Imbalance in Glucose Metabolism Regulates the Transition of Microglia from Homeostasis to Disease-Associated Microglia Stage 1.

Microglia undergo two-stage activation in neurodegenerative diseases, known as disease-associated microglia (DAM). TREM2 mediates the DAM2 stage transition, but what regulates the first DAM1 stage transition is unknown. We report that glucose dyshomeostasis inhibits DAM1 activation and PKM2 plays a role. As in tumors, PKM2 was aberrantly elevated in both male and female human AD brains, but unlike in tumors, it is expressed as active tetramers, as well as among TREM2+ microglia surrounding plaques in 5XFAD male and female mice. snRNAseq analyses of microglia without Pkm2 in 5XFAD mice revealed significant increases in DAM1 markers in a distinct metabolic cluster, which is enriched in genes for glucose metabolism, DAM1, and AD risk. 5XFAD mice incidentally exhibited a significant reduction in amyloid pathology without microglial Pkm2 Surprisingly, microglia in 5XFAD without Pkm2 exhibited increases in glycolysis and spare respiratory capacity, which correlated with restoration of mitochondrial cristae alterations. In addition, in situ spatial metabolomics of plaque-bearing microglia revealed an increase in respiratory activity. These results together suggest that it is not only glycolytic but also respiratory inputs that are critical to the development of DAM signatures in 5XFAD mice.

Transcriptional profiling of human cartilage endplate cells identifies novel genes and cell clusters underlying degenerated and non-degenerated phenotypes.

BACKGROUND: Low back pain is a leading cause of disability worldwide and is frequently attributed to intervertebral disc (IVD) degeneration. Though the contributions of the adjacent cartilage endplates (CEP) to IVD degeneration are well documented, the phenotype and functions of the resident CEP cells are critically understudied. To better characterize CEP cell phenotype and possible mechanisms of CEP degeneration, bulk and single-cell RNA sequencing of non-degenerated and degenerated CEP cells were performed. METHODS: Human lumbar CEP cells from degenerated (Thompson grade ≥ 4) and non-degenerated (Thompson grade ≤ 2) discs were expanded for bulk (N=4 non-degenerated, N=4 degenerated) and single-cell (N=1 non-degenerated, N=1 degenerated) RNA sequencing. Genes identified from bulk RNA sequencing were categorized by function and their expression in non-degenerated and degenerated CEP cells were compared. A PubMed literature review was also performed to determine which genes were previously identified and studied in the CEP, IVD, and other cartilaginous tissues. For single-cell RNA sequencing, different cell clusters were resolved using unsupervised clustering and functional annotation. Differential gene expression analysis and Gene Ontology, respectively, were used to compare gene expression and functional enrichment between cell clusters, as well as between non-degenerated and degenerated CEP samples. RESULTS: Bulk RNA sequencing revealed 38 genes were significantly upregulated and 15 genes were significantly downregulated in degenerated CEP cells relative to non-degenerated cells (|fold change| ≥ 1.5). Of these, only 2 genes were previously studied in CEP cells, and 31 were previously studied in the IVD and other cartilaginous tissues. Single-cell RNA sequencing revealed 11 unique cell clusters, including multiple chondrocyte and progenitor subpopulations with distinct gene expression and functional profiles. Analysis of genes in the bulk RNA sequencing dataset showed that progenitor cell clusters from both samples were enriched in "non-degenerated" genes but not "degenerated" genes. For both bulk- and single-cell analyses, gene expression and pathway enrichment analyses highlighted several pathways that may regulate CEP degeneration, including transcriptional regulation, translational regulation, intracellular transport, and mitochondrial dysfunction. CONCLUSIONS: This thorough analysis using RNA sequencing methods highlighted numerous differences between non-degenerated and degenerated CEP cells, the phenotypic heterogeneity of CEP cells, and several pathways of interest that may be relevant in CEP degeneration.

Association of ESR1 germline variants with TP53 somatic variants in breast tumors in a genome-wide study.

Background: In breast tumors, somatic mutation frequencies in TP53 and PIK3CA vary by tumor subtype and ancestry. HER2 positive and triple negative breast cancers (TNBC) have a higher frequency of TP53 somatic mutations than other subtypes. PIK3CA mutations are more frequently observed in hormone receptor positive tumors. Emerging data suggest tumor mutation status is associated with germline variants and genetic ancestry. We aimed to identify germline variants that are associated with somatic TP53 or PIK3CA mutation status in breast tumors. Methods: A genome-wide association study was conducted using breast cancer mutation status of TP53 and PIK3CA and functional mutation categories including TP53 gain of function (GOF) and loss of function mutations and PIK3CA activating/hotspot mutations. The discovery analysis consisted of 2850 European ancestry women from three datasets. Germline variants showing evidence of association with somatic mutations were selected for validation analyses based on predicted function, allele frequency, and proximity to known cancer genes or risk loci. Candidate variants were assessed for association with mutation status in a multi-ancestry validation study, a Malaysian study, and a study of African American/Black women with TNBC. Results: The discovery Germline x Mutation (GxM) association study found five variants associated with one or more TP53 phenotypes with P values <1×10-6, 33 variants associated with one or more TP53 phenotypes with P values <1×10-5, and 44 variants associated with one or more PIK3CA phenotypes with P values <1×10-5. In the multi-ancestry and Malaysian validation studies, germline ESR1 locus variant, rs9383938, was associated with the presence of TP53 mutations overall (P values 6.8×10-5 and 9.8×10-8, respectively) and TP53 GOF mutations (P value 8.4×10-6). Multiple variants showed suggestive evidence of association with PIK3CA mutation status in the validation studies, but none were significant after correction for multiple comparisons. Conclusions: We found evidence that germline variants were associated with TP53 and PIK3CA mutation status in breast cancers. Variants near the estrogen receptor alpha gene, ESR1, were significantly associated with overall TP53 mutations and GOF mutations. Larger multi-ancestry studies are needed to confirm these findings and determine if these variants contribute to ancestry-specific differences in mutation frequency.

Neutralization escape of Omicron XBB, BR.2, and BA.2.3.20 subvariants.

New Omicron subvariants continue to emerge throughout the world. In particular, the XBB subvariant, which is a recombinant virus between BA.2.10.1.1 and BA.2.75.3.1.1.1, as well as the BA.2.3.20 and BR.2 subvariants that contain mutations distinct from BA.2 and BA.2.75, are currently increasing in proportion of variants sequenced. Here we show that antibodies induced by 3-dose mRNA booster vaccination as well as BA.1- and BA.4/5-wave infection effectively neutralize BA.2, BR.2, and BA.2.3.20 but have significantly reduced efficiency against XBB. In addition, the BA.2.3.20 subvariant exhibits enhanced infectivity in the lung-derived CaLu-3 cells and in 293T-ACE2 cells. Overall, our results demonstrate that the XBB subvariant is highly neutralization resistant, which highlights the need for continued monitoring of the immune escape and tissue tropism of emerging Omicron subvariants.

Enhanced evasion of neutralizing antibody response by Omicron XBB.1.5, CH.1.1, and CA.3.1 variants.

Omicron subvariants continuingly challenge current vaccination strategies. Here, we demonstrate nearly complete escape of the XBB.1.5, CH.1.1, and CA.3.1 variants from neutralizing antibodies stimulated by three doses of mRNA vaccine or by BA.4/5 wave infection, but neutralization is rescued by a BA.5-containing bivalent booster. CH.1.1 and CA.3.1 show strong immune escape from monoclonal antibody S309. Additionally, XBB.1.5, CH.1.1, and CA.3.1 spike proteins exhibit increased fusogenicity and enhanced processing compared with BA.2. Homology modeling reveals the key roles of G252V and F486P in the neutralization resistance of XBB.1.5, with F486P also enhancing receptor binding. Further, K444T/M and L452R in CH.1.1 and CA.3.1 likely drive escape from class II neutralizing antibodies, whereas R346T and G339H mutations could confer the strong neutralization resistance of these two subvariants to S309-like antibodies. Overall, our results support the need for administration of the bivalent mRNA vaccine and continued surveillance of Omicron subvariants.

Extraordinary Evasion of Neutralizing Antibody Response by Omicron XBB.1.5, CH.1.1 and CA.3.1 Variants.

Newly emerging Omicron subvariants continue to emerge around the world, presenting potential challenges to current vaccination strategies. This study investigates the extent of neutralizing antibody escape by new subvariants XBB.1.5, CH.1.1, and CA.3.1, as well as their impacts on spike protein biology. Our results demonstrated a nearly complete escape of these variants from neutralizing antibodies stimulated by three doses of mRNA vaccine, but neutralization was rescued by a bivalent booster. However, CH.1.1 and CA.3.1 variants were highly resistant to both monovalent and bivalent mRNA vaccinations. We also assessed neutralization by sera from individuals infected during the BA.4/5 wave of infection and observed similar trends of immune escape. In these cohorts, XBB.1.5 did not exhibit enhanced neutralization resistance over the recently dominant BQ.1.1 variant. Notably, the spike proteins of XBB.1.5, CH.1.1, and CA.3.1 all exhibited increased fusogenicity compared to BA.2, correlating with enhanced S processing. Overall, our results support the administration of new bivalent mRNA vaccines, especially in fighting against newly emerged Omicron subvariants, as well as the need for continued surveillance of Omicron subvariants.

Enhanced neutralization resistance of SARS-CoV-2 Omicron subvariants BQ.1, BQ.1.1, BA.4.6, BF.7, and BA.2.75.2.

The continued evolution of SARS-CoV-2 has led to the emergence of several new Omicron subvariants, including BQ.1, BQ.1.1, BA.4.6, BF.7, and BA.2.75.2. Here, we examine the neutralization resistance of these subvariants against sera from 3-dose vaccinated healthcare workers, hospitalized BA.1-wave patients, and BA.4/5-wave patients. We found enhanced neutralization resistance in all new subvariants, especially in the BQ.1 and BQ.1.1 subvariants driven by N460K and K444T mutations, as well as the BA.2.75.2 subvariant driven largely by its F486S mutation. All Omicron subvariants maintained their weakened infectivity in Calu-3 cells, with the F486S mutation driving further diminished titer for the BA.2.75.2 subvariant. Molecular modeling revealed the mechanisms of antibody-mediated immune evasion by R346T, K444T, F486S, and D1199N mutations. Altogether, these findings shed light on the evolution of newly emerging SARS-CoV-2 Omicron subvariants.

Distinct Neutralizing Antibody Escape of SARS-CoV-2 Omicron Subvariants BQ.1, BQ.1.1, BA.4.6, BF.7 and BA.2.75.2.

Continued evolution of SARS-CoV-2 has led to the emergence of several new Omicron subvariants, including BQ.1, BQ. 1.1, BA.4.6, BF.7 and BA.2.75.2. Here we examine the neutralization resistance of these subvariants, as well as their ancestral BA.4/5, BA.2.75 and D614G variants, against sera from 3-dose vaccinated health care workers, hospitalized BA.1-wave patients, and BA.5-wave patients. We found enhanced neutralization resistance in all new subvariants, especially the BQ.1 and BQ.1.1 subvariants driven by a key N460K mutation, and to a lesser extent, R346T and K444T mutations, as well as the BA.2.75.2 subvariant driven largely by its F486S mutation. The BQ.1 and BQ.1.1 subvariants also exhibited enhanced fusogenicity and S processing dictated by the N460K mutation. Interestingly, the BA.2.75.2 subvariant saw an enhancement by the F486S mutation and a reduction by the D1199N mutation to its fusogenicity and S processing, resulting in minimal overall change. Molecular modelling revealed the mechanisms of receptor-binding and non-receptor binding monoclonal antibody-mediated immune evasion by R346T, K444T, F486S and D1199N mutations. Altogether, these findings shed light on the concerning evolution of newly emerging SARS-CoV-2 Omicron subvariants.

Targeting ETosis by miR-155 inhibition mitigates mixed granulocytic asthmatic lung inflammation.

Asthma is phenotypically heterogeneous with several distinctive pathological mechanistic pathways. Previous studies indicate that neutrophilic asthma has a poor response to standard asthma treatments comprising inhaled corticosteroids. Therefore, it is important to identify critical factors that contribute to increased numbers of neutrophils in asthma patients whose symptoms are poorly controlled by conventional therapy. Leukocytes release chromatin fibers, referred to as extracellular traps (ETs) consisting of double-stranded (ds) DNA, histones, and granule contents. Excessive components of ETs contribute to the pathophysiology of asthma; however, it is unclear how ETs drive asthma phenotypes and whether they could be a potential therapeutic target. We employed a mouse model of severe asthma that recapitulates the intricate immune responses of neutrophilic and eosinophilic airway inflammation identified in patients with severe asthma. We used both a pharmacologic approach using miR-155 inhibitor-laden exosomes and genetic approaches using miR-155 knockout mice. Our data show that ETs are present in the bronchoalveolar lavage fluid of patients with mild asthma subjected to experimental subsegmental bronchoprovocation to an allergen and a severe asthma mouse model, which resembles the complex immune responses identified in severe human asthma. Furthermore, we show that miR-155 contributes to the extracellular release of dsDNA, which exacerbates allergic lung inflammation, and the inhibition of miR-155 results in therapeutic benefit in severe asthma mice. Our findings show that targeting dsDNA release represents an attractive therapeutic target for mitigating neutrophilic asthma phenotype, which is clinically refractory to standard care.

COVID-19 Booster Uptake among First Responders and Their Household Members May Be Lower than Anticipated.

(1) Background: COVID-19 vaccination status varies widely among law enforcement and emergency medical services professionals. Though at high risk of exposure, these first responders have demonstrated significant vaccine hesitancy, with only 70% reportedly vaccinated. We sought to understand whether similar vaccine hesitancy exists for first responders and their household contacts around COVID-19 boosters. (2) Methods: In a prospective longitudinal cohort of first responders and their household contacts, survey data was collected, including demographics, medical history, COVID-19 exposure risks, and vaccination and/or booster status. The statistical analysis focused on primary vaccination and booster rates of both the first responders and their household contacts. (3) Results: Across 119 study participants, 73% reported having received some combination of vaccine and/or booster, and 26% were unvaccinated. Vaccinated individuals were older, reported less prior exposure to COVID-19 and had more comorbidities. Only 23% reported having received a COVID-19 booster. Pairing of the data for household contacts demonstrated a 60% agreement to receive primary vaccination but only a 20% agreement for boosters within households. (4) Conclusions: This study provides insight into the vaccination and booster rates of first responders and household contacts. Focused efforts to enhance vaccinations is essential for the protection and maintenance of this critical workforce.

Differences in somatic TP53 mutation type in breast tumors by race and receptor status.

PURPOSE: Somatic driver mutations in TP53 are associated with triple-negative breast cancer (TNBC) and poorer outcomes. Breast cancers in women of African ancestry (AA) are more likely to be TNBC and have somatic TP53 mutations than cancers in non-Hispanic White (NHW) women. Missense driver mutations in TP53 have varied functional impact including loss-of-function (LOF) or gain-of-function (GOF) activity, and dominant negative (DNE) effects. We aimed to determine if there were differences in somatic TP53 mutation types by patient ancestry or TNBC status. METHODS: We identified breast cancer datasets with somatic TP53 mutation data, ancestry, age, and hormone receptor status. Mutations were classified for functional impact using published data and type of mutation. We assessed differences using Fisher's exact test. RESULTS: From 96 breast cancer studies, we identified 2964 women with somatic TP53 mutations: 715 (24.1%) Asian, 258 (8.7%) AA, 1931 (65.2%) NHW, and 60 (2%) Latina. The distribution of TP53 mutation type was similar by ancestry. However, 35.8% of tumors from NHW individuals had GOF mutations compared to 29% from AA individuals (p = 0.04). Mutations with DNE activity were positively associated with TNBC (OR 1.37, p = 0.03) and estrogen receptor (ER) negative status (OR 1.38; p = 0.005). CONCLUSIONS: Somatic TP53 mutation types did not differ by ancestry overall, but GOF mutations were more common in NHW women than AA women. ER-negative and TNBC tumors are less likely to have DNE+ TP53 mutations which could reflect biological processes. Larger cohorts and functional studies are needed to further elucidate these findings.

The Utility of Point-of-Care Biomarkers to Detect Cardiotoxicity During Anthracycline Chemotherapy: A Feasibility Study.

BACKGROUND: Anthracycline chemotherapy is associated with an increased risk of developing heart failure (HF). The current standard for detecting HF or cardiotoxicity during chemotherapy involves episodic cardiac imaging typically at prescribed intervals and there are limited studies examining techniques beyond measuring left ventricular (LV) function. This study explores whether cardiac biomarkers troponin I (TnI) and B-type natriuretic peptide (BNP) could be part of a screening strategy for early detection of the development of cardiotoxicity in patients undergoing anthracycline chemotherapy. METHODS AND RESULTS: Patients were enrolled from a single medical center. Cardiac biomarkers (TnI, BNP) were measured before and within 24 hours after completion of anthracycline administration for each cycle of therapy. Cardiac imaging was obtained at baseline and at completion of chemotherapy (commonly at 6 or 12 months) or based on clinical suspicion of a cardiac event. Of the enrolled 109 patients, 11 (10.1%) experienced cardiac events; all of these patients had at least 1 BNP value >100 pg/mL before the cardiac event. Significant reduction in LV ejection fraction as defined for cardiotoxicity occurred in only 3 of 10 patients (30%) with a cardiac event. CONCLUSIONS: The use of cardiac biomarkers, particularly BNP, may allow early detection of cardiotoxicity related to anthracycline chemotherapy.

Cardiotoxicity due to Chemotherapy: the Role of Biomarkers.

An ever-increasing array of chemotherapeutic agents is being used in the treatment of solid organ or hematologic malignancies. The success of many of these agents has led to an increasing survival of patients with cancer. However, many of these agents, particularly anthracyclines and trastuzumab, are associated with the development of cardiotoxicity. The current standard for the evaluation of chemotherapy-associated cardiotoxicity typically involves the use of serial measurements of left ventricular (LV) function by echocardiogram (Echo) and radionuclide ventriculogram (MUGA). Unfortunately, this time-honored method offers low sensitivity to the early prediction or detection of cardiac events. Frequently, by the time cardiotoxicity is detected, significant LV dysfunction has occurred and ultimately this may not respond to standard cardioprotective treatment. Cardiac biomarkers, troponin I and B-type natriuretic peptide, may allow a more accurate and timely monitoring strategy. The current data and a summarized understanding of how to utilize cardiac biomarkers for the prevention and early detection of cardiac dysfunction during chemotherapy are presented.

Chronic rhinosinusitis osteoblasts differ in cellular properties from normal bone.

BACKGROUND: Osteitis, characterized by bony thickening and remodeling, is often considered a hallmark of recalcitrant rhinosinusitis. However, there is limited literature examining the bone in chronic rhinosinusitis (CRS) pathology. In this study we cultured osteoblasts from bone harvested during sinus surgery as well as from nondiseased controls to compare their cellular properties. METHODS: Sinus bone was collected during sinus and skull-base surgery and placed in proliferation media. Outgrowth of cells occurred at 2 weeks and the cells were confirmed to be osteoblasts by alkaline phosphatase staining. Cellular adhesion was determined by replating and counting adhered cells at 4 hours. Proliferation of cells plated for 24 hours was assayed by measuring [(3) H]-thymidine incorporation. Calcium content was measured by changing cells to differentiation media and measuring the calcium content on days 7, 14, and 21. RESULTS: Alkaline phosphatase assay showed more than 90% of osteoblasts staining in all samples. Osteoblasts from patients with CRS had significant decreases in adhesion (p < 0.01) compared to osteoblasts from skull-base patients. There was a significant (p < 0.05) increase in calcium content in rhinosinusitis samples compared with the nondiseased sinus bone samples. CONCLUSION: To date, this is the first known study that shows a direct comparison of osteoblast properties between patients with and without CRS. Our results indicate that there are fundamental phenotypic differences in adhesion and mineralization between osteoblasts in patients with CRS compared to controls.

Adult neuroblastoma complicated by increased intracranial pressure: a case report and review of the literature.

Neuroblastoma is the third most commonly occurring malignancy of the pediatric population, although it is extremely rare in the adult population. In adults, neuroblastoma is often metastatic and portends an extremely poor overall survival. Our case report documents metastatic neuroblastoma occurring in a healthy 29-year-old woman whose course was complicated by an unusual presentation of elevated intracranial pressures. The patient was treated with systemic chemotherapy, I(131) metaiodobenzylguanidine (MIBG) radiotherapy, and autologous stem cell transplant (SCT). Unfortunately the patient's response to therapy was limited and she subsequently died. We aim to review neuroblastoma in the context of increased intracranial pressure and the limited data of neuroblastoma occurring in the adult population, along with proposed treatment options.

Creatine protects against mitochondrial dysfunction associated with HIV-1 Tat-induced neuronal injury.

HIV-1 infected individuals live longer but experience a prevalence rate of over 50% for HIV-1 associated neurocognitive disorders (HAND) for which no effective treatment is available. Viral and cellular factors secreted by HIV-1 infected cells lead to neuronal injury and HIV-1 Tat continues to be implicated in the pathogenesis of HAND. Here we tested the hypothesis that creatine protected against HIV-1 Tat-induced neuronal injury by preventing mitochondrial bioenergetic crisis and/or redox catastrophe. Creatine blocked HIV-1 Tat(1-72)-induced increases in neuron cell death and synaptic area loss. Creatine protected against HIV-1 Tat-induced decreases in ATP. Creatine and creatine plus HIV-1 Tat increased cellular levels of creatine, and creatine plus HIV-1 Tat further decreased ratios of phosphocreatine to creatine observed with creatine or HIV-1 Tat treatments alone. Additionally, creatine protected against HIV-1 Tat-induced mitochondrial hypopolarization and HIV-1 Tat-induced mitochondrial permeability transition pore opening. Thus, creatine may be a useful adjunctive therapy against HAND.

Immune surveillance and lymphoid malignancy in immunocompromised host.

Immune surveillance is a dynamic process that involves an intact immune system to identify and protect the host against tumor development. The increased understanding of the genetics, infections and hematological malignancies in congenital immune deficiency states supports the concept that impaired T cells and Natural-killer/T cells leads to B-cell lymphoma. Furthermore, severe combined immunodeficient mice are prone to spontaneous tumor development and therefore serve as experimental models. Here we discuss the acquired conditions and mechanisms involved in dysregulation of the immune system that lead to lymphoma. Preemptive strategies to improve immune regulation and response and restore a competent immune system may lead to a decrease in lymphoid malignancies.

Advances and application of radioimmunotherapy in non-Hodgkin lymphoma.

The activity of radio-immuno conjugate in Non-Hodgkin Lymphoma (NHL) has resulted in FDA approval of two antibodies, Y(90) Ibritumomab tiuxetan and I(131) tositumomab. Both these agents target CD20, a receptor widely expressed in B-Cell NHL. These immunoconjugates deliver their radioactive payload to the malignant clone in the bone marrow and lymph node. Their use has been associated with modest improvement in survival end points among several lymphoma histologies. The promising effect on disease control as well as their efficacy in disease relapse is encouraging in low grade lymphoma. Radioimmunotherapy (RIT) is increasingly being explored in the setting of consolidation as well as conditioning regimens prior to stem cell transplantation. Here, we summarize the clinical use, complications and future applications of RIT in NHL.

The role of smoking in Crohn's disease as defined by clinical variables.

The development of Crohn's disease (CD) is related to an interaction of genetic and environmental factors, with tobacco smoking being one of the most commonly studied environmental factors. In 1998, the Vienna classification was created to define CD by using three accepted clinical variables: age at diagnosis, disease behavior, and disease location. In this qualitative systematic review, articles examining the relationship between smoking and CD, using variables outlined in the Vienna classification, were identified utilizing multiple health databases. Current smoking was found to be associated with late-onset CD (> or =40 years old) and current smokers were more likely to progress to stricturing or penetrating type CD than were nonsmoking patients. Conflicting evidence exists regarding the relationship between smoking with respect to CD disease location. The Vienna classification is an important tool in permitting comparisons and predicting clinical course among CD cases, especially when smoking status is taken into account.

Dose distribution to spinal structures from intrathecally administered yttrium-90.

Previous treatment of cerebrospinal fluid (CSF) malignancies by intrathecal administration of (131)I-radiolabelled monoclonal antibodies has led to the assumption that more healthy tissue will be spared when a pure beta-emitter such as (90)Y replaces (131)I. The purpose of this study is to compare and quantitatively evaluate the dose distribution from (90)Y to the CSF space and its surrounding spinal structures to (131)I. A 3D digital phantom of a section of the T-spine was constructed from the visible human project series of images which included the spinal cord, central canal, subarachnoid space, pia mater, arachnoid, dura mater, vertebral bone marrow and intervertebral disc. Monte Carlo N-particle (MCNP4C) was used to model the (90)Y and (131)I radiation distribution. Images of the CSF compartment were convolved with the radiation distribution to determine the dose within the subarachnoid space and surrounding tissues. (90)Y appears to be a suitable radionuclide in the treatment of central nervous system (CNS) malignancies when attached to mAb's and the dose distribution would be confined largely within the vertebral foramen. This choice may offer favourable dose improvement to the subarachnoid and surface of spinal cord over (131)I in such an application.