Mustafa Demir

Effects of allopurinol, ibuprofen and cyclosporin A on local microcirculatory disturbances due to burn injuries

This experiment was designed to study the reactions in the surrounding area of burn injury that may lead to further necrosis in 24 h. To prevent extension of burn size into the tissue adjacent to burn injury, it was attempted to reduce progressive microvascular damage by different drugs (ibuprofen, allopurinol or cyclosporin A (CyA)) in a rat model. The burn model consisted of a row of four 10 x 20 mm burn areas separated by three unburned 5 x 20 mm skin bridges (interspaces). To evaluate microcirculation and perfusion of panniculus carnosus muscle which is beneath the burned area of skin, the radioactive agent, technetium-99m methoxyisobutylisonitrile (99Tc01-MIBI) was used 24 h after the burn. Capillary permeability of injured tissue was assessed by the wet and dry weight technique. In all study groups, interspaces showed higher uptakes of 99Tc01-MIBI between 40 and 95 per cent, in comparison with burn sites in the first 24 h following burn. Among the treated rats better results were obtained by allopurinol and CyA treatment that commenced before burn than ibuprofen. Wet and dry ratios were found to be significantly lower in interspaces in rats pretreated with allopurinol and CyA. Results of this experiment showed that neutrophils and free radical-mediated injury may be involved in the pathogenesis of local response to thermal injury, and allopurinol and CyA have some effects to prevent progressive ischemia, capillary compromise and oedema.

Radiation protection for accompanying person and radiation workers in PET/CT

The purposes of the present study are to measure the total radiation doses for the radiation workers and for the accompanying person to the patients in positron emission tomography (PET)/computed tomography (CT) imaging. Urines samples from the patients were collected at 43, 62, 87, 117, 238, 362 min after the 555-MBq (18)flour-fluorodeoxyglucose ((18)F-FDG) injection and activities were measured. Dose rates were recorded using a Geiger-Muller counter and the total radiation doses were measured with using an electronic personnel dosemeter. According to the results here, 18.4 % of (18)F-FDG was excreted in the urine in 117 min after injection. At 117th min after injection, dose rates were determined as 345, 220, 140, 50 and 15 µSv h(-1), at proposed distances. The radiation doses after 117 min were measured as 3.92 mSv at 0.1 m, 2.11 mSv at 0.25 m and 1.08 mSv at 0.5 m. In conclusion, radiation protection will be sufficient within 2 h after (18)F-FDG injection for PET/CT imaging in daily practice.

The effects of exposure of 60Co on the oxidant/antioxidant status among radiation victims.

This retrospective study has been performed with radiation victims who were accidentally exposed to a 60Co source and its release into the environment. The aim of the study was to assess the effects of elevated radiation exposures on plasma level, on erythrocyte thio barbituric acid reactive substance (TBARS) level and on erythrocyte glutathione (GSH) levels. Patients were treated in different hospitals with different symptoms such as nausea, vomiting, dizziness, along with severe anemia in some patients. Blood samples were collected 3-5 days following the radiation accident. Increases in plasma (6.25 +/- 0.90 nmol ml(-1)) and erythrocyte TBARS levels (330.5 +/- 30.5 micromol gHb(-1)) were found in comparison to a healthy group (3.72 +/- 0.68 nmol ml(-1) and 150.7 +/- 20.5 micromol gHb(-1), respectively) at a significant level (p<0.001). Erythrocyte GSH levels (5.2 +/- 0.30 micromol gHb(-1)) were found to be decreased among the victims (healthy group: 10.2 +/- 0.7 micromol gHb(-1)) at the same significance level (p<0.001). These observations confirm a significant change induced by radiation in the oxidant/antioxidant status among the victims. It is suggested here that antioxidant supplementation therapy might be effective in preventing the harmful effects of 60Co radiation among radiation victims.

An experimental study of skin flap associated with muscle: is muscle nourishment possible through the musculocutaneous perforators?

&NA; An experimental study was planned to examine whether the blood supply of muscle would be maintained by reverse flow from the cutaneous arteriolar microcirculatory system via the musculocutaneous perforators. A flap model containing both muscle and skin based on the inferior superficial epigastric vessels was designed with the blood supplied directly from the cutaneous arteriolar microcirculatory system. A total of 154 male Wistar Albino rats were divided into three groups. Group I included the standard vertical rectus abdominis musculocutaneous flap based on the superior deep epigastric vessels (N = 48). Group II included the acute cutaneous muscle flap (N = 53). Group III contained the delayed cutaneous muscle flap (N = 53). Skin flap survival area, muscle scintigraphy with technetium‐99m‐me‐thoxy‐isobutyl‐isonitrile, microangiography, and histopathological examination of the flaps were conducted. The mean percentage of surviving skin paddle area was 96.4 ± 5.2%, 84.9 ± 21.6%, and 91.0 ± 16.8% in groups I, II, and III respectively. There was no significant difference between groups. Microangiography revealed the blood flow from skin to muscle through the musculocutaneous perforators. The radioisotope uptake of the muscle flap was expressed as A percentage of the intact contralateral muscle. Mean uptake in group I was 90.1 ± 4.9% immediately after flap elevation, 62.5 ± 13.5% on day 2, and 88.3 ± 12.0% on day 7. These values were 53.7 ± 7.1%, 63.6 ± 14.1%, and 89.2 ± 18.1% in group II, and 64 ± 7.8%, 75.5 ± 9.8%, and 92.8 ± 40.1% in group III. Radioisotope uptake in group I was significantly higher than groups II and III immediately after flap elevation (p < 0.05, analysis of variance), whereas there was no significant difference on days 2 and 7. Histopathological examination revealed surviving muscle tissue without marked atrophy. There was no marked difference between groups histopathologically. These results indicate that muscle tissue may survive by reverse flow through the musculocutaneous perforators when elevated with an axial skin flap. Yazar S, Ç;etinkale O, Senel O, Yücel A, Demir M, Demirkesen C, Öz B, Aydin Y. An experimental study of skin flap associated with muscle: is muscle nourishment possible through the musculocutaneous perforators?. Ann Plast Surg 2000;45:500‐508

Evaluation of radiation safety in (177)Lu-PSMA therapy and development of outpatient treatment protocol.

The aim of this study is to investigate the outpatient treatment protocol and radiation safety of a new-emerging lutetium-177 ((177)Lu) prostate specific membrane antigen (PSMA) therapy. This work analyzed the dose rate of 23 patients treated with 7400 MBq (177)Lu-PSMA at different distances (0, 0.25, 0.50, 1.0 and 2.0 m) and variable time marks (0, 1, 2, 4, 18, 24, 48 and 120 h) after the termination of infusion. Blood samples were withdrawn from 17 patients within the same group at 3, 10, 20, 40, 60 and 90 min and 2, 3, 24 h after termination of infusion. Seven different patients were asked to collect urine for 24 h and a gamma well counter was used for counting samples. Family members were invited to wear an optically stimulated luminescence dosimeter whenever they were in the proximity of the patients up to 4-5 d. The total dose of the medical team including the radiopharmacist, physicist, physician, nurse, and nuclear medicine technologist was estimated by an electronic personnel dosimeter. The finger dose was determined using a ring thermoluminescent dosimeter for the radiopharmacist and nurse. The mean dose rate at 1 m after 4 h and 6 h was 23  ±  6 μSv h(-1) and 15  ±  4 μSv h(-1) respectively. The mean total dose to 23 caregivers was 202.3  ±  42.7 μSv (range: 120-265 μSv). The radiation dose of the nurse and radiopharmacist was 6 and 4 μSv per patient, respectively, whereas the dose of the physicist and physician was 2 μSv. The effective half life of blood distribution and early elimination was 0.4  ±  0.1 h and 5  ±  1 h, respectively. Seven patients excreted a mean of 45% (range: 32%-65%) from the initial activity in 6 h. Our findings demonstrate that (177)Lu-PSMA is a safe treatment modality to be applied as an outpatient protocol, since the dose rate decreases below the determined threshold of  <30 μSv h(-1) after approximately 5 h and degrades to 20 μSv h(-1) after 6 h.

The evaluation of urine activity and external dose rate from patients receiving radioiodine therapy for thyroid cancer

The aim of this study was to determine the external dose rate of iodine retention as a function of time in the bodies of thyroid cancer patients during their isolation period in the hospital. Urine samples were collected at 6th, 12th, 18th, 24th h and 2nd, 3rd, 4th, 5th d from 83 patients after oral administration of (131)I and counted. The external dose rates were also simultaneously determined at the same time points. Then, it was expressed as retained radioiodine body activity versus dose rate. Effective half life calculated from urine sample measurements was found as 18.4±1.8 h within the first 24 h and 64±2.7 h between 48 and 120 h. According to this results, the external dose rate (<20 µSv h(-1)), which patients could be discharged, was achieved after 48 h for 3700 and 5550 MBq, and after 72 h for 7400 MBq of (131)I treatments.

Demonstration of circulation haemodynamics in random pattern thinned skin flap (an experimental study)

BACKGROUND Clinical applications and indications of the thin skin flap have been widely documented but its circulation haemodynamics are still controversial. An experiment was conducted on pigs to show the survival and circulation haemodynamics of random pattern thinned skin flap. METHODS Group I: Random pattern standard skin flaps; 5 x 5 cm (n=20 flaps), and 5 x 10 cm (n=20 flaps). Group II: Random pattern thin skin flaps; 5 x 5 cm (n=20 flaps), and 5 x 10 cm (n=20 flaps). Group III: Random pattern thin skin flaps with silicone sheet underneath; 5 x 5 cm (n=20 flaps), and 5 x 10 cm (n=20 flaps). RESULTS The mean surviving skin area of the 5 x 10 cm flaps was 95.5% in Group I, 64.9% in Group II, and 33.67% in Group III. A statistically significant difference (P<0.05, ANOVA) was found between the groups. The mean surviving skin area of the 5 x 5 cm flaps was 100% in Groups I and II, and 68.2% in Group III. A statistically significant difference (P<0.05, ANOVA) was also found between Groups I and III, and Groups II and III. In microangiographical studies, the distribution of subcutaneous plexuses was clearly visible in Group I. In Group II the subdermal vascular plexus was observed less frequently and was thinner, particularly on the distal part of the flaps. In Group III dilatation of the subdermal vascular plexus was evident, particularly on the proximal section of the flaps. In the technetium-99m-labelled microspheres uptake of the 5 x 10 cm flaps, there was no statistically significant difference between the first segments in Groups I and II, Groups II and III (P>0.05, ANOVA). A significant difference was found between the second segments in Groups I and III (P<0.05, ANOVA). CONCLUSION The results obtained in this study show that the effect of subdermal vascular plexus in the survival of the random pattern thinned skin flaps is supported by flap bed osmosis and plasma imbibition.

Evaluation of external radiation exposure rate from radioiodine-treated hyperthyroid patients and radiation safety considerations.

SummaryHyperthyroid patients treated with radioiodine (131I) pose an external radiation risk to individuals who come into close contact with them. In order to determine changes in levels of external radiation with time in relation to the dose administered, 38 hyperthyroid patients being treated with 131I were evaluated. Thyroid uptake, plasma T3, T4 and TSH levels were measured prior to treatment. Using a Geiger-Muller probe, levels of external radiation were measured at distances of 0.3, 0.6, 1.0 and 2.0 m from the patient – at the level at which the maximum activity was recorded – 30 min, 1, 3, 7 and 10 days post-therapy. The patients were split into two groups. Group I comprised 22 patients treated with ≤ 370 MBq 131I, 5 (23%) of whom registered > 0.46 mC kg-1 at a distance of 1.0 m 30 min post-therapy. Group II comprised 16 patients treated with > 370 MBq 131I, 13 (81%) of whom registered 0.46 mC kg-1 at a distance of 1.0 m one day post-therapy. At 3 days in Group I and 7 days in Group II, the estimated total radiation exposure rates were found to exceed the 1994 US Nuclear Regulatory Commission dose limits for children and pregnant women. Based on the results obtained, we present some guidelines intended to prevent the public from unnecessary radiation exposures.

An unknown pregnancy at term detected by a FDG-PET/CT study in a patient with Hodgkin's lymphoma: A case report

FDG-PET/CT is a well-established imaging modality in many cancer types, as for staging, restaging and evaluation of therapy response in lymphoma. However, in PET/CT scanning, radiation exposure to patients has become an important issue, particularly for pregnant patients, because its each component (PET and CT) is an independent source of ionizing radiation and consequently causes radiation dose burden for the patients. A 35-year-old woman was diagnosed with nodular sclerosing type Hodgkin’s lymphoma and given four cycles of chemotherapy. After completion of chemotherapy, the patient was referred for FDG-PET/CT for restaging. Patient signed a given informed consent form in which she also stated that she had no pregnant but irregular menstrual periods and the last one was 1 week ago. Ninety minutes after injection of 555 MBq 18F-FDG, a PET/CT study with a non-contrast enhanced, low dose (120 kVA, 61 mAS) CT component was obtained from the head to midthigh. During evaluation of PET/CT images, we noticed a bombshell gross mass appearance in the lower part of abdomen and pelvis representing a fetus in uterus, in spite of no detection of any abnormal FDG uptake related to residual primary disease (Fig. 1). The patient was questioned for possibility of pregnancy. However she answered negatively but she had irregular menstrual periods after the chemotherapy. When the CT report for initial staging was reevaluated, no pregnancy was reported possibly due to early weeks of pregnancy. Also the patient, who had somewhat lower social and

Verification and uniformity control of doses for 90 Sr/ 90 Y intravascular brachytherapy sources using radiochromic film dosimetry

Intravascular brachytherapy (IVBT) is a useful treatment modality for the recurrence of in-stent restenosis following drug-eluting stents (DES) or IVBT failure. The objective of this study was to measure the dose rate of 90Sr/90Y IVBT sources for comparison with that given by the manufacturer and to control the dose uniformities of these sources along the source axis. The dose rates of 90Sr/90Y beta sources were measured with a radiochromic film in a custom-made phantom. The films for calibration were irradiated using 60Co photon beams. The results for the three sources were 4.5%, 2.3%, and 3.5% higher than the corresponding certificate values. Maximum and minimum of the dose rates varied within ±10% of those at source center; and maximum dose discrepancy for the first 90Sr/90Y source train was 8.2%; for the second source train, 7.1%; and for the third source train, 5.1%. Our study showed that the dose rates given by the manufacturer for the three 90Sr/90Y IVBT sources were reliable and dose uniformities were within ±10% along two thirds of the treatment length.