Optical coherence tomography angiography suggests choriocapillaris perfusion deficit as etiology of acute macular neuroretinopathy.

PURPOSE: Acute macular neuroretinopathy (AMN) can cause sudden-onset and permanent scotoma in healthy young patients. Analysis of optical coherence tomography (OCT) and OCT angiography (OCTA) of AMN patients may provide insights into disease mechanism. METHODS: We conducted a retrospective study of consecutive SARS-Cov-2-related AMN patients that presented in our clinic between Jan 1st, 2022, and April 30th, 2023, within 30 days of symptom onset. Retinal vessel area density (VAD) of AMN lesions in OCTA was quantified and compared to an adjacent tissue control (ATC). This quantification was performed for the superficial vascular plexus (SVP), the intermediate capillary plexus (ICP), the deep capillary plexus (DCP), the choriocapillaris (CC), and choroid. Furthermore, en face OCT images were analyzed. RESULTS: Nine AMN patients were identified, 6 of these (4 female, 2 male, average age 25 years) fulfilled the inclusion criteria and were included into this study. Average time from symptom onset to OCTA was 14.3 days. No VAD differences between AMN and adjacent tissue were found in either retinal layer (SVP, ICP, DCP). In contrast, VAD in CC was reduced by 27% against the ATC (p = 0.007) and choroidal VAD was reduced by 41% (p = 0.017). Further analysis of en face OCT could show that the pathognomonic infrared hyporeflectivity in AMN is caused by photoreceptor alterations rather than changes in the inner retinal layers. CONCLUSIONS: Our data suggests that a perfusion deficit in the choroidal layers is responsible for AMN rather than in the DCP, which is the predominant hypothesis in current literature.

The neuroprotective effects of AMN082 on neuronal apoptosis in rats after traumatic brain injury.

BACKGROUND: The aim of this study was to investigate whether AMN082 exerts its neuroprotective effect by attenuating glutamate receptor-associated neuronal apoptosis and improving functional outcomes after traumatic brain injury (TBI). METHODS: Anesthetized male Sprague-Dawley rats were divided into the sham-operated, TBI + vehicle, and TBI + AMN082 groups. AMN082 (10 mg/kg) was intraperitoneally injected 0, 24, or 48 h after TBI. In the 120 min after TBI, heart rate, mean arterial pressure, intracranial pressure (ICP), and cerebral perfusion pressure (CPP) were continuously measured. Motor function, the infarct volume, neuronal nitrosative stress-associated apoptosis, and N-methyl-D-aspartate receptor 2A (NR2A) and NR2B expression in the pericontusional cortex were measured on the 3rd day after TBI. RESULTS: The results showed that the AMN082-treated group had a lower ICP and higher CPP after TBI. TBI-induced motor deficits, the increase in infarct volume, neuronal apoptosis, and 3-nitrotyrosine and inducible nitric oxide synthase expression in the pericontusional cortex were significantly improved by AMN082 therapy. Simultaneously, AMN082 increased NR2A and NR2B expression in neuronal cells. CONCLUSIONS: We concluded that intraperitoneal injection of AMN082 for 3 days may ameliorate TBI by attenuating glutamate receptor-associated nitrosative stress and neuronal apoptosis in the pericontusional cortex. We suggest that AMN082 administration in the acute stage may be a promising strategy for TBI.

Differentiation between acute macular neuroretinopathy and paracentral acute middle maculopathy in elderly persons: two case reports.

BACKGROUND: We report one case of rare acute macular neuroretinopathy (AMN) in an elderly patient with hypertension and one case of common paracentral acute middle maculopathy (PAMM) in a patient with diabetes mellitus to illustrate the difference between the two diseases. CASE PRESENTATION: This report describes two cases, one involving AMN and the other PAMM. The first patient was a 70-year-old man complaining of blurred vision for 3 days. He was examined with fundus photography, optical coherence tomography angiography (OCTA) and optical coherence tomography (OCT); a diagnosis of AMN was established. The second patient was a 50-year-old woman who complained of decreased vision during the past month. She had had diabetes mellitus for 6 years. From the ophthalmic imaging examination, the patient was diagnosed with PAMM and non-proliferative diabetic retinopathy (NPDR). Both patients were treated with drugs for improving microcirculation and neurotrophic drugs; however, there was no significant improvement in visual acuity. CONCLUSIONS: AMN is more common in young patients and is rarely observed in elderly patients with systemic diseases. The OCTA examination has an auxiliary diagnostic value for deep retinal capillary network ischaemia. Meanwhile, OCT examination has important imaging value in differentiating AMN from PAMM and can help avoid missed diagnoses.

The anti-cancer drug 5-fluorouracil affects cell cycle regulators and potential regulatory long non-coding RNAs in yeast.

5-fluorouracil (5-FU) was isolated as an inhibitor of thymidylate synthase, which is important for DNA synthesis. The drug was later found to also affect the conserved 3'-5' exoribonuclease EXOSC10/Rrp6, a catalytic subunit of the RNA exosome that degrades and processes protein-coding and non-coding transcripts. Work on 5-FU's cytotoxicity has been focused on mRNAs and non-coding transcripts such as rRNAs, tRNAs and snoRNAs. However, the effect of 5-FU on long non-coding RNAs (lncRNAs), which include regulatory transcripts important for cell growth and differentiation, is poorly understood. RNA profiling of synchronized 5-FU treated yeast cells and protein assays reveal that the drug specifically inhibits a set of cell cycle regulated genes involved in mitotic division, by decreasing levels of the paralogous Swi5 and Ace2 transcriptional activators. We also observe widespread accumulation of different lncRNA types in treated cells, which are typically present at high levels in a strain lacking EXOSC10/Rrp6. 5-FU responsive lncRNAs include potential regulatory antisense transcripts that form double-stranded RNAs (dsRNAs) with overlapping sense mRNAs. Some of these transcripts encode proteins important for cell growth and division, such as the transcription factor Ace2, and the RNA exosome subunit EXOSC6/Mtr3. In addition to revealing a transcriptional effect of 5-FU action via DNA binding regulators involved in cell cycle progression, our results have implications for the function of putative regulatory lncRNAs in 5-FU mediated cytotoxicity. The data raise the intriguing possibility that the drug deregulates lncRNAs/dsRNAs involved in controlling eukaryotic cell division, thereby highlighting a new class of promising therapeutical targets.

Imerslund-Gräsbeck Syndrome in an Infant with a Novel Intronic Variant in the AMN Gene: A Case Report.

Imerslund-Gräsbeck syndrome (IGS) is a rare autosomal recessive disorder clinically characterized by megaloblastic anemia, benign mild proteinuria, and other nonspecific symptoms. Several pathogenetic variants in the amnionless (AMN) or cubilin (CUBN) genes have been described in IGS. We describe a case of IGS with urinary tract infection and mild but persistent proteinuria at onset in an 11-month-old female child. With the appearance of macrocytic anemia, aphthous stomatitis, and neurological signs, IGS was clinically suspected, and vitamin B12 parenteral therapy was started. Sequence analysis showed the presence of a novel intronic variant c.513+5G>A of AMN, never before described in the literature, that was in compound heterozygosity with the known pathogenetic variant c.1006+34_1007-31del. Analysis extension to the parents revealed the presence of variant c.1006+34_1007-31 in the father and c.513+5G>A in the mother. In the present case with IGS, the novel intronic variant of AMN was identified in "trans" with a known pathogenic variant (c.1006-31 del) and the new variant was interpreted to be pathogenetic since it was not found in the public database of polymorphisms and because it was predicted to alter a donor splicing site. Our case underlines the relevance in detecting certain subtle symptoms, such as mild but persistent proteinuria associated with megaloblastic anemia, to reach a correct diagnosis of a rare but treatable disorder.

Classification and characterization of acute macular neuroretinopathy with spectral domain optical coherence tomography.

PURPOSE: To classify and characterize AMN lesions with SD-OCT during a follow-up as long as 5 years. METHODS: Retrospective study of 14 patients (18 eyes) with special focus on SD-OCT. We measured thickness of inner nuclear layer (INL), outer retinal layer (ONL), and hyperreflective band at baseline and during follow-up. AMN lesions were classified as type 1 and type 2. RESULTS: Of 14 patients (six males, eight females, mean age 29.7 years), three patients (four eyes) had type 1 and nine (12 eyes) had type 2. Two patients did not meet the criteria for AMN type 1 or 2 and were therefore classified as new subtype of AMN. In all patients, statistically significant thinning of ONL and INL was observable. Mean ONL of all patients was 90.2 ± 7.81 and 72.3 ± 15.64 µm (p < 0.05) during follow-up; mean INL was 54.4 ± 10.71 and 37.5 ± 6.18 µm (p < 0.05) in the course. In the subgroup analysis in AMN type 2, the thinning of both ONL and INL was also statistically significant (mean ONL: 87.4 ± 6.02 and 71.6 ± 12.7 µm (p < 0.05); mean INL: 48.5 ± 5.04 and 38.5 ± 5.6 µm (p < 0.05)) in the course. CONCLUSION: SD-OCT allows for classification, characterization, and further understanding of AMN lesions. Up to now, this is one of the largest AMN case series differentiating into different subtypes and following up for up to 5 years. Furthermore, we describe a new AMN subtype characterized by initially clinically visible yellowish parafoveal lesions, subtle pigmentary changes at late stage, lack of classic dark appearance on IR reflectance, involvement of RPE/Bruch's complex, and disruption of ellipsoid zone and interdigitation zone. The patients suffered from a prolonged visual impairment and paracentral scotomata. We propose the term AMN type 3 or "paracentral acute outer maculopathy."

Music and Mind: In Memoriam Professor Carlo Alberto Pagni, MD, PhD: February 13, 1931 -March 1, 2009.

Carlo Alberto Pagni, born in La Spezia, Italy, on February 13, 1931, was an eminent and respected professor of neurosurgery and chairman of the neurosurgical clinic of the University of Turin from 1980 to 2003. He died on March 1, 2009. As a professor of neurology and neurological surgery he was renowned as an expert on vascular, tumor, and functional neurosurgery. Beyond the Italian Neurosurgical Society, he was the doyen of functional neurosurgery, specializing in motor cortex stimulation for the treatment of focal dystonia, Parkinson's disease, and postictal spasticity and pain. His home was his castle, and his family was fundamental to his life. He shared with his wife, Sandra, his passion for piano playing and for their remarkable library, and together with friends, he and his wife enjoyed dinners with fine food and Barolo wines. Listening to this Grand Seigneur talking about and explaining the music of, above all, Ludwig van Beethoven, and Richard Wagner, one felt he was emotionally just "music and mind". You can imagine this from his books on music, chess, and neuroscience. Indeed, he adored playing correspondence chess worldwide. A sportsman too, he loved hiking, mountaineering, skiing, swimming, and fishing. Nature was his source for slowing down, for regenerating, and for collecting his strength for new projects and new challenges. Friends will remember Dr. Pagni as a Grand Seigneur.

The effect of nilotinib plus arsenic trioxide on the proliferation and differentiation of primary leukemic cells from patients with chronic myoloid leukemia in blast crisis.

AIM: To determine the effects of arsenic trioxide (ATO) and nilotinib (AMN107, Tasigna) alone or in combination on the proliferation and differentiation of primary leukemic cells from patients with chronic myeloid leukemia in the blast crisis phase (CML-BC). METHODS: Cells were isolated from the bone marrow of CML-BC patients and were treated with 1 µM ATO and 5 nM nilotinib, either alone or in combination. Cell proliferation was evaluated using a MTT assay. Cell morphology and the content of hemoglobin were examined with Wright-Giemsa staining and benzidine staining, respectively. The expression of cell surface markers was determined using flow cytometric analysis. The levels of mRNA and protein were analyzed using RT-PCR and Western blotting, respectively. RESULTS: ATO and nilotinib alone or in combination suppressed cell proliferation in a dose- and time-dependent pattern (P < 0.01 vs. control). Drug treatments promoted erythroid differentiation of CML-BC cells, with a decreased nuclei/cytoplasm ratio but increased hemoglobin content and glycophorin A (GPA) expression (P < 0.01 compared with control). In addition, macrophage and granulocyte lineage differentiation was also induced after drug treatment. The mRNA and protein levels of basic helix-loop-helix (bHLH) transcription factor T-cell acute lymphocytic leukemia protein 1 (TAL1) and B cell translocation gene 1 (BTG1) were both upregulated after 3 days of ATO and Nilotinib treatment. CONCLUSIONS: Our findings indicated that ATO and nilotinib treatment alone or in combination greatly suppressed cell proliferation but promoted the differentiation of CML-BC cells towards multiple-lineages. Nilotinib alone preferentially induced erythroid differentiation while combined treatment with ATO preferentially induced macrophage and granulocyte lineage differentiation.

Newborn screening for X-linked adrenoleukodystrophy: further evidence high throughput screening is feasible.

X-linked adrenoleukodystrophy (ALD) is characterized by adrenal insufficiency and neurologic involvement with onset at variable ages. Plasma very long chain fatty acids are elevated in ALD; even in asymptomatic patients. We demonstrated previously that liquid chromatography tandem mass spectrometry measuring C26:0 lysophosphatidylcholine reliably identifies affected males. We prospectively applied this method to 4689 newborn blood spot samples; no false positives were observed. We show that high throughput neonatal screening for ALD is methodologically feasible.

Advanced mucosal neoplasia of the anorectal junction: endoscopic resection technique and outcomes (with videos).

BACKGROUND: EMR at the anorectal junction (ARJ) is technically challenging. Issues of safety and procedural efficacy dictate that surgery is still performed as the primary management for noninvasive lesions in most centers. Modifications to the standard EMR technique may help to address the unique features and achieve safe and curative resection of most lesions. OBJECTIVE: To describe an effective and safe, modified EMR technique to remove advanced mucosal neoplasia (AMN) of the ARJ. DESIGN: Prospective, observational cohort study. SETTING: Academic, tertiary care referral center. PATIENTS: Patients undergoing EMR for AMN at the ARJ over 4.5 years, from June 2008 to December 2012. INTERVENTIONS: Use of long-acting local anesthetic in the submucosal injectate, endoscopic resection over the dentate line and hemorrhoidal columns, prophylactic antibiotics for resection of lesions at high risk for bacteremia, and cap and gastroscope-assisted resection. MAIN OUTCOME MEASUREMENTS: Procedural success and safety. RESULTS: Twenty-six patients with lesions involving the ARJ were referred for EMR (males 53.8%, median age 63, median lesion size 40 mm). Two patients went directly to surgery because of an endoscopic diagnosis of adenocarcinoma. EMR was performed in 24 lesions with complete adenoma clearance achieved in 100%. Four patients were admitted to the hospital. Focal adenoma recurrence was seen in 4 of 18 patients (22%) at first surveillance colonoscopy and was managed by snare diathermy resection. No recurrences were found at the second follow-up colonoscopy. Procedural success, adenoma recurrence, and admission rates were similar between EMRs performed at the ARJ and proximal rectum on univariate analysis (all P > .05). LIMITATIONS: Single tertiary center, nonrandomized study. CONCLUSIONS: Simple modifications to the EMR technique allow safe and effective treatment of AMN at the ARJ on an outpatient basis and should be the first-line management when the risk of invasive disease is low.

Intrathecal administration of mesenchymal stem cells in patients with adrenomyeloneuropathy.

Background and objectives: X-linked adrenomyeloneuropathy (AMN) is an inherited neurodegenerative disorder associated with mutations in the ABCD1 gene and the accumulation of very long-chain fatty acids (VLFCAs) in plasma and tissues. Currently, there is no effective treatment for AMN. We have aimed to evaluate the therapeutic effects of mesenchymal stem cell (MSC) transplantation in patients with AMN. Methods: This is a small cohort open-label study with patients with AMN diagnosed and treated at the University Hospital in Olsztyn, Poland. All patients met clinical, biochemical, MRI, and neuropsychological criteria for AMN. MSCs derived from Wharton jelly, 20 × 106 cells, were administered intrathecally three times every 2 months, and patients were followed up for an additional 3 months. The primary outcome measures included a blinded assessment of lower limb muscle strength with the Medical Research Council Manual Muscle Testing scale at baseline and on every month visits until the end of the study. Additional outcomes included measurements of the timed 25-feet walk (T25FW) and VLFCA serum ratio. Results: Three male patients with AMN with an age range of 26-37 years participated in this study. All patients experienced increased muscle strength in the lower limbs at the end of the study versus baseline. The power grade increased by 25-43% at the baseline. In addition, all patients showed an improvement trend in walking speed measured with the T25FW test. Treatment with MSCs in patients with AMN appeared to be safe and well tolerated. Discussion: The results of this study demonstrated that intrathecal administration of WJ-MSC improves motor symptoms in patients with AMN. The current findings lend support to the safety and feasibility of MSC therapy as a potentially viable treatment option for patients with AMN.

A case of adrenomyeloneuropathy caused by a novel point mutation in the ABCD1 gene and functional verification.

Adrenoleukodystrophy is a rare neurogenetic disease, and adrenomyeloneuropathy is the most common phenotype in adults. The clinical data of a patient with adrenoleukodystrophy and spinal-peripheral neuropathy caused by a novel point mutation in exon 4 of the ABCD1 gene (c.1256T > G (p.Val419Gly)) were retrospectively analyzed. Furthermore, we constructed wild-type and mutant vectors of the ABCD1 (NM0000334) gene to validate the effect of this mutation on the expression of the ABCD1 gene and protein and to explore the mechanism of X-linked adrenoleukodystrophy occurrence and development to identify therapeutic targets for clinical treatment.

Imerslund-Gräsbeck syndrome in a child with a novel compound heterozygous mutations in the AMN gene: a case report.

BACKGROUND: Imerslund-Gräsbeck syndrome (IGS) is an autosomal recessive disorder characterized by selective vitamin B12 malabsorption, resulting in vitamin B12 deficiency and impaired reabsorption of proximal tubular proteins.This case highlights a previously unidentified compound heterozygous variant in the Amnionless (AMN) gene that causes IGS syndrome and underscores the importance of long-term oral vitamin B12 replacement therapy in managing the condition. CASE PRESENTATION: In this retrospective analysis, we present the clinical data of a 3-year and 6-month-old female child diagnosed with IGS at Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, China, in November 2018. The child was admitted to the hospital due to a history of anemia persisting for over a month. There was no previous significant medical history. The admission examination revealed megaloblastic anemia with proteinuria. Serum vitamin B12 levels were decreased, while folic acid and renal function were normal. The patient was diagnosed with megaloblastic anemia and started long-term oral vitamin B12 replacement therapy. Throughout the follow-up period, blood tests consistently showed normal results, while proteinuria persisted. In November 2019, the child and her parents underwent whole exome sequencing analysis, which revealed a novel compound heterozygous variant in the AMN gene: c.162 + 1G > A and c.922 C > T (p.Q308X) in the child, c.162 + 1G > A in the father, and c.922 C > T (p.Q308X) in the mother. Therefore, this child was further diagnosed with IGS. CONCLUSIONS: In this case, whole exome sequencing proves to be highly practical in daily healthcare for diagnosing and refining rare or ultra-rare diseases with ambiguous phenotypes or genetic diversity. It is also valuable for prognostic evaluation and personalized management. Additionally, the oral vitamin B12 treatment demonstrated positive clinical effects for the child, offering a new option for patients unable to undergo intramuscular vitamin B12 replacement therapy.

Clinicopathologic Features of Antibrush Border Antibody Disease.

Introduction: Antibrush border antibody disease (ABBA) is an autoimmune tubulointerstitial kidney disease that primarily affects older individuals and results in progressive kidney failure. It is rare with only 20 reported cases. Here, we describe a case series to further define the clinicopathologic spectrum and natural history, and to inform management. Methods: We identified 67 patients with ABBA who underwent kidney biopsy, including 65 native and 2 transplants. Demographics, clinical findings, and laboratory data were obtained. Histopathologic data included light microscopy, immunofluorescence, electron microscopy and immunostaining for LRP2, CUBN, and AMN. Follow-up data, including treatment(s), laboratory values, and outcomes, were available from 51 patients. Results: Patients with ABBA were predominantly male with a median age of 72 years. Median serum creatinine was 2.7 mg/dl, proteinuria was 2.8 g/day, and hematuria was present in two-thirds of the patients. Tubular injury with LRP2-positive tubular basement membrane (TBM) deposits were seen in 94.2% of patients. Thirty-eight patients (56.7%) had a second kidney disease, commonly glomerular diseases with high-grade proteinuria. These diseases included podocytopathies, membranous nephropathy (MN), IgA nephropathy, diabetic glomerulopathy, lupus nephritis (LN), crescentic glomerulonephritis (GN), tubulointerstitial nephritis, and involvement by lymphoma. The majority of patients were treated with immunosuppression. Of those patients with follow-up, 29.4% achieved remission, 70.6% had no response, and 52.8% required dialysis or were deceased. Untreated patients were at the highest risk. Conclusion: ABBA is a rare autoimmune kidney disease that often occurs with other kidney diseases. Although the overall prognosis of ABBA is poor, there is potential benefit from immunosuppression.

Case report: dengue fever associated acute macular neuroretinopathy.

Dengue fever (DF), which is caused by the dengue virus (DENV) and transmitted through Aedes mosquitoes, is well recognized for its systemic manifestations, with its ocular involvement gaining recent attention. We present a case of a 41-year-old Taiwanese female who developed acute macular neuroretinopathy (AMN) following a DF diagnosis related to DENV-1, emphasizing the need for awareness of this complication. The patient, with a history of completely resolved optic neuritis (ON) and comorbidities, experienced blurred vision on day 10 after the onset of DF. The ophthalmic examination revealed macular edema, ellipsoid zone (EZ) infiltration, and choriocapillaris involvement. Despite pulse therapy with corticosteroids, visual disturbances persisted, highlighting the challenge of managing ocular complications. Ocular manifestations in DF include hemorrhages, inflammation, and vascular complications. DF-associated AMN, a rare presentation, poses challenges in diagnosis and treatment response evaluation. While most patients recover spontaneously, some face persistent visual impairment, especially with AMN. Our case emphasizes the importance of recognizing ocular complications in DF, necessitating a multidisciplinary approach for optimal management and further research to delineate treatment strategies and outcomes.

Urinary extracellular vesicles as a monitoring tool for renal damage in patients not meeting criteria for chronic kidney disease.

Background: Current definition of chronic kidney disease (CKD) identifies only advanced stages, but effective management demands early detection. Urinary albumin-to-creatinine ratio (ACR) 30 mg/g is a cut-off point for CKD clinical diagnosis. Patients with lower values (normoalbuminuria) and eGFR > 60 mL/min/1.73 m2 are considered at no increased cardiorenal risk. However, higher incidence of renal function decline and cardiovascular events have been shown within the normoalbuminuria range. Novel subclinical indicators may help to identify higher-risk patients. Urinary extracellular vesicles (uEVs) are sentinels of renal function non-invasively. Here we aimed to approach the early assessment of cardiorenal risk by investigating the protein cargo of uEVs. Methods: Hypertensive patients were classified in control group (C) with ACR < 10 mg/g, and high-normal group (HN) with ACR 10-30 mg/g. Isolated uEVs were characterized by western blotting and electron microscopy and the protein cargo was analyzed by untargeted proteomics (LC-MS/MS) in a first discovery cohort. Protein confirmation was performed in a different cohort by ExoView. Immunohistochemistry of human kidney biopsies was also performed to evaluate the potential of uEVs to reflect renal damage. Results: HN albuminuria does not affect the uEVs concentration, size, or tetraspanin profile. Among >6200 uEVs proteins identified, 43 define a panel significantly altered in HN patients without variation in urine, mostly annotated in the tubule (39 out of 43). The tubular transporter long-chain fatty acid transport protein 2 (SLC27A2) and the apical membrane protein amnionless (AMN) confirmed their alteration in HN patients evidencing impaired tubular reabsorption. SLC27A2 showed tubular expression and significantly reduced levels in patients with diagnostic criteria for CKD. Conclusions: Alterations in the EV-mediated molecular profile are evident before pathological ACR levels are reached. Direct quantitation of SLC27A2 and AMN in uEVs helps identifying normoalbuminuric subjects with higher cardiorenal risk in early monitoring of CKD.

Acute macular neuroretinopathy associated with COVID-19 pandemic: A real-world observation study.

PURPOSE: To evaluate the clinical and retinal imaging features of Chinese patients with acute macular neuroretinopathy (AMN) associated with COVID-19. DESIGN: A prospective observational study. METHODS: Retinal imaging, including color fundus photography, near-infrared imaging (NIR), swept-source optical coherence tomography (SS-OCT), optical coherence tomography angiography (OCTA), and Humphrey perimetry, were conducted for each case. RESULTS: All cases were included within the first three months following the pandemic outbreak. A total of 12 male patients (36.36 %) and 21 female patients (63.64 %) were prospectively recruited, and 29 cases (87.88 %) were bilaterally affected. The median interval between the onset of fever and the appearance of ocular symptoms was two days (range, 0.5-5.0 days). Apart from the outer retinal changes typical of AMN, changes in the inner retinal layers were observed, including intraretinal hemorrhage (8.06 %), cotton wool spots (9.68 %), and paracentral acute middle maculopathy (PAMM) (8.06 %). Smaller retinal inner nuclear layer hyperreflective speckles (RIHS) (41.94 %) were identified as a distinguishing feature from typical PAMM. Voids of vessel signals were found in the superficial (11.54 %), intermediate (82.69 %), and deep capillary plexus (98.08 %), and in the choriocapillaris (19.23 %) on OCTA. Humphrey perimetry illustrated central, paracentral, and peripheral scotomas. The occult lesions associated with AMN, PAMM, and some of the RIHS illustrated by OCT were visualized topographically and further confirmed by OCTA as perfusion defects. CONCLUSION: An increase in AMN cases correlated with the SARS-CoV-2 outbreak. Additional features, including widespread inner retinal perfusion deficits, were observed and may serve as potential biomarkers for systemic microcirculation dysregulation in COVID-19.

Peroxisomal multifunctional protein-2 deficiency causes neuroinflammation and degeneration of Purkinje cells independent of very long chain fatty acid accumulation.

Although peroxisome biogenesis and ß-oxidation disorders are well known for their neurodevelopmental defects, patients with these disorders are increasingly diagnosed with neurodegenerative pathologies. In order to investigate the cellular mechanisms of neurodegeneration in these patients, we developed a mouse model lacking multifunctional protein 2 (MFP2, also called D-bifunctional protein), a central enzyme of peroxisomal ß-oxidation, in all neural cells (Nestin-Mfp2(-/-)) or in oligodendrocytes (Cnp-Mfp2(-/-)) and compared these models with an already established general Mfp2 knockout. Nestin-Mfp2 but not Cnp-Mfp2 knockout mice develop motor disabilities and ataxia, similar to the general mutant. Deterioration of motor performance correlates with the demise of Purkinje cell axons in the cerebellum, which precedes loss of Purkinje cells and cerebellar atrophy. This closely mimics spinocerebellar ataxias of patients affected with mild peroxisome ß-oxidation disorders. However, general knockouts have a much shorter life span than Nestin-Mfp2 knockouts which is paralleled by a disparity in activation of the innate immune system. Whereas in general mutants a strong and chronic proinflammatory reaction proceeds throughout the brain, elimination of MFP2 from neural cells results in minor neuroinflammation. Neither the extent of the inflammatory reaction nor the cerebellar degeneration could be correlated with levels of very long chain fatty acids, substrates of peroxisomal ß-oxidation. In conclusion, MFP2 has multiple tasks in the adult brain, including the maintenance of Purkinje cells and the prevention of neuroinflammation but this is not mediated by its activity in oligodendrocytes nor by its role in very long chain fatty acid degradation.

An exon 53 frameshift mutation in CUBN abrogates cubam function and causes Imerslund-Gräsbeck syndrome in dogs.

Cobalamin malabsorption accompanied by selective proteinuria is an autosomal recessive disorder known as Imerslund-Gräsbeck syndrome in humans and was previously described in dogs due to amnionless (AMN) mutations. The resultant vitamin B12 deficiency causes dyshematopoiesis, lethargy, failure to thrive, and life-threatening metabolic disruption in the juvenile period. We studied 3 kindreds of border collies with cobalamin malabsorption and mapped the disease locus in affected dogs to a 2.9Mb region of homozygosity on canine chromosome 2. The region included CUBN, the locus encoding cubilin, a peripheral membrane protein that in concert with AMN forms the functional intrinsic factor-cobalamin receptor expressed in ileum and a multi-ligand receptor in renal proximal tubules. Cobalamin malabsorption and proteinuria comprising CUBN ligands were demonstrated by radiolabeled cobalamin uptake studies and SDS-PAGE, respectively. CUBN mRNA and protein expression were reduced ~10 fold and ~20 fold, respectively, in both ileum and kidney of affected dogs. DNA sequencing demonstrated a single base deletion in exon 53 predicting a translational frameshift and early termination codon likely triggering nonsense mediated mRNA decay. The mutant allele segregated with the disease in the border collie kindred. The border collie disorder indicates that a CUBN mutation far C-terminal from the intrinsic factor-cobalamin binding site can abrogate receptor expression and cause Imerslund-Gräsbeck syndrome.

Generation and characterization of an inducible renal proximal tubule-specific CreERT2 mouse.

Protein reabsorption in renal proximal tubules is essential for maintaining nutrient homeostasis. Renal proximal tubule-specific gene knockout is a powerful method to assess the function of genes involved in renal proximal tubule protein reabsorption. However, the lack of inducible renal proximal tubule-specific Cre recombinase-expressing mouse strains hinders the study of gene function in renal proximal tubules. To facilitate the functional study of genes in renal proximal tubules, we developed an AMN CreERT2 knock-in mouse strain expressing a Cre recombinase-estrogen receptor fusion protein under the control of the promoter of the amnionless (AMN) gene, a protein reabsorption receptor in renal proximal tubules. AMN CreERT2 knock-in mice were generated using the CRISPR/Cas9 strategy, and the tissue specificity of Cre activity was investigated using the Cre/loxP reporter system. We showed that the expression pattern of CreERT2-mEGFP in AMN CreERT2 mice was consistent with that of the endogenous AMN gene. Furthermore, we showed that the Cre activity in AMN CreERT2 knock-in mice was only detected in renal proximal tubules with high tamoxifen induction efficiency. As a proof-of-principle study, we demonstrated that renal proximal tubule-specific knockout of Exoc4 using AMNCreERT2 led to albumin accumulation in renal proximal tubular epithelial cells. The AMN CreERT2 mouse is a powerful tool for conditional gene knockout in renal proximal tubules and should offer useful insight into the physiological function of genes expressed in renal proximal tubules.