Inverting the Electronic Structure of Diylidylgermylenes by Backbone Modification

Owing to the strong electron-donating ability of ylide substituents, diylidyltetrylenes are usually highly nucleophilic species with strong donor capacities. Here, we demonstrate that their electronic properties are in fact highly flexible and can be effectively tuned through variation of the substituent in the ylide backbone. Initial density functional theory studies showed that cyano groups are particularly capable in lowering the LUMO energy of diylidyl germylenes thus turning these usually highly nucleophilic species into electrophilic compounds. This was confirmed by experimental studies. Attempts to synthesize the germylene (YCN)2Ge [with YCN = Ph3P-(C)-CN] from the corresponding metalated ylides YCNK selectively led to germanide [(YCN)3Ge)K]2 thus reflecting the electrophilic nature of the intermediate formed germylene. XRD analysis of single crystals of (YCN)2Ge - serendipitously obtained through protonative cleavage of one ylide from the germanide - revealed a monomeric structure with rather long Ge-ylide linkages, which corroborates well with a pure single bond and no stabilization of the empty pπ orbital at germanium through pi bonding. The germanide exhibits methanide-like reactivity towards chalcogens but a likewise weak Ge-C bond as demonstrated by the insertion of carbon dioxide.

Thiophosphinoyl-Tethered Ylide-Substituted Heavier Carbenes: Synthesis, Structures and Stabilities

The synthesis and structure analysis of a series of mono and diylide-substituted tetrylenes of type YEX and Y₂ E (E=Ge, Sn, Pb; X=Cl or Br) using a thiophosphinoyl-tethered metallated ylide (Y=Ph₂ P(S)-C-P(pip)Ph₂ with pip=piperidyl) is reported, amongst the first ylide-substituted plumbylenes. The tetrylenes feature distinct trends in the spectroscopic and structural properties of the ylide ligand with increasing atomic number of the tetrel element. For instance, an increasingly high-field shifted signal for the thiophosphinoyl group is observed in the ³¹ P{¹ H} NMR spectrum as a consequence of the increasing polarity of the element-carbon bond, which likewise results in a shortening of the ylidic C-P bond in the solid-state structure. The diylidyltetrylenes are unstable towards transylidation forming the mono(ylide)tetrylenes when treated with the tetrel dihalides according to the stability trend: Y₂ Pb<Y₂ Sn<Y₂ Ge<YPbBr<YSnCl<YGeCl. Starting from the monoylide-substituted chlorotertrylenes the first unsymmetrical diylidyltetrylenes of type YEY' can be accessed, whose solid-state structures revealed that not the C-E but the S-E bond to the thiophosphinoyl group is most affected by the second ylide substituent.

Ylide-stabilized phosphenium cations: Impact of the substitution pattern on the coordination chemistry

Although N‐heterocyclic phosphenium (NHP) cations have received considerable research interest due to their application in organocatalysis, including asymmetric synthesis, phosphenium cations with other substitution patterns have hardly been explored. Herein, the preparation of a series of ylide‐substituted cations of type [YPR]⁺ (with Y=Ph₃PC(Ph), R=Ph, Cy or Y) and their structural and coordination properties are reported. Although the diylide‐substituted cation forms spontaneous from the chlorophosphine precursor, the monoylidylphosphenium ions required the addition of a halide‐abstraction reagent. The molecular structures of the cations reflected the different degrees of electron donation from the ylide to the phosphorus center depending on the second substituent. Molecular orbital analysis confirmed the stronger donor properties of the ylide systems compared to NHPs with the mono‐ylide substituted cations featuring a more pronounced electrophilicity. This was mirrored by the reaction of the cations towards gold chloride, in which only the diylide‐substituted cation [Y₂P]⁺ formed the expected LAuCl]⁺ complex, while the monoylide‐substituted compounds reacted to the chlorophosphine ligands by transfer of the chloride from gold to the phosphorus center. These results demonstrate the tunability of ylide‐functionalized phosphorus cations, which should allow for further applications in coordination chemistry in the future.

Single‐Site and Cooperative Bond Activation Reactions with Ylide‐Functionalized Tetrylenes: A Computational Study

Due to their transition metal‐like behavior divalent group 14 compounds bear huge potential for their application in bond activation reactions and catalysis. Here we report on detailed computational studies on the use of ylide‐substituted tetrylenes in the activation of dihydrogen and phenol. A series of acyclic and cyclic ylidyltetrylenes featuring various α‐substituents with different σ‐ and π‐donating capabilities have been investigated which demonstrate that particularly π‐accepting boryl groups lead to beneficial properties and low barriers for single‐site activation reactions, above all in the case of silylenes. In contrast, for the thermodynamically more stable germylenes and stannylenes an alternative mechanism involving the active participation of the ylide ligand in the E−H bond (E=H or PhO) activation process by addition across the element carbon linkage was found to be energetically favored. Furthermore, the boryl substituted tetrylenes allowed for a further activation pathway involving the active participation of the boron element bond. These cooperative mechanisms are especially attractive for the heavier cyclic ylidyltetrylenes in which the loss of the protonated ylide group is prevented due to the cyclic framework. Overall, the present studies suggest that cyclic ylide‐substituted germylenes and stannylenes bear huge potential for cooperative bond activations at mild conditions which should be experimentally addressed in the future.

Towards the rational design of ylide-substituted phosphines for gold(i)-catalysis: from inactive to ppm-level catalysis

The implementation of gold catalysis into large-scale processes suffers from the fact that most reactions still require high catalyst loadings to achieve efficient catalysis thus making upscaling impractical. Here, we report systematic studies on the impact of the substituent in the backbone of ylide-substituted phosphines (YPhos) on the catalytic activity in the hydroamination of alkynes, which allowed us to increase the catalyst performance by orders of magnitude. While electronic changes of the ligand properties by introduction of aryl groups with electron-withdrawing or electron-donating groups had surprisingly little impact on the activity of the gold complexes, the use of bulky aryl groups with ortho-substituents led to a remarkable boost in the catalyst activity. However, this catalyst improvement is not a result of an increased steric demand of the ligand towards the metal center, but due to steric protection of the reactive ylidic carbon centre in the ligand backbone. The gold complex of the thus designed mesityl-substituted YPhos ligand Y_MesPCy₂, which is readily accessible in one step from a simple phosphonium salt, exhibited a high catalyst stability and allowed for turnover numbers up to 20 000 in the hydroamination of a series of different alkynes and amines. Furthermore, the catalyst was also active in more challenging reactions including enyne cyclisation and the formation of 1,2-dihydroquinolines.

Cationic Phosphorus Compounds Based on a Bis(1-piperidinyl)-Substituted Carbodiphosphorane: Syntheses, Structures, and Csp3–H Activation

The use of the bis(1-piperidinyl)-substituted carbodiphosphorane (Ph₂(Pip)P)₂C (1) as an NCN ligand for the stabilization of phosphorus cations was studied. A simple ligand for halide exchange allowed the synthesis and isolation of a series of phosphorus monocations of the type [1-PR₂]⁺ (with R = Cl, Br, I, CyCl, Ph). These cations exhibit characteristic NMR and structural properties which nicely correlate with the charge at the central phosphorus atom and the interaction between the ligand and the PR₂ moiety. Halide abstraction from the monocations does not result in isolable dicationic compounds but in an unexpected intramolecular C_sp³–H activation in the piperidinyl group. DFT studies show that the selective activation of the CH₂ group next to the nitrogen atom instead of a CH group at the phenyl substituents proceeds via an iminium intermediate formed by hydride transfer from the carbon atom to the cationic phosphorus center. This observation clearly demonstrates the pronounced π acidity of the dicationic phosphorus species in comparison to compounds with a further π-donor substituent.

Synthesis of Low-Valent Dinuclear Group 14 Compounds with Element-Element Bonds by Transylidation

Dinuclear low-valent compounds of the heavy main group elements are rare species owing to their intrinsic reactivity. However, they represent desirable target molecules due to their unusual bonding situations as well as applications in bond activations and materials synthesis. The isolation of such compounds usually requires the use of substituents that provide sufficient stability and synthetic access. Herein, we report on the use of strongly donating ylide-substituents to access low-valent dinuclear group 14 compounds. The ylides not only impart steric and electronic stabilization, but also allow facile synthesis via transfer of an ylide from tetrylene precursors of type R Y2 E to ECl2 (E=Ge, Sn; R Y=TolSO2 (PR3 )C with R=Ph, Cy). This method allowed the isolation of dinuclear complexes amongst a germanium analogue of a vinyl cation, [(Ph Y)2 GeGe(Ph Y)]+ with an electronic structure best described as a germylene-stabilized GeII cation and a ylide(chloro)digermene [Cy Y(Cl)GeGe(Cl)Cy Y] with an unusually unsymmetrical structure.

Efficient Pd-Catalyzed Direct Coupling of Aryl Chlorides with Alkyllithium Reagents

Organolithium compounds are amongst the most important organometallic reagents and frequently used in difficult metallation reactions. However, their direct use in the formation of C-C bonds is less established. Although remarkable advances in the coupling of aryllithium compounds have been achieved, Csp2 -Csp3 coupling reactions are very limited. Herein, we report the first general protocol for the coupling or aryl chlorides with alkyllithium reagents. Palladium catalysts based on ylide-substituted phosphines (YPhos) were found to be excellently suited for this transformation giving high selectivities at room temperature with a variety of aryl chlorides without the need for an additional transmetallation reagent. This is demonstrated in gram-scale synthesis including building blocks for materials chemistry and pharmaceutical industry. Furthermore, the direct coupling of aryllithiums as well as Grignard reagents with aryl chlorides was also easily accomplished at room temperature.

A diamino-substituted carbodiphosphorane as strong C-donor and weak N-donor: isolation of monomeric trigonal-planar L·ZnCl2

The isolation, structural characterization and coordination chemistry of a di(amino)-substituted carbodiphosphorane (CDP) are reported. Compared to the analogue, dianionic bis(iminophosphoryl)methandiides, the CDP is a stronger C-, but much weaker N-donor which led to the isolation of solely C-coordinated metal complexes amongst an unusual monomeric trigonal-planar L·ZnCl₂ complex.

Towards the Preparation of Stable Cyclic Amino(ylide)Carbenes

Cyclic amino(ylide)carbenes (CAYCs) are the ylide-substituted analogues of N-heterocyclic Carbenes (NHCs). Due to the stronger π donation of the ylide compared to an amino moiety they are stronger donors and thus are desirable ligands for catalysis. However, no stable CAYC has been reported until today. Here, we describe experimental and computational studies on the synthesis and stability of CAYCs based on pyrroles with trialkyl onium groups. Attempts to isolate two CAYCs with trialkyl phosphonium and sulfonium ylides resulted in the deprotonation of the alkyl groups instead of the formation of the desired CAYCs. In case of the PCy₃-substituted system, the corresponding ylide was isolated, while deprotonation of the SMe₂-functionalized compound led to the formation of ethene and the thioether. Detailed computational studies on various trialkyl onium groups showed that both the α- and β-deprotonated compounds were energetically favored over the free carbene. The most stable candidates were revealed to be α-hydrogen-free adamantyl-substituted onium groups, for which β-deprotonation is less favorable at the bridgehead position. Overall, the calculations showed that the isolation of CAYCs should be possible, but careful design is required to exclude decomposition pathways such as deprotonations at the onium group.

Teaching c-phosphanylimines the titanaaziridine coordination mode

The employment of a c-phosphanylimine for the synthesis of a novel titanaaziridine with an intramolecular phosphine donor side is reported, thus teaching the c-phosphanylimine a new coordination mode.

First catalyst-free CO2 trapping of N-acyliminium ions under ambient conditions: sustainable multicomponent synthesis of thia- and oxazolidinyl carbamates

The first trapping of N-acyliminium ions by in situ generated carbaminic acid (product of carbon dioxide (CO2) and amine) is reported. This catalyst-free reaction provides a convenient and feasible approach to prepare N-acyl thia- and oxazolidinyl carbamates with good functional-group compatibility and high efficiency under green conditions. Furthermore, the multicomponent method features a broad substrate scope, facile product diversification, smooth scale-up and notable potential for polymer applications.

The influence of sentinel lymph node tumour burden on additional lymph node involvement and disease-free survival in cutaneous melanoma--a retrospective analysis of 392 cases

Twenty per cent of sentinel lymph node (SLN)-positive melanoma patients have positive non-SLN lymph nodes in completion lymph node dissection (CLND). We investigated SLN tumour load, non-sentinel positivity and disease-free survival (DFS) to assess whether certain patients could be spared CLND. Sentinel lymph node biopsy was performed on 392 patients between 1999 and 2005. Median observation period was 38.8 months. Sentinel lymph node tumour load did not predict non-SLN positivity: 30.8% of patients with SLN macrometastases (> or =2 mm) and 16.4% with micrometastases (< or =2 mm) had non-SLN positivity (P=0.09). Tumour recurrences after positive SLNs were more than twice as frequent for SLN macrometastases (51.3%) than for micrometastases (24.6%) (P=0.005). For patients with SLN micrometastases, the DFS analysis was worse (P=0.003) when comparing those with positive non-SLNs (60% recurrences) to those without (17.6% recurrences). This difference did not translate into significant differences in DFS: patients with SLN micrometastasis, either with (P=0.022) or without additional positive non-SLNs (P<0.0001), fared worse than patients with tumour-free SLNs. The 2-mm cutoff for SLN tumour load accurately predicts differences in DFS. Non-SLN positivity in CLND, however, cannot be predicted. Therefore, contrary to other studies, no recommendations concerning discontinuation of CLND based on SLN tumour load can be deduced.

Baseline staging in cutaneous malignant melanoma

BACKGROUND

Baseline staging in patients with primary cutaneous malignant melanoma (MM) is routine, but the diagnostic accuracy and the impact on clinical outcome are still unclear.

OBJECTIVES

To evaluate the sensitivity and specificity of baseline staging in the early detection of regional lymph node metastases or distant metastases in patients with MM.

METHODS

One hundred consecutive patients with MM of Breslow's tumour thickness over 1.0 mm were enrolled. All patients had an extensive baseline staging including physical examination, ultrasound (US) of the abdomen and regional lymph nodes, chest X-ray, whole-body positron emission tomography (PET) and sentinel lymph node biopsy. The sensitivity and specificity of detection of macroscopic or microscopic metastases in the regional lymph nodes or at distant sites were calculated for each method.

RESULTS

Sentinel lymph node biopsy was positive in 26 patients. US detected two of 26 histologically tumour-positive sentinel nodes (sensitivity 8%, specificity 88%) and PET two of 26 (sensitivity 8%; specificity 100%). There were three lymph node metastases with a diameter > 4 mm. All of them were found suspect at physical examination. Two of them were detectable with US, two with PET, and all were identified with either US or PET. Nine patients had suspect findings at distant sites, which were all false positive on further investigation (specificity of the combined staging procedures 91%). At 18 (6-37) months' follow-up, five of 26 (19%) patients with a positive sentinel node and four of 74 (5%) of patients with a negative sentinel node had recurrent or progressive disease.

CONCLUSIONS

The combination of physical examination and lymph node US detects the great majority of patients with macroscopic lymph node metastasis (approximately 3% of patients at baseline). Only 10% of patients who have a histologically tumour-positive sentinel node are macroscopically detectable. Altogether, approximately 25% of patients have a positive sentinel node biopsy, among 90% microscopic. The value of whole body staging at baseline remains limited, since distant metastases can hardly ever be detected. The survival benefit of baseline staging and surveillance in patients with cutaneous MM remains to be established by comparative prospective trials.

Sentinel lymph node evaluation in squamous cell carcinoma of the head and neck

OBJECTIVE

The aim of our study was to assess the feasibility of sentinel lymph node (SLN) radiolocalization in N0 neck in squamous cell head and neck carcinoma and its predictive value for occult metastasis.

STUDY DESIGN

Nineteen patients of an open prospective trial.

SETTING

After peritumoral injection of a 99m Tc labeled radiocolloid, the SLN was localized preoperatively by lymphoscintigraphy and intraoperatively through the intact skin by a hand-held gamma-probe. The histology of the SLN and the nodes of the elective neck dissection were compared.

RESULTS

Localization of the SLN by lymphoscintigraphy was possible in 18 of 19, and with the hand-held gamma-probe in all 19 patients. Six SLN revealed occult metastatic disease. No skip metastasis were found in the 13 neck specimen with negative SLN.

CONCLUSION

SLN evaluation in N0 neck in squamous cell carcinoma of the head and neck is accurately feasible and seems to adequately predict the presence of occult metastasis.

Body composition abnormalities in children with Prader-Willi syndrome and long-term effects of growth hormone therapy

Obesity and hypothalamic GH deficiency contribute in different ways to the disturbances of body composition in Prader-Willi syndrome (PWS); while both increase the fat compartment, the reduction of lean tissue mass has been attributed mainly to GH deficiency. Therefore, body composition measured by dual-energy X-ray absorptiometry was prospectively studied in 12 overweight children with PWS and weight for height (WfH) SDS >0 before and during 3.5 years of treatment with hGH (0.037 mg/kg/day) on average. In the long term, there is a net reduction of body fat from 3.1 to 1.2 SD, with a minimum at the end of the second year of treatment. WfH SDS correctly reflects body fat mass and its changes. The initial deficit of lean mass (-1.6 SD) is counteracted by GH only during the first year of therapy (increase to -1.25 SD). But in the long term, GH therapy does not further compensate for this deficit, when lean mass is corrected for its growth-related increase. In conclusion, exogenous GH changes the phenotype of children with PWS: fat mass becomes normal, but, at least in the setting studied, GH is not sufficient to normalize lean tissue mass.

Cardiovascular risk factors improve during 3 years of growth hormone therapy in Prader-Willi syndrome

Cardiovascular risk factors in Prader-Willi syndrome (PWS, OMIM 176270) may be independently caused by overweight or hypothalamic growth hormone (GH) deficiency. The present observational study in 23 children with PWS, aged 0.3-14.6 years, focuses on the specific pattern, age-dependency and interrelation of cardiovascular risk factors, namely percentage fat mass and regional fat distribution, triglycerides (TG), lipoprotein cholesterols (LDL-C, HDL-C), lipoprotein (a) (Lp(a)), apolipoproteins A-I (Apo A-I) and B (Apo B), as well as on the longer-term effects of GH therapy (ca. 0.037 mg/kg per day for 3 years on average). We report that in children above 4 years, percentage body fat was increased in all and waist-to-hip-ratio (WHR) in 35%. Abnormal levels of LDL-C, Apo B, HDL-C and TG were found in 6, 7, 6 and 3 children, respectively. Lp(a) was above 300 mg/l in 5 patients and remained unchanged during GH therapy. However, percentage fat mass dropped to the upper normal range and WHR became normal in all patients receiving GH therapy, as did the ratio of LDL-C to HDL-C, subsequent to decreasing LDL-C and increasing HDL-C. Nevertheless, we could not find any significant correlation between parameters of total fat mass or fat distribution and serum lipid parameters, except for abdominal fat distribution (trunk-/leg-fat ratio) to TG before therapy.

CONCLUSION

Several cardiovascular risk factors are already present in prepubertal children with Prader-Willi-syndrome and they are improved by growth hormone treatment, acting both on body composition and lipid metabolism.

Prevention of osteoporosis in heart transplant recipients: a comparison of calcitriol with calcitonin and pamidronate

Bone loss and osteoporotic fractures are common in cardiac transplant recipients. To compare two prophylactic medical regimens after heart transplantation, 26 consecutive heart transplant recipients were randomized to receive either continuous oral calcitriol (0.5 microg/day) combined with nasal salmon calcitonin (200 U/day) for the first 3 months (group A) or intermittent intravenous pamidronate (0.5 mg/kg body weight) every third month (group B). Bone mineral density (BMD) and biochemical indices of bone turnover were measured at baseline and 3, 6, 12, and 18 months after transplantation. The mean pretransplant BMD, measured by dual energy X-ray absorptiometry (DXA) was significantly lower in the patients compared with age-matched healthy controls. During the first year of treatment, rates of bone loss at the lumbar spine and femoral neck were slightly but significantly slower in the patients treated with pamidronate, but there was no longer a significant difference between the two groups after 18 months of heart transplantation. Irrespective of the mode of osteoporosis prevention, osteocalcin levels increased whereas urinary deoxypyridinoline decreased after transplantation, and significant bone loss was observed in both treatment groups. We found no relationship between initial BMD, markers of bone turnover, cumulative glucocorticoid dose, or cyclosporine levels and the rate of bone loss after cardiac transplantation. In summary, we found that the rapid and severe bone loss following heart transplantation could be attenuated by two preventive measures, pamidronate or calcitriol with calcitonin.

Myocardial ischaemia in children with isolated ventricular non-compaction

AIMS

Isolated ventricular non-compaction is a rare congenital cardiomyopathy with a high morbidity and mortality due to malignant arrhythmias and pump failure. Areas affected by non-compaction are characterized by increased trabecularization and deep inter-trabecular spaces. We hypothesized perfusion defects in these areas and performed positron emission tomography to evaluate the myocardial perfusion in non-compacted areas.

METHODS AND RESULTS

Five children (age 10-14 years) with isolated ventricular non-compaction underwent positron emission tomography using N-13-ammonia as flow marker and intravenous dipyridamole for stress testing. Myocardial blood flow was quantified using the positron emission tomography time-activity curves in non-compacted areas and normal myocardium, which were diagnosed by echocardiography, magnetic resonance imaging, and angiography. Coronary angiography, performed in two children with extensive forms of left ventricular non-compaction, demonstrated normal coronary arteries. Myocardial blood flow measurements at rest and after dipyridamole application demonstrated 16-33% and 32-57% perfusion impairment, respectively, in non-compacted areas compared to normal myocardium. Areas of restricted myocardial perfusion corresponded well to the non-compacted areas, defined echographically and by magnetic resonance imaging.

CONCLUSION

Positron emission tomography demonstrates restricted myocardial perfusion and decreased flow reserve in areas of ventricular non-compaction in children. The myocardial perfusion defects in non-compacted areas may be the cause of myocardial damage and possibly form the basis of arrhythmias and pump failure.

Radiographically negative stress related bone injury. MR imaging versus two-phase bone scintigraphy

PURPOSE

To assess the diagnostic value of MR imaging relative to two-phase bone scintigraphy in radiographically negative stress-related injuries.

MATERIAL AND METHODS

Sixteen consecutive patients presenting with stress-related bone injuries and normal standard radiographs were examined with two-phase bone scans and MR imaging. MR imaging protocols varied according to the region to be examined. The MR and scintigraphic images were evaluated blindly and separately by respectively two radiologists and two nuclear medicine physicians. The standard of reference was represented by a combination of clinical and scintigraphic findings as well as clinical follow-up.

RESULTS

For MR imaging, sensitivity, specificity, and positive and negative predictive values for the presence of stress-related injuries for the two readers were 69/63%, 100/80%, 100/91%, and 50/40%, respectively. Interobserver agreement was good (kappa = 0.62). For scintigraphy, all abnormal and normal findings were correctly identified.

CONCLUSION

For patients with clinically suspected stress-related injuries and a low probability of other active bone diseases (such as infection or neoplasm), bone scintigraphy should be the initial imaging modality.

Treatment with human growth hormone in patients with Prader-Labhart-Willi syndrome reduces body fat and increases muscle mass and physical performance

Twelve children with documented Prader-Labhart-Willi syndrome were treated with human growth hormone (24 U/m2/week) during 1 year. The children were divided into three groups: group 1: overweight and prepubertal (n=6, age 3.8-7.0 years); group 2: underweight and prepubertal (n=3, age 0.6-4.1 years); group 3: pubertal (n=3, age 9.2-14.6 years). In group 1, height increased from -1.7 SD to -0.6 SD, while weight decreased from 1.1 SD to 0.4 SD, with a dramatic drop in weight for height from 3.8 SD to 1.2 SD. Hand length increased from -1.5 SD to -0.4 SD and foot length from -2.5 SD to -1.4 SD. Body fat, measured by dual X-ray energy absorptiometry, dropped by a third, whereas muscle mass increased by a fourth. Physical capability (Wingate test) improved considerably. The children were reported to be much more active and capable. In group 2, similar changes were seen, but weight for height increased, probably because muscle mass increase exceeded fat mass decrease. Changes in group 3 were similar as in group 1, even though far less distinct.

CONCLUSION

Growth hormone treatment in Prader-Labhart-Willi syndrome led to dramatic changes: distinct increase in growth velocity, height and muscle mass, as well as an improvement in physical performance. Fat mass and weight for height decreased in the initially overweight children, and weight for height increased in underweight children.

Effect of 6 months of growth hormone treatment in young children with Prader-Willi syndrome

Nine prepubertal children with Prader-Willi syndrome were treated with growth hormone (GH; 24 IU/m2/week) for 6 months. Mean height increased by 0.8 SD and mean weight for height decreased by 0.7 SD over this 6-month treatment period. Body fat, measured by dual-energy X-ray absorptiometry, decreased by 22.5% over the period of GH treatment, whereas fat-free mass increased by 14%. These preliminary results indicate that GH is effective in increasing height and normalizing body composition in patients with Prader-Willi syndrome.

Radioiodine-labelled alpha-methyl-tyrosine in malignant melanoma: cell culture studies and results in patients

Tyrosine is a precursor of melanin synthesis and might thus present a valuable marker for melanoma. The aim of this study was to evaluate the uptake of alpha-methyl-tyrosine (AMT) in melanoma cell cultures and to assess its usefulness as a radiopharmaceutical for staging melanoma patients with whole-body scintigraphy. Melanoma (M19-cell lines) and fibroblast (negative control) cell cultures were incubated with 125I-AMT and the radioactive uptake in the cell lines was measured in a gamma-counter over 24 h. For in vivo studies, planar whole-body scintigraphy and single photon emission computed tomography (SPECT) of the tumour region was performed following injection of 250-350 MBq 123I-AMT in six patients with known melanoma metastases. Findings were compared with results of whole-body positron emission tomography using 18F-fluorodeoxyglucose (FDG-PET) as a standard of reference. Fibroblasts showed an unchanged uptake of (mean +/- SD) 0.56 +/- 0.09% 15 min and 0.066 +/- 0.09% 24 h, respectively, after incubation of 125I-AMT, whereas there was an increased uptake in melanoma cell cultures over time from 0.9 +/- 0.05% to 7.5 +/- 1.6%. In staging melanoma patients, the sensitivity of whole-body AMT-scintigraphy compared with FDG-PET was 37% (10 of 27 metastases). AMT is transported and metabolized to a high extent in melanoma cells and 123I-AMT is accumulated in melanoma metastases. Owing to its low sensitivity, however, the clinical use of whole-body AMT scintigraphy cannot be recommended.

[123I-alpha-methyltyrosine scintigraphy in malignant melanoma]

AIM

The aim of the study was to evaluate the ranking of the scintigraphy with L-3-123I-alpha-methyltyrosine (123I-AMT) in metastasized melanoma.

METHODS

26 metastases and one primary tumor of a malignant melanoma in six patients were examined with 123I-AMT whole-body scintigraphy and SPECT. Positron Emission Tomography with 2-18F-fluoro-2-desoxy-D-glucose (18F-FDG) was used as the golden standard.

RESULTS

With 123I-AMT-SPECT 8/10 metastases in the thorax > 1.6 cm were detected (ratio T/NT 1.2-1.8), metastases < 1.6 cm were not detectable with SPECT. In 123I-AMT whole-body scintigraphy not one lesion showed a positive tumor uptake.

CONCLUSION

In single cases 123I-AMT scintigraphy can be helpful in staging of malignant melanoma.

Octreotide scintigraphy and catecholamine response to an octreotide challenge in malignant phaeochromocytoma

OBJECTIVE

Octreotide scintigraphy has been reported to visualize chromaffine tumours. This study in patients with malignant phaeochromocytoma was designed to assess octreotide in comparison with standard m-iodobenzylguanidine (MIBG) scintigraphy and to study functional activity of somatostatin receptors. Finally, two cases of octreotide treatment are reported.

DESIGN

Open, prospective clinical trial.

PATIENTS

In 12 patients with histologically proven malignant phaeochromocytoma, 111In-octreotide scintigraphy, 123I-MIBG scintigraphy and computed tomography were performed. In ten patients plasma catecholamine response to a single dose of octreotide (200 micrograms i.v.) was monitored up to 5 hours after injection. Two patients were treated with octreotide over several months.

MEASUREMENTS

Plasma catecholamines were measured by high performance liquid chromatography (HPLC). Scintigraphy was performed using a large field gamma camera and SPECT technique where appropriate.

RESULTS

At least one metastatic lesion was visualized by octreotide scintigraphy in eight patients while the remaining four patients had negative findings. In total, 43 out of 54 known metastases (79.6%) were detected by MIBG, 24 (44.4%) by octreotide. Nevertheless, octreotide scintigraphy detected six metastases that were negative by MIBG. There was no correlation between the results of octreotide scintigraphy and catecholamine suppression after i.v. octreotide. In two patients on octreotide treatment, symptomatic improvement, but not mass reduction, could be documented.

CONCLUSIONS

Octreotide scintigraphy behaves in part complementary to MIBG, thus, increasing diagnostic sensitivity. Presence of somatostatin receptors, as demonstrated by octreotide scintigraphy, does not necessarily predict functional activity or therapeutic response.

Malignant blue naevus with distant subcutaneous metastasis

Malignant blue naevus is a distinct but rarely documented variant of malignant melanoma, and we describe the triple recurrence of a suprapatellar cellular blue naevus over 12 years in a middle-aged woman. Staging investigations revealed a distant subcutaneous metastasis of the right thigh. Immunohistochemistry of the primary lesion and all recurrences showed S-100, HMB-45, NKI/C-3 and Ki-67 positive cells. However, non-malignant cellular blue naevi from five consecutive other patients were all Ki-67 negative. The change from negative to positive Ki-67 responsivity may therefore be a valuable marker of malignant and metastatic potential in early cellular blue naevi.

[Bone density and laboratory parameters of bone metabolism in patients with terminal heart disease]

PURPOSE

The purpose of this study was to assess bone mineral density (BMD) and parameters for bone metabolism in patients with end-stage heart disease awaiting heart transplantation to determine whether these patients are at increased risk of bone disease.

PATIENTS AND METHODS

39 adult men (mean age 52.3, range 21-65 years) with ischemic (41%), idiopathic (43.5%), valvular (2.5%) and diverse (13%) end-stage heart disease were studied prior to heart transplantation. BMD was measured using dual-energy x-ray absorptiometry at the lumbar spine (L2-L4) and at the upper femur (Ward's triangle and femoral neck). Renal and bone biochemical profiles, parathyroid hormone (PTH), 25-OH-vitamin D3, testosterone, alkaline bone phosphatase, osteocalcin, and deoxypyridinoline and calcium excretion were measured.

RESULTS

No fractures were found. Mean z-scores were -1.06 +/- 2.02 (mean +/- SD) at the lumbar spine, -1.12 +/- 2.03 at the femoral neck and -0.25 +/- 1.06 at Ward's triangle. Significantly decreased values were seen at the lumbar spine and at the femoral neck compared to age matched healthy controls. Mean values of serum creatinine and parathyroid hormone were elevated (114.4 +/- 29.5 mumol/l and 84.3 +/- 67.8 ng/l, respectively). 7 (18%), 10 (26%) and 22 (56%) of the 39 patients had values beneath the normal range of 25-OH-vitamin D3, testosterone and osteocalcin respectively. Mean urinary deoxypyridinoline/creatinine ratios were elevated (9.46 +/- 8.52 nmol/mmol, normal range 2.5-5). No correlation existed between osteocalcin and urinary deoxypyridinoline/creatinine ratio. Using a multiple linear regression model, serum PTH and cardiac ejection fraction (EF) weakly predicted BMD at the femoral neck (r2 = 0.26).

CONCLUSIONS

(1.) Lumbar spine and femoral neck BMD are low in patients awaiting heart transplantation. (2.) A low EF and a high PTH weakly correlate with a decrease in BMD at the femoral neck. (3.) In patients with end-stage heart failure the coupling of bone formation to bone resorption is frequently disturbed. (4.) Testosterone and 25-OH-vitamin D3 levels are low in a number of patients and in such cases replacement therapy may be appropriate.

[The value of 3-phase skeletal scintigraphy for early diagnosis of Sudeck disease]

PURPOSE

In a prospective study the value of the three-phase bone scintigraphy in the early diagnosis of Sudeck's atrophy was analysed.

MATERIAL AND METHODS

137 patients with the clinical suspicion on Sudeck's atrophy in stage I were examined. By means of the clinical course and additional examinations (block response), pain experts confirmed the diagnosis separately.

RESULTS

With the findings of hyperperfusion of all 5 phalanges, homogeneous hyperaemia of the affected hand or the foot and periarticular increased uptake of the whole extremity a reliable diagnosis of Sudeck's atrophy was possible. The sensitivity was 95.9%, the specificity 100%. With bone scintigraphy Sudeck's atrophy could be clearly differentiated from an inactivity atrophy.

CONCLUSION

Three-phase bone scintigraphy is an excellent tool for the objective diagnosis of Sudeck's atrophy in stage I.

Whole-body PET: physiological and artifactual fluorodeoxyglucose accumulations

The purpose of this study was to semiquantitatively identify artifactual and physiological soft-tissue accumulations in whole-body FDG-PET scans with the aim of defining their frequency and anatomic distribution.

METHODS

Fifty whole-body FDG-PET scans performed for the staging of malignant melanoma were obtained from transaxial scans and reconstructed without absorption correction by filtered backprojection in the form of coronal and sagittal sections. The patients were asked to stay n.p.o. for at least 4 hr and interrogated about their physical activity prior to injection and until scanning. Classification of FDG organ accumulations was done using grades 0-6. Means and standard deviations on this scale were then calculated for multiple organs and muscle groups and tabulated.

RESULTS

On this grading scale, viscera showed uptake grades between 1.7 +/- 0.5 and 2.05 +/- 1.0. Except for the intestines, the activity in these organs was homogeneously distributed. Relatively high average uptake values of 2.0-4.2 (s.d. > or = 2.3) were found in various muscle groups, especially the orbital musculature. Myocardial uptake was visible in 90% of the scans. Reconstruction artifacts were seen around the renal collecting system and the bladder.

CONCLUSION

Most of the "normal" accumulations of FDG in nonattenuation corrected whole-body PET are readily recognized and distinct from the usually focal FDG accumulation associated with metastatic disease, but the diagnostician must be familiar with them. Muscular FDG uptake is related to physical activity prior and immediately following injection and can be minimized by proper patient instructions and positioning.

Lack of expression of dopamine D2 receptors in malignant melanoma: evidence for interaction of iodobenzofurans with melanin

OBJECTIVES

(1) To compare scintigraphy using the new dopamine D2 receptor binding radioligand iodobenzofuran (IBF) versus whole-body positron emission tomography (PET) in demonstrating metastasizing melanoma, and (2) to determine, for the first time using a panel of histochemical techniques, whether the ability of D2 receptor binding radioligands to detect melanoma metastases is due to tumor-expressed D2 receptors.

METHODS

Seven patients with metastatic melanoma were examined using 123I-IBF scintigraphy. Findings were compared to the results of PET and metastasis histochemistry: D2 receptor mRNA assay (metastases: n = 5; melanoma cell lines: n = 4) using the reverse transcriptase polymerase chain reaction (RT-PCR) versus D2 receptor-transfected Chinese hamster ovary cell controls: in vitro 125I-IBF binding (n = 19), and immunohistochemical staining for dopamine D2 receptor protein (n = 19).

RESULTS

IBF scintigraphy detected 2/10 melanoma metastases detected by PET (sensitivity 20%). No dopamine D2 receptor mRNA was found in melanoma cells using RT-PCR. The binding of 125I-IBF correlated with the amount of melanin present in the metastases; two amelanotic melanomas both failed to bind 125I-IBF. Immunohistochemical staining was negative in all metastases.

CONCLUSION

Melanoma cells do not appear to express dopamine D2 receptors. Although IBF had high dopamine D2 receptor affinity, its ability to detect melanoma metastases is more likely explained by low affinity binding to melanin than by the presence of dopamine receptors.

[Dopamine-D2 receptor scintigraphy with 123I-iodobenzofuran in malignant melanoma]

In recent publications dopamine-D2 receptor scintigraphy with benzamides was postulated for specific imaging of melanoma. In a prospective study the value of 123I-iodobenzofuran (IBF), a highly specific and affine dopamine-D2 receptor ligand was evaluated for the detection of melanoma metastases. With IBF-D2 receptor scintigraphy only 2 of 17 melanoma metastases could be detected. The interpretation of the abdomen was impaired by the hepatobiliary and renal excretion of the radionuclide. The ratio striatum/frontal cortex of 2.75 +/- 0.49 3 h p.i. demonstrated a high D2-receptor binding of the ligand. IBF-D2-receptor scintigraphy is not suitable as a method of staging melanoma.

Staging of metastatic melanoma by whole-body positron emission tomography using 2-fluorine-18-fluoro-2-deoxy-D-glucose

Metastatic melanoma was staged in 15 patients using whole-body positron emission tomography (PET) and the radiopharmaceutical 2-fluorine-18-fluoro-2-deoxy-D-glucose (FDG). PET correctly demonstrated 30 metastases in lung, brain, pancreas, nasal cavity, skin and subcutaneous tissue, and lymph nodes. It detected 97% of all metastases exceeding its spatial resolution (> 5 mm). Two cutaneous metastases (approximately 3 mm) did not show increased FDG uptake; the overall detection sensitivity was 91%. Two false-positive lesions in one patient were due to severe wound infection. PET correctly excluded malignancy in four cases where suspicious lesions were found with conventional cross-sectional imaging modalities but later ruled out by fine-needle biopsy. PET therefore proved to be an excellent method for staging of metastatic melanoma. Due to its high sensitivity for malignant lesions and the possibility of covering the whole body in one examination, it can replace staging techniques employing multiple imaging modalities: chest X-ray, ultrasonography and computed tomography. Furthermore, it provides information on the malignant potential of the detected lesion.

Anti-melanoma monoclonal antibody 225.28S immunoscintigraphy in metastatic melanoma

BACKGROUND

Accurate staging and early detection of metastases are crucial to melanoma management. It would thus be of great value to have a widely available, cost-effective method that allows to examine the whole body and is more specific than current imaging modalities.

OBJECTIVE

The purpose of the study was to assess the value of immunoscintigraphy with 99mTc-radiolabeled F(ab')2 fragments of the 225.28S monoclonal antibody in the staging of melanoma.

METHODS

29 patients with known or suspected metastases were enrolled in the study and examined by monoclonal antibody fragment scintigraphy. The results were compared to physical examination, other imaging modalities and, where available, histology.

RESULTS

Antibody scintigraphy detected 9/34 metastases. There were 2 false-positive lesions. Diagnostic accuracy was 41%, sensitivity 26% and specificity 83%.

CONCLUSION

99mTc-radiolabeled F(ab')2 monoclonal antibody-fragment scintigraphy cannot be recommended for staging of melanoma patients. The search for more sensitive radiopharmaceuticals for scintigraphy should thus be encouraged.

Dopamin-D2-Rezeptorszintigraphie mit 123I-Jodbenzofuran beim malignen Melanom

In jüngsten Publikationen wurde die Dopamin-D2-Rezeptorszintigraphie mit Benz-amiden zur spezifischen Darstellung von Melanomen vorgeschlagen. In einer prospektiven Studie wurde die Wertigkeit von 123I-Jodbenzofuran (IBF), einem hochspezifischen und hochaffinen Dopamin-D2-Rezeptorliganden zum Nachweis von Melanommetastasen untersucht. Mit der IBF-D2-Rezeptorszintigraphie ließen sich nur 2 von 17 Melanommetastasen nachweisen. Die Beurteilung des Abdomens war durch die hepatobiliäre Ausscheidung des Radionuklids stark eingeschränkt. Der Quotient Striatum/Frontalhirn von 2,75 ± 0,49 3 h p.i. belegte die hohe D2-Rezeptorbindung des Liganden. Die IBF-D2-Rezeptorszintigraphie ist als Staginguntersuchung beim Melanom nicht geeignet.

Decreased benzodiazepine receptor binding in panic disorder measured by IOMAZENIL-SPECT. A preliminary report

Single photon emission tomography (SPECT) imaging of the central benzodiazepine receptor (BZr) became possible with the newly developed ligand 123I-IOMAZENIL. The BZr binding was investigated in ten patients with panic disorder (PP) compared to ten epileptic patients (EP). Panic patients had lower IOMAZENIL uptake rates in the frontal, occipital and temporal cortex than EP indicating the involvement of the BZr complex in panic disorder.

[Detection of primarily unrecognized fractures in severely injured patients by skeletal scintigraphy]

Even in despite of diligent investigation clinical and radiological diagnostics can leave fractures unrecognized in seriously injured patients. Bone-scans of 53 patients revealed 68 additional fractures. In 45% of all cases the initial diagnosis was altered, 19% resulted in therapeutical consequences. Routine diagnostics should be supplemented by a bone-scan if clinical and radiological findings are not in line. A bone-scan can exclude any osseous lesion and can survey the full extent of injuries especially in the disoriented or unconscious patient.

[Quantitative nuclear medicine kidney diagnosis with kidney tubule traversing radioisotopes]

In modern nuclear medicine, renal function scintigraphy has been improved and its range of applications extended by the development of new radiopharmaceuticals (iodine-123-hippuran, technetium-99m-MAG3) combining the properties of short half-life, favourable radiation energy and high renal clearance. Three significant advantages recommend the use of scintigraphic methods: 1. Being non-invasive and non-nephrotoxic, the examinations do not affect the patient. The radiation exposure the patient is subjected to is about the same as with a comparable X-ray investigation or, with respect to the reproductive glands, even lower. Allergic reactions do not occur. 2. In contrast to the situation with other imaging methods, the functional defect itself (and not only secondary changes in the morphology) can mostly be detected. Not only diffuse alterations, but also defined functional lesions of a small part of a kidney, can be diagnosed. 3. Various renal parameters can be calculated more accurately than with any other routine clinical method. The radioisotopic methods discussed yield reliable results with excellent reproducibility concerning glomerular filtration rate, effective renal plasma flow, side-to-side functional ratio, renal perfusion, and urine drainage. Most of these parameters can be obtained by means of a single investigation. These radioisotopic methods make it possible to detect or exclude a wide range of functional lesions of the kidneys and the urinary tract, which are often due to non-specific symptoms. In addition, they allow answers to highly specific clinical and scientific questions in nephrology and urology.