The latest medical research on Neurology

The resident astrocyte-retinal ganglion cell (RGC) lipoxin circuit is impaired during retinal stress, which includes ocular hypertension-induced neuropathy. Lipoxin B4 produced by homeostatic astrocytes directly acts on RGCs to increase survival and function in ocular hypertension-induced neuropathy. RGC death in the retina and axonal degeneration in the optic nerve are driven by the complex interactions between microglia and macroglia. Whether LXB4 neuroprotective actions include regulation of other cell types in the retina and/or optic nerve is an important knowledge gap.

Cellular targets and signaling of LXB4 in the retina were defined by single-cell RNA sequencing. Retinal neurodegeneration was induced by injecting silicone oil into the anterior chamber of mouse eyes, which induced sustained and stable ocular hypertension. Morphological characterization of microglia populations in the retina and optic nerve was established by MorphOMICs and pseudotime trajectory analyses. The pathways and mechanisms of action of LXB4 in the optic nerve were investigated using bulk RNA sequencing. Transcriptomics data was validated by qPCR and immunohistochemistry. Differences between experimental groups were assessed by Student's t-test and one-way ANOVA.

Single-cell transcriptomics identified microglia as a primary target for LXB4 in the healthy retina. LXB4 downregulated genes that drive microglia environmental sensing and reactivity responses. Analysis of microglial function revealed that ocular hypertension induced distinct, temporally defined, and dynamic phenotypes in the retina and, unexpectedly, in the distal myelinated optic nerve. Microglial expression of CD74, a marker of disease-associated microglia in the brain, was only induced in a unique population of optic nerve microglia, but not in the retina. Genetic deletion of lipoxin formation correlated with the presence of a CD74 optic nerve microglia population in normotensive eyes, while LXB4 treatment during ocular hypertension shifted optic nerve microglia toward a homeostatic morphology and non-reactive state and downregulated the expression of CD74. Furthermore, we identified a correlation between CD74 and phospho-phosphoinositide 3-kinases (p-PI3K) expression levels in the optic nerve, which was reduced by LXB4 treatment.

We identified early and dynamic changes in the microglia functional phenotype, reactivity, and induction of a unique CD74 microglia population in the distal optic nerve as key features of ocular hypertension-induced neurodegeneration. Our findings establish microglia regulation as a novel LXB4 target in the retina and optic nerve. LXB4 maintenance of a homeostatic optic nerve microglia phenotype and inhibition of a disease-associated phenotype are potential neuroprotective mechanisms for the resident LXB4 pathway.

Questions and recommendations from the prior version of these guidelines without changeTarget populationAdult patients (older than 18 years of age) with newly diagnosed World Health Organization (WHO) Grade II gliomas (Oligodendroglioma, astrocytoma, mixed oligoastrocytoma).QuestionIs there a role for chemotherapy as adjuvant therapy of choice in treatment of patients with newly diagnosed low-grade gliomas?RecommendationLevel III: Chemotherapy is recommended as a treatment option to postpone the use of radiotherapy, to slow tumor growth and to improve progression free survival (PFS), overall survival (OS) and clinical symptoms in adult patients with newly diagnosed LGG.QuestionWho are the patients with newly diagnosed LGG that would benefit the most from chemotherapy?RecommendationLevel III: Chemotherapy is recommended as an optional component alone or in combination with radiation as the initial adjuvant therapy for all patients who cannot undergo gross total resection (GTR) of a newly diagnosed LGG. Patients with residual tumor >1 cm on post-operative MRI, presenting diameter of 4 cm or older than 40 years of age should be considered for adjuvant therapy as well.QuestionAre there tumor markers that can predict which patients can benefit the most from initial treatment with chemotherapy?RecommendationLevel III: The addition of chemotherapy to standard RT is recommended in LGG patients that carry IDH mutation. In addition, temozolomide (TMZ) is recommended as a treatment option to slow tumor growth in patients who harbor the 1p/19q co-deletion.QuestionHow soon should the chemotherapy be started once the diagnosis of LGG is confirmed?RecommendationThere is insufficient evidence to make a definitive recommendation on the timing of starting chemotherapy after surgical/pathological diagnosis of LGG has been made. However, using the 12 weeks mark as the latest timeframe to start adjuvant chemotherapy is suggested. It is recommended that patients be enrolled in properly designed clinical trials to assess the timing of chemotherapy initiation once diagnosis is confirmed for this target population.QuestionWhat chemotherapeutic agents should be used for treatment of newly diagnosed LGG?RecommendationThere is insufficient evidence to make a recommendation of one particular regimen. Enrollment of subjects in properly designed trials comparing the efficacy of these or other agents is recommended so as to determine which of these regimens is superior.QuestionWhat is the optimal duration and dosing of chemotherapy as initial treatment for LGG?RecommendationInsufficient evidence exists regarding the duration of any specific cytotoxic drug regimen for treatment of newly diagnosed LGG. Enrollment of subjects in properly designed clinical investigations assessing the optimal duration of this therapy is recommended.QuestionShould chemotherapy be given alone or in conjunction with RT as initial therapy for LGG?RecommendationInsufficient evidence exists to make recommendations in this regard. Hence, enrollment of patients in properly designed clinical trials assessing the difference between chemotherapy alone, RT alone or a combination of them is recommended.QuestionShould chemotherapy be given in addition to other type of adjuvant therapy to patients with newly diagnosed LGG?RecommendationLevel II: It is recommended that chemotherapy be added to the RT in patients with unfavorable LGG to improve their progression free survival.Updated Question and Recommendations from the Prior Version of These GuidelinesQuestionIn adult patients with pathologically confirmed WHO Grade II diffuse glioma does chemotherapy alone, combined with radiation therapy or after radiation therapy compared to radiotherapy alone result in better overall survival, progression free survival, local control, fewer complications, neurocognitive preservation, and quality of life?RecommendationLevel I: It is recommended that chemotherapy (PCV) be added to radiation therapy (RT) in all patients with newly diagnosed high-risk WHO Grade II diffuse glioma (Patients younger than 40 unable to get gross total resection and older than 40 regardless of the degree of resection) to improve their overall survival.

It is suggested that chemotherapy alone should be considered in patients with newly diagnosed WHO Grade II diffuse glioma in cases with 1p/19q co-deletion.New questions and recommendationsTarget populationThese recommendations apply to adult patients diagnosed with WHO Grade II diffuse glioma.QuestionIn adult patients with newly diagnosed WHO grade II diffuse glioma does administration of chemotherapy prior to surgical resection improve extent of resection, provide longer progression free survival and overall survival when compared to chemotherapy alone?RecommendationLevel III: Neo-adjuvant temozolomide may be used in patients with WHO Grade II diffuse gliomas deemed unsafe for resection due to infiltration of eloquent areas or with large contralateral extension as an initial step to improve the extent of resection.There is insufficient evidence to support a recommendation regarding the ability of chemotherapy provided prior to surgical resection to improve progression free survival (PFS) and overall survival (OS).QuestionIn adult patients with newly diagnosed WHO grade II diffuse glioma does the administration of temozolomide increase the rate of malignant transformation when compared to no chemotherapy or other chemotherapy regimens?RecommendationThere is insufficient evidence to support a recommendation against the use of temozolomide for WHO Grade II diffuse gliomas due to concern over increasing the rate of malignant transformation.QuestionIn adult patients with newly diagnosed WHO grade II diffuse glioma does administration of multi-agent chemotherapy improve progression free survival and overall survival when compared to administration of single-agent chemotherapy?RecommendationThere is insufficient evidence to support a recommendation for or against the use of multi-agent chemotherapy to improve progression free survival and overall survival when compared to administration of single-agent chemotherapy in patients with newly diagnosed WHO Grade II diffuse glioma.

Although dopamine transporter (DAT) imaging has been reported to be useful for differentiating idiopathic Normal Pressure Hydrocephalus (iNPH) from its mimics, the radiological findings of DAT imaging in iNPH have not been established. We investigated [123I] N-ω-fluoropropyl-2β-carboxymethoxy-3β-(4-iodophenyl) nortropane (FP-CIT) single photon emission computed tomography (SPECT) images from patients with disproportionately enlarged subarachnoid-space hydrocephalus (DESH)-type iNPH to understand the characteristics of DAT images of iNPH.

We retrospectively collected 11 DESH-type iNPH patients without comorbidities who underwent FP-CIT SPECT imaging. The patients' FP-CIT SPECT were examined using both visual and quantitative evaluations. Visual assessment used Kahraman et al.'s five-step grading, and quantitative assessment used DaTView and MIM software to calculate specific binding ratios (SBRs) for four volumes of interest (VOIs): the entire striatum, caudate nucleus, anterior putamen, and posterior putamen. Intergroup comparisons were made between the DESH group and a normal control (NC) group adjusted for age and sex.

The visual assessment classified 91% of DESH patients as showing grade 4 'eagle-wing' on FP-CIT SPECT, with a Kappa coefficient of 0.601. The median SBR was lower in the DESH group than in the NC group for all four VOIs, and significantly lower in the anterior and posterior putamen (p < 0.05).

In DESH-type iNPH, FP-CIT SPECT imaging typically shows the 'eagle-wing' finding due to decreased DAT concentration in the putamen. Our results enhance the utility of FP-CIT SPECT in diagnosing iNPH and distinguishing it from mimics.