IMPROVEMENTS OF 111IN SPECT IMAGES RECONSTRUCTED WITH SPARSELY ACQUIRED PROJECTIONS BY DEEP LEARNING GENERATED SYNTHETIC PROJECTIONS

The aim was to improve single-photon emission computed tomography (SPECT) quality for sparsely acquired 111In projections by adding deep learning generated synthetic intermediate projections (SIPs). Method: The recently constructed deep convolutional network for generating synthetic intermediate projections (CUSIP) was used for improving 20 sparsely acquired 111In-octreotide SPECTs. Reconstruction was performed with 120 (120P) or 30 (30P) projections, or 120 projections with 90 SIPs generated from 30 projections (30-120SIP). The SPECT reconstructions were performed with attenuation, scatter and collimator response corrections. Postfiltered 30P reconstructed SPECT was also analyzed. Image quality were quantitatively evaluated with root-mean-square error, peak signal-to-noise ratio and structural similarity index metrics. Result: The 30-120SIP reconstructed SPECT had statistically significant improved image quality parameters compared to 30P reconstructed SPECT with and without post filtering. The images visual appearance was similar to slightly filtered 120P SPECTs. Thereby, substantial acquisition time reduction with SIPs seems possible without image quality degradation.

Age alters peripheral vascular endothelial function without affecting coronary flow reserve in healthy volunteers

Background

Age is a key risk factor contributing to vascular endothelial dysfunction. Whether the impact of ageing is uniform on various vascular beds is unknown. Endothelial function is classically evaluated by the brachial flow mediated dilatation (FMD) after a brief occlusion which mainly involves nitric oxide (NO) production. However, FMD measurement, requiring highly trained technicians, has been shown to be associated with a high degree of variability. Endothelial function could be also assessed by cutaneous iontophoresis combined with Laser Doppler. By contrast to FMD, this method is easily done by nurses and shows less variability. In parallel, myocardial imaging allows measurement of coronary flow reserve (CFR) coupled with an adenosine challenge leading to both a NO release and a modulation of potassium channels.

Purpose

The aim of this study was to determine the impact of ageing on vasodilation of peripheral (cutaneous) and coronary blood vessels in healthy volunteers.

Methods

This prospective single German center study enrolled 75 healthy non-smoking normotensive volunteers, taking no medication. They were divided into three age-subgroups (n=25/group): 18–30, 50–59, and 60–70 years (women: 54, 27 and 23%, respectively). All subjects underwent clinical and laboratory evaluation.

Peripheral endothelial function, expressed in cutaneous blood flow (delta CBF), was assessed through cutaneous microcirculation dilation by the non-invasive method using Laser Doppler Speckle Contrast Imaging (LSCI, Perimed) coupled with iontophoresis to locally deliver 125 nmoles of acetylcholine (Ach). The CFR was determined by cardiac magnetic resonance (CMR) coupling with an intravenous infusion of adenosine at 140 μg/kg/min for at least 3 minutes.

Results

Age was associated with a 23% reduction of peripheral endothelial function (delta CBF, p=0.005) in the elderly group (60–70y) vs. the younger one (18–30y) (median: 56.4 vs. 73.6). By contrast, calculated CFR was unchanged (median: 4.1 vs. 4.2, p=0.38). No relationship was observed between peripheral endothelial function (delta CBF) and CFR (r=0.01, p>0.97) in healthy volunteers.

Conclusion

In healthy volunteers, ageing is associated with a progressive peripheral but not with a coronary vascular dysfunction. This suggests that the impact of age on endothelial dysfunction depends on different vascular beds. Peripheral endothelial function assessment does not predict coronary vascular function in healthy volunteers.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Servier

Comparative intra- and interspecific sexual organ reciprocity in four distylous Primula species in the Himalaya-Hengduan Mountains

Distyly is a mechanism promoting cross-pollination within a balanced polymorphism. Numerous studies show that the degree of inter-morph sexual organ reciprocity (SOR) within species relates to its pollen-mediated gene flow. Similarly, a lower interspecific SOR should promote interspecific isolation when congeners are sympatric, co-blooming and share pollinators. In this comparative study, we address the significance of SOR at both intra- and interspecific levels. Seventeen allopatric and eight sympatric populations representing four Primula species (P. anisodora, P. beesiana, P. bulleyana and P. poissonii) native to the Himalaya-Hengduan Mountains were measured for eight floral traits in both long- and short-styled morphs. GLMM and spatial overlap methods were used to compare intra- and interspecific SOR. While floral morphology differed among four Primula species, SOR within species was generally higher than between species, but in species pairs P. poissonii/P. anisodora and P. beesiana/P. bulleyana, the SOR was high at both intra- and interspecific levels. We did not detect a significant variation in intraspecific SOR or interspecific SOR when comparing allopatric versus sympatric populations for all species studied. As intraspecific SOR increased, disassortative mating may be promoted. As interspecific SOR decreased, interspecific isolation between co-flowering species pairs also may increase. Hybridisation between congeners occurred when interspecific SOR increased in sympatric populations, as confirmed in two species pairs, P. poissonii/P. anisodora and P. beesiana/P. bulleyana.

Impact of pre- and post-pollination barriers on pollen transfer and reproductive isolation among three sympatric Pedicularis (Orobanchaceae) species

Pedicularis is the largest genus in the Orobanchaceae (>300) with many species co-occurring and co-blooming in subalpine to alpine meadows in the Himalayas. Although it is well known that different Pedicularis species place pollen on different parts of the same bumblebee's body, thus reducing interspecific pollen transfer, it is not known whether post-pollination components also contribute to reproductive isolation (RI). In this study, we quantified the individual strengths and absolute contributions of six pre- and post-pollination components of RI between three sympatric species in two pairs; Pedicularis gruina × Pedicularis tenuisecta (gru × ten) and Pedicularis comptoniifolia × Pedicularis tenuisecta (com × ten). All three Pedicularis species shared the same Bombus species. Individual foragers showed a high, but incomplete, floral constancy for each species. Therefore, pre-pollination barriers were potentially 'leaky' as Bombus species showed a low but consistent frequency of interspecific visitation. The RI strength of pre-pollination was lower in com × ten than in gru × ten. In contrast, post-pollination barriers completely blocked gene flow between both sets of species pairs. Two post-pollination recognition sites were identified. Late acting rejection of interspecific pollen tube growth occurred in com♀ × ten♂, while seeds produced in bi-directional crosses of gru × ten failed to germinate. We propose that, although floral isolation based on pollen placement on pollinators in the genus Pedicularis is crucial to avoid interspecific pollen transfer, the importance of this mode of interspecific isolation may be exaggerated. Post-pollination barriers may play even larger roles for currently established populations of co-blooming and sympatric species in this huge genus in the Himalayas.

Artificial ionospheric layers during pump frequency stepping near the 4th gyroharmonic at HAARP

We report on artificial descending plasma layers created in the ionosphere F region by high-power high-frequency (HF) radio waves from High-frequency Active Auroral Research Program at frequencies f(0) near the fourth electron gyroharmonic 4f(ce). The data come from concurrent measurements of the secondary escaping radiation from the HF-pumped ionosphere, also known as stimulated electromagnetic emission, reflected probing signals at f(0), and plasma line radar echoes. The artificial layers appeared only for injections along the magnetic field and f(0)>4f(ce) at the nominal HF interaction altitude in the background ionosphere. Their average downward speed ~0.5 km/s holds until the terminal altitude where the local fourth gyroharmonic matches f(0). The total descent increases with the nominal offset f(0)-4f(ce).

UV filters for hair protection

Synopsis Hair damage, caused by sunlight, and the possibility to protect hair against sunlight by means of cosmetic formulations was studied. For this, five UV-filters were tested: benzophenone-3 (UV-A/UV-B); benzophenone-4 (UV-A/UV-B); phenylbenzimidazole sulfonic acid (UV-B); butylmethoxydibenzoylmethane (UV-A); octyl dimethyl PABA (UV-B). The stability of the UV-filters was tested as pure substances as well as in two cosmetic formulations: a setting lotion and a shine spray. The degree of decolouration and stress strain behaviour were determined. The benzophenones had the best protection ability both on colour and on morphology. Stability data and UV-spectra are discussed.

Efficacy and safety of enteric-coated mycophenolate sodium in combination with two glucocorticoid regimens for the treatment of active lupus nephritis

Mycophenolic acid, in combination with glucocorticoids, has been shown in a series of trials to be safe and effective for treatment of lupus nephritis. Regimens that permit glucocorticoid dose reduction without loss of efficacy would be advantageous. MyLupus was a 24-week, multicentre, open-label, study in patients with active proliferative lupus nephritis treated with enteric-coated mycophenolate sodium (EC-MPS), randomized to standard-dose ( n = 42) or reduced-dose ( n = 39) glucocorticoids. Complete response at week 24, the primary endpoint, was achieved in 19.8% (16/81) of patients (19.0% standard-dose, 20.5% reduced-dose; lower limit of 97.5% CI for the difference −15.9%, p = 0.098, i.e. non-inferiority was not shown). Partial response occurred in 42.0% of patients (34/81). From baseline to week 24, the mean global British Isles Lupus Assessment Group (BILAG) score decreased from 14.0 ± 5.4 to 5.0 ± 3.8 ( p < 0.001). The incidence of adverse events was 80.2% (65/81), most frequently gastrointestinal complications (31/81, 38.3%). Infections were reported in 57.1% and 35.9% of standard- and reduced-dose glucocorticoid patients, respectively ( p = 0.056), with herpes zoster in 16.7% and 0% ( p = 0.012). Three patients discontinued study medication due to adverse events. This exploratory study suggests that EC-MPS may facilitate glucocorticoid reduction without loss of efficacy in patients with active lupus nephritis, but results require confirmation in a controlled, longer-term study versus the current standard of care.

Objective assessment of tumour response to therapy based on tumour growth kinetics

Background:

Current standards for assessment of tumour response to therapy (a) categorise therapeutic efficacy values, inappropriate for patient-specific and deterministic studies, (b) neglect the natural growth characteristics of tumours, (c) are based on tumour shrinkage, inappropriate for cytostatic therapies, and (d) do not accommodate integration of functional/biological means of therapeutic efficacy assessed with, for example, positron emission tomography or magnetic resonance imaging, with data from anatomical changes in tumour.

Methods:

A quantity for tumour response was formulated assuming that an effective treatment may decrease the cell proliferation rate (cytostatic) and/or increase the cell loss rate (cytotoxic) of the tumour. Tumour response values were analysed for 11 non-Hodgkin's lymphoma patients treated with ¹³¹I-labelled anti-B1 antibody and 12 prostate cancer patients treated with a nutritional supplement.

Results:

Tumour response was found to be equal to the logarithm of the ratio of post-treatment tumour volume to the volume of corresponding untreated tumour. Neglecting the natural growth characteristics of tumours results in underestimation of treatment effectiveness based on currently used methods. The model also facilitates the integration of data from tumour volume changes, with data from functional imaging.

Conclusion:

Tumour response to therapy can be assessed with a continuous dimensionless quantity for both cytotoxic and cytostatic treatments.

The pollination of zygogynum (winteraceae) by a moth, sabatinca (micropterigidae): an ancient association?

The primitive and vesselless angiosperm Zygogynum (Winteraceae), which is restricted to New Caledonia, is pollinated by a moth, Sabatinca (Micropterigidae). Fossil records of both the moth and the plant families extend to the Early Cretaceous. Adult Sabatinca have grinding mandibles and usually feed on the spores of ferns and on pollen. The insects use the flowers as mating sites and eat the pollen which is immersed in a dense pollenkitt. This mode of pollination in which flowers serve as mating and feeding stations with floral odors acting as cues may have been common in the early evolution of flowering plants.

Pollination by deceit in Paphiopedilum barbigerum (Orchidaceae): a staminode exploits the innate colour preferences of hoverflies (Syrphidae)

Paphiopedilum barbigerum T. Tang et F. T. Wang, a slipper orchid native to southwest China and northern Vietnam, produces deceptive flowers that are self-compatible but incapable of mechanical self-pollination (autogamy). The flowers are visited by females of Allograpta javana and Episyrphus balteatus (Syrphidae) that disperse the orchid's massulate pollen onto the receptive stigmas. Measurements of insect bodies and floral architecture show that the physical dimensions of these two fly species correlate with the relative positions of the receptive stigma and dehiscent anthers of P. barbigerum. These hoverflies land on the slippery centralised wart located on the shiny yellow staminode and then fall backwards through the labellum entrance. They are temporarily trapped in the inflated chamber composed of the interconnected labellum and column. The attractive staminode of P. barbigerum strongly reflects the colour yellow (500-560 nm), a colour preferred innately by most pollen-eating members of the Syrphidae. No scent molecules were detected using GC mass spectrometry analysis, showing that the primary attractant in this system is visual, not olfactory. Pollination-by-deceit in P. barbigerum is contrasted with its congener, P. dianthum, a brood site mimic that is pollinated by ovipositing females of E. balteatus. As the natural rate of fruit set in P. barbigerum (mean 26.3% pooled over three seasons) is lower than that of P. dianthum (mean 58.5% over two seasons), the evolution of false brood sites in some Paphiopedilum spp. should be selectively advantageous as they may provide an increase in the attention and return rates of dependable pollinators to flowers that always lack a reward.

Pollination of Cypripedium plectrochilum (Orchidaceae) by Lasioglossum spp. (Halictidae): the roles of generalist attractants versus restrictive floral architecture

The pollination of Cypripedium plectrochilum Franch. was studied in the Huanglong Nature Reserve, Sichuan, China. Although large bees (Bombus, Apis), small bees (Ceratina, Lasioglossum), ants (Formica sp.), true flies (Diptera) and a butterfly were all found to visit the flowers, only small bees, including three Lasioglossum spp. (L. viridiclaucum, L. sichuanense and L. sp.; Halictidae) and one Ceratina sp., carried the flower's pollen and contacted the receptive stigma. Measurements of floral architecture showed that interior floral dimensions best fit the exterior dimensions of Lasioglossum spp., leading to the consistent deposition and stigmatic reception of dorsally-placed, pollen smears. The floral fragrance was dominated by one ketone, 3-methyl-Decen-2-one. The conversion rate of flowers into capsules in open (insect) pollinated flowers at the site was more than 38%. We conclude that, while pigmentation patterns and floral fragrance attracted a wide variety of insect foragers, canalization of interior floral dimensions ultimately determined the spectrum of potential pollinators in this generalist, food-mimic flower. A review of the literature showed that the specialised mode of pollination-by-deceit in C. plectrochilum, limiting pollinators to a narrow and closely related guild of 'dupes' is typical for other members of this genus.

Estimation of metastatic cure after radionuclide therapy

Targeted radionuclide therapy of disseminated tumor disease involves many factors that will affect the therapeutic outcome. For optimization of such therapy, it is important to know how these factors affect the therapeutic outcome. In this paper, the metastatic cure probability (MCP) model is described. The MCP model is a valuable tool for analyses of the various factors influencing the metastatic cure. The factors discussed are: 1) the physical parameters (the energy and range of emitted particles, absorbed dose-distributions, and cross-irradiation of tumors from the surrounding normal tissue) and 2) the biological parameters (radiosensitivity of tumors, tumor distributions, tumor growth rate, metastasis formation rate, variable tumor activity concentration and non-homogeneous tumor activity distributions).

Contrast-enhanced adenosine-stress magnetic resonance imaging--feasibility and practicability of a protocol for detection or exclusion of ischemic heart disease in an outpatient setting

BACKGROUND

Evaluating myocardial function, assessing ischemic myocardial areas and detecting myocardial viability are necessary diagnostic information for guiding further therapy in patients with angina. The aim of this study was to show feasibility and safety of a compiled contrast- enhanced magnetic resonance imaging (ceMRI) protocol providing the above mentioned diagnostic possibilities and to demonstrate its applicability in daily routine.

METHODS

Consecutive patients with angina were screened on a 1.5 Tesla system. Functional images in short and long axis orientation were acquired for each patient. First-pass kinetics of a gadolinium-based contrast agent (0.1 mmol/kg) were measured after three minutes of stress with adenosine infusion (140 microg/kg/min). 10 min after a second bolus injection of contrast agent "late enhancement" (MLE) sequences were acquired for the detection of myocardial necrosis.

RESULTS

We enrolled 3174 patients referred for ceMRI for detection or exclusion of ischemic heart disease. One patient experienced a major complication due to hyperventilation followed by grand mal seizure. In 1121 (35.3%) patients minor complications, such as mild chest pain or dyspnea (30%), temporarily and asymptomatic AV block (3%) or nausea (2%) could be observed under adenosine infusion. Hypoperfusion in more than one myocardial segment and affecting more than 1/3 of the myocardial wall diameter could be detected in 1972 (62%) patients. Subendocardial hypoperfusion with limited duration could be shown in 897 (28%) patients. In 305 (10%) patients hypoperfusion could be excluded. MLE could be seen in 532 (17%) patients.

CONCLUSION

This compiled ceMRI protocol is suitable for detection or exclusion of ischemic heart disease in an outpatient routine. We showed feasibility, applicability and safety of our protocol. CeMRI may serve as a useful surrogate for non-invasive diagnostics prior to invasive coronary angiography in many outpatients.

Atrial fibrillation - patients at high risk for cerebral embolism

OBJECTIVE

Patients with atrial fibrillation (AF) have a risk of cerebral embolism. Echocardiographic parameters elevate this risk significantly. However, there is little knowledge about the long-term fate and the rate of clinically silent cerebral embolism under continued oral anticoagulation. The aims of our study were to assess prognosis of patients with AF and determine a high risk group with an increased risk of cerebral embolism under oral anticoagulation.

METHODS

Consecutive patients with persistent or permanent AF and left atrial (LA) thrombi, dense spontaneous echo contrast (SEC) and/or reduced LA appendage peak emptying velocities (LAAv) were included in the study (N = 128). Patients with AF and without echocardiographic risk factors (N = 114) served as controls. All patients were examined with transesophageal echocardiography, cranial magnetic resonance imaging and clinically during a period of three years.

RESULTS

During the three-year follow-up period 6 (5%) of the high risk patients had cerebral embolism with neurological deficits. 4 (3%) patients died due to embolic events and 17 (13%) patients had silent embolism as documented on MRI. In the control group 8 (7%) patients had embolic events (n = 1 clinically apparent and n = 7 silent embolism) documented on MRI, one was clinically apparent. Study patients with an event had more commonly previous thromboembolism (p < 0.0001).

CONCLUSIONS

Patients with peristent or permanent AF and LA thrombi, dense SEC or reduced LAAv have an explicitly increased risk of cerebral embolism (21%) despite oral anticoagulation. Previous thromboembolic event is another important predictor for an event.

Reversible cerebral hyperperfusion syndrome after stenting of the carotid artery—Two case reports

Hyperperfusion syndrome can complicate carotid revascularization, be it endarterectomy or carotid artery stenting (CAS). Although extensive effort has been devoted to reducing the incidence of ischemic stroke complicating CAS, little is known about the incidence, etiology, and prevention strategies for hyperperfusion following CAS. We report two cases (female patients 72 and 81 years) presenting severe internal carotid stenosis (> 90%), who underwent presurgical and therapeutic intervention with CAS. Both patients developed hyperperfusion symptoms at 2 hours and at 30 minutes, respectively, following stenting, in both cases unilateral hyperperfusion was CCT confirmed. Case 1 was presenting with acute edema of the right hemisphere, case 2 with distended focal edema (left fronto-temporoparietally). Hyperperfusion syndrome and neurological symptoms retroceded in both cases (conservative therapy) and both patients returned to full activity (case 2 within 48 hours).

Successful receptor-mediated radiation therapy of xenografted human midgut carcinoid tumour

Somatostatin receptor (sstr)-mediated radiation therapy is a new therapeutic modality for neuroendocrine (NE) tumours. High expression of sstr in NE tumours leads to tumour-specific uptake of radiolabelled somatostatin analogues and high absorbed doses. In this study, we present the first optimised radiation therapy via sstr using [(177)Lu-DOTA(0)-Tyr(3)]-octreotate given to nude mice xenografted with the human midgut carcinoid GOT1. The tumours in 22 out of 23 animals given therapeutic amounts showed dose-dependent, rapid complete remission. The diagnostic amount (0.5 MBq [(177)Lu-DOTA(0)-Tyr(3)]-octreotate) did not influence tumour growth and was rapidly excreted. In contrast, the therapeutic amount (30 MBq [(177)Lu-DOTA(0)-Tyr(3)]-octreotate) induced rapid tumour regression and entrapment of (177)Lu so that the activity concentration of (177)Lu remained high, 7 and 13 days after injection. The entrapment phenomenon increased the absorbed dose to tumours from 1.6 to 4.0 Gy MBq(-1) and the tumours in animals treated with 30 MBq received 120 Gy. Therapeutic amounts of [(177)Lu-DOTA(0)-Tyr(3)]-octreotate rapidly induced apoptosis and gradual development of fibrosis in grafted tumours. In conclusion, human midgut carcinoid xenografts can be cured by receptor-mediated radiation therapy by optimising the uptake of radioligand and taking advantage of the favourable change in biokinetics induced by entrapment of radionuclide in the tumours.

A comparison of (111)In-DOTATOC and (111)In-DOTATATE: biodistribution and dosimetry in the same patients with metastatic neuroendocrine tumours

[Yttrium-90-DOTA-Tyr(3)]-octreotide (DOTATOC) and [(177)Lu-DOTA-Tyr(3)-Thr(8)]-octreotide (DOTATATE) are used for peptide receptor-mediated radionuclide therapy (PRMRT) in neuroendocrine tumours. No human data comparing these two compounds are available so far. We used (111)In as a surrogate for (90)Y and (177)Lu and examined whether one of the (111)In-labelled peptides had a more favourable biodistribution in patients with neuroendocrine tumours. Special emphasis was given to kidney uptake and tumour-to-kidney ratio since kidney toxicity is usually the dose-limiting factor. Five patients with metastatic neuroendocrine tumours were injected with 222 MBq (111)In-DOTATOC and (111)In-DOTATATE within 2 weeks. Up to 48 h after injection, whole-body scans were performed and blood and urine samples were collected. The mean absorbed dose was calculated for tumours, kidney, liver, spleen and bone marrow. In all cases (111)In-DOTATATE showed a higher uptake (%IA) in kidney and liver. The amount of (111)In-DOTATOC excreted into the urine was significantly higher than for (111)In-DOTATATE. The mean absorbed dose to the red marrow was nearly identical. (111)In-DOTATOC showed a higher tumour-to-kidney absorbed dose ratio in seven of nine evaluated tumours. The variability of the tumour-to-kidney ratio was high and the significance level in favour of (111)In-DOTATOC was P=0.065. In five patients the pharmacokinetics of (111)In-DOTATOC and (111)In-DOTATATE was found to be comparable. The two peptides appear to be nearly equivalent for PRMRT in neuroendocrine tumours, with minor advantages for (111)In/(90)Y-DOTATOC; on this basis, we shall continue to use (90)Y-DOTATOC for PRMRT in patients with metastatic neuroendocrine tumours.

Uptake of meta-iodobenzylguanidine in neuroendocrine tumours is mediated by vesicular monoamine transporters

The radio-iodinated noradrenaline analogue meta-iodobenzylguanidine (MIBG) can be used for scintigraphy and radiation therapy of neuroendocrine (NE). The aim of the present study was to study the importance of vesicular monoamine transporters (VMATs) for the uptake of ¹²³I-MIBG in NE tumours. In nude mice, bearing the human transplantable midgut carcinoid GOT1, all organs and xenografted tumours accumulated ¹²³I after i.v. injection of ¹²³I-MIBG. A high concentration of ¹²³I was maintained in GOT1 tumours and adrenals, which expressed VMATs, but rapidly decreased in all other tissues. In the VMAT-expressing NE tumour cell lines GOT1 and BON and in VMAT-expressing primary NE tumour cell cultures (carcinoids, n=4 and pheochromocytomas, n=4), reserpine significantly reduced the uptake of ¹²³I-MIBG. The membrane pump inhibitor clomipramine had no effect on the uptake of ¹²³I-MIBG in GOT1 and BON cells, but inhibited the uptake in one out of four primary carcinoid cell cultures and three out of four primary pheochromocytoma cell cultures. In conclusion, VMATs and secretory granules are of importance for the uptake and retention of ¹²³I-MIBG in NE tumours. Information about the type and degree of expression of VMATs in NE tumours may be helpful in future to select patients suitable for radiation therapy with radio-iodinated MIBG.

Low-energy electron emitters for targeted radiotherapy of small tumours

The possibility of using electron emitters to cure a cancer with metastatic spread depends on the energy of the emitted electrons. Electrons with high energy will give a high, absorbed dose to large tumours, but the absorbed dose to small tumours or single tumour cells will be low, because the range of the electrons is too long. The fraction of energy absorbed within the tumour decreases with increasing electron energy and decreasing tumour size. For tumours smaller than 1 g, the tumour-to-normal-tissue mean absorbed dose-rate ratio, TND, will be low, e.g. for 131I and 90Y, because of the high energy of the emitted electrons. For radiotherapy of small tumours, radionuclides emitting charged particles with short ranges (a few microm) are required. A mathematical model was constructed to evaluate the relation between TND and electron energy, photon-to-electron energy ratio, p/e, and tumour size. Criteria for the selection of suitable radionuclides for the treatment of small tumours were defined based on the results of the TND model. In addition, the possibility of producing such radionuclides and their physical and chemical properties were evaluated. Based on the mathematical model, the energy of the emitted electrons should be < or = 40 keV for small tumours (< 1000 cells), and the photon-to-electron energy ratio, p/e, should be < or = 2 to achieve a high TND. Using the selection criteria defined, five low-energy electron emitters were found to be suitable: 58Co, 103mRh, 119Sb, 161Ho, and 189mOs. All of these nuclides decay by internal transition or electron capture, which yields conversion and Auger electrons, and it should be possible to produce most of them in therapeutic amounts. The five low-energy electron-emitting radionuclides identified may be relevant in the radiation treatment of small tumours, especially if bound to internalizing radiopharmaceuticals.

Simulation of DNA damage after proton and low LET irradiation

A module for proton track structure simulation in liquid water was implemented in the biophysical model PARTRAC. Simulated tracks of energy deposition events from the radiation under investigation were superimposed on a higher-order DNA target model describing the whole genome inside a human cell. The parameters controlling DNA damage from direct and indirect effects were adapted to agree with yields and pathway contributions derived from gamma ray irradiation experiments. Single and double strand break (DSB) induction was simulated for irradiations by protons, photons and electrons over a wide range of initial energies. The relative biological effectiveness for DSB induction after proton irradiation was found to rise from 1.2 at 5 keV.micron-1 to about 2.5 at 70 keV.micron-1. About half of this growth resulted from an increased production of DSB clusters associated with small (< 10 kbp) fragments.

Monte Carlo simulation of DNA damage by low LET radiation using inhomogeneous higher order DNA targets

To test possible effects of the heterogeneous nature of the cell nucleus on simulation results of radiation-induced DNA damage, inhomogeneous targets have been implemented in the biophysical code PARTRAC. The geometry of the DNA and the histones was defined by spheres around the constituent atoms. Electron cross sections in liquid water were scaled according to the mass density of the different materials, whereas photon cross sections were derived from the sum of the cross sections for the constituent atoms. In the case of higher energy electrons the simulations show an increase of energy deposition in the DNA proportional to its high mass density. For photons with energies in the range of the carbon and the oxygen K-shell (0.28-0.53 keV), cross sections of DNA are larger than those of water, leading to an increased yield of strand breaks per average absorbed dose in the cell nucleus.

Dosimetric comparison of radionuclides for therapy of somatostatin receptor-expressing tumors

PURPOSE

Therapy of tumors expressing somatostatin receptors, sstr, has recently been clinically tested using somatostatin analogues labeled with (111)In and (90)Y. Several other radionuclides, i.e., (131)I, (161)Tb, (64)Cu, (188)Re, (177)Lu, and (67)Ga, have also been proposed for this type of therapy. The aim of this work was to investigate the usefulness of the above-mentioned radionuclides bound to somatostatin analogues for tumor therapy.

METHODS

Biokinetic data of (111)In-labeled octreotide in mice and man were used, primarily from our studies but sometimes from the literature. Dosimetric calculations were performed with the assumption that biokinetics were similar for all radionuclides bound to somatostatin analogues. The cumulated tumor:normal-tissue activity concentration, TNC was calculated for the various physical half-lives of the radionuclides. Using mathematical models, the tumor:normal-tissue mean absorbed dose rate ratio, TN D and tumor:normal-tissue mean absorbed dose ratio, TND, were calculated for various tumor sizes in mice and humans.

RESULTS

TNC of radionuclide-labeled octreotide increased with physical half-life for most organs, both in mice and in humans. TN D showed that radionuclides emitting electrons with too high energy are not suitable for therapy of small tumors. Furthermore, radionuclides with a higher frequency of photon emissions relative to electron emissions will yield lower TN D and are thus less suitable for therapy than radionuclides with a lower frequency of photon emissions. The TND was highest for (161)Tb in both mice and humans.

CONCLUSIONS

The results demonstrate that long-lived radionuclides, which emit electrons with rather low energy and which have low frequency of photon emissions, should be the preferred therapy for disseminated small sstr-expressing tumors.

A transplantable human carcinoid as model for somatostatin receptor-mediated and amine transporter-mediated radionuclide uptake

A human midgut carcinoid tumor was successfully transplanted into nude mice and propagated for five consecutive generations (30 months) with well-preserved phenotype. Tumor cells in nude mice expressed identical neuroendocrine markers as the original tumor, including somatostatin receptors (somatostatin receptors 1 to 5) and vesicular monoamine transporters (VMAT1 and VMAT2). Because of the expression of somatostatin receptors and VMAT1 and VMAT2 the grafted tumors could be visualized scintigraphically using the somatostatin analogue 111In-octreotide and the catecholamine analogue 123I-metaiodobenzylguanidine. The biokinetics of the somatostatin analogue 111In-octreotide in the tumors was studied and showed a high retention 7 days after administration. Cell cultures were re-established from transplanted tumors. Immunocytochemical and ultrastructural studies confirmed the neuroendocrine differentiation. The human origin of transplanted tumor cells was confirmed by cytogenetic and fluorescence it situ hybridization analyses. Spontaneous secretion of serotonin and its metabolite, 5-hydroxyindole acetic acid, from tumor cells was demonstrated. The tumor cells increased their [Ca2+]i in response to beta-adrenoceptor stimulation (isoproterenol) and K+-depolarization. All somatostatin receptor subtypes could be demonstrated in cultured cells. This human transplantable carcinoid tumor, designated GOT1, grafted to nude mice, will give unique possibilities for studies of somatostatin receptor- and VMAT-mediated radionuclide uptake as well as for studies of secretory mechanisms.

Biokinetics of 111In-DTPA-D-Phe(1)-octreotide in nude mice transplanted with a human carcinoid tumor

The long time biokinetics of the radiolabeled somatostatin analogues 111In-DTPA-D-Phe(1)-octreotide was studied in nude mice transplanted with the human carcinoid tumor, GOT1. The results were compared with those from the patient with the original tumor. This patient has been diagnosed and later treated with 111In-DTPA-D-Phe(1)-octreotide. The animals received about 2 MBq 111In-DTPA-D-Phe(1)-octreotide (0.1 microg) by injection into a tail vein. The animals were killed 0.5 h-14 d after injection of the radiopharmaceutical. Tumor tissue and normal tissues were collected and weighed and measured for 111In activity. The 111In uptake in the tumor was higher than in all normal tissues except the kidneys. The tumor-to-normal-tissue activity concentration, TNC, increased with time for all normal tissues studied. These data were similar to those observed for the original tumor in the patient. The similar biokinetics for 111In-DTPA-D-Phe(1)-octreotide in the tumor-bearing mice and the patient makes this animal model suitable as a model for evaluation of therapy of somatostatin receptor (sstr) expressing tumors with radiolabeled somatostatin analogues. Furthermore, the increase with time of TNC both in mice and the patient indicates that long-lived radionuclides are preferred for therapy with radiolabeled somatostatin analogues.

Floral ontogeny, pattern formation, and evolution in Hibbertia and Adrastaea (Dilleniaceae)

Floral development was compared with scanning electron microscopy in 12 Australian species of Hibbertia representing most of its morphological variation, and in the related Adrastaea (Dilleniaceae). Calyx and corolla arise in quincuncial helices in radially symmetrical species, while the petals initiate unidirectionally from one side in zygomorphic species. Stamen number (3-200+) proliferates by centrifugal addition of individual primordia or by innovations of common primordia and ring meristems. Common primordia arise in single-stamen positions alternately with petals, and each produces one to several stamens centrifugally that remain attached to a shared base and form a stamen fascicle. A ring meristem in Adrastaea initiates a whorl of five stamens, alternate with the first stamens but outside their whorl. In radially symmetrical species of Hibbertia, a first ring of stamens is supplemented centrifugally by additional stamens on a meristem ring. The first stamens in zygomorphic species of Hibbertia initiate as a terminal ridge on the floral apex, with subsequent stamens added centrifugally on one side and two carpels initiated on the opposite side. The carpels arise as a simultaneous ring in radially symmetrical flowers, or as a simultaneous pair in zygomorphic species. Staminodial presence is viewed as of minor significance. Four pollinator syndromes are proposed for Hibbertia, related to differing floral architecture.

111In-DTPA-D-Phe1-octreotide binding and somatostatin receptor subtypes in thyroid tumors

The purpose of this study was to evaluate the potential for therapy of thyroid tumors using the radiolabeled somatostatin (SS) analog octreotide.

METHODS

Concentrations of 111In activity in human thyroid tumors and normal thyroid tissue and blood samples were determined 1-15 d after intravenous injection of 111In-diethylenetriaminepentaacetic acid-Phe1-octreotide. The results were compared with SS receptor (sstr subtype profile (by Northern blot analysis) and the relative expression of the second subtype, sstr2 (by ribonuclease protection assay, RPA). The true tumor volumes in lymph node metastases from 1 patient were estimated. In total, tissues from 68 patients were included in the study.

RESULTS

The highest tumor-to-blood ratio (T/B) for medullary thyroid carcinoma (MTC) was 360; for follicular adenoma (FA), 190; for Hurthle cell adenoma (HCA), 140; and for Hurthle cell carcinoma (HCC) and papillary carcinoma (PC), 70. The corresponding value was 7-18 for normal thyroid tissue, with higher values for colloid goiter (8-48) and thyroiditis (7-120). A high T/B was related to a large fraction of tumor cells in lymph node metastases. T/Bs were higher for the tumor samples with expression of sstr2 at Northern blot analysis than for those without. All thyroid tumor types regularly expressed sstr1, sstr3, sstr4, and sstr5. sstr2 was expressed in most MTC tumors but was not detected in FA or PC and was irregularly expressed in HCA and HCC. However, RPA analysis detected sstr2 in all tumors studied.

CONCLUSION

Despite the lack of sstr2 at Northern blot analysis in most of the thyroid tumors studied, high T/Bs were in general found when compared with corresponding values for normal thyroid tissue. The sometimes extremely high ratios are promising and indicate a possibility of using radiolabeled octreotide for radiation therapy of sstr-positive tumors in the future.

114mIn, a candidate for radionuclide therapy: low-energy cyclotron production and labeling of DTPA-D-phe-octreotide

A method for production of carrier-free (114m)In (half-life 49.5 days), which is a potential radionuclide for radionuclide therapy of slowly growing tumors, is presented. A target consisting of five enriched cadmium ((114)Cd) foils, each 50 microm thick, was irradiated by protons (from 12.6-6.5 MeV) giving a target yield of 0. 8 MBq/microAh. A simple and cost-efficient thermal diffusion method was used for the separation. The irradiated target foils were heated for 2 h at 306 degrees C and then etched in 0.05 M HCl. The obtained cadmium/indium solution was purified using a cation ion-exchange resin (AG 1 x 8, Bio-Rad Laboratories, Hercules, CA USA). An overall yield of approximately 60% was obtained, whereas the loss of the target material was <1% per separation cycle. The (114m)In production gave (114m)In with high specific radioactivity and was successfully used to label diethylenetriamine pentaacetic acid (DTPA)-D-Phe-octreotide. Furthermore, no difference in biodistribution between [(114m)In]- and [(111)In]-DTPA-D-Phe(1)-octreotide in tumor-bearing nude mice was seen. The high radionuclide uptake in the tumors indicates a good receptor binding of the labeled octreotide.

Evaluation of three gamma detectors for intraoperative detection of tumors using 111In-labeled radiopharmaceuticals

Attempts to detect tumors with intraoperative scintillation using tumor-binding radiopharmaceuticals have intensified recently. In some cases previously unknown lesions were found, but in most cases no additional lesions were detected. In this study the physical characteristics of three detector systems and their ability to detect tumors through accumulation of an 111In-labeled radiopharmaceutical were investigated. The first was a sodium iodide (NaI[TI]) detector; the second, a cesium iodide (CsI[TI]) detector; and the third, a cadmium telluride (CdTe) detector.

METHODS

A body phantom and tumor phantoms (diameter 5-20 mm) made of water, agarose gel or epoxy with a density and attenuation coefficient similar to those of soft tissue were used to simulate a clinical situation. The activity concentration in the body phantom was based on reported values of 111In-octreotide in normal tissue in humans. The 111In activity concentration in the tumor phantoms varied from 3 to 80 times the 111In activity concentration in the body phantom. Data were processed to determine tumor detection levels.

RESULTS

The NaI(TI) detector showed the lowest values for full width at half maximum because this detector had the best collimation, leading to a high ratio between counts from tumor and counts from background, i.e., small tumors could be detected. Because of high efficiency, the CsI(TI) detector sometimes required a somewhat shorter acquisition time to produce a statistically significant difference between tumor phantom and background. For deep-lying tumors the NaI(TI) detector was superior, whereas the CdTe detector was best suited for superficial tumors with a high activity concentration in the underlying tissue.

CONCLUSION

At a maximum acquisition time of 30 s, almost all superficial tumors with a diameter of 10 mm or larger were detected if the ratio between the 111In concentration in the tumor and the 111In concentration in the background exceeded 3. However, in clinical situations, biologic variations in the uptake of 111In-octreotide in tumors and in normal tissue makes difficult the determination of a distinct detection level. For such clinical conditions, the NaI(TI) detector is the best choice because it has good resolution despite a lower efficiency. Documentation of detector characteristics is important so that clinicians can make an adequate device in relation to tumor location and receptor expression.

Multiple muscle force simulation in axial rotation of the cervical spine

OBJECTIVE

To produce axial rotation of the cervical spine in vitro by coordinated application of eight simulated muscle forces.

DESIGN

Biomechanical testing of the cervical spine by controlled pneumatics.

BACKGROUND

Some muscle simulation experiments have been performed in vitro in the lumbar spine but data generally are lacking for this testing mode in the cervical spine. Thus, physiological biomechanical behavior in this region remains poorly understood.

METHODS

Six human donor cervical spines were loaded by a set of computer-controlled pneumatic cylinders representing pairs of trapezius, splenius and sternocleiodmastoid muscles, plus longus and splenius colli left. Muscle functions were derived from a previously-developed mathematical optimization model. Muscle forces generally were achievable within 2 N of the intended values provided by the model.

RESULTS

Rotation of the head followed fairly closely that predicted by the model. The resulting force components to produce 37 degrees were dominated by axial compression of about--100 N and the resulting moments were similar in all planes at about 2 Nm. Coupled motions were larger than primary motions in some intersegmental behavior.

CONCLUSIONS

Slow, physiologic axial rotation of the head may be simulated by a complex and representative series of controlled pneumatics. Controlled rotation results in a relatively high compressive force and occurs through fairly balanced and small moments.

RELEVANCE

Experimental approaches in biomechanics are generally limited to one or two simplified muscle forces whose representation of in vivo loading conditions can only be presumed. Improvements in the application of pneumatic technology are a promising approach to more thoroughly duplicating the physiological loading environment.

Relevance of macro creatine kinase type 1 and type 2 isoenzymes to laboratory and clinical data

From 8322 patients for whom creatine kinase (CK; EC 2.7.3.2) isoenzyme analysis was ordered, we identified 136 patients with macro CK isoenzyme in their serum. There were 36 cases with type 1 (prevalence: 0.43%) and 100 cases with type 2 isoenzyme (prevalence: 1.20%). About three-fourths of the patients were ambulatory at the time of testing, and approximately 90% of the first 68 patients identified survived at least 1 year after macro CK was found in their serum. Age and gender did not differ significantly between the two groups. The serum total CK was significantly higher (P < 0.0005), and an increased CK-MB proportion (> 0.05 of total CK) was also significantly more common (P < 0.0005) in patients with macro CK type 1 than in those with type 2. On average, macro CK type 2 accounted for approximately 25% and macro CK type 1 for approximately 10% of the serum total CK activity. Patients with macro CK type 1 most often had myositis, whereas those with macro CK type 2 most commonly had a malignancy. We conclude that the presence of macro CK isoenzymes has a low prognostic value for impending death, but may support the diagnosis of an autoimmune process (type 1) or malignant cell proliferation (type 2).

Relevance of macro creatine kinase type 1 and type 2 isoenzymes to laboratory and clinical data

From 8322 patients for whom creatine kinase (CK; EC 2.7.3.2) isoenzyme analysis was ordered, we identified 136 patients with macro CK isoenzyme in their serum. There were 36 cases with type 1 (prevalence: 0.43%) and 100 cases with type 2 isoenzyme (prevalence: 1.20%). About three-fourths of the patients were ambulatory at the time of testing, and approximately 90% of the first 68 patients identified survived at least 1 year after macro CK was found in their serum. Age and gender did not differ significantly between the two groups. The serum total CK was significantly higher (P &lt; 0.0005), and an increased CK-MB proportion (&gt; 0.05 of total CK) was also significantly more common (P &lt; 0.0005) in patients with macro CK type 1 than in those with type 2. On average, macro CK type 2 accounted for approximately 25% and macro CK type 1 for approximately 10% of the serum total CK activity. Patients with macro CK type 1 most often had myositis, whereas those with macro CK type 2 most commonly had a malignancy. We conclude that the presence of macro CK isoenzymes has a low prognostic value for impending death, but may support the diagnosis of an autoimmune process (type 1) or malignant cell proliferation (type 2).