Pain and salivary biomarkers of stress in temperomandibular disorders were affected by maxillary splints

BACKGROUND

Longitudinal intervention studies on treatment options in temporomandibular dysfunction (TMD) including self reports and salivary biomarkers of stress are rare and the exact therapeutic function of occlusal splints widely unknown.

METHODS

We examined the therapeutic effects of a Michigan splint with occlusal relevance in patients with TMD using a placebo-controlled, delayed-start design. Two intervention groups received a Michigan splint, while one of them had a placebo palatine splint for the first 3 weeks. We collected pain intensities (at rest and after five occlusal movements), salivary measures associated with stress (cortisol and alpha-amylase) and self-reported psychological distress (stress, anxiety, catastrophizing) at baseline and 3 and 7 weeks after onset of intervention.

RESULTS

At baseline, we observed increased pain intensity and psychological distress in TMD patients compared to 11 matched healthy controls. Baseline anxiety was linked to movement pain intensity through stress. Over therapy reductions in pain intensity and morning cortisol were more pronounced in those patients starting immediately with the Michigan splint, while psychological distress decreased similarly in both groups.

CONCLUSION

Our results suggest that perceived stress plays a role for the association between anxiety and TMD pain and underlines the need for an interdisciplinary perspective on the pathogenesis and therapy of TMD in a setting where psychotherapeutic knowledge is still scarce or rarely applied.

Caveolar Compartmentalization is Required for Stable Rhythmicity of Sinus Nodal Cells and is Disrupted in Heart Failure

Background

Heart rhythm relies on complex interactions between the electrogenic membrane proteins and intracellular Ca 2+ signaling in sinoatrial node (SAN) myocytes; however, the mechanisms underlying the functional organization of the proteins involved in SAN pacemaking and its structural foundation remain elusive. Caveolae are nanoscale, plasma membrane pits that compartmentalize various ion channels and transporters, including those involved in SAN pacemaking, via binding with the caveolin-3 scaffolding protein, however the precise role of caveolae in cardiac pacemaker function is unknown. Our objective was to determine the role of caveolae in SAN pacemaking and dysfunction (SND).

Methods

In vivo electrocardiogram monitoring, ex vivo optical mapping, in vitro confocal Ca 2+ imaging, immunofluorescent and electron microscopy analysis were performed in wild type, cardiac-specific caveolin-3 knockout, and 8-weeks post-myocardial infarction heart failure (HF) mice. SAN tissue samples from donor human hearts were used for biochemical studies. We utilized a novel 3-dimensional single SAN cell mathematical model to determine the functional outcomes of protein nanodomain-specific localization and redistribution in SAN pacemaking.

Results

In both mouse and human SANs, caveolae compartmentalized HCN4, Ca v 1.2, Ca v 1.3, Ca v 3.1 and NCX1 proteins within discrete pacemaker signalosomes via direct association with caveolin-3. This compartmentalization positioned electrogenic sarcolemmal proteins near the subsarcolemmal sarcoplasmic reticulum (SR) membrane and ensured fast and robust activation of NCX1 by subsarcolemmal local SR Ca 2+ release events (LCRs), which diffuse across ∼15-nm subsarcolemmal cleft. Disruption of caveolae led to the development of SND via suppression of pacemaker automaticity through a 50% decrease of the L-type Ca 2+ current, a negative shift of the HCN current ( I f ) activation curve, and 40% reduction of Na + /Ca 2+ -exchanger function. These changes significantly decreased the SAN depolarizing force, both during diastolic depolarization and upstroke phase, leading to bradycardia, sinus pauses, recurrent development of SAN quiescence, and significant increase in heart rate lability. Computational modeling, supported by biochemical studies, identified NCX1 redistribution to extra-caveolar membrane as the primary mechanism of SAN pauses and quiescence due to the impaired ability of NCX1 to be effectively activated by LCRs and trigger action potentials. HF remodeling mirrored caveolae disruption leading to NCX1-LCR uncoupling and SND.

Conclusions

SAN pacemaking is driven by complex protein interactions within a nanoscale caveolar pacemaker signalosome. Disruption of caveolae leads to SND, potentially representing a new dimension of SAN remodeling and providing a newly recognized target for therapy.

Is Appendectomy During Late Stages of Pregnancy Associated with an Increased Cesarean Delivery Rate? - a Retrospective Analysis of One Center During 10 Years

Introduction

About one in 500 pregnant women requires a surgical intervention that is not pregnancy-related. One of the most common surgical interventions during pregnancy is appendectomy. The primary aim of this study was to assess surgical access of appendectomy during pregnancy and pregnancy outcome. Secondary outcomes were clinical symptoms and diagnostics as well as histopathological analysis.

Methods and Material

This is a single-center retrospective data analysis conducted at a tertiary perinatal center. A digital search of the hospital record archive was conducted focusing on pregnant women beyond 24 0/7 weeks of pregnancy encoding appendectomy. Descriptive statistical analysis was performed.

Results

Between January 2013 and January 2023, a total of 20 appendectomies were performed during pregnancy with gestational age beyond 24 0/7 weeks of pregnancy. All of them were performed as lower midline laparotomy. The rate of appendix perforation was 3/20 (15.0%). 19/20 patients (95.0%) delivered via cesarean. In 7/20 patients (35.0%) appendectomy was performed during cesarean delivery due to incidental finding of irritated or abnormal vermiform appendix. In the pathological work-up, only 2/7 (28.6%) of these subjects had inflammation.

Conclusion

In this small monocentric cohort, only open appendectomies were performed. Our data indicate that it is safe to perform open appendectomy during pregnancy if necessary. In this small patient group, there was an increase in simultaneous cesarean deliveries.

Covid-19 during Pregnancy - Histopathological Lesions of the Placenta

INTRODUCTION

Pregnant women and their offspring represented a vulnerable patient collective during the Covid-19 pandemic. Beyond the direct effect of SARS-CoV-2 via vertical transmission, an indirect impact on the fetus can occur through placental lesions deteriorating placental villous function. We performed a histopathological analysis of placentas of parturients with SARS-CoV-2 compared to healthy controls.

METHODS AND MATERIALS

Between February 2022 and July 2022 we conducted a prospective case-control study analyzing placental specimens of parturients with SARS-CoV-2 infection compared to specimens of placentas of healthy controls. Patient history, Covid-19-specific symptoms, and obstetric outcomes were recorded. Statistical analysis was performed.

RESULTS

During the observation period 71 patients were included with a gestational age 37 1/7-41 5/7 weeks. Thirty-six patients presented with SARS-CoV-2 infection. The control group consisted of 35 patients and showed no placental abnormalities. Among SARS-CoV-2-positive parturients, 66.7% of placentas of the case group showed histopathological abnormalities classified as vascular or inflammatory abnormalities. 22.2% of placentas showed acute ischemic infarction areas. 8.3% of placentas showed subchorionic layered thrombi. There was one case of severe acute subchorionitis. SARS-CoV-2 increased the risk of placental lesions significantly (OR 3.000, CI 1.890-4.762, p=0.0001). Placental lesions had no significant impact on perinatal acidosis (OR 0.455, CI 0.044-4.667, p=0.498) or number of cesarean sections (OR 2.314, CI 0.717-7.473, p=0.156).

CONCLUSION

SARS-CoV-2 infection during labor and delivery increased the risk of adverse outcomes. Histopathological analysis indicated that the placenta as a maternal-fetal interface was affected by SARS-CoV-2, leading to systemic vasculopathy and inflammation.

The spatial structure of the tumor immune microenvironment can explain and predict patient response in high-grade serous carcinoma

Despite ovarian cancer being the deadliest gynecological malignancy, there has been little change to therapeutic options and mortality rates over the last three decades. Recent studies indicate that the composition of the tumor immune microenvironment (TIME) influences patient outcomes but are limited by a lack of spatial understanding. We performed multiplexed ion beam imaging (MIBI) on 83 human high-grade serous carcinoma tumors - one of the largest protein-based, spatially-intact, single-cell resolution tumor datasets assembled - and used statistical and machine learning approaches to connect features of the TIME spatial organization to patient outcomes. Along with traditional clinical/immunohistochemical attributes and indicators of TIME composition, we found that several features of TIME spatial organization had significant univariate correlations and/or high relative importance in high-dimensional predictive models. The top performing predictive model for patient progression-free survival (PFS) used a combination of TIME composition and spatial features. Results demonstrate the importance of spatial structure in understanding how the TIME contributes to treatment outcomes. Furthermore, the present study provides a generalizable roadmap for spatial analyses of the TIME in ovarian cancer research.

A platform-independent framework for phenotyping of multiplex tissue imaging data

Multiplex imaging is a powerful tool to analyze the structural and functional states of cells in their morphological and pathological contexts. However, hypothesis testing with multiplex imaging data is a challenging task due to the extent and complexity of the information obtained. Various computational pipelines have been developed and validated to extract knowledge from specific imaging platforms. A common problem with customized pipelines is their reduced applicability across different imaging platforms: Every multiplex imaging technique exhibits platform-specific characteristics in terms of signal-to-noise ratio and acquisition artifacts that need to be accounted for to yield reliable and reproducible results. We propose a pixel classifier-based image preprocessing step that aims to minimize platform-dependency for all multiplex image analysis pipelines. Signal detection and noise reduction as well as artifact removal can be posed as a pixel classification problem in which all pixels in multiplex images can be assigned to two general classes of either I) signal of interest or II) artifacts and noise. The resulting feature representation maps contain pixel-scale representations of the input data, but exhibit significantly increased signal-to-noise ratios with normalized pixel values as output data. We demonstrate the validity of our proposed image preprocessing approach by comparing the results of two well-accepted and widely-used image analysis pipelines.

The funny current If is essential for the fight-or-flight response in cardiac pacemaker cells

The sympathetic nervous system fight-or-flight response is characterized by a rapid increase in heart rate, which is mediated by an increase in the spontaneous action potential (AP) firing rate of pacemaker cells in the sinoatrial node. Sympathetic neurons stimulate sinoatrial myocytes (SAMs) by activating β adrenergic receptors (βARs) and increasing cAMP. The funny current (If) is among the cAMP-sensitive currents in SAMs. If is critical for pacemaker activity, however, its role in the fight-or-flight response remains controversial. In this study, we used AP waveform analysis, machine learning, and dynamic clamp experiments in acutely isolated SAMs from mice to quantitatively define the AP waveform changes and role of If in the fight-or-flight increase in AP firing rate. We found that while βAR stimulation significantly altered nearly all AP waveform parameters, the increase in firing rate was only correlated with changes in a subset of parameters (diastolic duration, late AP duration, and diastolic depolarization rate). Dynamic clamp injection of the βAR-sensitive component of If showed that it accounts for ∼41% of the fight-or-flight increase in AP firing rate and 60% of the decrease in the interval between APs. Thus, If is an essential contributor to the fight-or-flight increase in heart rate.

Intracellular Na+ Modulates Pacemaking Activity in Murine Sinoatrial Node Myocytes: An In Silico Analysis

Background: The mechanisms underlying dysfunction in the sinoatrial node (SAN), the heart's primary pacemaker, are incompletely understood. Electrical and Ca2+-handling remodeling have been implicated in SAN dysfunction associated with heart failure, aging, and diabetes. Cardiomyocyte [Na+]i is also elevated in these diseases, where it contributes to arrhythmogenesis. Here, we sought to investigate the largely unexplored role of Na+ homeostasis in SAN pacemaking and test whether [Na+]i dysregulation may contribute to SAN dysfunction. Methods: We developed a dataset-specific computational model of the murine SAN myocyte and simulated alterations in the major processes of Na+ entry (Na+/Ca2+ exchanger, NCX) and removal (Na+/K+ ATPase, NKA). Results: We found that changes in intracellular Na+ homeostatic processes dynamically regulate SAN electrophysiology. Mild reductions in NKA and NCX function increase myocyte firing rate, whereas a stronger reduction causes bursting activity and loss of automaticity. These pathologic phenotypes mimic those observed experimentally in NCX- and ankyrin-B-deficient mice due to altered feedback between the Ca2+ and membrane potential clocks underlying SAN firing. Conclusions: Our study generates new testable predictions and insight linking Na+ homeostasis to Ca2+ handling and membrane potential dynamics in SAN myocytes that may advance our understanding of SAN (dys)function.

Assessing the spreading potential of an undetected case of COVID-19 in orthopaedic surgery

BACKGROUND

With the novel coronavirus-induced disease (COVID-19), there is the fear of nosocomial infections and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmissions to healthcare workers (HCW). We report the case of a 64-year-old male patient who underwent explantation of a shoulder prosthesis due to a periprosthetic infection. He was tested SARS-CoV-2 positive 7 days after admission to the orthopaedic department following strict infection control measures, routinely including screening all patients for multi-drug-resistant organism (MDRO) colonization upon admission. Aim of our study is to report on the spreading potential of SARS-CoV-2 in a healthcare setting if standard contact precautions and infection control measures have been established.

METHODS

All HCW with exposure to the patient from day of admission until confirmed diagnosis of COVID-19 were identified and underwent oropharyngeal swab testing for SARS-CoV-2 by real-time RT-PCR.

RESULTS

Sixty-six HCW were identified: nine orthopaedic surgeons, four anaesthesiologists, 25 orthopaedic nurses, five nurse anesthetists, eight scrub nurses, five nursing students, two medical assistants and seven service employees. Fourteen HCW (21%) showed clinical symptoms compatible with a SARS-CoV-2 infection: cough (n = 4), sore throat (n = 3), nasal congestion (n = 3), dyspnea (n = 2), fever (n = 1), headache and myalgia (n = 1). SARS-CoV-2 was not detected in any of the 66 HCW.

CONCLUSION

Hygienic measures and contact precautions, aimed at preventing the spread of MRDO, may have helped to prevent a SARS-CoV-2 transmission to HCW-despite high-risk exposure during intubation, surgical treatment and general care.

LEVEL OF EVIDENCE

IV, case series.

ParamAP: Standardized Parameterization of Sinoatrial Node Myocyte Action Potentials

Sinoatrial node myocytes act as cardiac pacemaker cells by generating spontaneous action potentials (APs). Much information is encoded in sinoatrial AP waveforms, but both the analysis and the comparison of AP parameters between studies is hindered by the lack of standardized parameter definitions and the absence of automated analysis tools. Here we introduce ParamAP, a standalone cross-platform computational tool that uses a template-free detection algorithm to automatically identify and parameterize APs from text input files. ParamAP employs a graphic user interface with automatic and user-customizable input modes, and it outputs data files in text and PDF formats. ParamAP returns a total of 16 AP waveform parameters including time intervals such as the AP duration, membrane potentials such as the maximum diastolic potential, and rates of change of the membrane potential such as the diastolic depolarization rate. ParamAP provides a robust AP detection algorithm in combination with a standardized AP parameter analysis over a wide range of AP waveforms and firing rates, owing in part to the use of an iterative algorithm for the determination of the threshold potential and the diastolic depolarization rate that is independent of the maximum upstroke velocity, a parameter that can vary significantly among sinoatrial APs. Because ParamAP is implemented in Python 3, it is also highly customizable and extensible. In conclusion, ParamAP is a powerful computational tool that facilitates quantitative analysis and enables comparison of sinoatrial APs by standardizing parameter definitions and providing an automated work flow.

Two-Dimensional Trap for Ultrasensitive Quantification of Transient Protein Interactions

We present an ultrasensitive technique for quantitative protein-protein interaction analysis in a two-dimensional format based on phase-separated, micropatterned membranes. Interactions between proteins captured to lipid probes via an affinity tag trigger partitioning into the liquid-ordered phase, which is readily quantified by fluorescence imaging. Based on a calibration with well-defined low-affinity protein-protein interactions, equilibrium dissociation constants >1 mM were quantified. Direct capturing of proteins from mammalian cell lysates enabled us to detect homo- and heterodimerization of signal transducer and activator of transcription proteins. Using the epidermal growth factor receptor (EGFR) as a model system, quantification of low-affinity interactions between different receptor domains contributing to EGFR dimerization was achieved. By exploitation of specific features of the membrane-based assay, the regulation of EGFR dimerization by lipids was demonstrated.

Domain movements during CCA-addition: a new function for motif C in the catalytic core of the human tRNA nucleotidyltransferases

CCA-adding enzymes are highly specific RNA polymerases that synthesize and maintain the sequence CCA at the tRNA 3'-end. This nucleotide triplet is a prerequisite for tRNAs to be aminoacylated and to participate in protein biosynthesis. During CCA-addition, a set of highly conserved motifs in the catalytic core of these enzymes is responsible for accurate sequential nucleotide incorporation. In the nucleotide binding pocket, three amino acid residues form Watson-Crick-like base pairs to the incoming CTP and ATP. A reorientation of these templating amino acids switches the enzyme's specificity from CTP to ATP recognition. However, the mechanism underlying this essential structural rearrangement is not understood. Here, we show that motif C, whose actual function has not been identified yet, contributes to the switch in nucleotide specificity during polymerization. Biochemical characterization as well as EPR spectroscopy measurements of the human enzyme reveal that mutating the highly conserved amino acid position D139 in this motif interferes with AMP incorporation and affects interdomain movements in the enzyme. We propose a model of action, where motif C forms a flexible spring element modulating the relative orientation of the enzyme's head and body domains to accommodate the growing 3'-end of the tRNA. Furthermore, these conformational transitions initiate the rearranging of the templating amino acids to switch the specificity of the nucleotide binding pocket from CTP to ATP during CCA-synthesis.

Clustering and dynamics of phototransducer signaling domains revealed by site-directed spin labeling electron paramagnetic resonance on SRII/HtrII in membranes and nanodiscs

In halophilic archaea the photophobic response is mediated by the membrane-embedded 2:2 photoreceptor/-transducer complex SRII/HtrII, the latter being homologous to the bacterial chemoreceptors. Both systems bias the rotation direction of the flagellar motor via a two-component system coupled to an extended cytoplasmic signaling domain formed by a four helical antiparallel coiled-coil structure. For signal propagation by the HAMP domains connecting the transmembrane and cytoplasmic domains, it was suggested that a two-state thermodynamic equilibrium found for the first HAMP domain in NpSRII/NpHtrII is shifted upon activation, yet signal propagation along the coiled-coil transducer remains largely elusive, including the activation mechanism of the coupled kinase CheA. We investigated the dynamic and structural properties of the cytoplasmic tip domain of NpHtrII in terms of signal transduction and putative oligomerization using site-directed spin labeling electron paramagnetic resonance spectroscopy. We show that the cytoplasmic tip domain of NpHtrII is engaged in a two-state equilibrium between a dynamic and a compact conformation like what was found for the first HAMP domain, thus strengthening the assumption that dynamics are the language of signal transfer. Interspin distance measurements in membranes and on isolated 2:2 photoreceptor/transducer complexes in nanolipoprotein particles provide evidence that archaeal photoreceptor/-transducer complexes analogous to chemoreceptors form trimers-of-dimers or higher-order assemblies even in the absence of the cytoplasmic components CheA and CheW, underlining conservation of the overall mechanistic principles underlying archaeal phototaxis and bacterial chemotaxis systems. Furthermore, our results revealed a significant influence of the NpHtrII signaling domain on the NpSRII photocycle kinetics, providing evidence for a conformational coupling of SRII and HtrII in these complexes.

Hydrogen bonding of nitroxide spin labels in membrane proteins

On the basis of experiments at 275 GHz, we reconsider the dependence of the continuous-wave EPR spectra of nitroxide spin-labeled protein sites in sensory- and bacteriorhodopsin on the micro-environment.

The signal transfer from the receptor NpSRII to the transducer NpHtrII is not hampered by the D75N mutation

Sensory rhodopsin II (NpSRII) is a phototaxis receptor of Natronomonas pharaonis that performs its function in complex with its cognate transducer (NpHtrII). Upon light activation NpSRII triggers by means of NpHtrII a signal transduction chain homologous to the two component system in eubacterial chemotaxis. The D75N mutant of NpSRII, which lacks the blue-shifted M intermediate and therefore exhibits a significantly faster photocycle compared to the wild-type, mediates normal phototaxis responses demonstrating that deprotonation of the Schiff base is not a prerequisite for transducer activation. Using site-directed spin labeling and time resolved electron paramagnetic-resonance spectroscopy, we show that the mechanism revealed for activation of the wild-type complex, namely an outward tilt motion of the cytoplasmic part of the receptor helix F and a concomitant rotation of the transmembrane transducer helix TM2, is also valid for the D75N variant. Apparently, the D75N mutation shifts the ground state conformation of NpSRII-D75N and its cognate transducer into the direction of the signaling state.

Paradoxical hepatic tumor: Undifferentiated embryonal sarcoma of the liver

Undifferentiated embryonal sarcoma (UES) is a rare primary malignant tumor of the liver that typically presents in late childhood. We report a case of primary UES, which had a typical paradoxical appearance on different imaging modalities.

Cerebellar astrocytoma presenting with precocious puberty in a girl. Case report

Central precocious puberty in girls is uncommon and tends to be idiopathic in most cases. In about 20 to 30% of cases there is an intracranial mass lesion. The common lesions are hypothalamic hamartomas, optic nerve gliomas, suprasellar arachnoid cysts, hydrocephalus, germinomas, and other sellar/suprasellar lesions. Central precocious puberty secondary to a cerebellar astrocytoma is extremely rare. The authors report the first case in a girl who presented with several episodes of bleeding per vaginum. There was no clinical or radiological evidence of raised intracranial pressure.

Development of a pilocytic astrocytoma in a dysembryoplastic neuroepithelial tumor. Case report

Dysembryoplastic neuroepithelial tumors (DNETs) are benign supratentorial tumors based in the cerebral cortex. They usually are found in children and young adults with seizures that tend to become refractory to medical treatment. In the vast majority of cases resection results in good seizure control, and adjuvant therapy is not required. When tumors thought to be DNETs are not resected due to their proximity to eloquent cortex, lack of change in the clinical and neuroimaging features over time supports the diagnosis of DNET. The authors report on a patient in whom a pilocytic astrocytoma developed within a DNET, raising questions regarding the classification of these lesions and the need for lifelong clinical and imaging surveillance. This paper adds to the growing body of literature about the biological behavior of these lesions.

Cerebral AL lambda-amyloidoma: clinical and pathomorphological characteristics. Review of the literature and of a patient

BACKGROUND

Amyloid deposits within the brain can be found in a heterogeneous group of diseases. Some of them involve only the central nervous system (AD); others are of systemic origin. Isolated deposits either in the brain, cranial nerves or within the spinal neural structures are extremely rare. So far, we do not know the natural origin, nor the clinical course.

METHODS

We reviewed the overall published cases as far as available and added our own case to learn more about the natural history, clinical and imaging characteristics of this rare brain lesion.

RESULTS

Together with our own case, 27 patients with cerebral amyloidoma were collected in the literature. The lesion always occurred supratentorially, moreover in another two cases also infratentorially. The initial symptoms as well as the results of different neuroimaging features were not specific. There was no predominance for sex and localization. Diagnosis could only be established by histopathological examination after surgical intervention. No recurrence was seen after radical resection; but there was progression in some cases of tumor biopsy.

CONCLUSION

Complete surgical removal of cerebral AL amyloidoma seems to be the only way to prevent progression or recurrence of such a brain lesion.

Sequential scintigraphic strategy for the differentiation of brain tumours

Both thallium-201 and iodine-123 alpha-methyltyrosine (123I-IMT) have been shown to be useful in the diagnostic evaluation of brain tumours. The aim of this study was to investigate the respective contributions of 201Tl and 123I-IMT single-photon emission tomography (SPET) in the non-invasive evaluation of intracerebral tumours. We analysed 65 patients with the following brain tumours: 8 non-neoplastic lesions, 4 meningiomas, 12 low-grade gliomas, 28 high-grade gliomas, 11 metastases and 2 high-grade lymphomas. 201Tl SPET and 123I-IMT SPET were performed [start of 201Tl SPET: 15 min p.i. (early) and 180 min p.i. (delayed); start of 123I-IMT SPET: 15 min p.i.]. The intensity of uptake was quantified as the ratio between tracer accumulation in the tumour and in the contralateral hemisphere. None of the non-neoplastic lesions or low-grade gliomas expressed marked 201Tl uptake. All malignant tumours except one small metastasis and all meningiomas except one small, cystic and degenerated lesion showed significant 201Tl accumulation [Tl(15')>2.0]; 123I-IMT uptake was either absent or intermediate in non-malignant lesions except in two low-grade gliomas; the highest levels were observed in high-grade gliomas followed by metastases and lymphomas (mean IMT: 2.7 vs. 2.1 vs. 1.8), with metastases showing a high variability in 123I-IMT uptake (range: 0.8-3.6). Using 201Tl to distinguish non-neoplastic lesions from malignant tumours and meningiomas, 63 of 65 patients were characterised correctly. In the latter group, high-grade gliomas were correctly identified in 27 of 28 cases by their amino acid uptake. It is concluded that the combination of 201Tl and 123I-IMT surpasses the accuracy of each single test in the differentiation of space-occupying lesions of the brain. Based on these preliminary results, a sequential strategy is proposed involving an initial 201Tl SPET study and an additional 123I-IMT SPET study in the event of positive 201Tl uptake.

Evaluation of the extension of cerebral gliomas by scintigraphy

BACKGROUND

Single photon emission computed tomography (SPECT) with 201Tl and 123I-alpha-methyl tyrosine (123I-IMT) are routine methods for the evaluation of brain tumors. 123I-IMT transport across the blood brain barrier is mediated by an amino acid carrier, 201Tl accumulation is analogous to cerebral potassium uptake.

PATIENTS AND METHODS

To determine the differences in glioma extension as shown by the 2 methods, 17 patients with malignant gliomas were included in this comparative imaging study: astrocytoma III: n = 6, ependymoma III: n = 1, oligodendroglioma III: n = 1, glioblastoma IV: n = 9. The tomographic image sets were matched anatomically and the slices showing maximal tumor extension were identified in both image sets respectively. Tumor spread was compared visually and the tumor extension was quantified.

RESULTS

In gliomas WHO III tumor extension was delineated significantly larger by 123I-IMT-SPECT than by 201Tl-SPECT (mean +/- SD: 816 +/- 281 pixels vs 600 +/- 220 pixels, n = 8, p < 0.05). The size of glioblastomas was shown in a comparable manner by the 2 methods (977 +/- 571 vs 1.051 +/- 588, n = 9, ns, p = 0.57), but there were considerable regional differences between the area of 201Tl uptake and amino acid retention. In the whole group a weak but significant negative correlation between intensity of 201Tl uptake on the one hand and a ratio of the area as depicted by 123I-IMT vs area as depicted by 201Tl on the other hand, was found (n = 17, r = 0.49, p < 0.05). Thus the differences in the delineation of areas became smaller with increasing 201Tl uptake.

CONCLUSIONS

These preliminary data indicate that the extension of gliomas is depicted differently by the 2 methods. 123I-IMT-SPECT shows a larger tumor extension especially in gliomas WHO III. Since 201Tl uptake has previously been shown to correlate with disruption of the blood brain barrier, 123I-IMT-SPECT may delineate tumor parts without endothelial leakage. This additional information may be helpful in planning surgical or radiation therapy. The advantages of 123I-IMT in this respect decrease with increasing 201Tl uptake and with increasing malignancy.

The embryonic central nervous system lineages of Drosophila melanogaster. II. Neuroblast lineages derived from the dorsal part of the neuroectoderm

In Drosophila, central nervous system (CNS) formation starts with the delamination from the neuroectoderm of about 30 neuroblasts (NBs) per hemisegment. They give rise to approximately 350 neurons and 30 glial cells during embryonic development. Understanding the mechanisms leading to cell fate specification and differentiation in the CNS requires the identification of the NB lineages. The embryonic lineages derived from 17 NBs of the ventral part of the neuroectoderm have previously been described (Bossing et al., 1996). Here we present 13 lineages derived from the dorsal part of the neuroectoderm and we assign 12 of them to identified NBs. Together, the 13 lineages comprise approximately 120 neurons and 22 to 27 glial cells which we include in a systematic terminology. Therefore, NBs from the dorsal neuroectoderm produce about 90% of the glial cells in the embryonic ventral ganglion. Two of the NBs give rise to glial progeny exclusively (NB 6-4A, GP) and five to glia as well as neurons (NBs 1-3, 2-5, 5-6, 6-4T, 7-4). These seven NBs are arranged as a group in the most lateral region of the NB layer. The other lineages (NBs 2-4, 3-3, 3-5, 4-3, 4-4, 5-4, clone y) are composed exclusively of neurons (interneurons, motoneurons, or both). Additionally, it has been possible to link the lateral cluster of even-skipped expressing cells (EL) to the lineage of NB 3-3. Along with the previously described clones, the vast majority (more than 90%) of cell lineages in the embryonic ventral nerve cord (thorax, abdomen) are now known. Moreover, previously identified neurons and most glial cells are now linked to certain lineages and, thus, to particular NBs. This complete set of data provides a foundation for the interpretation of mutant phenotypes and for future investigations on cell fate specification and differentiation.

The homeobox gene repo is required for the differentiation and maintenance of glia function in the embryonic nervous system of Drosophila melanogaster

We describe the cloning, expression and phenotypic characterisation of repo, a gene from Drosophila melanogaster that is essential for the differentiation and maintenance of glia function. It is not, however, required for the initial determination of glial cells. In the embryo, the gene, which encodes a homeodomain protein, is expressed exclusively in all developing glia and closely related cells in both the central and peripheral nervous systems. The only observed exceptions in the CNS are the midline glia derived from the mesectoderm and two of three segmental nerve root glial cells. Using a polyclonal antibody we traced the spatial and temporal pattern of the protein expression in detail. Embryos homozygous for null alleles of the protein exhibit late developmental defects in the nervous system, including a reduction in the number of glial cells, disrupted fasciculation of axons, and the inhibition of ventral nerve cord condensation. The expression of an early glial-specific marker is unaffected in such homozygotes. By contrast, the expression of late glial-specific markers is either substantially reduced or absent. The specificity of expression is also observed in the locust Schistocerca gregaria and is thus evolutionarily conserved.