RNA methyltransferase SPOUT1/CENP-32 links mitotic spindle organization with the neurodevelopmental disorder SpADMiSS

SPOUT1/CENP-32 encodes a putative SPOUT RNA methyltransferase previously identified as a mitotic chromosome associated protein. SPOUT1/CENP-32 depletion leads to centrosome detachment from the spindle poles and chromosome misalignment. Aided by gene matching platforms, we identified 24 individuals with neurodevelopmental delays from 18 families with bi-allelic variants in SPOUT1/CENP-32 detected by exome/genome sequencing. Zebrafish spout1/cenp-32 mutants showed reduction in larval head size with concomitant apoptosis likely associated with altered cell cycle progression. In vivo complementation assays in zebrafish indicated that SPOUT1/CENP-32 missense variants identified in humans are pathogenic. Crystal structure analysis of SPOUT1/CENP-32 revealed that most disease-associated missense variants mapped to the catalytic domain. Additionally, SPOUT1/CENP-32 recurrent missense variants had reduced methyltransferase activity in vitro and compromised centrosome tethering to the spindle poles in human cells. Thus, SPOUT1/CENP-32 pathogenic variants cause an autosomal recessive neurodevelopmental disorder: SpADMiSS ( SPOUT1 Associated Development delay Microcephaly Seizures Short stature) underpinned by mitotic spindle organization defects and consequent chromosome segregation errors.

TrkB-dependent EphrinA reverse signaling regulates callosal axon fasciculate growth downstream of Neurod2/6

Abnormal development of corpus callosum is relatively common and causes a broad spectrum of cognitive impairments in humans. We use acallosal Neurod2/6-deficient mice to study callosal axon guidance within the ipsilateral cerebral cortex. Initial callosal tracts form but fail to traverse the ipsilateral cingulum and are not attracted towards the midline in the absence of Neurod2/6. We show that the restoration of Ephrin-A4 (EfnA4) expression in the embryonic neocortex of Neurod2/6-deficient embryos is sufficient to partially rescue targeted callosal axon growth towards the midline. EfnA4 cannot directly mediate reverse signaling within outgrowing axons, but it forms co-receptor complexes with TrkB (Ntrk2). The ability of EfnA4 to rescue the guided growth of a subset of callosal axons in Neurod2/6-deficient mice is abolished by the co-expression of dominant negative TrkBK571N (kinase-dead) or TrkBY515F (SHC-binding deficient) variants, but not by TrkBY816F (PLCγ1-binding deficient). Additionally, EphA4 is repulsive to EfnA4-positive medially projecting axons in organotypic brain slice culture. Collectively, we suggest that EfnA4-mediated reverse signaling acts via TrkB-SHC and is required for ipsilateral callosal axon growth accuracy towards the midline downstream of Neurod family factors.

Adhesion dynamics in the neocortex determine the start of migration and the post-migratory orientation of neurons

The neocortex is stereotypically organized into layers of excitatory neurons arranged in a precise parallel orientation. Here we show that dynamic adhesion both preceding and following radial migration is essential for this organization. Neuronal adhesion is regulated by the Mowat-Wilson syndrome-associated transcription factor Zeb2 (Sip1/Zfhx1b) through direct repression of independent adhesion pathways controlled by Neuropilin-1 (Nrp1) and Cadherin-6 (Cdh6). We reveal that to initiate radial migration, neurons must first suppress adhesion to the extracellular matrix. Zeb2 regulates the multipolar stage by transcriptional repression of Nrp1 and thereby downstream inhibition of integrin signaling. Upon completion of migration, neurons undergo an orientation process that is independent of migration. The parallel organization of neurons within the neocortex is controlled by Cdh6 through atypical regulation of integrin signaling via its RGD motif. Our data shed light on the mechanisms that regulate initiation of radial migration and the postmigratory orientation of neurons during neocortical development.

The murine ortholog of Kaufman oculocerebrofacial syndrome protein Ube3b regulates synapse number by ubiquitinating Ppp3cc

Kaufman oculocerebrofacial syndrome (KOS) is a severe autosomal recessive disorder characterized by intellectual disability, developmental delays, microcephaly, and characteristic dysmorphisms. Biallelic mutations of UBE3B, encoding for a ubiquitin ligase E3B are causative for KOS. In this report, we characterize neuronal functions of its murine ortholog Ube3b and show that Ube3b regulates dendritic branching in a cell-autonomous manner. Moreover, Ube3b knockout (KO) neurons exhibit increased density and aberrant morphology of dendritic spines, altered synaptic physiology, and changes in hippocampal circuit activity. Dorsal forebrain-specific Ube3b KO animals show impaired spatial learning, altered social interactions, and repetitive behaviors. We further demonstrate that Ube3b ubiquitinates the catalytic γ-subunit of calcineurin, Ppp3cc, the overexpression of which phenocopies Ube3b loss with regard to dendritic spine density. This work provides insights into the molecular pathologies underlying intellectual disability-like phenotypes in a genetically engineered mouse model.

mTORC1 and mTORC2 Differentially Regulate Cell Fate Programs to Coordinate Osteoblastic Differentiation in Mesenchymal Stromal Cells

Vascular regeneration depends on intact function of progenitors of vascular smooth muscle cells such as pericytes and their circulating counterparts, mesenchymal stromal cells (MSC). Deregulated MSC differentiation and maladaptive cell fate programs associated with age and metabolic diseases may exacerbate arteriosclerosis due to excessive transformation to osteoblast-like calcifying cells. Targeting mTOR, a central controller of differentiation and cell fates, could offer novel therapeutic perspectives. In a cell culture model for osteoblastic differentiation of pluripotent human MSC we found distinct roles for mTORC1 and mTORC2 in the regulation of differentiation towards calcifying osteoblasts via cell fate programs in a temporally-controlled sequence. Activation of mTORC1 with induction of cellular senescence and apoptosis were hallmarks of transition to a calcifying phenotype. Inhibition of mTORC1 with Rapamycin elicited reciprocal activation of mTORC2, enhanced autophagy and recruited anti-apoptotic signals, conferring protection from calcification. Pharmacologic and genetic negative interference with mTORC2 function or autophagy both abolished regenerative programs but induced cellular senescence, apoptosis, and calcification. Overexpression of the mTORC2 constituent rictor revealed that enhanced mTORC2 signaling without altered mTORC1 function was sufficient to inhibit calcification. Studies in mice reproduced the in vitro effects of mTOR modulation with Rapamycin on cell fates in vascular cells in vivo. Amplification of mTORC2 signaling promotes protective cell fates including autophagy to counteract osteoblast differentiation and calcification of MSC, representing a novel mTORC2 function. Regenerative approaches aimed at modulating mTOR network activation patterns hold promise for delaying age-related vascular diseases and treatment of accelerated arteriosclerosis in chronic metabolic conditions.

Polarity Acquisition in Cortical Neurons Is Driven by Synergistic Action of Sox9-Regulated Wwp1 and Wwp2 E3 Ubiquitin Ligases and Intronic miR-140

The establishment of axon-dendrite polarity is fundamental for radial migration of neurons during cortex development of mammals. We demonstrate that the E3 ubiquitin ligases WW-Containing Proteins 1 and 2 (Wwp1 and Wwp2) are indispensable for proper polarization of developing neurons. We show that knockout of Wwp1 and Wwp2 results in defects in axon-dendrite polarity in pyramidal neurons, and their aberrant laminar cortical distribution. Knockout of miR-140, encoded in Wwp2 intron, engenders phenotypic changes analogous to those upon Wwp1 and Wwp2 deletion. Intriguingly, transcription of the Wwp1 and Wwp2/miR-140 loci in neurons is induced by the transcription factor Sox9. Finally, we provide evidence that miR-140 supervises the establishment of axon-dendrite polarity through repression of Fyn kinase mRNA. Our data delineate a novel regulatory pathway that involves Sox9-[Wwp1/Wwp2/miR-140]-Fyn required for axon specification, acquisition of pyramidal morphology, and proper laminar distribution of cortical neurons.

Targeting proinflammatory cytokines ameliorates calcifying phenotype conversion of vascular progenitors under uremic conditions in vitro

Severe vascular calcification develops almost invariably in chronic kidney patients posing a substantial risk to quality of life and survival. This unmet medical need demands identification of novel therapeutic modalities. We aimed to pinpoint components of the uremic microenvironment triggering differentiation of vascular progenitors to calcifying osteoblast-like cells. In an unbiased approach, assessing the individual potency of 63 uremic retention solutes to enhance calcific phenotype conversion of vascular progenitor cells, the pro-inflammatory cytokines IL-1β and TNF-α were identified as the strongest inducers followed by FGF-2, and PTH. Pharmacologic targeting of these molecules alone or in combination additively antagonized pro-calcifying properties of sera from uremic patients. Our findings stress the importance of pro-inflammatory cytokines above other characteristic components of the uremic microenvironment as key mediators of calcifying osteoblastic differentiation in vascular progenitors. Belonging to the group of "middle-sized molecules", they are neither effectively removed by conventional dialysis nor influenced by established supportive therapies. Specific pharmacologic interventions or novel extracorporeal approaches may help preserve regenerative capacity and control vascular calcification due to uremic environment.

Intrinsic Deregulation of Vascular Smooth Muscle and Myofibroblast Differentiation in Mesenchymal Stromal Cells from Patients with Systemic Sclerosis

Introduction

Obliterative vasculopathy and fibrosis are hallmarks of systemic sclerosis (SSc), a severe systemic autoimmune disease. Bone marrow-derived mesenchymal stromal cells (MSCs) from SSc patients may harbor disease-specific abnormalities. We hypothesized disturbed vascular smooth muscle cell (VSMC) differentiation with increased propensity towards myofibroblast differentiation in response to SSc-microenvironment defining growth factors and determined responsible mechanisms.

Methods

We studied responses of multipotent MSCs from SSc-patients (SSc-MSCs) and healthy controls (H-MSCs) to long-term exposure to CTGF, b-FGF, PDGF-BB or TGF-β1. Differentiation towards VSMC and myofibroblast lineages was analyzed on phenotypic, biochemical, and functional levels. Intracellular signaling studies included analysis of TGF-β receptor regulation, SMAD, AKT, ERK1/2 and autocrine loops.

Results

VSMC differentiation towards both, contractile and synthetic VSMC phenotypes in response to CTGF and b-FGF was disturbed in SSc-MSCs. H-MSCs and SSc-MSCs responded equally to PDGF-BB with prototypic fibroblastic differentiation. TGF-β1 initiated myofibroblast differentiation in both cell types, yet with striking phenotypic and functional differences: In relation to H-MSC-derived myofibroblasts induced by TGF-β1, those obtained from SSc-MSCs expressed more contractile proteins, migrated towards TGF-β1, had low proliferative capacity, and secreted higher amounts of collagen paralleled by reduced MMP expression. Higher levels of TGF-β receptor 1 and enhanced canonical and noncanonical TGF-β signaling in SSc-MSCs accompanied aberrant differentiation response of SSc-MSCs in comparison to H-MSCs.

Conclusions

Deregulated VSMC differentiation with a shift towards myofibroblast differentiation expands the concept of disturbed endogenous regenerative capacity of MSCs from SSc patients. Disease related intrinsic hyperresponsiveness to TGF-β1 with increased collagen production may represent one responsible mechanism. Better understanding of repair barriers and harnessing beneficial differentiation processes in MSCs could widen options of autologous MSC application in SSc patients.

Triphos derivatives and diphosphines as ligands in the ruthenium-catalysed alcohol amination with NH3

The ruthenium-triphos and diphosphine-catalysed amination of alcohols with ammonia is reported.

SPOC1: a novel PHD-containing protein modulating chromatin structure and mitotic chromosome condensation

In this study, we characterize the molecular and functional features of a novel protein called SPOC1. SPOC1 RNA expression was previously reported to be highest in highly proliferating tissues and increased in a subset of ovarian carcinoma patients, which statistically correlated with poor prognosis and residual disease. These observations implied that SPOC1 might play a role in cellular proliferation and oncogenesis. Here we show that the endogenous SPOC1 protein is labile, primarily chromatin associated and its expression as well as localization are regulated throughout the cell cycle. SPOC1 is dynamically regulated during mitosis with increased expression levels and biphasic localization to mitotic chromosomes indicating a functional role of SPOC1 in mitotic processes. Consistent with this postulate, SPOC1 siRNA knockdown experiments resulted in defects in mitotic chromosome condensation, alignment and aberrant sister chromatid segregation. Finally, we have been able to show, using micrococcal nuclease (MNase) chromatin-digestion assays that SPOC1 expression levels proportionally influence the degree of chromatin compaction. Collectively, our findings show that SPOC1 modulates chromatin structure and that tight regulation of its expression levels and subcellular localization during mitosis are crucial for proper chromosome condensation and cell division.

Threshold extraction in metabolite concentration data

MOTIVATION

Continued development of analytical techniques based on gas chromatography and mass spectrometry now facilitates the generation of larger sets of metabolite concentration data. An important step towards the understanding of metabolite dynamics is the recognition of stable states where metabolite concentrations exhibit a simple behaviour. Such states can be characterized through the identification of significant thresholds in the concentrations. But general techniques for finding discretization thresholds in continuous data prove to be practically insufficient for detecting states due to the weak conditional dependences in concentration data.

RESULTS

We introduce a method of recognizing states in the framework of decision tree induction. It is based upon a global analysis of decision forests where stability and quality are evaluated. It leads to the detection of thresholds that are both comprehensible and robust. Applied to metabolite concentration data, this method has led to the discovery of hidden states in the corresponding variables. Some of these reflect known properties of the biological experiments, and others point to putative new states.

AVAILABILITY

An implementation of this approach can be obtained from the authors upon request.

High glucose dialysis solutions increase synthesis of vascular endothelial growth factors by peritoneal vascular endothelial cells

OBJECTIVE

Increased peritoneal vasculature has been reported in long-term peritoneal dialysis (PD), and vascular endothelial growth factors (VEGFs) have been found in dialysate. High concentrations of glucose or lactate, glucose degradation products (GDPs), and low pH of dialysis solutions are all possible factors in increased peritoneal VEGF synthesis. In this study, we investigated the effects of high glucose dialysis solutions on VEGF synthesis by peritoneal vascular endothelial cells (PVECs).

METHODS

The PVECs were isolated from rat omentum and were incubated for 4 hours in three different culture media [M199 media (control), conventional dialysis solutions containing 4.25% glucose diluted with an equal volume of M199 media (HGD), and M199 media containing 118 mmol/L mannitol as an osmolar control (mannitol)]. Levels of VEGF protein in the culture supernatant were measured by ELISA, and mRNA expression was determined by Northern blot analysis. Data are presented as percent of control.

RESULTS

After incubation for 4 hours, the number of cells did not differ between the 3 groups. Levels of VEGF in culture supernatant were significantly higher in the HGD group (124% +/- 19%, p = 0.006) as compared with the control and mannitol (85% +/- 10%) groups. The mRNA expression of VEGF appeared to be higher in the HGD group (128% +/- 49%) than in the control and mannitol (94% +/- 18%) groups.

CONCLUSION

High glucose dialysis solutions increased VEGF synthesis by PVECs. The relationship between VEGF synthesis by PVECs and neovascularization of the peritoneum observed in long-term peritoneal dialysis patients has to be studied further.

Developmental regulation of FKBP65. An ER-localized extracellular matrix binding-protein

FKBP65 (65-kDa FK506-binding protein) is a member of the highly conserved family of intracellular receptors called immunophilins. All have the property of peptidyl-prolyl cis-trans isomerization, and most have been implicated in folding and trafficking events. In an earlier study, we identified that FKBP65 associates with the extracellular matrix protein tropoelastin during its transport through the cell. In the present study, we have carried out a detailed investigation of the subcellular localization of FKBP65 and its relationship to tropoelastin. Using subcellular fractionation, Triton X-114 phase separation, protease protection assays, and immunofluorescence microscopy (IF), we have identified that FKBP65 is contained within the lumen of the endoplasmic reticulum (ER). Subsequent IF studies colocalized FKBP65 with tropoelastin and showed that the two proteins dissociate before reaching the Golgi apparatus. Immunohistochemical localization of FKBP65 in developing lung showed strong staining of vascular and airway smooth muscle cells. Similar areas stained positive for the presence of elastic fibers in the extracellular matrix. The expression of FKBP65 was investigated during development as tropoelastin is not expressed in adult tissues. Tissue-specific expression of FKBP65 was observed in 12-d old mouse tissues; however, the pattern of expression of FKBP65 was not restricted to those tissues expressing tropoelastin. This suggests that additional ligands for FKBP65 likely exist within the ER. Remarkably, in the adult tissues examined, FKBP65 expression was absent or barely detectable. Taken together, these results support an ER-localized FKBP65-tropoelastin interaction that occurs specifically during growth and development of tissues.

Characterization of an in vitro model of elastic fiber assembly

Elastic fibers consist of two morphologically distinct components: elastin and 10-nm fibrillin-containing microfibrils. During development, the microfibrils form bundles that appear to act as a scaffold for the deposition, orientation, and assembly of tropoelastin monomers into an insoluble elastic fiber. Although microfibrils can assemble independent of elastin, tropoelastin monomers do not assemble without the presence of microfibrils. In the present study, immortalized ciliary body pigmented epithelial (PE) cells were investigated for their potential to serve as a cell culture model for elastic fiber assembly. Northern analysis showed that the PE cells express microfibril proteins but do not express tropoelastin. Immunofluorescence staining and electron microscopy confirmed that the microfibril proteins produced by the PE cells assemble into intact microfibrils. When the PE cells were transfected with a mammalian expression vector containing a bovine tropoelastin cDNA, the cells were found to express and secrete tropoelastin. Immunofluorescence and electron microscopic examination of the transfected PE cells showed the presence of elastic fibers in the matrix. Biochemical analysis of this matrix showed the presence of cross-links that are unique to mature insoluble elastin. Together, these results indicate that the PE cells provide a unique, stable in vitro system in which to study elastic fiber assembly.

[Value of imaging techniques in the diagnosis of lumbar intervertebral disk prolapse]

As a seeming law of nature the possibility of making use of various multiplanar sectional imaging techniques is accompanied by diagnostic exaggeration. Simple and cost effective procedures with low radiation dosage such as plain x-rays of the spine are being thrust into the background. Not seldom are patients referred to the spine surgeon with MRI or Cat scan at hand but lacking standard radiographs. As far as the assessment of intervertebral disc disease is concerned the combination of plain X-rays of the spine and computed tomography of the level in question turned out to be sufficient for indication of the operation in more than 90% of 450 patients after nucleotomie at the Orthopedic University Clinic Mainz. To our mind MRI should be restricted to cases in whom disc surgery had failed to relieve sciatica. Here it allows to distinguish between a recurrent HNP and postoperative scar tissue. In our patients myelography, an invasive procedure, has its role only in emergency diagnostics, and in the dynamic-functional examination.

[Use of the tumor prosthesis in secondary neoplastic destruction of the proximal end of the femur]

Total hip arthroplasty was performed with PMMA-augmented tumor prostheses in 42 individuals suffering from metastatic destruction of the proximal end of the femur at the Orthopedic University Hospital Mainz from 1980 to 1992. Neoplastic lesions had been triggered by carcinomas of the breast in 25 female patients. 24 of our patients presented with pathologic fractures. In all patients capable of walking preoperatively early mobilization could be attained by total hip arthroplasty. Pain relief was achieved in each patient. Resection of the major trochanter and, partially, of the pelvitrochanteric muscle sleeve entailed luxation of the prosthesis six times in 5 individuals during the first postoperative two months; closed reduction was practicable in all of them. Postoperative survival time amounted to an average of 10.5 months. Leg length and hip function were successfully re-established by implanting tumor prostheses after resection of the proximal part of the femur.

[Computed tomography following extracorporeal shockwave lithotripsy of the kidneys. III. A prospective CT study of 105 patients and a 3-year follow-up of 23 patients using CT and 99mTc-MAG3 clearance]

In 105 patients CT studies were done prospectively after renal ESWL with a second generation lithotripter. 33 (31%) of the patients had renal oedema (n = 8), renal (n = 20) or extrarenal (n = 31) bleeding. Three of the 23 patients who had a three year follow-up had chronic renal changes, 10 had renal stones. As blunt renal trauma can be the cause of renal hypertension a longterm follow-up is necessary in ESWL patients, particularly if there was renal bleeding after treatment. Further studies are needed to determine the exact risk of renal hypertension after ESWL.

[99m-Technetium-mercaptoacetyltriglycine (MAG3) for the demonstration of the kidney changes following extracorporeal shockwave lithotripsy. A prospective study of 117 patients]

Extracorporeal shock wave lithotripsy (ESWL) has become the treatment of choice for urinary calculi. 117 patients were studied prospectively with 99mTc mercaptoacetyltriglycine (MAG3) before and after ESWL. 79 (66%) of the 119 kidneys treated had abnormal findings. Of these 63/119 (53%) had abnormal scans. 41 (65%) had focal lesions with a delayed intrarenal transport. The remaining 22 had a diffuse delay of intrarenal transport. A loss of relative renal function of 3% and more compared to the pretreatment values was observed in 50/119 (42%) patients. 99mTc MAG3 should be done routinely together with radiologic tests (CT or MRI) before and after ESWL to select the patients at risk for post ESWL hypertension.

[Computed tomography after extracorporeal shockwave lithotripsy (ESWL) of the kidneys. II. A correlation with the histopathologic findings 3 weeks later in an animal experiment]

In a pig model, 13 kidneys were treated with a second generation lithotripter and examined by CT immediately and three weeks after ESWL. 9 (69%) acute traumatic lesions were seen in CT without, and 10 (77%) in CT with contrast in the 13 treated kidneys. After 3 weeks only 1 residual lesion persisted in CT contrast studies. On the histopathologic specimens residuals of bleeding were found in 3 (23%) of the 13 kidneys treated, which could not be seen in CT studies. CT is accurate in monitoring acute traumatic renal lesions after ESWL, but appears less reliable in chronic ones. Three weeks after ESWL traumatic renal lesions show marked regression.

[Computed tomography following extracorporeal shockwave lithotripsy (ESWL) of the kidneys. I: Correlation with acute histopathological findings in experimental animals]

In an experimental study on pigs, 28 stone-free kidneys were treated with a second generation lithotripter. Histologically, acute bleeding was seen after ESWL in 23 (82%) of the 28 treated kidneys. CT studies before and after contrast were correct in 20/28 (74%) cases. It was shown that extracorporeal shock waves cause renal bleeding that is only partially detected by computed tomography. It can be concluded that the CT findings seen in a high percentage of renal stone patients after ESWL represent bleeding. The incidence of renal bleeding after ESWL and thus the possible risk of hypertension has obviously been underestimated so far in clinical studies.

ATP-dependent leukotriene export from mastocytoma cells

The biosynthesis of leukotrienes (LT) C4 and B4 is followed by an export of these mediators into the extracellular space. This transport was characterized using plasma membrane vesicles prepared from mastocytoma cells and identified as an ATP-dependent primary active process. The apparent Km-values were 110 nM for LTC4 and 48 microM for ATP. The transport rate was highest for LTC4, whereas LTD4, LTE4, and N-acetyl-LTE4 were transported with relative rates of 31, 12 and 8%, respectively, at a concentration of 10 nM. LTB4 transport was also dependent on ATP. LTC4 transport was inhibited by LTD4 receptor antagonists (IC50 = 1.0 microM for MK-571 and 1.3 microM for LY245769) and by the inhibitor of leukotriene biosynthesis MK-886 (IC50 = 1.8 microM). The ATP-dependent export carrier for leukotrienes in leukotriene-synthesizing cells represents a novel member of the family of ATP-dependent exit pumps.

[Acute effects of the natural atmospheric ozone exposure on lung function of clinically normal smokers and non-smokers]

The influence of moderate ambient ozone exposure on spirometric lung function and bronchial responsiveness was analyzed in 13 healthy adult nonsmokers and 11 asymptomatic smokers. The study was divided into an initial investigation at low atmospheric ozone concentrations of about 80 (range 68-102) micrograms/m3 and a subsequent similar testing at moderately elevated ozone concentrations above 140 (range 145-205) micrograms/m3. Overall there was a slight but significant impairment in forced expiratory volumes (p less than 0.002) at elevated compared with low ozone concentrations. Furthermore, a significant increase in bronchial responsiveness was shown, with a decrease in threshold dose for inhaled metacholine to produce a 50% fall in specific airway conductance (p less than 0.02). In both smokers and nonsmokers there was a similar change in lung function at ambient ozone concentrations, with more pronounced bronchial irritation in the smokers group. It is concluded that even moderately elevated ambient ozone concentrations can induce slight but significant ventilatory obstruction and an obvious increase in bronchial responsiveness in healthy adults. Although the minor impairment of lung function did not cause manifest acute respiratory problems, it still reduced maximal physical ventilation capacity. The results further support the assumption that air pollution may act as a primary trigger in the development of obstructive airway disease.

ATP-dependent primary active transport of cysteinyl leukotrienes across liver canalicular membrane. Role of the ATP-dependent transport system for glutathione S-conjugates

The liver is the major organ which eliminates leukotriene C4 (LTC4) and other cysteinyl leukotrienes from the blood circulation into bile. Transport of LTC4 was studied using inside-out vesicles enriched in canalicular and sinusoidal membranes from rat liver. The incubation of canalicular membrane vesicles with [3H]LTC4 in the presence of ATP resulted in an uptake of LTC4 into vesicles. The initial rate of ATP-stimulated LTC4 uptake was about 40-fold higher in canalicular than in sinusoidal membrane vesicles. When liver plasma membrane vesicles were incubated in the absence of ATP, an apparent transient uptake of LTC4 was observed which was temperature-dependent and not affected by the osmolarity. This indicates that LTC4 was bound to proteins on the surface of plasma membrane vesicles. Two proteins with relative molecular weights of 17,000 and 25,000 were detected by direct photoaffinity labeling as major LTC4-binding proteins. One protein (Mr 25,000) was ascribed to subunit 1 (Ya) of glutathione S-transferase which was associated with the membrane. LTD4, LTE4, N-acetyl-LTE4, and omega-carboxy-N-acetyl-LTE4 were also transported into liver plasma membrane vesicles in an ATP-dependent manner with initial rates relative to LTC4 (1.0) of 0.46, 0.11, 0.35, and 0.22, respectively. Mutual competition between the cysteinyl leukotrienes and S-(2,4-dinitrophenyl)-glutathione for uptake indicated that they are transported by a common carrier. Apparent Km values of the transport system for LTC4, LTD4, and N-acetyl-LTE4 were 0.25, 1.5, and 5.2 microM, respectively. The ATP-dependent transport of LTC4 into vesicles was not inhibited by doxorubicin, daunorubicin, or verapamil, or by the monoclonal antibody C219, suggesting that the transport system differs from P-glycoprotein. Liver plasma membrane vesicles prepared from mutant rats deficient in the hepatobiliary excretion of cysteinyl leukotrienes lacked the ATP-dependent transport of cysteinyl leukotrienes and S-(2,4-dinitrophenyl)-glutathione. These results demonstrate that the ATP-dependent carrier system is responsible for the transport of cysteinyl leukotrienes and glutathione S-conjugates from the hepatocytes into bile.

[Melorheostosis, osteopoikilosis and ostiopathia striata. Their clinical significance and the value of scintigraphy in the differential diagnosis]

Melorheostosis, Osteopoikilosis and Osteopathia striata Clinical Relevance and Bone Scintigraphy Melorheostosis, Osteopoikilosis and Osteopathia striata are rare conditions. Although there is no casual therapy for any of the three diseases, differential diagnosis is important because concomitant or resulting impairments deserve orthopaedic or medical treatment. The analysis of typical cases with their clinical, roentgenological and radionuclide presentation shows the need of an accurate diagnosis to prevent senseless treatment or lost therapeutic opportunities.

Nuclear medicine studies in the differential diagnosis of diseases with spinal involvement

Plain X-rays computed tomographic and magnetic resonance images all yield information on the pathophysiology of diseases with spinal involvement. Descriptions of the following nuclear medicine methods are presented: Bone scanning with 99 m-technetium labeled phosphonate complexes used for the evaluation of skeletal metastases, primary bone tumors, traumatic, degenerative, and postoperative changes as well as in inflammatory conditions. Specific radionuclides used for the localization of inflammatory conditions are radioactive labeled leucocytes. Iodine total body scans used to detect spinal metastases of follicular and papillary thyroid carcinoma. 201-thalliumchloride is used as a tumor-marker with high affinity and sensitivity in malignant thyroid tumors. 131- or 123-iodine-meta-iodobenzylguanidine scans used in the detection of metastases of pheochromocytoma and neuroblastoma. Immunoscintigraphy with radioactive labeled anti-CEA antibodies used for the specific labelling of metastases of gastrointestinal tract tumors, melanoma, breast, and ovarian carcinoma. The value of the various nuclear medicine methods in the diagnostic schedule is illustrated in case reports.

[A computed tomographic analysis of vertebral rotation before and after surgical correction of idiopathic scoliosis]

Preoperative and postoperative computer tomographs in 24 patients suffering from idiopathic scolioses who were treated by CD (Cotrel-Dubousset) surgery, showed a mean correction of the rotatory angle in the apex vertebra amounting to 28.5% in relation to the anterior midline of the body, and 23.8% in relation to the sagittal plane. Best results were seen in lumbar curves and in the lumbar curves of double major curves. In thoracic curves only minor corrections were observed. CD instrumentation is the first dorsal procedure that allows a three-dimensional correction of the scoliotic spine.

[The place of bone scintigraphy in the diagnosis and follow-up of Ewing's sarcoma]

The radiological and scintigraphic findings of 26 patients with histologically proven Ewing's sarcoma were analysed. Three-phase bone scan should be done early in patients presenting with pain and normal radiographs. Perfusion and metabolism of a bone lesion can be assessed by skeletal scintigraphy. Bone metastases are first seen on bone scan. In the follow-up of the patient bone scans at regular intervals are essential to detect bone metastases and tumour recurrence. The scintigraphic findings have to be correlated with radiographs and if these are negative a short-term control is indicated. Three-phase bone scans can assess the tumours response to therapy.

[Tumors of the ceruminous glands]

Tumours originating from the ceruminous glands can be classified into five types: adenomas, adenocarcinomas, adenoid-cystic carcinomas, pleomorphic adenomas and mucoepidermoid carcinomas. The diagnosis is based on histological findings and can be quite difficult if the tumour status has to be determined. Classification into one of the five types of tumours may be facilitated at times by studying the clinical pattern. Three case reports are quoted as examples to illustrate that neoplasias originating from the ceruminous glands can assume considerable proportions and must be considered in differential diagnosis when assessing space-occupying growths in the soft tissue of the neck. Whereas prognosis of adenomas and pleomorphic adenomas can be considered to be good, it must be regarded as likely to be infaust in the case of adenocarcinomas, adenoid-cystic carcinomas and mucoepidermoid carcinomas. The use of cytostatics resulted in a marked reduction of the tumour in one of the described cases of adenocarcinoma.

["False" sinking abscess]

In a 43 year old man with an inguinal abscess a paravertebral soft tissue swelling suggested a gravitation abscess. On CT only a retrocrural fat accumulation was identified.

Radionuclide imaging in histiocytosis X

Radionuclide imaging (99mTc bone scans, 99mTc S colloid scans, 99mTc brain scans and 67gallium scans) and bone radiographs were done in 54 children with histiocytosis X. The results are discussed, compared with the literature and indications for the different nuclear medicine studies are given.

[Difficulties in the diagnosis of osteoid osteoma]

The difficulties arising in diagnosing osteoidosteoma are demonstrated by means of 30 surgically treated cases and the results are compared with those available from the literature. The value of bone scintigraphy and of tomography within the framework of a diagnostic concept is underlined. Diagnosis is confirmed and treatment is effected by the successful surgical removal of the nidus.

[Diagnosis of Ewing sarcoma of the thoracic spine--differential diagnostic difficulties]

Spinal Ewing's sarcomas are rare and cause problems in differential diagnosis. The radiologic, nuclear medicine and CT findings in two children with histologically proven Ewing's sarcoma are presented and problems in differential diagnosis discussed. Biopsy should be done early.

[Diagnosis and course of synovial sarcoma. Comparison of x-ray diagnosis and bone scintigraphy]

The unfavourable prognosis of malignant synoviomas makes it essential to arrive at an early diagnosis. The early clinical symptoms and radiological appearances may be minimal and sometimes absent. It is therefore advisable to obtain bone scintigrams with perfusion and early images as well as the radiographs. The local extent of the tumour can be evaluated by ultrasound and CT. Angiography is required only if the relationship to the vessels cannot otherwise be ascertained, or if intra-arterial therapy is being considered. The final diagnosis depends on a biopsy. For subsequent observation, both scintigrams and radiographs should be obtained. It is essential to perform a three-phase scintigram. This improves the recognition of recurrences and of soft tissue or bone metastases. Most bone metastases are visible on scintigraphy, but a normal scintigram in the presence of an osteolytic lesion on a radiograph may be obtained. Pulmonary metastases can only be demonstrated radiologically.

Digital subtraction angiography in staging renal cell carcinoma: comparison with computerized tomography and histopathology

Digital subtraction angiography was compared to computerized tomography and histopathological findings for staging renal cell carcinoma in 24 patients. Injection of contrast material through a 16 gauge angiocatheter into the femoral vein provided digital subtraction cavography, digital subtraction arteriography and excretory urography during 1 investigation. Computerized tomography established the diagnosis in all patients, while digital subtraction angiography showed all angiographic signs of renal cell carcinoma in 14 (58 per cent). T staging was correct on computerized tomography in 18 patients and on digital subtraction angiography in 16. Absence or presence of venous involvement was indicated correctly by computerized tomography in 20 patients and by digital subtraction angiography in 21. In small tumors the combination of ultrasonography, digital subtraction angiography and excretory urography is sufficient for an operation. In all other tumors digital subtraction angiography cannot replace computerized tomography but adds useful information about arterial distribution, possible venous tumor thrombus and the anatomical relationship of vessels.