H2 production under stress: [FeFe]‑hydrogenases reveal strong stability in high pressure environments

Hydrogenases are a diverse group of metalloenzymes that catalyze the conversion of H2 into protons and electrons and the reverse reaction. A subgroup is formed by the [FeFe]‑hydrogenases, which are the most efficient enzymes of microbes for catalytic H2 conversion. We have determined the stability and activity of two [FeFe]‑hydrogenases under high temperature and pressure conditions employing FTIR spectroscopy and the high-pressure stopped-flow methodology in combination with fast UV/Vis detection. Our data show high temperature stability and an increase in activity up to the unfolding temperatures of the enzymes. Remarkably, both enzymes reveal a very high pressure stability of their structure, even up to pressures of several kbars. Their high pressure-stability enables high enzymatic activity up to 2 kbar, which largely exceeds the pressure limit encountered by organisms in the deep sea and sub-seafloor on Earth.

A Dynamic Water Channel Affects O2 Stability in [FeFe]-Hydrogenases

[FeFe]-hydrogenases are capable of reducing protons at a high rate. However, molecular oxygen (O2 ) induces the degradation of their catalytic cofactor, the H-cluster, which consists of a cubane [4Fe4S] subcluster (4FeH ) and a unique diiron moiety (2FeH ). Previous attempts to prevent O2 -induced damage have focused on enhancing the protein's sieving effect for O2 by blocking the hydrophobic gas channels that connect the protein surface and the 2FeH . In this study, we aimed to block an O2 diffusion pathway and shield 4FeH instead. Molecular dynamics (MD) simulations identified a novel water channel (WH ) surrounding the H-cluster. As this hydrophilic path may be accessible for O2 molecules we applied site-directed mutagenesis targeting amino acids along WH in proximity to 4FeH to block O2 diffusion. Protein film electrochemistry experiments demonstrate increased O2 stabilities for variants G302S and S357T, and MD simulations based on high-resolution crystal structures confirmed an enhanced local sieving effect for O2 in the environment of the 4FeH in both cases. The results strongly suggest that, in wild type proteins, O2 diffuses from the 4FeH to the 2FeH . These results reveal new strategies for improving the O2 stability of [FeFe]-hydrogenases by focusing on the O2 diffusion network near the active site.

The Alga Uronema belkae Has Two Structural Types of [FeFe]-Hydrogenases with Different Biochemical Properties

Several species of microalgae can convert light energy into molecular hydrogen (H2) by employing enzymes of early phylogenetic origin, [FeFe]-hydrogenases, coupled to the photosynthetic electron transport chain. Bacterial [FeFe]-hydrogenases consist of a conserved domain that harbors the active site cofactor, the H-domain, and an additional domain that binds electron-conducting FeS clusters, the F-domain. In contrast, most algal hydrogenases characterized so far have a structurally reduced, so-termed M1-type architecture, which consists only of the H-domain that interacts directly with photosynthetic ferredoxin PetF as an electron donor. To date, only a few algal species are known to contain bacterial-type [FeFe]-hydrogenases, and no M1-type enzymes have been identified in these species. Here, we show that the chlorophycean alga Uronema belkae possesses both bacterial-type and algal-type [FeFe]-hydrogenases. Both hydrogenase genes are transcribed, and the cells produce H2 under hypoxic conditions. The biochemical analyses show that the two enzymes show features typical for each of the two [FeFe]-hydrogenase types. Most notable in the physiological context is that the bacterial-type hydrogenase does not interact with PetF proteins, suggesting that the two enzymes are integrated differently into the alga's metabolism.

The [4Fe-4S]-Cluster of HydF is not Required for the Binding and Transfer of the diiron site of [FeFe]-Hydrogenases

The active site of [FeFe]-hydrogenases contains a cubane [4Fe-4S]-cluster and a unique diiron cluster with biologically unusual CO and CN- ligands. The biogenesis of this diiron site, termed [2FeH], requires the maturation proteins HydE, HydF and HydG. During the maturation process HydF serves as a scaffold protein for the final assembly steps and the subsequent transfer of the [2FeH] precursor, termed [2FeP], to the [FeFe]-hydrogenase. The binding site of [2FeP] in HydF has not been elucidated, however, the [4Fe-4S]-cluster of HydF was considered as a possible binding partner of [2FeP]. By targeting individual amino acids in HydF from Thermosipho melanesiensis using site directed mutagenesis, we examined the postulated binding mechanism as well as the importance and putative involvement of the [4Fe-4S]-cluster for binding and transferring [2FeP]. Surprisingly, our results suggest that binding or transfer of [2FeP] does not involve the proposed binding mechanism or the presence of a [4Fe-4S]-cluster at all.

Increasing the O2 Resistance of the [FeFe]-Hydrogenase CbA5H through Enhanced Protein Flexibility

The high turnover rates of [FeFe]-hydrogenases under mild conditions and at low overpotentials provide a natural blueprint for the design of hydrogen catalysts. However, the unique active site (H-cluster) degrades upon contact with oxygen. The [FeFe]-hydrogenase fromClostridium beijerinckii (CbA5H) is characterized by the flexibility of its protein structure, which allows a conserved cysteine to coordinate to the active site under oxidative conditions. Thereby, intrinsic cofactor degradation induced by dioxygen is minimized. However, the protection from O₂ is only partial, and the activity of the enzyme decreases upon each exposure to O₂. By using site-directed mutagenesis in combination with electrochemistry, ATR-FTIR spectroscopy, and molecular dynamics simulations, we show that the kinetics of the conversion between the oxygen-protected inactive state (cysteine-bound) and the oxygen-sensitive active state can be accelerated by replacing a surface residue that is very distant from the active site. This sole exchange of methionine for a glutamate residue leads to an increased resistance of the hydrogenase to dioxygen. With our study, we aim to understand how local modifications of the protein structure can have a crucial impact on protein dynamics and how they can control the reactivity of inorganic active sites through outer sphere effects.

Changing the tracks: screening for electron transfer proteins to support hydrogen production

Abstract

Ferredoxins are essential electron transferring proteins in organisms. Twelve plant-type ferredoxins in the green alga Chlamydomonas reinhardtii determine the fate of electrons, generated in multiple metabolic processes. The two hydrogenases HydA1 and HydA2 of. C. reinhardtii compete for electrons from the photosynthetic ferredoxin PetF, which is the first stromal mediator of the high-energy electrons derived from the absorption of light energy at the photosystems. While being involved in many chloroplast-located metabolic pathways, PetF shows the highest affinity for ferredoxin-NADP⁺ oxidoreductase (FNR), not for the hydrogenases. Aiming to identify other potential electron donors for the hydrogenases, we screened as yet uncharacterized ferredoxins Fdx7, 8, 10 and 11 for their capability to reduce the hydrogenases. Comparing the performance of the Fdx in presence and absence of competitor FNR, we show that Fdx7 has a higher affinity for HydA1 than for FNR. Additionally, we show that synthetic FeS-cluster-binding maquettes, which can be reduced by NADPH alone, can also be used to reduce the hydrogenases. Our findings pave the way for the creation of tailored electron donors to redirect electrons to enzymes of interest.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00775-022-01956-1.

The oxygen-resistant [FeFe]-hydrogenase CbA5H harbors an unknown radical signal

[FeFe]-hydrogenases catalyze the reversible conversion of molecular hydrogen into protons and electrons with remarkable efficiency. However, their industrial applications are limited by their oxygen sensitivity. Recently, it was shown that the [FeFe]-hydrogenase from Clostridium beijerinckii (CbA5H) is oxygen-resistant and can be reactivated after oxygen exposure. In this work, we used multifrequency continuous wave and pulsed electron paramagnetic resonance (EPR) spectroscopy to characterize the active center of CbA5H, the H-cluster. Under oxidizing conditions, the spectra were dominated by an additional and unprecedented radical species. The generation of this radical signal depends on the presence of an intact H-cluster and a complete proton transfer pathway including the bridging azadithiolate ligand. Selective ⁵⁷Fe enrichment combined with isotope-sensitive electron-nuclear double resonance (ENDOR) spectroscopy revealed a spin density distribution that resembles an H-cluster state. Overall, we uncovered a radical species in CbA5H that is potentially involved in the redox sensing of CbA5H.

Electron paramagnetic resonance spectroscopy revealed an unprecedented radical species in the oxygen-resistant [FeFe]-hydrogenase CbA5H. Analysis of the isotope-sensitive data suggests that it is related to the active site, the H-cluster.

Correction: The oxygen-resistant [FeFe]-hydrogenase CbA5H harbors an unknown radical signal

Correction for ‘The oxygen-resistant [FeFe]-hydrogenase CbA5H harbors an unknown radical signal’ by Melanie Heghmanns et al., Chem. Sci., 2022, 13, 7289–7294, https://doi.org/10.1039/D2SC00385F.

Fine-tuning of FeS proteins monitored via pulsed EPR redox potentiometry at Q-band

As essential electron translocating proteins in photosynthetic organisms, multiple plant-type ferredoxin (Fdx) isoforms are involved in a high number of reductive metabolic processes in the chloroplast. To allow quick cellular responses under changing environmental conditions, different plant-type Fdxs in Chlamydomonas reinhardtii were suggested to have adapted their midpoint potentials to a wide range of interaction partners. We performed pulsed electron paramagnetic resonance (EPR) monitored redox potentiometry at Q-band on three Fdx isoforms for a straightforward determination of their midpoint potentials. Additionally, site-directed mutagenesis was used to tune the midpoint potential of CrFdx1 in a range of approximately -338 to -511 mV, confirming the importance of single positions in the protein environment surrounding the [2Fe2S] cluster. Our results present a new target for future studies aiming to modify the catalytic activity of CrFdx1 that plays an essential role either as electron acceptor of photosystem I or as electron donor to hydrogenases under certain conditions. Additionally, the precisely determined redox potentials in this work using pulsed EPR demonstrate an alternative method that provides additional advantages compared with the well-established continuous wave EPR technique.

Crystallographic and spectroscopic assignment of the proton transfer pathway in [FeFe]-hydrogenases

The unmatched catalytic turnover rates of [FeFe]-hydrogenases require an exceptionally efficient proton-transfer (PT) pathway to shuttle protons as substrates or products between bulk water and catalytic center. For clostridial [FeFe]-hydrogenase CpI such a pathway has been proposed and analyzed, but mainly on a theoretical basis. Here, eleven enzyme variants of two different [FeFe]-hydrogenases (CpI and HydA1) with substitutions in the presumptive PT-pathway are examined kinetically, spectroscopically, and crystallographically to provide solid experimental proof for its role in hydrogen-turnover. Targeting key residues of the PT-pathway by site directed mutagenesis significantly alters the pH-activity profile of these variants and in presence of H₂ their cofactor is trapped in an intermediate state indicative of precluded proton-transfer. Furthermore, crystal structures coherently explain the individual levels of residual activity, demonstrating e.g. how trapped H₂O molecules rescue the interrupted PT-pathway. These features provide conclusive evidence that the targeted positions are indeed vital for catalytic proton-transfer.

[FeFe]-hydrogenases catalyze H₂-evolution and -oxidation at very high turnover-rates. Here the authors provide experimental evidence for the proposed proton-transfer (PT) pathway by kinetically, spectroscopically, and crystallographically characterizing eleven mutants from the two [FeFe]-hydrogenases CpI and HydA1.

A structural view of synthetic cofactor integration into [FeFe]-hydrogenases

Crystal structures of semisynthetic [FeFe]-hydrogenases with variations in the [2Fe] cluster show little structural differences despite strong effects on activity.

[FeFe]-hydrogenases are nature's fastest catalysts for the evolution or oxidation of hydrogen. Numerous synthetic model complexes for the [2Fe] subcluster (2Fe_H) of their active site are known, but so far none of these could compete with the enzymes. The complex Fe₂[μ-(SCH₂)₂X](CN)₂(CO)₄^2– with X = NH was shown to integrate into the apo-form of [FeFe]-hydrogenases to yield a fully active enzyme. Here we report the first crystal structures of the apo-form of the bacterial [FeFe]-hydrogenase CpI from Clostridium pasteurianum at 1.60 Å and the active semisynthetic enzyme, CpI^ADT, at 1.63 Å. The structures illustrate the significant changes in ligand coordination upon integration and activation of the [2Fe] complex. These changes are induced by a rigid 2Fe_H cavity as revealed by the structure of apoCpI, which is remarkably similar to CpI^ADT. Additionally we present the high resolution crystal structures of the semisynthetic bacterial [FeFe]-hydrogenases CpI^PDT (X = CH₂), CpI^ODT (X = O) and CpI^SDT (X = S) with changes in the headgroup of the dithiolate bridge in the 2Fe_H cofactor. The structures of these inactive enzymes demonstrate that the 2Fe_H-subcluster and its protein environment remain largely unchanged when compared to the active enzyme CpI^ADT. As the active site shows an open coordination site in all structures, the absence of catalytic activity is probably not caused by steric obstruction. This demonstrates that the chemical properties of the dithiolate bridge are essential for enzyme activity.

Cystic leukoencephalopathy without megalencephaly: A distinct disease entity in 15 children

OBJECTIVE

To describe a distinctive syndrome of nonprogressive encephalopathy, normo- or microcephaly, and early onset of severe psychomotor impairment in 15 white patients, including two siblings and two first cousins.

METHODS AND RESULTS

MRI revealed bilateral cysts in the anterior part of the temporal lobe and white matter abnormalities with pericystic abnormal myelination and symmetric lesions in frontal and occipital periventricular regions. None of the usual inborn errors of metabolism/infectious diseases associated with leukoencephalopathy and bilateral anterior temporal lobe cysts were detected.

CONCLUSIONS

These patients' clinical signs and cranial MRI abnormalities are strikingly similar and may represent a distinctive disease with autosomal-recessive inheritance: cystic leukoencephalopathy without megalencephaly.

Vaginaler Fremdkörper als Ursache einer rektovaginalen Fistel

A case of 56-year-old patient is presented with the diagnosis "carcinoma of the cervix". She suffered from brown, bad smelling vaginal discharge since half a year without any pain. Three weeks before she had noticed a postmenopausal bleeding. At the examination under anaesthesia with cysto- and rectoscopy we saw a rectovaginal fistula. In the vagina a white plastic object was found which could not be removed. Some days later a hysterectomy with extraction of the foreign body (aerosol cap) was done and the fistula was treated together with the surgeons. There was no evidence of a carcinoma. The patient suffers from multiple sclerosis since 20 years. On asking she told us that the foreign body was in place since about two years. She was not willing to relate any other information.

[MRT diagnosis for degenerative changes in the spine]

MRT is very well suited to the diagnosis of degenerative alterations in the spine. The option of imaging in multiple planes, the excellent soft-tissue contrast offering tissue differentiation, the absence of hardening artefacts and the avoidance of exposure to radiation have led to a shift in favour of MRT for diagnosis. In the present paper the MRT characteristics of the most important degenerative alterations that affect the spine are discussed.

An Approach for Cure: PEI-Chemotherapy and Regional Deep Hyperthermia in Children and Adolescents with Unresectable Malignant Tumors

BACKGROUND

Elevated temperatures of 40 - 44 degrees C increase the actions of various anticancer drugs including N-lost derivatives, cytotoxic antibiotics and platinum analoga. In clinical usage thermochemotherapy (TCH) should facilitate surgical resection and ameliorate local tumor control.

PATIENTS AND METHODS

From 07/1993 to 12/2002 a total of 39 patients have been enrolled onto a phase-II study (female = 24, male = 15, age 1 - 37.5 years, median 5.2). Among these, 24 patients had extracranial non-testicular germ cell tumors and 15 patients soft tissue or chondrosarcomas.

INDICATION

locoregional relapse (n = 29) or unresectable tumor after neoadjuvant chemotherapy (n = 10). Among these two groups, there were ten patients with poor response or progressive disease under primary or relapse chemotherapy. Ten out of the 29 relapse patients had more than one relapse. Tumor site: pelvis (30), abdomen (4), head and neck (2), proximal leg (2) and lumbar spine (1). Thermochemotherapy (TCH): 1800 - 2000 mg ifosfamide/m (2) and 100 mg etoposide/m (2) on days 1 - 4 and 40 mg cisplatin/m (2) on days 1 + 4 combined with regional deep hyperthermia (42 - 44 degrees C, 1 h) on days 1 + 4.

RESULTS

In 39 protocol patients a total of 166 TCH courses (332 heat sessions) were applied. 20 patients achieved complete response, and 10 patients achieved partial response. TCH was followed by surgical tumor resection in 28/39 patients and/or radiotherapy in 13/39 patients. At a median follow-up of 27 months, outcome in this high-risk patient population was 22 NED, 3 AWD, 12 DOD, 2 DOC. Five year event free (EFS) and overall survival (OS) for the whole study cohort was 0.39 +/- 0.11 (20/39 patients) and 0.52 +/- 0.11 (25/39 patients), respectively.

CONCLUSION

TCH shows substantial therapeutic efficacy and facilitates complete tumor resection in 14 out of 28 operated patients. Multimodal treatment including TCH, surgical resection and/or radiotherapy leads to sustained remission in the majority of patients with locoregional tumor recurrence. The therapeutic effect is most pronounced, if TCH is administered at first relapse. Due to the clinical and histologic heterogeneity the number of patients eligible for TCH is limited. Therefore, a more valid assessment of treatment efficacy can only be made by a matched-pair comparison in cooperation with the clinical registers.

Hemodynamically relevant hematuria several months after biopsy of a kidney graft: an unusual cause

We report the case of a 52-year-old female patient, who after a complicated living donor kidney transplantation, underwent kidney biopsy for suspected rejection. Duplex scanning revealed a small, asymptomatic arteriovenous (AV) fistula which was assessed as being hemodynamically unimportant. During follow-up, several urinary tract infections occurred and recurrent short episodes of hematuria were attributed to cystitis, urethritis and urosepsis. Eight months later, the patient developed suddenly massive hematuria, tamponade of the urinary bladder and hemorrhagic shock as well as urosepsis. Duplex sonography showed a massive pseudoaneurysm in addition to the AV fistula. Arteriography confirmed the Duplex sonographic findings and embolization was performed after treatment of concomitant urosepsis. The fistula was closed completely and bleeding ceased. Although AV fistulas are rare complications of kidney biopsies and in most cases they remain asymptomatic, life-threatening hematuria can present several months after a biopsy due to the development of a pseudoaneurysm. Concomitant infectious complications of the urinary tract, bleeding disorders and other factors can be misleading during the assessment of the cause of gross hematuria. Regular Duplex sonographic follow-up examinations in patients with AV fistulas are advisable.

[Imaging of supradiaphragmatic manifestations of extranodal non-Hodgkin's lymphoma]

Malignant lymphomas are differentiated into Hodgkin's and non-Hodgkin's-lymphoma (NHL). The following article discusses the imaging of extranodal NHL in supradiaphragmatic localizations. Lymphoma can affect nearly all tissues, and represent a rare entity as primary extranodal NHL. A secondary involvement of non-nodal tissue as consequence of a generalized lymphoproliferative disease is more common,and may be seen as well in HIV-positive patients defining AIDS. As extranodal lymphoma mimic the radiologic appearance of other malignant tumors, direct diagnosis without histologic analysis is often impossible. The article describes typical manifestations of lymphoma of the lungs, the head and neck area including the large glands, and rare localizations as the heart or the breast.

Diagnostic difficulties in childhood bilateral thalamic astrocytomas

We report on two children with bilateral thalamic astrocytomas. The first patient developed psychomotor regression at the age of 20 months followed by rapidly progressive ataxia, intention tremor, slurred speech, and bouts of drowsiness. Magnetic resonance imaging (MRI) of the brain showed swelling and high signal intensity in both thalami accompanied by supratentorial hydrocephalus. The second patient presented with progressive cerebellar ataxia, headache, and vomiting at the age of 11 years. MRI of the brain revealed symmetrical, hyperintense and sharply delineated swelling of both thalami. Additional lesions were seen in the cerebellum and the right temporal lobe. In both cases proton magnetic resonance spectroscopy (MRS) of the lesions showed a striking decrease of the neuronal marker N-acetylaspartate, an increase of choline-containing compounds, and a minimal lactate peak. Stereotactic biopsies from the thalamus of the first patient and from a cerebellar lesion of the second patient finally revealed glial tumors, namely a diffuse astrocytoma of World Health Organization (WHO) grade II in the first patient and an anaplastic astrocytoma of WHO grade III in the second patient. We conclude that the clinical manifestations and MRI patterns of bilateral thalamic astrocytomas are very similar to those of encephalitis and neurometabolic disorders and should therefore be included in the differential diagnosis of these encephalopathies.

Comparative follow-up of enhancement phenomena with MRI and Proton MR Spectroscopic Imaging after intralesional immunotherapy in glioblastoma--Report of two exceptional cases

The morphologic pattern of contrast enhancement in magnetic resonance imaging (MRI) of glioblastoma patients could be non specific and metabolic investigations can be useful for the differentiation of tumorous and non tumorous enhancement. Following initial therapy secondary tissue changes can occur and non specific non tumorous enhancement phenomena have been observed after local immuno- and gene therapy strategies. Magnetic resonance spectroscopic imaging (MRSI) has the potential to give more specific information on the metabolism of the suspective tissue and to differentiate enhancing phenomena. We demonstrate two cases of patients suffering from a glioblastoma with simultaneous MRI and MRSI follow-up after multimodal treatment with surgery, radiation, intralesional immunotherapy (IL-4 toxin) and ongoing chemotherapy. MRI demonstrated extensive and increasing enhancement. This was highly suspicious of rapid progressive local tumor recurrency in both patients. Simultaneously obtained MRSI did not show the expected result of extensive and increasing choline concentration within these enhancing areas. This indicated that the enhancement did most likely not reflect vital tumor tissue. Chemotherapy treatment was continued and further MRI follow up revealed nearly complete regression of all enhancement. In pretreated glioblastoma metabolic data of MRSI seem to be potentially helpful to differentiate tumorous and non tumorous enhancement phenomena after local immunotherapy, which might be useful for further treatment decisions.

[Does dynamic contrast-enhanced MRI enable recognition of development of vertebral fractures in multiple myeloma?]

PURPOSE

To compare the value of MRI sequences with dynamic MRI measurements (d-MRT) for the assessment of risk of lumbar vertebral fractures in patients with multiple myeloma.

MATERIAL AND METHODS

In 10 patients with multiple myeloma a sagittal T 1 -, T 2 -weighted spin-echo and an inversion-recovery sequence were performed. For dynamic measurements a fast gradient-echo sequence (turbo fast low angle shot 2 D) with machine-controlled Gd-DTPA administration was used. The presence of bone marrow abnormalities was determined and additionally the value of the highest signal increase (amplitude Alpha) was calculated for each of the 50 vertebral bodies. The subsequent development of vertebral fractures was assessed by MRI at a mean time interval of 6.2 months after the initial d-MRI. The pattern of marrow involvement and the amplitudes of the vertebral bodies that collapsed in the observation period were statistically compared with those of the vertebral bodies that did not collapse.

RESULTS

During the follow-up period newly or progressive fractures occurred in 6 of 10 patients (7 of 50 vertebral bodies). The degree of pathological signal changes that preceded fractures was not significantly different (p > 0.05) from that of the other contemporary lesions identified in vertebral bodies that did not collapse in follow-up. In contrast, the amplitude of vertebrae that collapsed (A: 33.1 +/- 8.2) was significantly higher (p < 0.0001) than the amplitude of vertebrae that did not collapse (A: 16.7 +/- 4.2). The amplitude was a reliable predictor of vertebrae that collapsed in all cases.

CONCLUSION

In contrast to the analysis of marrow lesions detected with non-dynamic MRI, this study suggests that the perfusion-parameter amplitude in dynamic contrast-enhanced MRI is a potentially relevant value to predict the risk of vertebral fractures in patients with multiple myeloma.

Sexual precocity and recurrent beta-human chorionic gonadotropin upsurges preceding the diagnosis of a malignant mediastinal germ-cell tumor in a 9-year-old boy

Numerous disorders are known to cause sexual precocity. Beta-human chorionic gonadotropin (beta-HCG)-secreting germ-cell tumors are one of the sources that have to be considered in the differential diagnosis of processes inducing a peripheral precocious puberty. Germ-cell tumors might be located in the ovaries or testes, retroperitoneum, mediastinum or the cranium. We present the case of a 9-year-old boy with sexual precocity and a recurrent transient beta-HCG elevation. After an interval of 2 years with repeated radiological examinations including the mediastinum, a mediastinal tumor was identified by magnetic resonance imaging. To our knowledge, this is the first case of a diagnosis of a mediastinal choriocarcinoma with a recurrent serum beta-HCG elevation. So far, factors that might be responsible for the repeated spontaneous beta-HCG decline are unknown.

[Dynamic contrast-enhanced MRI for evaluating bone marrow microcirculation in malignant hematological diseases before and after thalidomide therapy]

PURPOSE

The aim of the study was to measure microcirculation parameters by dynamic contrast-enhanced MRI (d-MRI) and to evaluate the anti-angiogentic effects during treatment with thalidomide in different hematologic malignancies.

METHODS

In 20 healthy normal persons, 20 patients with myelodysplastic syndromes (MDS), 10 patients with multiple myeloma (MM) and 10 with myelofibrosis (MF) a fast gradient echo sequence (Turbo fast low angle shot 2D) with a pump controlled bolus infusion of gadolinium-DTPA was performed before and in 18 of these after beginning (average of 4.3 months) of a thalidomide therapy. Two pharmacokinetic parameters--the amplitude and exchange-rate-constant--were calculated and a statistical comparison of these values between healthy persons and patients as well as a correlation with the clinical course was executed.

RESULTS

Compared with the normal controls the patients showed a higher amplitude (normal persons 14.4 +/- 5.2, MDS 24.8 +/- 8.1, MF 35.9 +/- 4.3, MM 23.4 +/- 3.6) and exchange-rate-constant (normal persons 0.124 +/- 0.042, MDS 0.136 +/- 0.036, MF 0.144 +/- 0.068, MM 0.131 +/- 0.034). In the d-MRI-follow-up examinations a significant (p < 0.005) reduction of the amplitude and exchange rate constant values was evident in 14 of 18 patients undergoing a thalidomide therapy. Clinically all of these patients showed a therapy responding with complete or partial diseases remission.

CONCLUSIONS

In patients with hematologic malignancies significantly higher d-MRI-microcirculation parameters of the lumbar spine can be demonstrated than in normal persons. During anti-angiogenetic treatment with thalidomide a decrease of these values was observed in case of a responding to therapy.

[Dynamic MRI of the lumbar spine for the evaluation of microcirculation during anti-angiogenetic therapy in patients with myelodysplastic syndromes]

PURPOSE

Evaluation of MRI perfusion parameters of the lumbar spine in patients with myelodysplastic syndromes (MDS) to determine the vascularisation and anti-angiogenetic effects of thalidomide therapy.

MATERIAL AND METHODS

In 20 healthy normal persons and 28 MDS patients a dynamic contrast-enhanced MRI (d-MRI) of the lumbar spine was performed. After the initial d-MRI-investigation 24 of the 28 MDS patients received an anti-angiogenetic therapy with thalidomide. With an average of 4.2 months after the beginning of therapy a d-MRI-follow-up examination in 9 of these patients was performed. The amplitude and exchange-rate constant were calculated and a statistical comparison of these values between healthy persons and MDS patients as well as a correlation with the clinical course was executed.

RESULTS

Compared with the normal controls the MDS patients showed a higher amplitude (normal persons: 14.4 +/- 5.2, MDS: 24.8 +/- 8.1) and exchange-rate constant (normal persons: 0.124 +/- 0.042, MDS: 0.136 +/- 0.036). In 7 of 9 MDS patients undergoing thalidomide therapy a reduction of the amplitude and exchange rate constant values was evident in the d-MRI follow-up examinations. Clinically these patients showed a therapy response with complete or partial disease remission.

CONCLUSIONS

In MDS patients significantly higher d-MRI parameters can be demonstrated than in normal persons. Under anti-angiogenetic treatment these values decrease in case of a response to therapy. Thus, d-MRI seems suitable for the evaluation of anti-angiogenetic therapy effects.

Proton MR spectroscopy of the lumbar spine in patients with glycogen storage disease type Ib

Glycogen storage disease type Ib is an autosomal recessive inherited metabolic disorder resulting from deficiency of the microsomal glucose-6-phosphatase enzyme system. Six patients (three of which were treated with granulocyte colony stimulating factor) suffering from this disease were examined using image guided localized proton magnetic resonance (MR) spectroscopy. The relative signal intensities of water and lipid protons of the lumbar spine were determined. Comparison was made with iliac crest biopsies in the glycogen storage disease type Ib patients and localized proton MR spectroscopic values of the lumbar spine obtained by thirteen healthy volunteers. The data demonstrate for the first time that hypercellularity and myeloid hyperplasia in subjects with glycogen storage disease type Ib due to functionally impaired leucocytes results in a strongly increased water proton signal with a very low or absent lipid signal in localized proton MR spectroscopy. Upon granulocyte colony stimulating factor treatment, the water proton signal in the lumbar spine is not further augmented.

[MR-morphological changes of the metacarpophalangeal joints in patients with rheumatoid arthritis: Comparison of early and chronical stages]

MR-morphological changes of the metacarpophalangeal joints in patients with rheumatoid arthritis: Comparison of early and chronical stages.

PURPOSE

Evaluation of MRI findings in the metacarpophalangeal (MCP) joints in patients with early (eRA) and chronical rheumatoid arthritis (cRA).

MATERIAL AND METHODS

In 22 RA patients (9 with disease duration </= 1.5 years = eRA) the dominant hands were examined by MRI in coronal T(2) weighted turbo-spin-echo (TSE). T(1) weighted spin-echo (SE) sequences before and after injection of Gd-DTPA and fat-suppressed short tau inversion recovery (STIR) sequences, followed by miniarthroscopy (MA) of the MCP II joint after an interval of 24 hours. MRI and MA findings were assessed using standardised semiquantitative items of synovial and bony pathologies and a statistical comparison between eRA and cRA patients was performed.

RESULTS

In MRI synovial proliferation was detected in 13/13 cRA and 8/9 eRA patients. It was statistically not significant; the degree of synovial proliferation was however lower in the eRA group. All eRA patients with synovial changes showed enhancement after administration of contrast medium, a marker which correlated with the clinical activity. In 2/13 cRA patients no uptake of contrast medium was evident. Bony erosions and strongly narrowing joint space correlated with disease duration and were documented significantly rarer in the eRA patients (1/9, 2/9) than in the cRA patients (9/13, 10/13).

CONCLUSION

In RA patients, MRI of the metacarpophalangeal joints can detect specific pathological changes which are observed significantly more often in either early or chronic stages and which are associated with disease activity and duration.

MR imaging of bone marrow in glycogen storage disease type IB in children and young adults

OBJECTIVE

Patients with glycogen storage disease type IB have neutropenia and neutrophil dysfunction that predispose them to frequent infections, for which they are given granulocyte colony--stimulating factor. Because neutropenia is a consequence of defects in myeloid maturation, the bone marrow aspirations show hypercellularity due to myeloid hyperplasia. This study evaluated MR imaging of bone marrow in glycogen storage disease type IB with and without granulocyte colony-stimulating factor.

CONCLUSION

As confirmed by the histologic results in bone marrow aspirations, abnormal findings on MR images of bone marrow in patients with glycogen storage disease type IB indicate an increased myelopoietic activity, which is augmented by treatment with granulocyte colony-stimulating factor.

[MRI of the cerebellopontine angle in patients with cleidocranial dysostosis]

PURPOSE

Cleidocranial dysostosis (CCD) is an autosomal dominant bone disorder in which deafness is common secondary to malformation of the middle ear structures. The study aimed at MRI evaluation of the cerebellopontine angle in 7 patients with a history of CCD--two generation spanned relatives.

MATERIAL AND METHODS

Cranial MRI in 7 patients with CCD (4 women/3 men aged between 8 and 46 years) was performed. In two patients hearing disorders were present. The examinations encompassed multi-planar spinecho sequences of the cerebellopontine angle in 3-mm slice thickness before and after administration of contrast medium.

RESULTS

The clinically most conspicuous female patient (hearing loss, ataxia, headache) showed a strongly contrast-enhancing tumor in MRI that was histologically proved to be an acoustic schwannoma. Concerning the other family members, no pathological findings were noted except for non-pneumatized mastoids.

CONCLUSION

The first report of a patient with CCD and an acoustic schwannoma shows that in case of hearing loss in these patients also a retrocochlear cause must be considered.

Global estimation of myelination in the developing brain on the basis of magnetization transfer imaging: a preliminary study

BACKGROUND AND PURPOSE

In the developing brain, myelination occurs in an orderly and predetermined sequence. The aim of this study was to determine whether such changes can be tracked using volumetric magnetization transfer imaging.

METHODS

Three-dimensional magnetization transfer imaging was performed in 50 children (age range, 0.6-190 months) with no evidence of developmental delay or structural abnormalities. Volumetric magnetization transfer ratio (MTR) parameters generated of the whole brain were mean MTR and height and location of the MTR histogram peak. Relationships between volumetric MTR parameters and age were assessed using nonlinear regression analysis.

RESULTS

With age, all volumetric MTR parameters changed exponentially in a way that was best expressed by the function y = a + b.exp(-x/c) (P < .0001). The peak height of the MTR histogram was the parameter that changed most predictably and that continued to change for the longest period of time.

CONCLUSION

With this preliminary study, we show that by using volumetric MTR analysis, it is possible to monitor changes in the developing brain, presumably the myelination progress. This method has a potential role for detecting myelination disorders in the pediatric population, for studying the natural history of these diseases, and for monitoring the effects of treatment.

[MRI follow-up study of aseptic osteonecrosis (AON) in children treated with chemotherapy for malignant diseases]

PURPOSE

The aim of the study was to evaluate by MRI the course of aseptic osteonecrosis (AON) after chemotherapy in children with different malignancies.

MATERIAL AND METHODS

Retrospective analysis of 72 MRI studies in 20 children (age: 3.2-18.4 years) presenting with AON after chemotherapy. 8 children were treated exclusively with relief of weightbearing structures, whereas 12 children were additionally treated with hyperbaric oxygen therapy (HBO). Within a range of 3-76 months each patient received 1-6 follow-up exams. The acquired series included multi planar spin-echo as well as fatt-suppressed inversion recovery sequences. The MRI examinations were evaluated by a point-score system (1-6) by two radiologists.

RESULTS

AON was most commonly seen in the pedal bones (26.4%), in the hip (23.6%), and in the knee joints (19.4%). Initial findings revealed an average score of 3.1 points. Based upon these initial findings, subsequent analyses show a statistically significant (p < 0.05) score increase of 0.6 score-points. For the observed intervals a: < 6 months, b: 6-12 months, and c: > 12 months the mean scores were: a: 3.3, b: 3.7, and c: 4.5 points. During the observed time period 5 patients were surgically treated in the affected bone areas.

CONCLUSION

The majority of chemotherapy associated AON which initially present with advanced findings showed in MRI a progression with frequent destruction of the joint surface over their further course. More discrete forms of AON, especially osteoedema, can be positively influenced by conservative therapy.

[Signal changes of the bone marrow in MRI under long-term treatment with granulocyte colony-stimulating factors]

PURPOSE

Recurrent infections in patients with glycogen storage disease (GSD) type Ib resulting from an associated neutropenia are frequently treated with granulocyte colony-stimulating factors (G-CSF). The aim of this study was to evaluate the changes occurring in bone marrow by magnetic resonance imaging (MRI) in these patients.

MATERIAL AND METHODS

The distal femoral and tibial bones of six patients with GSD Ib were evaluated by MRI. Four of these patients were treated with G-CSF for at least 3.9 to a maximum of 8.2 years (mean 5.8 years). The imaging sequences encompassed spin-echo as well as short-time inversion recovery sequences. 4 of the 6 patients had bone marrow aspirations.

RESULTS

The patients who had undergone therapy with G-CSF showed a marked increase in signal strength in STIR sequences which encompassed the entire medullar cavity. In T1-weighted images these areas were hypointense. Biopsies obtained from these patients showed a bone marrow hypercellularity. The patients without G-CSF therapy showed the same signal intensity changes but with a more discrete and localized pattern in the metaphyseal cavities.

CONCLUSION

In subjects with GSD Ib, an increased myelopoetic activity of the bone marrow which is intensified under long-term treatment with G-CSF can be demonstrated by MRI.

Imaging diagnosis of retroperitoneal ganglioneuroma in childhood

PURPOSE

To demonstrate the typical appearance of retroperitoneal ganglioneuromas on CT and MRI.

MATERIALS AND METHODS

Retrospective analysis of diagnostic imaging (five CT scans, three MRI scans) in five children aged 3-15 years with the histological diagnosis of ganglioneuroma.

RESULTS

The scans showed large (maximum 11 cm diameter), round or oval tumours with sharply defined margins. Intraspinal tumour involvement occurred in two cases. Comparing CTwith MRI, MRI was more accurate in defining the intraspinal involvement. The ganglioneuromas were hypodense on unenhanced CT and showed moderate enhancement with administration of contrast medium. In three patients, CT demonstrated tumour calcification with a disseminated speckled pattern. On T1-weighted MRI the tumours were homogeneous and hypointense, showing marked enhancement after gadolinium administration. On T2-weighted scans the tumours were hyperintense.

CONCLUSION

At the time of diagnosis, retroperitoneal ganglioneuromas are generally large tumours that can be shown well by CT and MRI. The appearance on CT more readily suggests the diagnosis, but MRI is superior for documenting local or intraspinal tumour extension and lacks radiation load.

MRI evaluation of aseptic osteonecrosis in children over the course of hyperbaric oxygen therapy

PURPOSE

The study aimed at MRI evaluation of aseptic osteonecrosis (AON) in children over the course of hyperbaric oxygen (HBO) therapy.

MATERIAL AND METHODS

Retrospective analysis of 72 MRI studies in 20 children presenting with AON during chemotherapy. Two groups were differentiated: Gr. I (n = 8) was treated exclusively with relief of weightbearing structures, Gr. II (n = 12) was additionally treated with HBO therapy. The MRI examinations were evaluated by a point-score system (1-6 points) by two radiologists.

RESULTS

Gr. II initially showed more severe findings (average score: 3.4) in comparison to Gr. I (average score: 2.65). During the follow-up time period the average scores rose to 3.2 score-points in Gr. I and 4.1 points in Gr. II. No statistically significant difference was evident between the two groups in the course of AON.

CONCLUSION

The majority of chemotherapy associated AON which initially present with advanced findings show a progression in MRI over their further course. HBO therapy in addition to the relief of affected weightbearing structures statistically shows no significant improvement in MRI morphology during the course of the treatment.

Multiple intracranial juvenile xanthogranulomas. Case report

The authors report on an 11-year-old boy in whom proptosis of the eye caused by a benign intraosseous xanthofibroma of the left orbital wall became clinically apparent at the age of 4 years. Two years later he developed bilateral papilledema, at which time computerized tomography and magnetic resonance studies revealed multiple enhancing intracranial lesions. The largest mass was located in the left middle fossa; other lesions were located at the tentorium cerebelli, in both lateral ventricles, near the superior sagittal sinus, and extracranially near the left jugular vein. The mass in the left middle fossa was resected and diagnosed as juvenile xanthogranuloma (JXG). Thirty months later, the patient again became symptomatic, exhibiting behavioral abnormalities and a decrease in mental powers. At that time, the two remaining lesions in both lateral ventricles had grown enough to cause trapping of the temporal horns and raised intracranial pressure. These lesions were successively resected and histopathologically confirmed to be JXGs. However, resection of the second intraventricular lesion was complicated by postoperative bilateral amaurosis, presumably caused by postdecompression optic neuropathy. According to a review of the literature, fewer than 20 patients with JXG involving the central nervous system have been reported. The patient described in this report is the first in whom multiple intracranial JXGs developed in the absence of cutaneous manifestations. Although JXGs are biologically benign lesions, the treatment of patients with multifocal and/or progressive intracranial manifestations is problematic.

Boswellic acids in the palliative therapy of children with progressive or relapsed brain tumors

19 children and adolescents with intracranial tumors received a palliative therapy with H 15 at a maximum dose of 126 mg/kg BW/day. All patients had previously been treated with conventional therapy. No side effects were observed during a median 9 months application. The recently reported antiedematous effect of H 15 was documented by MRI in one patient with a peritumoral edema, thus sparing steroid therapy with its typical side effects. Five/19 children reported an improvement of their general health status; this might be a psychological effect of hope for tumor response during palliative care. Three/17 patients with malignant tumors showed a mainly transient improvement of neurological symptoms such as pareses and ataxia. Three further patients showed an increased muscular strength and one cachectic patient achieved a weight gain. These improvements might be attributed to the antiedematous effect of H 15. Because of the palliative situation of these patients, H 15 application was performed without prior rebiopsy for histological evaluation. Overlapping effects with a previous radiotherapy or chemotherapy may have occurred. An antiproliferative effect cannot be stated. To prevent an uncritical use of H 15, further studies with prospective central documentation have to be initiated to evaluate the clinical indications for H 15 in palliative therapy, optimal dosage and duration of application.

[Follow-up of patients with osteosarcoma and Ewing's sarcoma: a retrospective cost-benefit analysis]

PURPOSE

Determination of the respective roles of clinical investigation, laboratory tests and various imaging techniques in the follow up of children and adolescents with osteosarcoma and Ewing's sarcoma.

METHODS

In a retrospective monocenter analysis, charts of 72 patients with osteosarcoma and 47 patients with Ewing's sarcoma were reviewed with respect to ability of different diagnostic methods to detect the relapse, and correlated outcome.

RESULTS

In about 25% of relapses, a second remission could be achieved. The most sensitive methods to detect a potentially curable relapse were clinical investigations and chest x-ray in the case of osteosarcoma and chest x-ray and whole body scintigraphy in the case of Ewing's sarcoma.

CONCLUSIONS

The different value of diagnostic methods in the follow-up of the two illnesses may be explained by the different tumor biologies and by distinct therapeutic strategies for the treatment of relapses in the two tumor entities. However, an ongoing evaluation of current follow-up strategies is necessary to take into account new therapeutic developments which may shift the importance of certain imaging techniques.

[Ganglioneuromas in childhood: CT and MRI characteristics]

PURPOSE

The aim of this study was to demonstrate the typical appearance of ganglioneuromas in computer-assisted tomography (CT), and magnetic resonance imaging (MRI).

MATERIAL AND METHODS

Retrospective analysis of diagnostic imaging (9 CT, 6 MRI) in 9 children aged 3 to 15 years with the histological diagnosis of ganglioneuroma.

RESULTS

The tomographies showed large (max. 13.4 cm in diameter) round or oval tumors with sharp delineation. The sites of the tumors were the retroperitoneum (5), the mediastinum (3), and the adrenal gland (1). Intraspinal tumor involvement occurred in 4 cases. On comparing CT with MRI, MRI was more accurate in defining the intraspinal involvement. The ganglioneuromas were of hypodense appearance in the native CT scan and showed moderate enhancement upon administration of contrast media. In five patients tumor calcifications with a disseminated sprinkled pattern were seen in CT. In MRI T1-weighted scans the tumors were homogeneous and hypointense, after gadolinium application a marked enhancement was evident. In T2-weighted scans the tumors were hyperintense.

CONCLUSION

At the time of diagnosis ganglioneuromas are generally large tumors which can be well detected by CT and MRI. Information towards the diagnosis is given by the appearance of the ganglioneuromas in CT and MRI. However, MRI is the modality of choice due to its superiority in documenting intraspinal tumor expansion.

[MRI of aseptic osteonecrosis in children and adolescents with acute lymphoblastic leukemia]

PURPOSE

To evaluate the incidence, localisation, and course of symptomatic aseptic osteonecrosis (AON) in children undergoing treatment for acute lymphoblastic leukemia (ALL).

METHODS

72 MRI examinations obtained from 26 children with bone pain selected from a group of 121 children with ALL were evaluated retrospectively. The area of the AON was determined by computer assisted planimetry. Follow-up examinations after 2-5 years were considered.

RESULTS

10/121 (8.3%) of the children had symptomatic AON, the number of lesions varied between 1 and 24 per child. 62/66 lesions were localized within the lower extremities. 58% of the AON were positioned in the epiphysis and 42% in the meta- and diaphysis. The mean area of AON was 7.6 cm2 with a range of 0.5 to 50 cm2. Follow-up examinations revealed a regression in 19 AON, no change in 43 and a progression in 4 lesions. AON within the epiphysis with joint involvement or lesions greater than 9 cm2 more frequently showed a progression of AON with final joint destruction. An elevated risk for AON was seen in children older than 10 years and in children with intensified chemotherapy due to high-risk ALL.

CONCLUSION

AON is a common complication in ALL-children under chemotherapy. Most frequently, the course is benign but large AON with joint involvement have an elevated risk for progression of AON with final joint destruction.

Neurocutaneous melanosis with hydrocephalus, intraspinal arachnoid collections and syringomyelia: case report and literature review

Neurocutaneous melanosis (NCM) is a rare nonfamilial syndrome, characterised by large or numerous congenital pigmented nevi and excessive proliferation of melanin-containing cells in the leptomeninges. We report the MR findings in the brain and spine of a child with NCM who underwent neurosurgical treatment and was followed up for 8 years. The findings in this child (small hyperintense collections of melanocytes in both temporal lobes, mild meningeal enhancement along the spine and the development of an extensive subarachnoid CSF accumulation with cord compression and syringomyelia) are believed to be exceptionally rare.

Idiopathic ileoileal intussusception in an adult with spontaneous reduction during enteroclysis: a case report

We report a rare case of recurring idiopathic ileoileal intussusception in an adult. Diagnosis was established with abdominal computed tomography (CT) and enteroclysis, which led to a spontaneous reduction of the invagination. After a short period of physical improvement, a follow-up CT showed a recurrence. Surgery proved the diagnosis, but no predisposing factor was found.

CT appearance of a renal aspergilloma in a patient with the acquired immunodeficiency syndrome

The appearance of a unilateral renal aspergilloma on computed tomography is described in a 32-year-old man with acquired immunodeficiency syndrome (AIDS). Aspergillus infections are uncommon in the AIDS population. Only 9 cases of renal aspergilloma have been described in AIDS. The treatment performed was percutaneous drainage followed by antifungal drug administration and unilateral nephrectomy. This case report emphasizes the fact that renal fungal infections need to be considered in differential diagnosis of kidney infections in AIDS patients.