Atrial Natriuretic Peptide and Acute Changes in Central Blood Volume by Hyperthermia in Healthy Humans.

BACKGROUND: Hyperthermia induces vasodilatation that reduces central blood volume (CBV), central venous pressure (CVP) and mean arterial pressure (MAP). Inhibition of atrial natriuretic peptide (ANP) could be a relevant homeostatic defense mechanism during hyperthermia with a decrease in CBV. The present study evaluated how changes in plasma ANP reflect the changes in CBV during hyperthermia. METHODS: Ten healthy subjects provided with a water perfused body suit increased body core temperature 1 °C. In situ labeled autologous red blood cells were used to measure the CBV with a gamma camera. Regions of interest were traced manually on the images of the whole body blood pool scans. Two measures of CBV were used: Heart/whole body ratio and thorax/whole body ratio. CVP and MAP were recorded. Arterial (ANPart) and venous plasma ANP were determined by radioimmunoassay. RESULTS: The ratio thorax/whole body and heart/whole body decreased 7 % and 11 %, respectively (p<0.001). MAP and CVP decreased during hyperthermia by 6.8 and 5.0 mmHg, respectively (p<0.05; p<0.001). Changes in both thorax/whole body (R=0.80; p<0.01) and heart/whole body ratios (R=0.78; p<0.01) were correlated with changes in ANPart. However, there was no correlation between venous ANP and changes in CBV, nor between ANPart and MAP or CVP. CONCLUSION: Arterial but not venous plasma concentration of ANP, is correlated to changes in CBV, but not to pressures. We suggest that plasma ANPart may be used as a surrogate marker of acute CBV changes.

Diagnostic evaluation of three cardiac software packages using a consecutive group of patients.

PURPOSE: The aim of this study was to compare the diagnostic performance of the three software packages 4DMSPECT (4DM), Emory Cardiac Toolbox (ECTb), and Cedars Quantitative Perfusion SPECT (QPS) for quantification of myocardial perfusion scintigram (MPS) using a large group of consecutive patients. METHODS: We studied 1,052 consecutive patients who underwent 2-day stress/rest 99mTc-sestamibi MPS studies. The reference/gold-standard classifications for the MPS studies were obtained from three physicians, with more than 25 years each of experience in nuclear cardiology, who re-evaluated all MPS images. Automatic processing was carried out using 4DM, ECTb, and QPS software packages. Total stress defect extent (TDE) and summed stress score (SSS) based on a 17-segment model were obtained from the software packages. Receiver-operating characteristic (ROC) analysis was performed. RESULTS: A total of 734 patients were classified as normal and the remaining 318 were classified as having infarction and/or ischemia. The performance of the software packages calculated as the area under the SSS ROC curve were 0.87 for 4DM, 0.80 for QPS, and 0.76 for ECTb (QPS vs. ECTb p = 0.03; other differences p < 0.0001). The area under the TDE ROC curve were 0.87 for 4DM, 0.82 for QPS, and 0.76 for ECTb (QPS vs. ECTb p = 0.0005; other differences p < 0.0001). CONCLUSION: There are considerable differences in performance between the three software packages with 4DM showing the best performance and ECTb the worst. These differences in performance should be taken in consideration when software packages are used in clinical routine or in clinical studies.

The role of SPECT-CT in the lymphoscintigraphic identification of sentinel nodes in patients with oral cancer.

CONCLUSION: SPECT-CT may improve the localization of sentinel nodes (SNs) in patients with oral squamous cell carcinoma (OSCC). Compared with planar lymphoscintigraphy SPECT-CT detected more SNs and provided additional anatomical and spatial information about their localization. New generation SPECT with higher resolution CT scanners are expected to provide more accurate information about the localization of SNs. OBJECTIVE: To assess the role of combined SPECT-CT in SN identification in the clinically negative neck of patients with OSCC. MATERIALS AND METHODS: Lymphoscintigraphy comprising planar and SPECT-CT acquisition was performed in 34 consecutive patients with OSCC stage I and II (T1-2N0M0) prior to sentinel node biopsy (SNB) and selective neck dissection. The number of SNs and anatomical location was recorded according to lymphoscintigraphy and operative findings. RESULTS: SNB was conducted in 33 patients. SNs were identified in 94% (32/34) of the patients using SPECT-CT. In 91% (29/32) of the patients SNs were harvested from all of the levels involved on SPECT-CT. SPECT-CT imaging demonstrated extra SNs compared with planar lymphoscintigraphic imaging in 47% (15/32) of patients. In seven cases the anatomical level of SN according to SPECT-CT was reclassified during surgery. The overall incidence of lymph node metastases was 19% (6/32). There were no false negative SNs.

Continuous methimazole therapy and its effect on the cure rate of hyperthyroidism using radioactive iodine: an evaluation by a randomized trial.

BACKGROUND: A randomized clinical trial was performed to clarify whether continuous use of methimazole (MTZ) during radioiodine ((131)I) therapy influences the final outcome of this therapy. DESIGN: Consecutive patients with Graves' disease (n = 30) or a toxic nodular goiter (n = 45) were rendered euthyroid by MTZ and randomized to stop MTZ 8 d before (131)I (-MTZ; n = 36) or to continue MTZ until 4 wk after (131)I (+MTZ; n = 39). Calculation of the (131)I activity included an assessment of the (131)I half-life and the thyroid volume. RESULTS: The 24-h thyroid (131)I uptake was lower in the +MTZ group than in the -MTZ group (44.8 +/- 15.6% vs. 62.1 +/- 9.9%, respectively; P < 0.001). At 3 wk after therapy, no significant change in serum free T(4) index was observed in the +MTZ group (109 +/- 106 vs. 83 +/- 28 nmol/liter at baseline; P = 0.26), contrasting an increase in the -MTZ group (180 +/- 110 vs. 82 +/- 26 nmol/liter; P < 0.001). The number of cured patients was 17 (44%) and 22 (61%) in the +MTZ and -MTZ groups, respectively (P = 0.17). Cured patients tended to have a lower 24-h thyroid (131)I uptake (50.1 +/- 13.8% vs. 56.4 +/- 17.1%; P = 0.09). By adjusting for a possible interfactorial relationship through a regression analysis (variables: randomization, 24- and 96-h thyroid (131)I uptake, type and duration of disease, age, gender, presence of antithyroid peroxidase antibodies, thyroid volume, dose of MTZ), only the continuous use of MTZ correlated with treatment failure (P = 0.006), whereas a low 24-h thyroid (131)I uptake predicted a better outcome (P = 0.006). CONCLUSION: Continuous use of MTZ hinders an excessive increase of the thyroid hormones during (131)I therapy of hyperthyroid diseases. However, such a strategy seems to reduce the final cure rate, although this adverse effect paradoxically is attenuated by the concomitant reduction of the thyroid (131)I uptake.

Total zinc absorption in young women, but not fractional zinc absorption, differs between vegetarian and meat-based diets with equal phytic acid content.

Zn bioavailability is often lower in vegetarian diets mainly due to low Zn and high phytic acid contents. The objective of the present study was to determine the fractional and total absorption of Zn from a vegetarian diet in comparison with meat diets with equal concentrations of phytic acid. A randomized cross-over design, comprising three whole-day diet periods of 5 d each, with a vegetarian diet or diets containing Polish-produced meat or Danish-produced meat, was conducted. Twelve healthy female subjects completed the study. All diets had a high content of phytic acid (1250 micromol/d) and in the meat diets the main meals contained 60 g pork meat. All main meals were extrinsically labelled with the radioactive isotope 65Zn and absorption of Zn was measured in a whole-body counter. The mean Zn content of the whole-day diet was: Polish meat diet 9.9 (SE 0.14) mg, Danish meat diet 9.4 (SE 0.19) mg and vegetarian diet 7.5 (SE 0.18) mg. No difference was observed in the fractional absorption of Zn (Polish meat diet: 27 (SE 1.2) %, Danish meat diet: 27 (SE 1.9) % and vegetarian diet: 23 (SE 2.6) %). A significantly lower amount of total Zn was absorbed from the vegetarian diet (mean Zn absorption of Polish meat diet: 2.7 (SE 0.12) mg/d (P<0.001), Danish meat diet: 2.6 (SE 0.17) mg/d (P=0.006) and vegetarian diet: 1.8 (SE 0.20) mg/d). In conclusion, the vegetarian diet compared with the meat-based diets resulted in lower amounts of absorbed Zn due to a higher content of Zn in the meat diets, but no difference was observed in the fractional absorption of Zn.

Pork meat increases iron absorption from a 5-day fully controlled diet when compared to a vegetarian diet with similar vitamin C and phytic acid content.

Meat increases absorption of non-haem iron in single-meal studies. The aim of the present study was to investigate, over a 5 d period, the potential increasing effect of consumption of pork meat in a whole diet on the fractional absorption of non-haem iron and the total absorption of iron, when compared to a vegetarian diet. A randomised cross-over design with 3 x 5 d whole-diet periods with diets containing Danish-produced meat, Polish-produced meat or a vegetarian diet was conducted. Nineteen healthy female subjects completed the study. All main meals in the meat diets contained 60 g of pork meat and all diets had high phytic acid content (1250 mumol/d). All main meals were extrinsically labelled with the radioactive isotope (59)Fe and absorption of iron was measured in a whole body counter. The non-haem iron absorption from the Danish meat diet was significantly higher compared to the vegetarian diet (P=0.031). The mean fractional absorption of non-haem iron was 7.9 (se1.1), 6.8 (se 1.0) and 5.3 (se 0.6) % for the Danish and Polish meat diets and vegetarian diet, respectively. Total absorption of iron was higher for both meat diets compared to the vegetarian diet (Danish meat diet: P=0.006, Polish meat diet: P=0.003). The absorption ratios of the present study were well in accordance with absorption ratios estimated using algorithms on iron bioavailability. Neither the meat diets nor the vegetarian diets fulfilled the estimated daily requirements of absorbed iron in spite of a meat intake of 180 g/d in the meat diets.

Acute effects of smoking on left ventricular function and neuro-humoral responses in patients with known or suspected ischaemic heart disease.

Systolic left ventricular function was examined by radionuclide ventriculography in 12 habitual smokers with known or suspected ischaemic heart disease, aged 33-69 years, before, during, and after smoking of two cigarettes in a row and was repeated on a non-smoking control day. Plasma concentrations of adrenaline, noradrenaline, renin, and angiotensin II were determined on the smoking day, before and immediately after smoking. During smoking, there were significant increases in heart rate (+27%), rate-pressure product (+23%), and cardiac output (+14%) in the face of a significant increase in left ventricular end-systolic volume (+5%) and significant decreases in ejection fraction (-6%) and stroke volume (-8%). Blood pressure was virtually unchanged, and total peripheral resistance remained constant. Plasma adrenaline increased by 100%, renin decreased by 21%, and noradrenaline and angiotensin II did not change. The humoral changes were not correlated to changes in any of the haemodynamic variables. Areas of myocardial hypokinesis emerged or widened during smoking in 11 of 12 patients. Thus, in patients with known or suspected ischaemic heart disease, smoking was associated with an acute decrease in systolic ventricular function and development of widespread hypokinesis despite adrenaline stimulation.

Resumption of methimazole after 131I therapy of hyperthyroid diseases: effect on thyroid function and volume evaluated by a randomized clinical trial.

OBJECTIVE: Retrospective studies have indicated that anti-thyroid drugs (ATD) might possess a radioprotective effect, leading to a higher rate of recurrence of hyperthyroidism after iodine-131 ((131)I) therapy. DESIGN: A randomized clinical trial was performed to clarify whether resumption of methimazole after (131)I influences the final outcome of this treatment. METHODS: We assigned 149 patients with Graves' disease or a toxic nodular goitre to groups either to resume (+ATD) or not to resume (-ATD) methimazole 7 days after (131)I. Before (131)I therapy, all patients were rendered euthyroid by methimazole, which was discontinued 4 days before the (131)I therapy. RESULTS: During the follow-up period of 12 Months, 13 patients developed hypothyroidism, 42 were euthyroid, and 18 had recurrence of hyperthyroidism in the +ATD group; the respective numbers in the -ATD group were 16, 42 and 18 (P=0.88). At 3 weeks after (131)I therapy, the serum free-thyroxine index was slightly decreased (by 5.7%; 95% confidence interval (CI) -15.5 to 5.4%) in the +ATD group, in contrast to an increase of 35.9% (95% CI 18.8 to 55.5%) in the -ATD group (P<0.001 between groups). In the subgroup that remained euthyroid during follow-up, thyroid Volume reduction, assessed by ultrasonography, was smaller in the +ATD group [38.7% (95% CI 33.3 to 44.1%)] than in the -ATD group [48.6% (95% CI: 41.5-55.6%)] (P<0.05). CONCLUSION: No radioprotective effect could be demonstrated, with regard to final thyroid function, for the resumpton of methimazole 7 days after (131)I therapy. Although resumption of methimazole slightly reduced the magnitude of shrinkage of the goitre obtained by (131)I, the prevention of a temporary thyrotoxicosis in the early period after radiation favours this regimen.

The diagnostic value of digital subtraction arthrography and radionuclide bone scan in revision hip arthroplasty.

A prospective analysis of plain serial radigraphs (PSR), digital subtraction arthrography (DSA), and radionuclide bone scans (RBS) was performed in 56 cemented total hip arthroplasties to evaluate the efficacy and usefulness of each study in the diagnosis of loosening. To avoid selection bias in the evaluation of DSA and RBS, the decision to perform repeat surgery was based exclusively on the clinical history and PSR. Results of each study were compared with intraoperative assessment of the status of components and expressed in terms of sensitivity, specificity, and accuracy. Overall accuracy for the acetabular component by PSR was 66%; by DSA, 93%; by RBS, 46%. Overall accuracy for the femoral component by PSR was 79%; by DSA, 93%; RBS, 50%. Our results indicate that DSA can be recommended as a further analysis in cases with a painful hip prosthesis and no or inconclusive findings on PSR. RBS did not give any useful information and cannot be recommended routinely.