Involvement of the Spinal Cord in Primary Mitochondrial Disorders: A Neuroimaging Mimicker of Inflammation and Ischemia in Children.

BACKGROUND AND PURPOSE: Little is known about imaging features of spinal cord lesions in mitochondrial disorders. The aim of this research was to assess the frequency, imaging features, and pathogenic variants causing primary mitochondrial disease in children with spinal cord lesions. MATERIALS AND METHODS: This retrospective analysis included patients seen at Children's Hospital of Philadelphia between 2000 and 2019 who had a confirmed diagnosis of a primary (genetic-based) mitochondrial disease and available MR imaging of the spine. The MR imaging included at least both sagittal and axial fast spin-echo T2-weighted images. Spine images were independently reviewed by 2 neuroradiologists. Location and imaging features of spinal cord lesions were correlated and tested using the Fisher exact test. RESULTS: Of 119 children with primary mitochondrial disease in whom MR imaging was available, only 33 of 119 (28%) had available spine imaging for reanalysis. Nineteen of these 33 individuals (58%) had evidence of spinal cord lesions. Two main patterns of spinal cord lesions were identified: group A (12/19; 63%) had white ± gray matter involvement, and group B (7/19; 37%) had isolated gray matter involvement. Group A spinal cord lesions were similar to those seen in patients with neuromyelitis optica spectrum disorder, multiple sclerosis, anti-myelin oligodendrocyte glycoprotein-IgG antibody disease, and leukoencephalopathy with brain stem and spinal cord involvement and lactate elevation. Group B patients had spinal cord findings similar to those that occur with ischemia and viral infections. Significant associations were seen between the pattern of lesions (group A versus group B) and the location of lesions in cervical versus thoracolumbar segments, respectively (P < .01). CONCLUSIONS: Spinal cord lesions are frequently observed in children with primary mitochondrial disease and may mimic more common causes such as demyelination and ischemia.

The Perirolandic Sign: A Unique Imaging Finding Observed in Association with Polymerase γ-Related Disorders.

Pathogenic variants in the polymerase γ gene (POLG) cause a diverse group of pathologies known as POLG-related disorders. In this report, we describe brain MR imaging findings and electroencephalogram correlates of 13 children with POLG-related disorders at diagnosis and follow-up. At diagnosis, all patients had seizures and 12 had abnormal MR imaging findings. The most common imaging findings were unilateral or bilateral perirolandic (54%) and unilateral or bilateral thalamic signal changes (77%). Association of epilepsia partialis continua with perirolandic and thalamic signal changes was present in 86% and 70% of the patients, respectively. The occipital lobe was affected in 2 patients. On follow-up, 92% of the patients had disease progression or fatal outcome. Rapid volume loss was seen in 77% of the patients. The occipital lobe (61%) and thalamus (61%) were the most affected brain regions. Perirolandic signal changes and seizures may represent a brain imaging biomarker of early-onset pediatric POLG-related disorders.

Specific in vitro anti-tumour activity of methotrexate-monoclonal antibody conjugates prepared using human serum albumin as an intermediary.

Methotrexate (MTX) is a folic acid antagonist widely used in the treatment of cancer but, like other such agents, has non-specific toxic side effects. With the aim of reducing these toxic effects, MTX was coupled to monoclonal antibodies (MoAb) in one of two ways; either (a) directly using an active ester derivative or (b) via human serum albumin (HSA), to act as an intermediary and so increase the amount of MTX bound. The MTX coupled directly to anti-Ly-2.1 antibody had approximately 10 molecules of MTX per antibody molecule, whereas the HSA coupled material had 24 molecules of MTX per antibody molecule. After coupling MTX directly to antibody there was a loss of potency of the MTX, and MTX-MoAb conjugates were 30-fold less potent than free MTX, although the antibody-coupled material was more specific than free MTX and bound only to the antibody-reactive target cells. By contrast, the MTX-HSA-MoAb conjugates were 3.5 times less potent than free MTX and were 8.5 times more potent than MTX-MoAb conjugates. Thus, by increasing the amount of drug bound to antibody, more toxic conjugates were made--an important principle for the use of such conjugates for the treatment of cancer in man.

Anti-tumour activity of aminopterin-monoclonal antibody conjugates; in vitro and in vivo comparison with methotrexate-monoclonal antibody conjugates.

Two related folate antagonists aminopterin (AMN) and methotrexate (MTX) were used to produce drug-antibody conjugates and their tumouricidal effects compared in vitro and in vivo. Active ester derivatives were produced with the use of N-hydroxysuccinimide (NHS) and covalently coupled to monoclonal antibodies (MoAb) reactive with murine cell surface antigens; approximately 11 molecules of AMN or 13 molecules of MTX were specifically bound per molecule of anti-Ly-2.1, with good retention of antibody activity and protein recovery. AMN was a more effective inhibitor of tumour cell growth in vitro than MTX, and AMN-anti-Ly-2.1 conjugates were also more potent in vitro than MTX-anti-Ly-2.1 conjugates. Although there was some loss of drug activity on binding to antibody, AMN-MoAb conjugates were as toxic as free MTX. However, in contrast to free drugs (which can act on any target), the toxicity of drug-MoAb conjugates was entirely specific for the target cells. In addition, AMN-MoAb conjugates were effective anti-tumour agents in vivo, and in mice bearing established thymoma grafts AMN-MoAb conjugates inhibited tumour proliferation better than MTX-MoAb, free AMN or MTX or antibody alone. AMN coupled to specific MoAb is a potentially useful agent for immunotherapy and is of particular relevance in man as free AMN has been discarded because of its systemic toxicity. Now, coupled with antibody, there will be specific tumouricidal effects in the absence of toxicity.