Iodine-129 concentrations in marginal seas of the north Pacific and Pacific-influenced waters of the Arctic Ocean.

Water sampling during the 1993 IV Russian-US Joint Expedition to the Bering and Chukchi Seas (BERPAC) indicates that Pacific Ocean burdens of the long-lived radionuclide 129I are relatively low in the Pacific-influenced Arctic, particularly compared to high latitude waters influenced by the North Atlantic. These low concentrations occur despite the presence of potential submerged anthropogenic sources in the East Sea (Sea of Japan), and in the northwest Pacific Ocean, east of the Kamchatka Peninsula. The concentration of 129I entering the Arctic Ocean through Bering Strait, approximately 0.7 x 10(8) atoms kg(-1), is only slightly higher than observed in deep Pacific waters. Similar concentrations (0.44-0.76 x 10(8) atoms kg(-1)) measured in Long Strait indicate no significant transfer of 129I eastward into the Chukchi Sea in the Siberian Coastal Current from the Siberian marginal seas to the west. However, the concentrations reported here are more than an order of magnitude higher than the Bering Strait input concentration estimated (1.0 x 10(6) atoms kg(-1)) from bomb fallout mass balances, which supports other existing evidence for a significant atmospheric deposition term for this radionuclide in surface ocean waters. Near-bottom water samples collected in productive waters of the Bering and Chukchi Seas also suggest that sediment regeneration may locally elevate 129I concentrations, and impact its utility as a water mass tracer. As part of this study, two deep 129I profiles were also measured in the East Sea in 1993-1994. The near-surface concentration of 129I ranged from 0.12 to 0.31 x 10(8) atoms kg(-1). The 129I concentration showed a steady decrease with depth, although because of active deep water ventilation, the entire 3000 m water column exceeded natural concentrations of the radionuclide. Atom ratios of 129I/137Cs in the East Sea also suggest an excess of 129I above bomb fallout estimates, also possibly resulting from atmospheric deposition ultimately originating from nuclear facilities.

Rapid and early export of Phaeocystis antarctica blooms in the Ross Sea, Antarctica.

The Southern Ocean is very important for the potential sequestration of carbon dioxide in the oceans and is expected to be vulnerable to changes in carbon export forced by anthropogenic climate warming. Annual phytoplankton blooms in seasonal ice zones are highly productive and are thought to contribute significantly to pCO2 drawdown in the Southern Ocean. Diatoms are assumed to be the most important phytoplankton class with respect to export production in the Southern Ocean; however, the colonial prymnesiophyte Phaeocystis antarctica regularly forms huge blooms in seasonal ice zones and coastal Antarctic waters. There is little evidence regarding the fate of carbon produced by P. antarctica in the Southern Ocean, although remineralization in the upper water column has been proposed to be the main pathway in polar waters. Here we present evidence for early and rapid carbon export from P. antarctica blooms to deep water and sediments in the Ross Sea. Carbon sequestration from P. antarctica blooms may influence the carbon cycle in the Southern Ocean, especially if projected climatic changes lead to an alteration in the structure of the phytoplankton community.

NMR monitoring of rheumatoid arthritis patients receiving anti-TNF-alpha monoclonal antibody therapy.

The aim of this study was to investigate if dynamic gadolinium-DTPA-supported magnetic resonance (MR) imaging can monitor the therapeutic effect of a fast-acting immuno-modulating drug like anti-tumour necrosis factor alpha (anti-TNF-alpha) monoclonal antibody (moab) in patients with rheumatoid arthritis (RA). Dynamic MR imaging was performed on 64 joints in a total of 18 patients before and after infusion with either a placebo or 1 or 10 mg/kg of anti-TNF-alpha moab. Additionally, treating the placebo group and reinfusing the verum group with either 3 or 10 mg/kg was monitored by quantitative nuclear magnetic resonance (NMR). Time-dependent signal intensity changes were then correlated with a total of five Paulus criteria and with ESR and C-reactive protein (CRP). No changes in either the gadolinium uptake or clinical parameters were seen after the infusion of a placebo. Therapy with 1 mg/kg anti-TNF-alpha moab resulted in a significant decrease in clinical disease activity, as well as in gadolinium-DTPA uptake in dynamic NMR studies. However, correlations between singal intensity changes and Paulus criteria were only demonstrated for the variable "doctor's evaluation of disease activity". Patients given 10 mg/kg moab demonstrated a very significant improvement in all clinical manifestations of their disease, as well as a high significant reduction in gadolinium uptake (P = 0.004). In addition, the latter group showed significant correlations between time-dependent signal intensity changes and five Paulus criteria: "number of swollen joints", "number of painful joints", "duration of morning stiffness", "doctor's evaluation of disease activity" and "patient's evaluation of disease activity". No differences and correlations were seen for ESR and CRP. We concluded that dynamic NMR studies are suitable to monitor inflammatory activity in RA patients under therapy with biological response modifiers such as anti-TNF-alpha moab.

[Hypoxia-radiotherapy: the changes in selected physiological parameters of healthy tissue during the breathing of a hypoxic gas mixture]. / Hypoxie-Radiotherapie: Veränderungen ausgewählter physiologischer Parameter des gesunden Gewebes bei Atmung eines hypoxischen Gasgemisches.

BACKGROUND: Chronic hypoxia in tumors is generally accepted to be one of the most important factors concerning sensibility to irradiation. The principle of hypoxyradiotherapy is to achieve a limited (maximal 30 min) radioresistance of the healthy (actually euoxic) tissue by acute aerogen hypoxia, without protecting effects in the average chronic hypoxic tissue of the tumor. This study investigates changes in selected physiological parameters in vivo during acute aerogen hypoxia. PATIENTS AND METHODS: In 31 persons (group A) we documented changes in blood-gas-analysis, ECG-parameters, blood pressure and pulse during acute hypoxia lasting 5 minutes. During 30 minutes of acute hypoxia we determined in another 10 persons (group B) the relations between different phosphoryl-metabolites by means of 31-phosphorus magnetic resonance spectroscopy (31P-MRS). The 31P-MRS of the Musculus triceps surae was performed on our 1.5 T imaging system (Magnetom, Siemens) using a 8 cm diameter surface coil. To achieve the hypoxic condition in the persons tested, a gas-mixture with 8.2% O2 was used. RESULTS: In group A the acute hypoxia led to significant changes in O2-pressure, the blood O2-saturation and pulse frequency. The pO2-values drop in the 5th minute to about 50% of the initial value. Concerning group B the relations of the phosphoryl metabolites show no significant changes during acute hypoxia. CONCLUSIONS: The results show an excellent tolerability of breathing of the hypoxic gas-mixture, and confirm that this mixture containing 8.2% of O2 ensures a decrease in the pO2-levels of more than 50%. This is necessary to achieve a dose modifying factor (DMF) of at least 1.15 to 1.2. The changes in relations of phosphoryl metabolites seem to reflect the ability of healthy tissue to adapt to hypoxic conditions starting after 10 minutes and leading to the loss of the radioprotective effect after 30 minutes.

[Somatostatin receptor scintigraphy in neuroendocrine tumors exemplified by a patient with hepatic metastases of gastrinoma]. / Somatostatin-Rezeptor-Szintigraphie bei neuroendokrinen Tumoren am Beispiel einer Patientin mit hepatisch metastasiertem Gastrinom.

In a 66-year old woman, who suffered from recurrent melena, diarrhea and hematemesis with multiple untreatable gastric and duodenal ulcers, a markedly increased basal and secretin-stimulated gastrin level, clinically a Zollinger-Ellison syndrome was assumed. The conventional diagnostic procedures (esophago-gastro-duodenoscopy, colonoscopy, endosonography, ERCP, abdominal CT and small bowel enema) had failed to reveal the localisation of any gastrinoma. The thereupon performed scintigraphy with In-111-pentetreotide showed four somatostatin receptor expressing liver lesions: two of them could be detected at first site in the consecutively performed MR scans, another retrospectively bearing in mind the scintigraphic images. Today, the somatostatin receptor imaging seems to be a highly sensitive procedure for detecting and localizing hormonally active gastroenteropancreatic tumors. At the same time it is a method for in vivo evaluation of the somatostatin receptor status of localized GEP tumors, thus delivering a decisive diagnostic step for the evaluation of the effectiveness of a therapy with somatostatin analogues before such an expensive therapy is started.

Single-photon-emission computed tomography analysis of cerebral blood flow in the evaluation of central nervous system involvement in patients with systemic lupus erythematosus.

OBJECTIVE: Single-photon-emission computed tomography (SPECT) scanning was used to detect potential central nervous system (CNS) involvement in patients with systemic lupus erythematosus (SLE), by determining cerebral blood flow abnormalities. METHODS: SPECT scans were performed on 35 SLE patients, grouped into 3 categories: those without neuropsychiatric symptoms (n = 10), those with definite neurologic or psychiatric disorders (n = 10), and those with mild symptoms such as headache or memory disturbances (n = 15). SPECT scan features were classified as normal or as focal or diffuse defects in uptake. RESULTS: SPECT findings were normal in 9 of the 10 patients without CNS symptoms, and abnormal in 9 of the 10 patients with overt neuropsychiatric disease (with motor or sensory deficits). Interestingly, only 4 of the 15 patients (26.7%) with mild symptoms suggestive of CNS disease had normal SPECT findings; the 11 remaining patients showed focal (53.3%) or diffuse (20%) uptake defects. An association between SPECT findings and disease duration was also observed, but there was no correlation of SPECT results with overall disease activity, serologic findings, or medications used. CONCLUSION: Our data suggest that in a substantial proportion of patients, SPECT analysis may provide additional information on potential CNS involvement, and may therefore be useful in therapeutic decision-making and disease monitoring in order to prevent CNS damage.

[In-vitro-study and patient examinations with MRT: the significance of metal implants]. / In-vitro- und Patientenuntersuchungen mittels MRT: Bedeutung metallischer Implantate.

This study presents the results of in-vitro and clinical experiences with metallic implants during MRT investigations. In-vitro temperature measurements of various implants showed little temperature rise depending on the shape and the orientation in the static magnetic field (max. 0.3 degrees C). Ferromagnetic forces could not be detected with these implants. In contrast, severe temperature increase (9.4 degrees C) was observed with an intratracheal spiral tube. Tubes of this type should not be used in MR imaging to avoid the risk of burning. 105 MR examinations were performed in patients with metallic implants (CNS shunts, aortocoronary bypass grafts, aortic-, mitral-prosthesis, orthopedic implants, skin staples, shrapnels). Patients with vascular clips were accepted for MR imaging when the clips were non-ferromagnetic only. No adverse effects were observed in these patients.

[A comparison of arthrography and magnetic resonance tomography in painful limited movements of the hand]. / Vergleich Arthrographie--Kernspintomographie bei schmerzhaften Bewegungseinschränkungen der Hand.

In 18 patients with unclear pain in the wrist limiting hand movement, arthrography and magnetic resonance imaging (MRI) were compared. The FISP gradient echo sequence turned out to be superior to the T1 weighted spin-echo sequence in the imaging of the triangular fibrocartilage complex. MRI is very sensitive in detecting triangular fibrocartilage lesions and therefore represents a suitable non-invasive screening method. It is, however, not possible to assess the degree of the lesion. Ruptures in carpal tendons could only be diagnosed by means of arthrography.