Biomedical subjects

S E Strand

Publications and source records attributed to S E Strand.

At least 19 recordsLinked to original sources

PubMed2000

Enhanced metabolism of halogenated hydrocarbons in transgenic plants containing mammalian cytochrome P450 2E1.

Chlorinated solvents, especially trichloroethylene (TCE), are the most widespread groundwater contaminants in the United States. Existing methods of pumping and treating are expensive and laborious. Phytoremediation, the use of plants for remediation of soil and groundwater pollution, is less expensive and has low maintenance; however, it requires large land areas and there are a limited number of suitable plants that are known to combine adaptation to a particular environment with efficient metabolism of the contaminant. In this work, we have engineered plants with a profound increase in metabolism of the most common contaminant, TCE, by introducing the mammalian cytochrome P450 2E1. This enzyme oxidizes a wide range of important pollutants, including TCE, ethylene dibromide, carbon tetrachloride, chloroform, and vinyl chloride. The transgenic plants had a dramatic enhancement in metabolism of TCE of up to 640-fold as compared with null vector control plants. The transgenic plants also showed an increased uptake and debromination of ethylene dibromide. Therefore, transgenic plants with this enzyme could be used for more efficient remediation of many sites contaminated with halogenated hydrocarbons.

Animals↗

PubMed2000

Palliative radiation with a radiolabeled diphosphonate (rhenium-186 etidronate) in patients with hormone-refractory disseminated prostate carcinoma.

MATERIAL AND METHODS: The present study investigates the safety and efficacy of 2590 MBq rhenium-186 (186Re) etidronate (i.e. twice the activity normally used) administered intravenously in 15 patients with disseminated prostatic carcinoma and bone pain. RESULTS: Pain relief was observed in 11 of 14 evaluable patients (79%), 4 of whom became completely free from pain. Five of the responding patients also noted an improvement in daily activity and two found it possible to reduce or discontinue morphine medication. Pain relief occurred within one week in four patients, and within two weeks in eight of the responding patients. The mean duration of pain relief after the first course of 186Re-etidronate was 6 weeks (range 4-10). The toxicity was mild (< or = grade 2), transient, and restricted to hematological toxicity. CONCLUSIONS: 186Re-etidronate provided rapid pain-relief and had mild toxicity in most patients with disseminated hormone-refractory prostatic carcinoma, but doubling the activity did not markedly improve the efficacy.

Bone Neoplasms↗

PubMed2000

Anaerobic naphthalene degradation by microbial pure cultures under nitrate-reducing conditions.

Pure bacterial cultures were isolated from a highly enriched denitrifying consortium previously shown to anaerobically biodegrade naphthalene. The isolates were screened for the ability to grow anaerobically in liquid culture with naphthalene as the sole source of carbon and energy in the presence of nitrate. Three naphthalene-degrading pure cultures were obtained, designated NAP-3-1, NAP-3-2, and NAP-4. Isolate NAP-3-1 tested positive for denitrification using a standard denitrification assay. Neither isolate NAP-3-2 nor isolate NAP-4 produced gas in the assay, but both consumed nitrate and NAP-4 produced significant amounts of nitrite. Isolates NAP-4 and NAP-3-1 transformed 70 to 90% of added naphthalene, and the transformation was nitrate dependent. No significant removal of naphthalene occurred under nitrate-limited conditions or in cell-free controls. Both cultures exhibited partial mineralization of naphthalene, representing 7 to 20% of the initial added (14)C-labeled naphthalene. After 57 days of incubation, the largest fraction of the radiolabel in both cultures was recovered in the cell mass (30 to 50%), with minor amounts recovered as unknown soluble metabolites. Nitrate consumption, along with the results from the (14)C radiolabel study, are consistent with the oxidation of naphthalene coupled to denitrification for NAP-3-1 and nitrate reduction to nitrite for NAP-4. Phylogenetic analyses based on 16S ribosomal DNA sequences of NAP-3-1 showed that it was closely related to Pseudomonas stutzeri and that NAP-4 was closely related to Vibrio pelagius. This is the first report we know of that demonstrates nitrate-dependent anaerobic degradation and mineralization of naphthalene by pure cultures.

Bacteria, Anaerobic↗

PubMed1999

Radiation dosimetry in nuclear medicine.

Radionuclides are used in nuclear medicine in a variety of diagnostic and therapeutic procedures. A knowledge of the radiation dose received by different organs in the body is essential to an evaluation of the risks and benefits of any procedure. In this paper, current methods for internal dosimetry are reviewed, as they are applied in nuclear medicine. Particularly, the Medical Internal Radiation Dose (MIRD) system for dosimetry is explained, and many of its published resources discussed. Available models representing individuals of different age and gender, including those representing the pregnant woman are described; current trends in establishing models for individual patients are also evaluated. The proper design of kinetic studies for establishing radiation doses for radiopharmaceuticals is discussed. An overview of how to use information obtained in a dosimetry study, including that of the effective dose equivalent (ICRP 30) and effective dose (ICRP 60), is given. Current trends and issues in internal dosimetry, including the calculation of patient-specific doses and in the use of small scale and microdosimetry techniques, are also reviewed.

Alpha Particles↗

PubMed1999

Anaerobic transformation of 1,1,1-trichloroethane by municipal digester sludge.

Anaerobic transformations of 1,1,1-trichloroethane (TCA), 1,1-dichloroethane (DCA), and chloroethane (CA) were studied with sludge from a lab-scale, municipal wastewater sludge digester. TCA was biologically transformed to DCA and CA and further to ethane by reductive dechlorination. TCA was also converted to acetic acid and 1,1-dichloroethene (11DCE) by cell-free extract. 11DCE was further biologically converted to ethene. This pathway was confirmed by transformation tests of TCA, DCA and CA, by tests with cell-free extract, and by chloride release during TCA degradation. With cell-free extract, acetic acid accounted for approximately 90% of the TCA transformed; tests with live cells indicate that the fraction of TCA transformed by this pathway decreased with lower biomass. The dechlorination of DCA to CA and CA to ethane was not stoichiometric. A high rate of TCA removal was observed under the experimental conditions. The results indicate that removal of TCA in anaerobic digestion should be complete, but DCA and CA could persist in a normally operating digester.

Anaerobiosis↗

PubMed1999

Survival of mammalian cells exposed to ultrahigh dose rates from a laser-produced plasma x-ray source.

PURPOSE: To determine whether intense laser-produced x rays have an increased radiation hazard. MATERIALS AND METHODS: Mammalian cells were exposed to x rays from a laser-produced plasma that produced ultrahigh peak absorbed dose rates, up to a factor of 10(10) higher than those produced by conventional x rays used in imaging. The cell survival was studied as a function of the absorbed dose. The survival of mammalian cells exposed to high peak absorbed dose rates with laser-produced x rays was compared with the survival of cells exposed to standard absorbed dose rates with conventional x-ray sources. Comparative survival studies were performed by using a conventional x-ray tube and a cobalt 60 source. The absorbed doses in the irradiation field were measured with thermoluminescent dosimeters. RESULTS: Cell survival following irradiation by filtered, laser-produced x rays with a high dose rate was not markedly different from the survival following irradiation by conventional sources. There was, however, a notable difference between the survival after exposure to filtered, laser-produced x rays and the survival after exposure to unfiltered laser-produced x rays. CONCLUSION: Exposure to filtered, laser-produced x rays with a high dose rate does not lead to increased harm to mammalian cells exposed in vitro compared with the harm from exposure to x rays from conventional sources, which indicates that the use of high-power laser facilities for medical imaging is justified.

Animals↗

PubMed1999

A new rectal model for dosimetry applications.

UNLABELLED: A revised geometric representative model of the lower part of the colon, including the rectum, the urinary bladder and prostate, is proposed for use in the calculation of absorbed dose from injected radiopharmaceuticals. The lower segment of the sigmoid colon as described in the 1987 Oak Ridge National Laboratory mathematical phantoms does not accurately represent the combined urinary bladder/rectal/prostate geometry. In the revised model in this study, the lower part of the abdomen includes an explicitly defined rectum. The shape of sigmoid colon is more anatomically structured, and the diameters of the descending colon are modified to better approximate their true anatomic dimensions. To avoid organ overlap and for more accurate representation of the urinary bladder and the prostate gland (in the male), these organs are shifted from their originally defined positions. The insertion of the rectum and the shifting of the urinary bladder will not overlap with or displace the female phantom's ovaries or the uterus. In the adult male phantom, the prostatic urethra and seminal duct are also included explicitly in the model. The relevant structures are defined for the newborn and 1-, 5-, 10- and 15-y-old (adult female) and adult male phantoms. METHODS: Values of the specific absorbed fractions and radionuclide S values were calculated with the SIMDOS dosimetry package. Results for 99mTc and other radionuclides are compared with previously reported values. RESULTS: The new model was used to calculate S values that may be crucial to calculations of the effective dose equivalent. For 131I, the S (prostate<--urinary bladder contents) and S (lower large intestine [LLI] wall<--urinary bladder contents) are 6.7 x 10(-6) and 3.41 x 10(-6) mGy/MBq x s, respectively. Corresponding values given by the MIRDOSE3 computer program are 6.23 x 10(-6) and 1.53 x 10(-6) mGy/MBq x s, respectively. The value of S (rectum wall<--urinary bladder contents) is 4.84 x 10(-5) mGy/MBq x s. For 99mTc, we report S (testes<--prostate) and S (LLI wall<--prostate) of 9.41 x 10(-7) and 1.53 x 10(-7) mGy/MBq x s versus 1.33 x 10(-6) and 7.57 x 10(-6) mGy/MBq x s given by MIRDOSE3, respectively. The value of S (rectum wall<--prostate) for 99mTc is given as 4.05 x 10(-6) mGy/MBq x s in the present model. CONCLUSION: The new revised rectal model describes an anatomically realistic lower abdomen region, thus giving improved estimates of absorbed dose. Due to shifting the prostate gland, a 30%-45% reduction in the testes dose and the insertion of the rectum leads to 48%-55% increase in the LLI wall dose when the prostate is the source organ.

Adult↗

PubMed1999

Comparison of 125I- and (111)In-labeled monoclonal antibody BR96 for tumor targeting in combination with extracorporeal immunoadsorption.

Extracorporeal whole blood immunoadsorption (ECIA) accelerates the clearance of radiolabeled monoclonal antibodies (mAbs) without significantly affecting tumor uptake by removing the excess of these mAbs from the blood, thus increasing tumor:normal tissue (T:N) ratios. The present study is focused on comparing the capacity of ECIA in tumor targeting with the same mAb (chiBR96-biotin) labeled with either (111)In or 125I. Forty-five Brown Norwegian rats with syngeneic rat colon carcinoma isografted both in liver and intramuscularly were used. chiBR96 is a highly tumor-specific mAb directed against the Lewis-type antigen. ECIA of whole blood was started 15 h after the injection of 125I- or (111)In-labeled BR96-biotin. The procedure lasted for 2 h and was repeated for (111)In-labeled BR96-biotin in a few rats after 3 or 24 h. ECIA reduced the whole body activity by the same magnitude (between 39% and 52%), irrespective of whether (111)In- or 125I-labeled chiBR96 was used. A similar observation was also made for the reduction in blood radioactivity after ECIA (79-94%). Time-activity curves during ECIA showed that the major reduction (approximately 85%) in blood radioactivity occurred during the first 45-60 min. Repeating the ECIA with (111)In-BR96 caused only an additional minimal reduction of blood activity, whereas a further reduction of whole body activity of 14-20% was achieved. The T:N uptake ratios were significantly enhanced immediately after ECIA with (111)In- or 125I-labeled chiBR96. Due to greater accumulation of (111)In-BR96 in tumors, a long-term improvement in T:N ratios was obtained after ECIA compared with 125I-labeled BR96. Our results therefore indicate that (111)In/(90Y)-labeled BR96-biotin could be more advantageous than 125I/131I for radioimmunotargeting/radioimmunotherapy in combination with ECIA due to better activity retention by the tumor.

Animals↗

PubMed1999

Radioimmunotherapy using 131I-labeled anti-CD22 monoclonal antibody (LL2) in patients with previously treated B-cell lymphomas.

Experience in using rapidly internalizing antibodies, such as the anti-CD22 antibody, for radioimmunotherapy of B-cell lymphomas is still limited. The present study was conducted to assess the efficacy and toxicity of a 131I-labeled anti-CD22 monoclonal antibody (mAb), LL2, in patients with B-cell lymphomas failing first- or second-line chemotherapy. Eligible patients were required to have measurable disease, less than 25% B cells in unseparated bone marrow, and an uptake of 99mTc-labeled LL2Fab' in at least one lymphoma lesion on immunoscintigram. Eight of nine patients examined with immunoscintigraphy were unequivocally found to have an uptake, and therapy with 131I-labeled anti-CD22 [1330 MBq/m2 (36 mCi/m2)] preceded by 20 mg of naked anti-CD22 mAb was administered. Three patients achieved partial remission (duration, 12, 3, and 2 months), and one patient with progressive lymphoma showed stable disease for 17 months. Four patients exhibited progressive disease. The toxicity was hematological. Patients with subnormal counts of neutrophils or platelets before therapy seemed to be more at risk for hematological side effects. Radioimmunotherapy in patients with B-cell lymphomas using 131I-labeled mouse anti-CD22 can induce objective remission in patients with aggressive as well as indolent lymphomas who have failed prior chemotherapy.

Adult↗

PubMed1998

An alternative method to normalize clinical FDG studies.

UNLABELLED: An alternative method of determining the integrated input function, necessary in the quantitative [18F]fluorodeoxyglucose (FDG) autoradiographic model, has been developed. Using erythrocytes as reference tissue, researchers require only one blood sample after injection of FDG to obtain the integrated input function. METHODS: The amount of FDG-6-PO4 in the erythrocytes is proportional to their exposure to FDG, that is, the integrated input function. Free FDG is removed by washing the erythrocytes twice. Inter- and intraindividual differences of the metabolic rate of erythrocytes are corrected for by an in vitro incubation with a known amount of FDG. RESULTS: Validation of the proposed method was done by correlating the integrated input function, based on the glucose metabolism of the erythrocytes, to the integrated input function obtained by multiple venous blood samples. The new method provides the integrated input function with an accuracy better than +/-8%. CONCLUSION: By using erythrocytes as a reference tissue, researchers can determine the integrated input function in the quantitative FDG autoradiographic model with an accuracy sufficient for clinical PET studies. The simplicity of the method also makes it suitable for FDG studies on small children. With two samples, the method can also be used for a simplified graphical Patlak analysis.

Erythrocytes↗

PubMed1997

Improving tumor-to-normal-tissue ratios of antibodies by extracorporeal immunoadsorption based on the avidin-biotin concept: development of a new treatment strategy applied to monoclonal antibodies murine L6 and chimeric BR96.

BACKGROUND: Several strategies have been explored to accelerate monoclonal antibody (MAb) conjugate clearance without affecting intratumoral uptake. One of the most promising is extracorporeal immunoadsorption (ECIA), in which excess radiolabeled MAb circulating in blood is removed. METHODS: Extracorporeal immunoadsorption (ECIA) based on the avidin-biotin concept enables direct adsorption of radiolabeled and biotinylated MAb from plasma and consequently increases the tumor-to-normal-tissue uptake ratio by reducing background radioactivity in all radiosensitive organs. Because the concept is based on an antibody's being biotinylated prior to injection, the blood clearance efficiency is independent of the idiotype or isotype of the antibody employed. As a result, there is no need to develop new adsorption columns for each antibody system used. We have technically simplified the method recently by removing biotinylated MAb directly from blood without separation from plasma preceding the removal. The current study focused on both the development of ECIA and evaluating the effects of ECIA in terms of tumor targeting with two biotinylated radiolabeled MAbs that have different biokinetics, namely, murine MAb L6 and chimeric Mab BR96. RESULTS: The start time of ECIA should be determined for each MAb individually before radioimmunotherapy and be based on previous tumor biokinetics. BR96 with rapid tumor targeting seems more suitable than L6 for the ECIA procedure; it allows the procedure to start earlier and thereby further reduce whole body activity and exposure of critical organs to radiation. CONCLUSIONS: ECIA enables direct adsorption of radiolabeled and biotinylated monoclonal antibody from blood and consequently increases the tumor-to-normal-tissue uptake ratio. The method is even applicable to both the internalizing and already highly tumor-selective BR96 in a syngeneic tumor model.

Animals↗

PubMed1997

Early prediction of treatment outcome in head and neck cancer with 2-18FDG PET.

The development of alternative treatment regimens in clinical oncology has increased the need for early prediction of cancer therapy outcome. The aim of this study was, early in the treatment phase, to identify patients with advanced head and neck cancer, responding or not responding to initiated therapy. The tumour metabolic rate of glucose (MRgl) examined by 2-18FDG-PET was determined in 17 patients before and after the first weeks of either radiotherapy (16-35 Gy) or one course of combination chemotherapy. Metabolic values uptake values normalized to plasma activity integrals--were correlated to loco-regional outcome, as evaluated 5-6 weeks after completion of treatment. Initial low tumour MRgl (<20 micromol/min/100 g tissue), in primary lesions or regional metastases, predicted a local complete response. When a high initial tumour MRgl was found, the magnitude of the reduction of MRgl in the second PET examination might be an adjunct in predicting local tumour response.

Adult↗

PubMed1997

Biokinetics of indium-111-bleomycin complex in head and neck cancer--implementations for radiochemotherapy.

Bleomycin (BLM) has been used successfully for treatment of head and neck cancer. Combining radionuclide therapy with chemotherapy is a fascinating possibility. We have studied the biokinetics of BLM labeled with indium-111 (In-111). A complex formed at low pH had an activity of 100 MBq/mg BLM. This substance was intravenously injected into 10 head and neck cancer patients in escalating doses of 75, 175, and 375 MBq. Scintigraphic data from these patients were compared with tissue samples obtained at surgery. The activity distribution and penetration into tumor tissue was not affected by increasing the injected activity. In-111-BLMC uptake was directly proportional to Ki-67/MIB-1 activity and number of mitoses in tumor tissue. Based on the biokinetics, dosimetric calculations for In-111 and In-114m have been performed. S values for realistic geometry (a phantom designed from Patient CT) have been calculated. In-114m could deliver a 4-fold absorbed radiation dose into the tumor compared with In-111. We think that In-111-BLMC could be used for radiochemotherapy in head and neck cancer or adjuvant Auger-electron therapy using In-114m combined with BLM. Further studies on cellular dosimetry should be undertaken.

Adult↗

PubMed1997

Extracorporeal whole-blood immunoadsorption enhances radioimmunotargeting of iodine-125-labeled BR96-biotin monoclonal antibody.

UNLABELLED: This study investigates the efficacy of tumor radioimmunotargeting with 125I-labeled BR96-biotin monoclonal antibody using a new method, whole-blood immunoadsorption (WBIA), based on direct adsorption of unbound monoclonal antibody (MAb) from blood without preceding separation of plasma. METHODS: Highly tumor-reactive, internalizing, chimeric BR96 MAb of isotype IgG1 binds to a tumor-associated Lewis-type (Le(Y)) cell surface antigen. Forty-six Brown Norwegian male rats were inoculated intramuscularly and beneath the liver or kidney capsule with syngeneic rat colon carcinoma BN7005, expressing Lewis-type antigen, and investigated. The rats were injected intravenously with 3.5-4.5 MBq 125I-labeled BR96-biotin. Twenty of the rats underwent WBIA starting 5 or 12 hr after injection. About six blood volumes were passed through an avidin-gel adsorption column during 2 hr. RESULTS: By using WBIA, whole-body radioactivity was reduced by 50%, and plasma activity by 85%. Both directly after completion of WBIA and 33 hr later, the activity uptake in tumors manifested only a nonsignificant decrease as compared with corresponding controls (p > 0.05) and had approximately similar time-activity curves. Uptake ratios for tumor (T):bone marrow, T:liver, T:kidney and T:lung were enhanced 2.3- to 3.5-fold in all three tumor models, as compared with controls. The ratio of liver tumor to bone marrow was improved from 10:1 to 30:1. CONCLUSION: This new method of WBIA yields significantly improved radioimmunotargeting of highly tumor-reactive, internalizing MAb BR96.

Animals↗

PubMed1997

Extracorporeal immunoadsorption compared to avidin chase: enhancement of tumor-to-normal tissue ratio for biotinylated rhenium-188-chimeric BR96.

UNLABELLED: Based on the biodistribution and kinetics of biotinylated 188Re-chimeric BR96 (chiBR96), the enhancement of the tumor-to-normal tissue (T/N) radioactivity ratio using extracorporeal immunoadsorption (ECIA) was evaluated and compared with that of avidin "chase" in colon carcinoma-isografted Brown Norwegian rats. METHODS: Extracorporeal immunoadsorption (ECIA) was performed 6 or 12 hr after intravenous administration of biotinylated 188Re-chiBR96. Radioactivity redistribution was investigated just after ECIA [8 or 14 hr postinjection of the antibody] and 40 or 34 hr after ECIA performance (48 hr postinjection). Avidin was administered intraperitoneally at 6 hr postinjection. Tumor radioactivity uptake and T/N activity ratios of biotinylated 188Re-chiBR96 were compared using ECIA and avidin chase and were also compared with controls. RESULTS: Both ECIA and avidin chase can rapidly increase the radioactivity tumor-to-blood ratio without significantly interfering with the tumor uptake. ECIA at 8 hr postinjection increased the T/N ratios in blood-rich tissues, such as liver and bone marrow, from 6 and 8 to 10 and 18, respectively. Corresponding T/N ratios at 14 hr increased from 9 and 10 to 24 and 36. In contrast, when avidin chase was used, there were no T/N improvements, except in blood. Moreover, avidin chase caused a significant accumulation of radioactivity in the liver. CONCLUSION: The ECIA approach, with direct removal of unbound circulating biotinylated 188Re-chiBR96, thus can rapidly improve and maintain T/N ratios without overloading the liver with radioactivity, in contrast to avidin chase.

Animals↗

PubMed1996

Skin plasma exudation and vasodilatation monitored by external detection of conversion electrons.

We have examined the plasma exudation response of inflammation in guinea pig skin by a noninvasive method and have evaluated the influence of vasodilatation. Indium radionuclides have been used to label plasma and blood and conversion electrons have been detected by an external detector. Transferrin (79,600 Da) was labeled by 111In or 113mIn in vivo and red blood cells were labeled by 111In in vitro. These tracers were given to separate groups of anesthetized guinea pigs and baseline activities were recorded from shaved skin surface areas. Skin prick tests with histamine and saline were performed and time-activity curves were recorded. The measurements with 111In-transferrin and 111In-labeled red blood cells demonstrated that histamine produced dose-dependent accumulation of plasma (up to a 6.5-fold increase) and blood (up to a 2.0-fold increase) in the skin. Hence, about one-third of accumulation of plasma induced by histamine may be explained by vasodilatation. With 113mIn-transferrin as plasma tracer greater effects of histamine were recorded, probably reflecting that the measurements also included deeper sections of the skin. We conclude that the intensity of accumulation of plasma in skin inflammation can be monitored by external detection of conversion electrons from 111In- and 113mIn-transferrin, and that the influence of vasodilatation can be estimated by detection of 111In-labeled red blood cells.

Animals↗

PubMed1996

Indium-111 bleomycin complex for radiochemotherapy of head and neck cancer--dosimetric and biokinetic aspects.

Bleomycin (BLM) is used for the treatment of head and neck cancer. In order to improve the effectiveness of this chemotherapeutic drug, BLM was combined with indium-111. A complex of these agents (111In-BLMC), formed at low pH, was injected intravenously into ten head and neck cancer patients in escalating activities of 75, 175 and 375 MBq. The internally delivered dose to the tumours varied from 0.20 to 2.73 mGy at 75 MBq, from 0.33 to 2.51 mGy at 175 MBq, and from 0.87 to 31.3 mGy at the 375 MBq activity level. Uptake of radioactivity was 0.45+/-0.24x10(-3)% ID/g in primary tumours and 0. 52+/-0.20x10(-3)% ID/g in metastases (at 48 h). Tumour volumes varied from 0.51 to 49.0 cm3. The radioactivity half-lives in the tumours were 30+/-7 h. The activity distribution and penetration into tumour tissue were not affected by increasing the injected activity. There was a positive correlation between BLMC uptake and Ki-67/Mib activity as well as number of mitoses in tumour tissue. These data indicate that 111In-BLMC has potential as a radiochemotherapeutic agent in head and neck cancer and that adjuvant Auger-electron therapy is possible using 114mIn-labelled BLMC.

Adult↗

PubMed1996

Plasma exudation in the skin measured by external detection of conversion electrons.

A novel technique for measurement of plasma exudation in the skin is described. Transferrin labelled in vivo with indium-113m is used as a plasma tracer. The conversion electrons from 113mIn are detected with a polystyrene crystal mounted on a photomultiplier tube. Owing to the short range of the electrons in tissue, background radiation from tracer circulating in underlying tissue will be very small, allowing plasma exudation in the skin to be detected with a high signal to noise ratio. The characteristics of the detector system are described in model experiments using sheets of mylar to simulate soft tissue. The acute inflammatory response to histamine provocation was studied in guinea pig skin. A dose-related increase in count rate representing vasodilatation and plasma exudation was detected over the skin after histamine provocation. The electron radiation system appears suitable for detection of low levels of superficial radioactivity and for pathophysiological studies of the skin.

Animals↗