and dnaT-like genes in the cryptic prophage, Rac, and a number of genes originated probably from plasmids.


Subject(s)
Chromosome Mapping , Escherichia coli/genetics , Genes, Bacterial/genetics , Sequence Analysis, DNA , Multigene Family , Open Reading Frames , Operon , Plasmids/genetics , Replicon , Sequence Alignment , Sequence Homology, Amino Acid , Sequence Homology, Nucleic Acid , Siphoviridae/genetics
15.
DNA Res ; 3(3): 137-55, 1996 Jun 30.
Article in English | MEDLINE | ID: mdl-8905232

ABSTRACT

The 718,122 base pair sequence of the Escherichia coli K-12 genome corresponding to the region from 12.7 to 28.0 minutes on the genetic map is described. This region contains at least 681 potential open reading frames, of which 277 (41%) have been previously identified, 147 (22%) are homologous to other known genes, 139 (20%) are identical or similar to the hypothetical genes registered in databases, and the remaining 118 (17%) do not show a significant similarity to any other gene. In this region, we assigned a cluster of cit genes encoding multienzyme citrate lyase, two clusters of fimbrial genes and a set of lysogenic phage genes encoding integrase, excisionase and repressor in the e14 genetic element. In addition, a new valine tRNA gene, designated valZ, and a family of long directly repeated sequences, LDR-A, -B and -C, were found.


Subject(s)
DNA, Bacterial , Escherichia coli/genetics , Genetic Linkage , Genome, Bacterial , Molecular Sequence Data , Open Reading Frames
17.
Int J Radiat Oncol Biol Phys ; 34(2): 333-9, 1996 Jan 15.
Article in English | MEDLINE | ID: mdl-8567334

ABSTRACT

PURPOSE: To examine the incidence of mandibular bone complication in patients who underwent radiotherapy for T1 and T2 carcinomas of the oral tongue and to analyze the factors contributing to its occurrence. METHODS AND MATERIALS: The clinical records of 148 patients with T1 and T2 carcinoma of the oral tongue treated with radiotherapy alone between 1978 and 1989 were examined retrospectively. Interstitial brachytherapy, used as the major treatment modality, was performed using cobalt needles, radium needles, or iridium hairpins. The prescribed dose at the plane 5 mm from the plane of the radioactive sources was 65-70 Gy in interstitial brachytherapy alone, and 50-60 Gy in the combined treatment with external irradiation. An external irradiation dose of 30 Gy was usually used. RESULTS: Eleven of the patients showed radiation-induced mandibular bone complication. Two (1 T1, 1 T2) had been treated with interstitial brachytherapy alone, and nine (2 T1, 7 T2) with the combination of external irradiation and interstitial brachytherapy. The incidence of radiation complication of bone was significantly higher in the patients with T2 tumors (p = 0.04) and in those who received the combined treatment (p < 0.01). Multivariate analysis revealed that the total dose (p = 0.04) and dose rate of interstitial brachytherapy (p = 0.03) were significant factors contributing to radiation bone complication. A significant difference in the incidence of bone complication was also seen between patients who received a total dose of 90 Gy or more and those who received less than 90 Gy (p < 0.01), as well as between patients who were treated with 0.55 Gy/h or higher and those who were treated with less than 0.55 Gy/h (p = 0.03). CONCLUSION: A significant increase in the incidence of bone complication was found at the total dose of 90 Gy or more and at the dose rate of 0.55 Gy/h or higher. In combined treatment with external irradiation and interstitial brachytherapy, the interstitial brachytherapy dose of 60 Gy appears to be the threshold at which mandibular bone complication is induced when the external irradiation dose is 30 Gy.


Subject(s)
Carcinoma, Squamous Cell/radiotherapy , Mandible/radiation effects , Mandibular Diseases/epidemiology , Osteoradionecrosis/epidemiology , Tongue Neoplasms/radiotherapy , Adult , Aged , Aged, 80 and over , Brachytherapy/adverse effects , Female , Humans , Incidence , Male , Mandibular Diseases/etiology , Middle Aged , Multivariate Analysis , Neoplasm Recurrence, Local , Osteoradionecrosis/etiology , Radiotherapy Dosage , Retrospective Studies , Survival Analysis
18.
Oral Surg Oral Med Oral Pathol ; 77(6): 589-93, 1994 Jun.
Article in English | MEDLINE | ID: mdl-8065721

ABSTRACT

Dose-reducing effects of spacers with and without a Lipowitz metal plate for the purpose of decreasing osteoradionecrosis after interstitial brachytherapy for tongue cancers were examined experimentally and clinically. The thicker the sample or spacer and the thicker the metal plate, the greater was the dose reduction achieved. A more marked dose reduction was achieved with iridium than with radium because of lower gamma ray energy of iridium. Iridium has been used widely as a radioactive source for interstitial brachytherapy. It was concluded therefore that a metal plate should be used as a shield into the spacer in interstitial brachytherapy both to reduce the radiation dose to surrounding normal tissues and to help prevent osteoradionecrosis.


Subject(s)
Alloys , Brachytherapy/instrumentation , Radiation Protection/instrumentation , Tongue Neoplasms/radiotherapy , Bismuth , Brachytherapy/adverse effects , Cadmium , Humans , Iridium Radioisotopes , Lead , Mandibular Diseases/prevention & control , Osteoradionecrosis/prevention & control , Radiotherapy Dosage , Radium , Thermoluminescent Dosimetry , Tin
20.
Oral Surg Oral Med Oral Pathol ; 76(6): 797-803, 1993 Dec.
Article in English | MEDLINE | ID: mdl-8284088

ABSTRACT

The difference of radiation dose reduction effect with spacers of different materials, a heat-curing denture base resin and a silicon impression material, was examined experimentally and clinically. Radium needles and iridium hairpins were used as radioactive sources. In both studies, it was revealed that a dose reduction effect of silicon impression material was greater than that of denture base resin. Silicon impression material was thought to be a better material for spacers because of its larger radiation dose reduction effect and the time saving to produce the spacer.


Subject(s)
Brachytherapy/instrumentation , Radiation Protection/instrumentation , Tongue Neoplasms/radiotherapy , Dental Impression Materials , Humans , Methylmethacrylates , Polyvinyls , Radiation Dosage , Radiation Protection/methods , Silicone Elastomers , Siloxanes , Thermoluminescent Dosimetry
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