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1.
BMJ Case Rep ; 16(11)2023 Nov 03.
Article in English | MEDLINE | ID: mdl-37923332

ABSTRACT

A man in his late 50s without notable medical background was admitted with subacute onset of bilateral lower extremity weakness. Blood and physiological examinations revealed no significant abnormalities. Cerebrospinal fluid (CSF) examination revealed elevated cell count and protein levels and an immunoglobulin G index of 2.01. T1-weighted MRI showed swelling and enhancement of the cauda equina. After admission, the patient developed bowel and bladder incontinence, deteriorated to manual muscle test 0 and developed right trochlear, trigeminal and facial nerve palsy. He underwent a cauda equina biopsy and was diagnosed with neurosarcoidosis. After methylprednisolone pulse therapy and corticosteroid treatment, cauda equina syndrome including lower extremity weakness and cerebral nerve palsy improved. The patient's daily activities improved to the baseline level over 2 months after discharge. Serum and CSF soluble interleukin-2 receptor levels were within the reference range and decreased with the improvement of neurological and imaging findings.


Subject(s)
Cauda Equina , Central Nervous System Diseases , Humans , Male , Cauda Equina/pathology , Central Nervous System Diseases/diagnosis , Central Nervous System Diseases/diagnostic imaging , Muscle Weakness/pathology , Paralysis , Middle Aged
2.
BMJ Case Rep ; 16(6)2023 Jun 14.
Article in English | MEDLINE | ID: mdl-37316284

ABSTRACT

A man in his early 70s with a 4-year history of diffuse large B cell lymphoma (DLBCL) was admitted to our hospital with diplopia and achromatopsia. Neurological examination revealed visual impairment, ocular motility disorder and diplopia on looking to the left. Blood and cerebrospinal fluid investigations showed no significant findings. MRI revealed diffusely thickened dura mater and contrast-enhanced structures in the left apical orbit, consistent with hypertrophic pachymeningitis (HP). We performed an open dural biopsy to distinguish the diagnosis from lymphoma. The pathological diagnosis was idiopathic HP, and DLBCL recurrence was ruled out. Following methylprednisolone pulse and oral prednisolone therapy, his neurological abnormalities gradually receded. Open dural biopsy played an important role not only in diagnosing idiopathic HP but also in relieving the pressure on the optic nerve.


Subject(s)
Lymphoma, Large B-Cell, Diffuse , Meningitis , Male , Humans , Diplopia , Lymphoma, Large B-Cell, Diffuse/complications , Lymphoma, Large B-Cell, Diffuse/diagnosis , Lymphoma, Large B-Cell, Diffuse/drug therapy , Patients , Biopsy , Meningitis/diagnosis , Meningitis/drug therapy
3.
J Neuroimmunol ; 349: 577399, 2020 12 15.
Article in English | MEDLINE | ID: mdl-32980672

ABSTRACT

Since autonomic dysfunction is closely associated with autoimmune encephalitis (AE), the objective of this study was to determine the autonomic symptoms and the prevalence of anti-α3 subunit of the ganglionic-type nicotinic acetylcholine receptor (gAChRα3) antibodies in the patients with AE. We reviewed the clinical features of 19 AE patients, and specifically analyzed sera for anti-gAChRα3 antibodies using the luciferase immunoprecipitation system (LIPS) assay. Cardiovascular autonomic symptoms were found to be common in patients with AE, and hypersalivation was seen only in patients with NMDAR encephalitis. LIPS detected anti-gAChRα3 antibodies in the sera from patients with AE (5/29, 26%). This study is the first to demonstrate that clinical characteristics including autonomic symptoms of AE patients with seropositivity for gAChR autoantibodies. It will be important to verify the role of gAChR antibodies in autonomic dysfunction and brain symptoms to clarify the pathogenesis of AE.


Subject(s)
Autoantibodies/blood , Encephalitis/blood , Encephalitis/diagnosis , Hashimoto Disease/blood , Hashimoto Disease/diagnosis , Receptors, Nicotinic/blood , Adult , Aged , Biomarkers/blood , Female , Humans , Male , Middle Aged , Protein Subunits/blood , Retrospective Studies , Young Adult
4.
Neurocase ; 26(5): 285-292, 2020 10.
Article in English | MEDLINE | ID: mdl-32804589

ABSTRACT

We report a patient with alexia with agraphia accompanied by letter-by-letter reading after hemorrhage in the left middle and inferior occipital gyri that spared the angular gyrus and the fusiform gyrus. Kanji (Japanese morphograms) and kana (Japanese phonetic writing) reading and writing tests revealed that alexia with agraphia was characterized by kana-predominant alexia and kanji-predominant agraphia. This type of "dorsal" letter-by-letter reading is discernable from conventional ventral type letter-by-letter reading that is observed in pure alexia in that (1) kinesthetic reading is less effective, (2) kana or literal agraphia coexists, and (3) fundamental visual discrimination is nearly normal.


Subject(s)
Agraphia/physiopathology , Cerebral Hemorrhage/pathology , Dyslexia, Acquired/physiopathology , Occipital Lobe/pathology , Agraphia/etiology , Cerebral Hemorrhage/complications , Dyslexia, Acquired/etiology , Humans , Male , Middle Aged , Pattern Recognition, Visual/physiology , Psycholinguistics
5.
Rinsho Shinkeigaku ; 59(12): 834-839, 2019 Dec 25.
Article in Japanese | MEDLINE | ID: mdl-31761838

ABSTRACT

We report a case of acyclovir encephalopathy in a 77-year-old man who was introduced to peritoneal dialysis three years earlier. He developed herpes zoster and was treated with acyclovir (ACV) at 800 mg daily per oral. Two days later, he developed consciousness disturbance, hallucinations and asterixis. Acyclovir was stopped and continuous ambulatory peritoneal dialysis (CAPD) was switched to hemodialysis, which resulted in the resolution of his symptoms. Because the optimal dose of ACV varies among individuals depending on the bioavailability of ACV and metabolic enzyme activity, ACV encephalopathy can occur even when the acyclovir dose is modified according to the renal function of the affected patient. Because CAPD provides a poorer ACV clearance than hemodialysis, CAPD patients tend to have a higher risk of developing ACV encephalopathy and to recover more slowly. If CAPD patients develop ACV encephalopathy, a temporary change in the type of dialysis to hemodialysis should be considered.


Subject(s)
Acyclovir/administration & dosage , Acyclovir/adverse effects , Antiviral Agents/administration & dosage , Antiviral Agents/adverse effects , Brain Diseases/etiology , Herpes Zoster/drug therapy , Peritoneal Dialysis/adverse effects , Administration, Oral , Aged , Humans , Male , Renal Dialysis
6.
Neuropathology ; 39(2): 147-155, 2019 Apr.
Article in English | MEDLINE | ID: mdl-30868686

ABSTRACT

Miliary brain metastasis is a rare type of brain metastasis, in which carcinoma cells disseminate to numerous foci confined to Virchow-Robin/subpial spaces. Symptoms usually progress within several months, and magnetic resonance imaging (MRI) shows multiple small contrast-enhancing lesions. We report an autopsy case of a patient who rapidly deteriorated within a week due to miliary brain metastasis after epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) discontinuation, without contrast-enhancing lesions on MRI. A 74-year-old woman was diagnosed with stage IV lung adenocarcinoma with EGFR L868R mutation 2 years before presentation. Gefitinib, an EGFR-TKI was started. After 7 months, multiple new punctate contrast-enhancing lesions in the cerebral cortex appeared. After switching to another EGFR-TKI, erlotinib, these lesions disappeared. One year later, erlotinib was discontinued because of disease progression in the lung and docetaxel was initiated. Sixteen days later, cognitive decline appeared which rapidly progressed to bedridden state in 4 days. MRI showed multiple cortical small fluid-attenuated inversion recovery high intensity lesions which lacked contrast enhancement. The patient exhibited a state of akinetic mutism within a few days, and died 52 days after the appearance of neurological symptoms. The rapid progression indicated disease flare after EGFR-TKI discontinuation. Autopsy revealed numerous foci of metastasis in the cerebral cortex, basal ganglia, thalamus, and cerebellum, in which cancer cells were mostly confined to the Virchow-Robin/subpial spaces. These pathological findings were compatible with previous reports of miliary brain metastasis. Recent reports suggest that early disseminated cancer cells can survive for a long time and even remain after chemotherapy in supportive niches, and Virchow-Robin spaces are the niches in the brain. Our case suggests that these cancer cells may rapidly proliferate as a withdrawal burst after discontinuation of molecular targeted drugs, and show pathological findings of miliary brain metastasis.


Subject(s)
Brain Neoplasms/pathology , Brain Neoplasms/secondary , Disease Progression , Lung Neoplasms/pathology , Protein Kinase Inhibitors/therapeutic use , Aged , Brain Neoplasms/genetics , ErbB Receptors/antagonists & inhibitors , ErbB Receptors/genetics , Female , Humans , Lung Neoplasms/drug therapy , Lung Neoplasms/genetics , Mutation
8.
Case Rep Neurol ; 10(1): 72-82, 2018.
Article in English | MEDLINE | ID: mdl-29681826

ABSTRACT

We report a patient with phonological agraphia (selective impairment of kana [Japanese phonetic writing] nonwords) and acalculia (mental arithmetic difficulties) with impaired verbal short-term memory after a cerebral hemorrhage in the opercular part of the left precentral gyrus (Brodmann area 6) and the adjacent postcentral gyrus. The patient showed phonemic paragraphia in five-character kana nonword writing, minimal acalculia, and reduced digit and letter span. Mental arithmetic normalized after 8 months and agraphia recovered to the normal range at 1 year after onset, in parallel with an improvement of the auditory letter span score from 4 to 6 over a period of 14 months and in the digit span score from 6 to 7 over 24 months. These results suggest a close relationship between the recovery of agraphia and acalculia and the improvement of verbal short-term memory. The present case also suggests that the opercular part of the precentral gyrus constitutes the phonological route in writing that conveys phonological information of syllable sequences, and its damage causes phonological agraphia and acalculia with reduced verbal short-term memory.

9.
Cogn Neuropsychiatry ; 23(1): 1-14, 2018 01.
Article in English | MEDLINE | ID: mdl-29199507

ABSTRACT

INTRODUCTION: Bálint's syndrome involves bilateral damage to the parieto-occipital area. The extent of the effect of unilateral damage on the Bálint's triad (oculomotor apraxia, optic ataxia, and simultanagnosia) remains unknown. METHODS: We examined a 63-year-old, right-handed woman who developed right hemianopia, oculomotor apraxia, optic ataxia, simultanagnosia, and hemispatial neglect (HSN) for the right after a cerebral infarction, with detailed neuropsychological tests, magnetic resonance imaging, and single photon emission computed tomography (SPECT). RESULTS: Neuropsychological examination showed that oculomotor apraxia, optic ataxia, and simultanagnosia were more pronounced in the right hemi-space, probably due to the limited eye movement in the right visual field, whereas HSN was restricted to the right hemi-space. Diffusion-weighted MR images revealed hyperintensity in the left parieto-temporo-occipital region, and several spotty areas of the bilateral frontal and parietal subcortical regions. SPECT revealed hypoperfusion in the left parieto-occipital region and frontal operculum and small areas of the right superior parietal lobule. CONCLUSIONS: The case suggests that asymmetric (more pronounced in the right hemi-space) oculomotor apraxia, optic ataxia, and simultanagnosia occur in an extensive lesion of the left parieto-occipital cortices. Although HSN is not a prerequisite for simultanagnosia, the coexistence of HSN aggravates simultanagnosia in the hemi-space opposite the lesion.


Subject(s)
Agnosia/diagnostic imaging , Apraxias/congenital , Ataxia/diagnostic imaging , Cogan Syndrome/diagnostic imaging , Occipital Lobe/diagnostic imaging , Parietal Lobe/diagnostic imaging , Perceptual Disorders/diagnostic imaging , Agnosia/complications , Apraxias/complications , Apraxias/diagnostic imaging , Ataxia/complications , Cogan Syndrome/complications , Fatal Outcome , Female , Humans , Magnetic Resonance Imaging , Middle Aged , Neuropsychological Tests , Perceptual Disorders/complications
10.
eNeurologicalSci ; 6: 4-5, 2017 Mar.
Article in English | MEDLINE | ID: mdl-29260006

ABSTRACT

Proteinase 3 anti-neutrophil cytoplasmic antibody (PR3-ANCA) is reported to be highly specific to vasculitis compared to myeloperoxidase (MPO)-ANCA. We report a case of a 19-year-old woman with chronic inflammatory demyelinating polyneuropathy (CIDP) with high PR3-ANCA positivity. The patient responded well to intravenous immunoglobulin plus oral steroid, and showed no signs of systemic vasculitis during the subsequent 10 months of follow-up. Our present case suggests that CIDP may accompany high PR3-ANCA levels, which should be differentiated from axonal neuropathy due to vasculitis.

12.
Neurocase ; 22(1): 122-9, 2016.
Article in English | MEDLINE | ID: mdl-26207875

ABSTRACT

We report a patient with ventral simultanagnosia, prosopagnosia for "unfamiliar faces" (dorsal prosopagnosia), spatial agraphia, and constructional disorder, particularly on the left spatial side, due to a lesion in the right posterior superior and middle temporal gyri and angular gyrus. The patient showed impairment of fundamental visual and visuospatial recognition, such as in object size, configuration, and horizontal point location, which probably underlay the mechanism of simultanagnosia and prosopagnosia. This case also suggests that the coexistence of simultanagnosia and prosopagnosia results from a right hemispheric insult, and damage to the temporoparietal area interrupts the incorporation of spatial information into object recognition. This disconnection of information flow, together with impaired object recognition per se, may impair the parallel processing of multiple objects, leading to object-by-object or part-by-part recognition.


Subject(s)
Agnosia/etiology , Brain Injuries/complications , Parietal Lobe/injuries , Prosopagnosia/etiology , Temporal Lobe/injuries , Aged , Face , Female , Humans , Neuropsychological Tests
13.
Intern Med ; 53(13): 1441-5, 2014.
Article in English | MEDLINE | ID: mdl-24990337

ABSTRACT

We herein report the case of a 65-year-old woman who presented with the subacute onset of dementia and subsequently developed abnormal behavior and a gait disturbance. Her condition transiently improved; however, within one month, she became drowsy and poorly responsive, with limb chorea and urinary incontinence. Her history of frequently using charcoal led us to diagnose her with carbon monoxide (CO) poisoning. The findings of this case and a literature review suggest that subacute dementia due to CO poisoning recovers late, after a year or more, in patients above sixty years of age, and both hyperbaric oxygen and corticosteroid pulse therapy should be considered in such cases, even after one month.


Subject(s)
Carbon Monoxide Poisoning/complications , Carbon Monoxide Poisoning/diagnosis , Dementia/etiology , Leukoencephalopathies/etiology , Adrenal Cortex Hormones/therapeutic use , Aged , Brain/diagnostic imaging , Brain/pathology , Carbon Monoxide Poisoning/therapy , Cysteine/analogs & derivatives , Female , Gait , Humans , Hyperbaric Oxygenation , Magnetic Resonance Imaging , Movement Disorders/etiology , Organotechnetium Compounds , Radiopharmaceuticals , Time Factors , Tomography, Emission-Computed, Single-Photon
14.
Case Rep Neurol ; 6(3): 291-6, 2014.
Article in English | MEDLINE | ID: mdl-25685138

ABSTRACT

BACKGROUND: Little is known about the difference between anti-N-methyl-D-aspartate receptor (NMDAR) antibody-positive encephalitis and anti-glutamate receptor (GluR) antibody-positive encephalitis. OBJECTIVES: To characterize anti-GluR antibody-positive encephalitis. METHODS: We report a 33-year-old man with nonparaneoplastic anti-GluR ∊2, ζ1 and δ2 antibody-positive and anti-NMDAR antibody-negative encephalitis, using neuropsychological tests and imaging studies including magnetic resonance imaging and single photon emission computed tomography (SPECT) with a (99m)Tc-ethylcysteinate dimer. RESULTS: The patient exhibited global aphasia and swallowing apraxia (inability to transfer food to the pharyngeal cavity without sialorrhea). He was treated with 3 courses of corticosteroid pulse therapy and had recovered markedly 3 weeks after onset. Magnetic resonance diffusion-weighted images revealed hyperintensity in the bilateral frontal and left parietal cortices. Seven months later, a small area of hyperintensity in the left supramarginal gyrus remained. SPECT revealed hypoperfusion in extensive regions of the bilateral frontal lobes and left supramarginal gyrus. Thirteen months later, blood flow reduction was restricted to diffuse areas in the frontal lobes. CONCLUSIONS: Frontal lobar encephalitis without medial temporal involvement, marked cognitive impairment with a relatively preserved level of consciousness, and a favorable response to corticosteroid therapy, with nearly reversible cortical damage, may characterize anti-GluR antibody-positive encephalitis.

15.
J Neurol ; 260(8): 1982-91, 2013 Aug.
Article in English | MEDLINE | ID: mdl-23589191

ABSTRACT

A 65-year-old woman developed progressive apraxic agraphia, characterized by poorly formed graphemes, a kanji (Japanese morphograms) recall impairment, relatively preserved oral spelling of kanji characters, and incorrect stroke sequences on writing accompanied by micrographia over a 3-year period. She also showed minor degrees of rigidity, limb-kinetic apraxia, and ideomotor apraxia of the left hand. Although asymmetric rigidity and limb-kinetic apraxia strongly suggested corticobasal degeneration, (11)C-Pittsburgh compound B positron emission tomography (PiB-PET) showed the predominantly right-sided accumulation of amyloid ß in the cortices and striatum. (18)F-fluoro-deoxy-glucose PET and single photon emission computed tomography with a (99m)Tc-ethylcysteinate dimer (ECD-SPECT) also revealed predominantly right-sided hypometabolism and hypoperfusion in the primary sensorimotor cortex, posterior cingulate gyrus, temporoparietal cortices, frontal cortices, thalamus, and basal ganglia, a pattern characteristic of both corticobasal degeneration and Alzheimer's disease. The findings suggest that progressive apraxic agraphia with micrographia presenting as corticobasal syndrome can show an Alzheimer's disease pathology. It is also suggested that ideomotor apraxia of the left hand can occur without a callosal lesion, and is caused by hypometabolism or hypoperfusion in the right frontal and parietal cortices, as revealed by PET and SPECT.


Subject(s)
Agraphia/diagnostic imaging , Aniline Compounds , Apraxias/diagnostic imaging , Basal Ganglia Diseases/diagnostic imaging , Cerebral Cortex/diagnostic imaging , Neurodegenerative Diseases/diagnostic imaging , Radiopharmaceuticals , Thiazoles , Aged , Agraphia/physiopathology , Apolipoproteins E/cerebrospinal fluid , Apraxias/physiopathology , Basal Ganglia Diseases/physiopathology , Brain/pathology , Cerebral Cortex/physiopathology , Cysteine/analogs & derivatives , Disease Progression , Executive Function , Female , Handwriting , Humans , Image Processing, Computer-Assisted , Intelligence Tests , Neurodegenerative Diseases/physiopathology , Neurologic Examination , Neuropsychological Tests , Organotechnetium Compounds , Positron-Emission Tomography , Reading , Tomography, Emission-Computed, Single-Photon
16.
J Neurol ; 258(8): 1528-37, 2011 Aug.
Article in English | MEDLINE | ID: mdl-21380791

ABSTRACT

Two patients with isolated thalamic agraphia are described. Both showed kanji (Japanese morphograms) agraphia due to impaired character recall, grapheme deformity and micrographia (progressive reduction in character size during writing) after a lesion that involved the ventral lateral and ventroposterolateral nuclei. Single photon emission computed tomography with a (99m)Tc-ethylcysteinate dimer revealed hypoperfusion in the left precentral gyrus (Brodmann Area 6) and anterior supramarginal gyrus in both. Six months later, the extent of blood flow reduction decreased in the supramarginal gyrus in both patients and the precentral gyrus in patient 1. By this time, the writing impairment improved to nearly the normal range. Our study suggests that kanji agraphia (corresponding to lexical agraphia in Western countries) with poor grapheme formation and micrographia arises from a lesion in the ventral lateral and ventroposterolateral nuclei in the left thalamus. The accompaniment of poor grapheme formation and micrographia may reflect disruption of the cortico-subcortical motor circuit involving the putamen, thalamus, premotor cortex and sensorimotor cortex. It is also suggested that multiple cortical sites can be a target for secondary dysfunction that yields agraphia in a thalamic lesion, and that the recovery of reduced cortical blood flow does not always proceed in parallel with that of agraphia.


Subject(s)
Agraphia/diagnostic imaging , Agraphia/physiopathology , Thalamus/diagnostic imaging , Thalamus/physiopathology , Agraphia/etiology , Cerebral Hemorrhage/complications , Female , Humans , Magnetic Resonance Imaging , Male , Middle Aged , Neuropsychological Tests , Tomography, Emission-Computed, Single-Photon
17.
Mov Disord ; 22(5): 728-31, 2007 Apr 15.
Article in English | MEDLINE | ID: mdl-17269131

ABSTRACT

We report a 40-year-old man with severe hypokinesis as paraneoplastic manifestation of a microscopic "carcinoma in situ" of the testis. The young age of the patient, along with progressive neurologic deterioration, detection of anti-Ma2 antibodies, and ultrasound findings of bilateral microcalcifications, led to bilateral orchiectomy, revealing the tumor in both testes. After orchiectomy, neurological symptoms stabilized, but the patient eventually died of systemic complications caused by his severe neurological deficits. Anti-Ma2 paraneoplastic encephalitis should be considered in patients with severe hypokinesis, and intensive investigation and aggressive approach to treatment is encouraged to prevent progression of the neurological deficits.


Subject(s)
Antigens, Neoplasm/immunology , Autoantibodies/blood , Carcinoma in Situ/diagnosis , Hypokinesia/diagnosis , Limbic Encephalitis/diagnosis , Neoplasms, Germ Cell and Embryonal/diagnosis , Nerve Tissue Proteins/immunology , Paraneoplastic Syndromes/diagnosis , Seminiferous Tubules , Testicular Neoplasms/diagnosis , Adult , Brain/immunology , Brain/pathology , Carcinoma in Situ/immunology , Carcinoma in Situ/pathology , Carcinoma in Situ/surgery , Disease Progression , Fatal Outcome , Humans , Hypokinesia/immunology , Hypokinesia/pathology , Limbic Encephalitis/immunology , Limbic Encephalitis/pathology , Magnetic Resonance Imaging , Male , Neoplasms, Germ Cell and Embryonal/immunology , Neoplasms, Germ Cell and Embryonal/pathology , Neoplasms, Germ Cell and Embryonal/surgery , Orchiectomy , Paraneoplastic Syndromes/immunology , Paraneoplastic Syndromes/pathology , Seminiferous Tubules/pathology , Testicular Neoplasms/immunology , Testicular Neoplasms/pathology , Testicular Neoplasms/surgery
18.
Rinsho Shinkeigaku ; 44(7): 438-42, 2004 Jul.
Article in Japanese | MEDLINE | ID: mdl-15384705

ABSTRACT

We report a 73-year-old man who presented symptoms of low back pain and SIADH followed by weakness of all four limbs and sensory disturbance of the lower legs 2 month after the first symptoms. He was referred to our department because of the evolution of weakness. Neurological examination on admission revealed weakness of the arms and legs, areflexia, and hypoesthesia of the lower legs. The straight leg raising test induced prominent radiating pain bilaterally. The level of sodium was 114 mEq/l, the plasma osmolality was 239 mOsm/kg, and the level of plasma antidiuretic hormone was 3.45 pg/ml. Other blood chemical values were unremarkable. The urine osmolality was 527 mOsm/kg. T1-weighted MR image with gadolinium showed thickening and enhancement of the nerve root. Nerve conduction study revealed compromised conduction with demyelinating features, and somatosensory evoked potential study could not show any potentials. He was diagnosed as having CIDP complicating with SIADH. An association between SIADH and AIDP has been much reported previously. To our knowledge, however, there has been no report of SIADH complicating with CIDP.


Subject(s)
Extremities , Inappropriate ADH Syndrome/etiology , Low Back Pain/etiology , Muscle Weakness/etiology , Polyradiculoneuropathy, Chronic Inflammatory Demyelinating/complications , Acute Disease , Aged , Chronic Disease , Humans , Hypesthesia/etiology , Inappropriate ADH Syndrome/diagnosis , Male , Polyradiculoneuropathy, Chronic Inflammatory Demyelinating/diagnosis , Time Factors
19.
J Biol Chem ; 279(45): 47372-8, 2004 Nov 05.
Article in English | MEDLINE | ID: mdl-15347659

ABSTRACT

The relationship between the DNA replication and spindle checkpoints of the cell cycle is unclear, given that in most eukaryotes, spindle formation occurs only after DNA replication is complete. Fission yeast rad3 mutant cells, which are deficient in DNA replication checkpoint function, enter, progress through, and exit mitosis even when DNA replication is blocked. In contrast, the entry of cds1 mutant cells into mitosis is delayed by several hours when DNA replication is inhibited. We show here that this delay in mitotic entry in cds1 cells is due in part to activation of the spindle checkpoint protein Mad2p. In the presence of the DNA replication inhibitor hydroxyurea (HU), cds1 mad2 cells entered and progressed through mitosis earlier than did cds1 cells. Overexpression of Mad2p or inactivation of Slp1p, a regulator of the anaphase-promoting complex, also rescued the checkpoint defect of HU-treated rad3 cells. Rad3p was shown to be involved in the physical interaction between Mad2p and Slp1p in the presence of HU. These results suggested that Mad2p and Slp1p act downstream of Rad3p in the DNA replication checkpoint and that Mad2p is required for the DNA replication checkpoint when Cds1p is compromised.


Subject(s)
Carrier Proteins/physiology , DNA Replication , DNA, Fungal , Schizosaccharomyces/physiology , Spindle Apparatus/ultrastructure , Cell Cycle Proteins/metabolism , Checkpoint Kinase 2 , Culture Media , DNA/chemistry , DNA/metabolism , Flow Cytometry , Green Fluorescent Proteins/metabolism , Hydroxyurea/pharmacology , Immunoblotting , Immunoprecipitation , Indoles/pharmacology , Mad2 Proteins , Methyl Methanesulfonate , Mitosis , Mutagens , Mutation , Nuclear Proteins , Phenotype , Phosphorylation , Protein Kinases/metabolism , Protein Serine-Threonine Kinases/metabolism , Schizosaccharomyces pombe Proteins , Temperature , Time Factors , Tyrosine/chemistry , Ultraviolet Rays
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