共查询到20条相似文献,搜索用时 31 毫秒
1.
《International journal of radiation applications and instrumentation. Part B, Nuclear medicine and biology》1990,17(6):561-565
We investigated the feasibility of using 123I-iodoantipyrine (123I-IAP) and 99mTc-labeled macroaggregated albumin (99mTc-MAA) to describe and compare the distributions of perfusion and water content in lung injuries. These radiopharmaceuticals were administered to 9 rabbits, 5 control and 4 with lung injuries. Isolated lungs were imaged by a scintillation γ camera. The distribution of 123I-IAP outlined the entire lung mass whereas perfusion defect in the distribution of 99mTc-MAA was seen clearly in the case of severe lung injury. 相似文献
2.
Two laminin-derived peptides containing either YIGSR or IKVAV (single amino acid code) sequences were radiolabeled with 99mTc and their biological distribution evaluated in rodents. Both 99mTC-peptides cleared rapidly from the circulation though the kidney, and to a lesser extent, through the liver. 99mTC-YIGSR peptide did not accumulate in any organ examined in normal, tumored, and emphysemic mice. The 99mTc-IKVAV peptide localized within 10 min to the lung of normal animals, resulting in lung-to-blood ratios of approximately 23:1. The 99mTc-IKVAV peptide localized to lung after submicron filtration and after intraperitoneal injection, suggesting that particulates do not play a major role in localization. Pre-incubation of 99mTc-IKVAV peptide in whole blood decreased lung localization, suggesting that margination of radiolabeled blood cells does not play a major role in the lung localization. When 99mTc-IKVAV was injected into mice with tumored lungs (melanoma), the lung uptake was markedly increased (up to 20% injected dose higher than control lungs) at all time points examined (10, 30, and 120 min). When 99mTc-IKVAV was injected into mice with genetic emphysema, the lung uptake was markedly decreased at all time points. The localization of the 99mTc-IKVAV-containing peptide to the lung is consistent with a receptor-based mechanism. 相似文献
3.
Renal scintigraphy is an imaging method that uses small amount of radioactive materials called radiotracers, a Gamma camera and a computer to evaluate kidney functions and its anatomy. The present work reports the comparison of the relative renal functions (RRF) calculated with technetium-99m dimercaptosuccinic acid (99mTc‑DMSA) and technetium-99m diethylenetriaminepentaacetic acid (99mTc‑DTPA) for kidney patients of ages between 5 months and 71 years. A total of 50 patients including 29 male and 21 female has been selected and studied for renography. The mean RRFs have been found to be 52.68 ± 23.63% and 47.32 ± 23.63% respectively for the left and right kidneys with 99mTc-DMSA measurement. With 99mTc-DTPA the values are 52.74 ± 23.54% and 47.26 ± 23.54% for the same. In bivariate correlation analysis, a significant positive correlation (r = 0.996, P < .001) has been found between the RRFs calculated with the two methods. Following the patients’ diagnosis, in ANOVA test, no difference has been found between the RRFs calculated for the left and right kidneys. In Bland-Altman plots, the mean difference between the two methods has been found to be 0.1 and the correlation limit lies between −4.3 and 4.2. According to the result obtained in the present work, both the 99mTc-DMSA and 99mTc-DTPA scanning methods provide almost the same RRF values. It is, therefore, always not necessary to calculate the RRFs with both the methods. This study suggests that 99mTc-DMSA may be the primary choice for the evaluation of RRF, but if the glomerular filtration rate (GFR) and renogram curve are required, 99mTc-DTPA can be the obvious selection. 相似文献
4.
Ashok Behera Indranil Banerjee Kakali De Rudra Narayan Munda Sankha Chattopadhayay Amalesh Samanta Bharat Sarkar Santanu Ganguly Mridula Misra 《Amino acids》2013,44(3):933-946
Peptides are attracting increasing interest in nuclear oncology for targeted tumor diagnosis and therapy. We therefore synthesized new cyclic octapeptides conjugated with HYNIC by Fmoc solid-phase peptide synthesis. These were purified and analyzed by RP-HPLC, MALDI mass, 1H NMR, 13C NMR, HSQC, HMBC, COSY and IR spectroscopy. Conformational analysis of the peptides was performed by circular dichroism spectroscopy, in pure water and trifluoroethanol–water (1:1), revealed the presence of strong secondary structural features like β-sheet and random coils. Labeling was performed with 99mTc using Tricine and EDDA as coligands by SnCl2 method to get products with excellent radiochemical purity >99.5 %. Metabolic stability analysis did not show any evidence of breaking of the labeled compounds and formation of free 99mTc. Internalization studies were done and IC50 values were determined in somatostatin receptor-expressing C6 glioma cell line and rat brain cortex membrane, and the results compared with HYNIC-TOC as standard. The IC50 values of 99mTc-HYNIC-His3-Octreotate (21 ± 0.93 nM) and 99mTc-HYNIC-TOC (2.87 ± 0.41 nM) proved to be comparable. Biodistribution and image study on normal rat under gamma camera showed very high uptake in kidney and urine, indicating kidney as primary organ for metabolism and route of excretion. Biodistribution and image study on rats bearing C6 glioma tumor found high uptake in tumor (1.27 ± 0.15) and pancreas (1.71 ± 0.03). Using these findings, new derivatives can be prepared to develop 99mTc radiopharmaceuticals for imaging somatostatin receptor-positive tumors. 相似文献
5.
Liqin Liu Jingli Xu Jianquan Yang Changjian Feng Yubin Miao 《Bioorganic & medicinal chemistry letters》2017,27(22):4952-4955
The purpose of this study was to determine the metastatic melanoma imaging property of 99mTc(EDDA)-HYNIC-Aoc-Nle-CycMSHhex {hydrazinonicotinamide-8-aminooctanoic acid-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-CONH2}. HYNIC-Aoc-Nle-CycMSHhex was synthesized using fluorenylmethyloxy carbonyl (Fmoc) chemistry. The IC50 value of HYNIC-Aoc-Nle-CycMSHhex was 0.78?±?0.13?nM for B16/F10 melanoma cells. 99mTc(EDDA)-HYNIC-Aoc-Nle-CycMSHhex displayed significantly higher uptake (14.26?±?2.74 and 10.45?±?2.31%?ID/g) in B16/F10 metastatic melanoma-bearing lung than that in normal lung (0.90?±?0.15 and 0.53?±?0.14%?ID/g) at 2 and 4?h post-injection, respectively. B16/F10 pulmonary metastatic melanoma lesions were clearly visualized by SPECT/CT using 99mTc(EDDA)-HYNIC-Aoc-Nle-CycMSHhex as an imaging probe at 2?h post-injection, underscoring its potential as an imaging probe for metastatic melanoma detection. 相似文献
6.
《International journal of radiation applications and instrumentation. Part B, Nuclear medicine and biology》1991,18(2):227-233
We have evaluated five compounds, stannous chloride (SnCl2), 2-mercaptoethanol (2-ME), dithiothreitol (DTT), dithioerythritol (DTE), and ascorbic acid (AA) to reduce monoclonal antibody MoAb (disulfide groups and compared their efficacy for labeling MoAbs with 99mTc. The reduction of 99mTc with dithionite at pH 11 was nearly quantitative. The use of AA, at a molar ratio of 3500:1, for three IgG and three IgM antibodies examined, gave a labeling efficiency greater than 95%. Hence no purification was needed. The immunospecificity of AA preparations determined by specific antigen assay was 84 ± 1% for an IgM and 82.6 ± 1.1% for an IgG, highest among all agents tested. The stability of the tracer was evaluated by challenging the product with such 99mTc avid agents as cysteine, DTPA, and human serum albumin. By HPLC analysis, no 99mTc was transchelated using chelating agent to protein molar ratios as high as 500:1. In two separate groups of five mice each, the liver uptake at 4 h post injection averaged 6.8 ± 2.9% per gram for 125I-TNT-1 (IgG) and 6 ± 5.1% per gram for the same MoAb labeled with 99mTc using AA. The AA technique promises to label antibodies with 99mTc and perhaps with 186Re, by a simple “kit” procedure. 相似文献
7.
《International journal of radiation applications and instrumentation. Part B, Nuclear medicine and biology》1991,18(5):461-468
Platelets pretinned with a neutral Sn(II)-2-mercaptopyridme-N-oxide (SN-MPO) were labeled with 99mTc and compared to those labeled with 99mTc-HMPAO. The conditions of labeling platelets, e.g. concentrations of platelets and Sn(II)-MPO, 99mTc in ACD-saline or ACD-plasma media, pH and incubation time, were optimized using canine platelets. Moderate labeling efficiency was obtained with 20 μg of tin(II) chloride and 30 min incubation with Sn-MPO and pertechnetate. The viability of labeled platelets was determined by platelet recovery and platelet survival times in Beagle dogs. The labeling efficiency with platelets from 43 mL of blood was 62.8 ± 7.6%. The platelet recovery was 35.7 ± 5.0% and exponential survival time was 34.6 ± 3.1 h compared to 43.3 ± 12.0% and 29.5 ± 3.3 h for 99mTc-HMPAO-labeled platelets. These values were significantly (P < 0.01) lower than 111In-labeled platelets. Biodistribution in dogs indicates lower retention in blood, spleen and liver after some initial 99mTc excretion in urine. The platelet deposition with 99mTc platelets (Sn-MPO method) on polyurethane angio-catheters was similar to 99mTc-HMPAO-labeled platelets. This study indicates that the platelets could be successfully labeled with pertechnetate in a cost-effective manner for the evaluation of thromboembolic complications. 相似文献
8.
《International journal of radiation applications and instrumentation. Part B, Nuclear medicine and biology》1992,19(3):251-256
A simplified and efficient procedure for 99mTc-HMPAO-labelling of leukocytes is described. For this purpose, the pH and concentration of the 99mTc-HMPAO preparation was modified. Leukocytes were isolated from a 20 mL mixture of patient blood, 5 mL ACD and 0.8 mL methylcellulose after 1 h sedimentation of erythrocytes and centrifugation (at 400 g) of the obtained plasma layer. Simultaneously, 99mTc-HMPAO was prepared (one single-dose kit for two patients) by adding 2.2 mL 99mTc-generator eluate and, after 10 min, 0.3 mL of phosphate buffer to lower the pH to 7. The isolated WBCs were then labelled by the addition of 1-1.2 mL of 99mTc-HMPAO solution and incubated for 20 min. The unbound tracer was then discarded, the labelled WBC washed and finally resuspended in autologous cell-free plasma. Leukocytes labelled by this procedure were used for scintigraphic localization of inflammatory lesions and abscesses in the gastro-intestinal tract.The labelling efficiency was 60 ± 9%, with a separation yield of 55 ± 11%. 相似文献
9.
Max Kaufmann Jorgen Marqverson Kenneth E. Stanley Christian Mouritzen Hans Hvid-Hansen 《Cancer immunology, immunotherapy : CII》1986,22(1):56-61
Summary The distribution of Corynebacterium parvum labeled with 131iodine or 99mtechnetium was studied in 17 patients with bronchogenic carcinoma. The labeled bacteria were given intravenously or intrapleurally and monitored by whole-body gamma tracking and samples of blood and urine. Even though the rate of physical decay is quite different for 131iodine and 99mtechnetium, the tracking time of labeled bacteria was limited to 24 h after injection for both radioactive isotopes. Technetium labeling was preferred because of greater imaging resolution and less radiation dose to the patient. Following intravenous administration, labeled C. parvum was found predominantly in the liver and spleen, and in a lesser amount in the lung. Radioactivity was confined to the pleural cavity after intrapleural injection. These results suggest the combined intravenous and intrapleural route of adjuvant immunosupportive agents such as C. parvum for operable lung cancer patients. 相似文献
10.
《International journal of radiation applications and instrumentation. Part B, Nuclear medicine and biology》1991,18(6):605-612
Polyclonal human IgG (IgG), antinuclear antibody (TNT-1), and human serum albumin (HSA), were labeled with 99mTc by a method recently developed in our laboratory, and administered i.v., each to a separate group of five mice, bearing inflammatory foci induced by an i.m. injection of 40μL turpentine or 5 × 108E. coli and 5 × 108 Entercocci. TNT-1 labeled with 125I served as a control and 67Ga-citrate as a “gold standard”. At 4 or 24 h post injection, animals were imaged and sacrificed for tissue distribution studies. At 4 h in the turpentine group, the abscess-to-muscle ratios were: 67Ga, 4.8 ± 2.1, 125I-TNT-1, 4.3 ± 1; 99mTc-TNT-1, 3.5 ± 1.8; 99mTc-IgG, 3.9 ± 0.6; and 99mTc-HSA, 4.3± 1. In the microorganism group, these ratios were 2.6 ± 0.6, 3.3 ± 0.5, 3.4 ± 0.08, 3± 1.1 and 4.1 ± 0.6, respectively. Autoradiographic examination of infected tissues indicated that leakage of labeled proteins into interstitial space due to increased capillary permeability may be one of the major mechanisms of uptake. 相似文献
11.
《International journal of radiation applications and instrumentation. Part B, Nuclear medicine and biology》1986,13(3):253-255
67Ga citrate and 99mTc citrate (Solcocitran) were injected sequentially, with an interval of 48 h, into Balb/c mice bearing transplanted EMT-6 tumors. Tissue distributions of 67Ga and 99mTe were measured simultaneously at intervals of 1, 3, 5 and 8 h after injection of the 99mTc citrate (49, 51, 53 and 56 h after 67Ga citrate). Maximal tumor:blood ratios for 99mGa and 99mTc were 13.8 ± 3.2 and 4.0 ± 1.0 respectively, both occurring at the final period. The maximum tumor index (T.I. = T:B x % dose/g) for 67Ga was 71 ± 23% 56 h after injection, and for Tc was 13 ± 12% 1 h after injection. Liver, kidney and spleen had equal or higher concentrations of radioactivity than tumor for either radiotracer. The somewhat higher tumor:blood ratio for 67Ga citrate was offset by the time required for this optimum to be reached. Alternatively, the best 99mTc citrate tumor:blood ratios were attained within 8 h, with less liver and gut radioactivity. These data fall within the range of results from other clinical and animal model studies of 67Ga citrate and Tc citrate. In view of the radiation dose, the inconvenience of the 48–72 h wait, and the cost of 67Ga, and because neither radiopharmaceutical is tumor specific, 99mTc citrate may have a place in early oncological screening. The results are discussed as part of a comprehensive review of the 99mTc citrate literature. 相似文献
12.
《International journal of radiation applications and instrumentation. Part B, Nuclear medicine and biology》1991,18(6):613-620
Small cell lung cancer (SCC) has the most rapid growth rate of the four cell types and metastasizes early. Present imaging modalities for staging include chest x-ray, CT, MRI and bone scans. In this preliminary study, we assessed the clinical role of 99mTc-monoclonal antibody (MOAB) scintigraphy in five patients with histologically proven SCC. Each patient was infused with 20–30 mCi of 99mTc labeled Fab fragment of MOAB (NR-LU-10, NeoRx, Seattle, Wash.). Total body simultaneous anterior and posterior images were obtained 14–16 h post injection. SPECT images of the chest were obtained through a 360 ° rotation of the gamma camera and recorded on a 62 × 64 × 16 matrix. Images (1.2cm thick) were generated in transaxial, sagittal and coronal views.Fourteen of fifteen chest lesions detected by CT were confirmed by 99mTc MOAB scintigraphy. Scintigraphy detected one additional chest lesion not seen by CT. Scintigraphy failed to detect a brain lesion (2 cm), a chest lesion, and two adrenal lesions, all of which were seen by CT. In one patient with multiple (more than 10) lesions in the liver, both scintigraphy and CT detected all lesions. Three spine lesions seen on 99mTc MDP scan and positive for metastasis on MRI concentrated 99mTc MOAB, but two rib lesions seen on 99mTc MDP bone scan did not concentrate 99mTc MOAB. It is concluded from these preliminary results that the potential usefulness of 99mTc MOAB scintigraphy as a complementary imaging modality in the staging of small cell lung cancer should be investigated further. 相似文献
13.
Abstract: The radionuclide determination of glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) has been validated in man, but not in the primate. GFR, ERPF, and renal blood flow (RBF) were measured in a group of 12 adult male chacma baboons using radiopharmaceuticals. GFR was determined using 99mtechnetium-labelled diethylenetriamine-pentacetic acid. ERPF was measured with 131iodine-labelled hippuran. RBF, body surface area, and kidney weights were calculated using standard formulae. GFR was 49 ± 11 ml/min and ERPF was 237.9 ± 54.2 ml/min. Calculated RBF was 430.7 ± 111.9 ml/min and 507.4 ± 138.4 ml/min/100g of renal tissue. The results are in agreement with those obtained using more laborious nonradioisotopic techniques such as para-aminohippurate (PAH) and creatinine clearance and could serve as baseline normal values in the adult male chacma baboon. 相似文献
14.
《Translational oncology》2020,13(12):100854
Discovery of 99mTc-labeled imidazole derivatives as a potential radiotracer for hypoxic tumor imaging is considered to be of great interest because of non-invasive detection capabilities. 2-Mercaptobenzimidazole (2-MBI) was successfully synthesized, characterized and radiolabeled with [99mTc (CO)3(H2O)3]+ intermediate to form 99mTc-2-MBI complex with radiochemical purity of ≥95% yield as observed by instant-thin layer chromatography (ITLC) and radio-high performance liquid chromatography (radio-HPLC). The 99mTc-2-MBI complex was observed to be stable in saline and serum with no noticeable decomposition at room temperature and 37 °C, respectively, over a time period of 24 h. Biodistribution results in Balb/c mice bearing S180 tumor show that 99mTc-2-MBI highly internalized in tumor tissue, also possess preferably high tumor/muscle and tumor/blood ratios 4.14 ± 0.77 and 3.91 ± 0.63, respectively at 24 h incubation. Scintigraphic imaging study shows 99mTc-2-MBI is visibly accumulated in hypoxic tumor tissue, suggesting it would be a promising radiotracer for early stage diagnosis of tumor hypoxia. 相似文献
15.
《International journal of radiation applications and instrumentation. Part B, Nuclear medicine and biology》1990,17(2):209-216
The tissue distribution of 131I-transferrin (131I-Tf) was studied in athymic nude mice having s.c. human colonic adenocarcinoma HT-29 xenografts. Four days after 131I-Tf injection, the 131I specific activity measured in the HT-29 tumor, i.e. amount of radioactivity per gram of fresh tissue, represented 0.31 ± 0.09% of the injected radioactivity and was 1.90 fold more than that measured in the murine colon (P < 0.05). After correction for intravascular 131I-Tf as estimated by means of 99mTc-Sn in vivo labeling of red blood cells, the 131I specific activity observed in the HT-29 tumor was 7.21 fold more than that observed in the murine colon. This subtracting method enabled us to localize a HT-29 tumor xenograft by γ scintigraphy of the entire animal and demonstrated that 131I-Tf could be a non-specific but potent marker for human colon cancer. 相似文献
16.
B. Desrues F. Brichory H. Léna P. Bourguet P. Delaval L. Toujas L. Dazord 《Cancer immunology, immunotherapy : CII》1997,43(5):269-274
Po66, a mouse monoclonal antibody, is directed against an intracytoplasmic antigen present in human lung squamous cell carcinoma
cells. In previous work it was found that the co-administration of 125I-radiolabelled Po66 and doxorubicin strongly enhanced the uptake of radioactivity by the tumour. The present-work was designed
to evaluate, in a tumour-bearing mouse model of lung carcinoma, the ability of 131I-labelled Po66 to retard tumour growth when injected alone, or in combination with doxorubicin (8 mg kg – 1 at 1-week intervals). A single dose of 550 μCi 131I-Po66 alone had no effect on tumour growth, whereas three fractionated doses of 250 μCi 131I-Po66 decreased it over two doubling times from 14.5±1.5 days for untreated control mice to 24.8±2.7 days. Mice treated with
doxorubicin alone had a double tumour doubling time of 22.6±4.9 days, compared to 35.2±2.9 days (1.55-fold increase) in mice
treated with doxorubicin and a single dose of 550 μ Ci 131I-Po66. Doxorubicin combined with three fractionated doses of 250 μCi 131I-Po66 provoked a twofold decrease in tumour growth compared to mice treated with doxorubicin alone. The administration of
fractionated doses of 131I-Po66 simultaneously with doxorubicin resulted in a highly delayed mortality, which was not observed when 131I-Po66 was administered after doxorubicin. Thus, in a non-small-cell lung tumour model, a 131I-radiolabelled monoclonal antibody, directed against an intracellular antigen, significantly potentiated the effect of chemotherapy.
Such a therapeutic approach could be used as an adjuvant therapy and improve the effect of chemotherapy on distant small metastases.
Received: 20 June 1996 / Accepted: 3 October 1996 相似文献
17.
Zusammenfassung Es wird eine Methode zur Mikrohistoautoradiographie wasserlöslicher Isotope beschrieben und an der Verteilung von 131J sowie 99mTc in der Magenschleimhaut demonstriert.Auf Grund mikrohistoautoradiographischer Untersuchungen wird gezeigt, daß Technetium-99m selektiv durch die Belegzellen der Magenschleimhaut ausgeschieden wird. Jod-131 wird demgegenüber von den Hauptzellen des Oberflächenepithels der Magenschleimhaut sezerniert. Die selektive Anreicherung von Technetium-99m in den Belegzellen macht wahrscheinlich, daß Technetium in den Belegzellen eine unmittelbare metabolisch gesteuerte Ausscheidung erfährt. Autoradiographisch wird somit in den Schleimhautzellen nach Gabe von Technetium fast die gesamte Aktivität im Fundus und nur wenig im Antrum gesehen. Die Aktivitätsverteilung in den Lymphgefäßen und Kapillaren der Submucosa ist in Antrum und Fundus gleich.Die Ergebnisse der quantitativen Bestimmung der Aktivitätsverteilung in den verschiedenen Magenabschnitten in Abhängigkeit von der Zeit geben eine gute Bestätigung der mikrohistoautoradiographischen Befunde.
Distribution of Technetium-99m and Jodine-131 in the gastric mucosaA technique to determine microhistoautoradiographical distribution of water soluble isotopes
Summary A method for microhistoautoradiographic examination of water soluble radioactive isotopes and its use in studying the distribution of 131J and 99mTc in the gastric mucosa is described.It is shown that technetium is selectively secreted by the parietal cells of the gastric mucosa. In contrast 131J is secreted by the chief and mucosal cells. The selective accumulation of 99mTc in the parietal cells suggests that technetium is secreted via a metabolic pathway. The main activity of 99mTc is observed in the gastric fundus. The distribution of both isotopes within the submucous lymphoid and capillary vessels of the antrum and fundus is equal.The microhistoautoradiographic results in the different parts of the stomach are confirmed by quantitative scintillation counting.相似文献
18.
BackgroundTo improve therapy outcome of Yttrium-90 selective internal radiation therapy (90Y SIRT), patient-specific post-therapeutic dosimetry is required. For this purpose, various dosimetric approaches based on different available imaging data have been reported. The aim of this work was to compare post-therapeutic 3D absorbed dose images using Technetium-99m (99mTc) MAA SPECT/CT, Yttrium-90 (90Y) bremsstrahlung (BRS) SPECT/CT, and 90Y PET/CT.MethodsTen SIRTs of nine patients with unresectable hepatocellular carcinoma (HCC) were investigated. The 99mTc SPECT/CT data, obtained from 99mTc-MAA-based treatment simulation prior to 90Y SIRT, were scaled with the administered 90Y therapy activity. 3D absorbed dose images were generated by dose kernel convolution with scaled 99mTc/90Y SPECT/CT, 90Y BRS SPECT/CT, and 90Y PET/CT data of each patient. Absorbed dose estimates in tumor and healthy liver tissue obtained using the two SPECT/CT methods were compared against 90Y PET/CT.ResultsThe percentage deviation of tumor absorbed dose estimates from 90Y PET/CT values was on average −2 ± 18% for scaled 99mTc/90Y SPECT/CT, whereas estimates from 90Y BRS SPECT/CT differed on average by −50 ± 13%. For healthy liver absorbed dose estimates, all three imaging methods revealed comparable values.ConclusionThe quantification capabilities of the imaging data influence 90Y SIRT tumor dosimetry, while healthy liver absorbed dose values were comparable for all investigated imaging data. When no 90Y PET/CT image data are available, the proposed scaled 99mTc/90Y SPECT/CT dosimetry method was found to be more appropriate for HCC tumor dosimetry than 90Y BRS SPECT/CT based dosimetry. 相似文献
19.
High productivity and waterlogged conditions make many freshwater wetlands significant carbon sinks. Most wetland carbon studies focus on boreal peatlands, however, with less attention paid to other climates and to the effects of hydrogeomorphic settings and the importance of wetland vegetation communities on carbon sequestration. This study compares six temperate wetland communities in Ohio that belong to two distinct hydrogeomorphic types: an isolated depressional wetland site connected to the groundwater table, and a riverine flow‐through wetland site that receives water from an agricultural watershed. Three cores were extracted in each community and analyzed for total carbon content to determine the soil carbon pool. Sequestration rates were determined by radiometric dating with 137Cs and 210Pb on a set of composite cores extracted in each of the six communities. Cores were also extracted in uplands adjacent to the wetlands at each site. Wetland communities had accretion rates ranging from 3.0 to 6.2 mm yr?1. The depressional wetland sites had higher (P < 0.001) organic content (146 ± 4.2 gC kg?1) and lower (P < 0.001) bulk density (0.55 ± 0.01 Mg m?3) than the riverine ones (50.1 ± 6.9 gC kg?1 and 0.74 ± 0.06 Mg m?3). The soil carbon was 98–99% organic in the isolated depressional wetland communities and 85–98% organic in the riverine ones. The depressional wetland communities sequestered 317 ± 93 gC m?2 yr?1, more (P < 0.01) than the riverine communities that sequestered 140 ± 16 gC m?2 yr?1. The highest sequestration rate was found in the Quercus palustris forested wetland community (473 gC m?2 yr?1), while the wetland community dominated by water lotus (Nelumbo lutea) was the most efficient of the riverine communities, sequestering 160 gC m?2 yr?1. These differences in sequestration suggest the importance of addressing wetland types and communities in more detail when assessing the role of wetlands as carbon sequestering systems in global carbon budgets. 相似文献
20.
Strain GW Wang J Gagner M Pomp A Inabnet WB Heymsfield SB 《Obesity (Silver Spring, Md.)》2008,16(8):1953-1956
Objective: As the acceptance of surgical procedures for weight loss in morbid obesity is increasing, clinically useful baseline and follow‐up measures of total body water (TBW) and resting energy expenditure (REE) are important. Research methods such as deuterium (D2O) dilution and metabolic carts are problematic in the clinical setting. We compared bioimpedance analysis (BIA) predicted (Tanita TBF‐310) and measured TBW and REE. Methods and Procedures: Forty‐two paired presurgery studies were completed using BIA and D2O in patients with BMI (mean ± s.d.) 50.2 ± 8.8 kg/m2 for TBW, and 30 patients with BMI 51.0 ± 13 kg/m2 completed paired determinations of REE with metabolic carts and the Tanita balance with weight, height, sex, and age modifiers. Regression analysis and Bland‐Altman plots were applied. Results: When regression analysis was completed for TBW, regression line was consistent with the identity line “y = x.” The intercept was not different from 0 (95% confidence interval ?2.5 ± 7.0). The slope of the line was not different from 1.0 ± 0.1. The measured TBW 51.2 ± 10.1 l had a correlation with the predicted 49.5 ± 11.27 l of 0.92. There also was no significant difference (P = 0.33) between predicted (2,316 ± 559 kcal/day) and measured REE (2,383 ± 576 kcal/day);δ 66.7 ± 273 kcal/day. The two measures were highly correlated (r = 0.88) with no bias detected. Discussion: These observations support the use of the BIA system calibration in subjects with severe obesity. Without the use of complex, costly equipment and invasive procedures, BIA measurements can easily be obtained in clinical practice to monitor patient responses to treatment. 相似文献