Creutzfeldt-Jakob disease associated with high titer of antithyroid autoantibodies: case report and literature review

Hashimoto's encephalopathy and Creutzfeldt-Jakob disease (CJD) often have similar clinical features and may be confused, especially at onset. A 61-year-old woman developed rapidly progressive ataxia, myoclonus and dementia, with abnormalities seen on electroencephalography (EEG). Serum analysis disclosed high titers of antithyroid autoantibodies. Both clinical course and autopsy led to a definitive diagnosis of CJD. This case and a literature review of previous cases confirm that CJD may be confused with Hashimoto's encephalopathy. EEG, clinical and laboratory findings (including the positivity of 14.3.3 protein in the cerebrospinal fluid) are not conclusive for a differential diagnosis, especially at early stages. Only the results of genetic exams can allow a definitive diagnosis in a small percentage of cases while patients are still alive. In patients with unclear symptomatology and rapid onset of myoclonus, dementia and ataxia, the presence of antithyroid antibodies should be examined. If their levels are abnormal, corticosteroid therapy remains mandatory.

Seizure disorder mimicking an acute confusional state as clinical presentation of neurocysticercosis: neuroimaging, EEG findings and clinical correlations

Epilepsy is the main clinical manifestation of neurocysticercosis (NC). We studied an adult subject who presented a seizure disorder mimicking an acute confusional state as clinical expression of NC. Diagnosis was made with neuroimaging and western blot determination of specific antibodies on serum. Computed tomography and magnetic resonance imaging displayed multiple calcifications and a few transitional cysts in the cerebral parenchyma. Electroencephalography showed a pattern of periodic lateralized epileptiform discharges (PLEDs) which could be related topographically to a cystic lesion located in the left parietal lobe. In our view there was a clear pathogenic correlation between the seizure disorder and the parasitic cyst located in the left parietal lobe. Neither antiepileptic drugs nor steroids were prescribed. Follow-up to one year ruled out other clinical manifestations of the disease. This case is an example of acute symptomatic seizure related to a transitional cystic lesion of NC.

SH3GLB, a new endophilin-related protein family featuring an SH3 domain

A new cDNA encoding a protein of 362 amino acids designated SH3GLB1, for SH3 domain GRB2-like endophilin B1, was identified in a yeast two-hybrid screen devoted to the identification of new partners interacting with the apoptosis inducer Bax. SH3GLB1 shows strong similarities to the SH3 domain-containing proteins of the endophilin family and presumably represents the human homologue of the potential Caenorhabditis elegans SH3 containing-protein identified by systematic translation of the C. elegans genome (GenBank Accession No. U46675). Reversing prey to bait in the yeast screen, a second protein, SH3GLB2, of 395 amino acids showing 65% identity to SH3GLB1 was identified as an interacting partner of SH3GLB1. The discovery of SH3GLB1 itself in the screening with SH3GLB1 as a bait and further mapping experiments demonstrated that a core coiled-coil-type region is required for the formation of SH3GLB homo- and/or heterodimers, whereas the SH3 domain is not involved in these interactions. Interestingly, the similarities with the endophilin proteins cover the entire sequence of the SH3GLB family, suggesting a common fold and presumably a common mode of action. Furthermore, SH3GLB members colocalize to the cytoplasmic compartment of the cell together with Bax and are excluded from the nucleus. SH3GLB1 and SH3GLB2 do not significantly influence the onset and time course of Bax-mediated apoptosis in HeLa or 293T cells.

SAC3 may link nuclear protein export to cell cycle progression

Selective movement of proteins between the nucleus and the cytoplasm is a regulatory mechanism exploited extensively by the eukaryotic cell. We have identified the evolutionarily conserved Sac3 protein, which was implicated previously in the regulation of mitosis [Bauer, A. & Kölling, R. (1996) J. Cell Sci. 109, 1575-1583] as a novel mediator of nuclear protein export. We show that Sac3p is localized to the nuclear pore, where it interacts with nucleoporins. Loss of SAC3 function results in a block in nuclear export of a nuclear export signal-containing reporter protein. Our results also demonstrate that SAC3 interacts genetically with the nuclear protein export factors Crm1p/Xpo1p and Yrb2p. Taken together, these data indicate a link between nuclear protein export and transition through the cell cycle.

Species-specific, postentry barriers to primate immunodeficiency virus infection

By using replication-defective vectors derived from human immunodeficiency virus type 1 (HIV-1), simian immunodeficiency virus (SIV(mac)), and murine leukemia virus (MuLV), all of which were pseudotyped with the vesicular stomatitis virus (VSV) G glycoprotein, the efficiency of postentry, early infection events was examined in target cells of several mammalian species. Titers of HIV-1 vectors were significantly lower than those of SIV(mac) and MuLV vectors in most cell lines and primary cells from Old World monkeys. By contrast, most New World monkey cells exhibited much lower titers for the SIV(mac) vector compared with those of the HIV-1 vector. Prosimian cells were resistant to both HIV-1 and SIV(mac) vectors, although the MuLV vector was able to infect these cells. Cells from other mammalian species were roughly equivalent in susceptibility to the three vectors, with the exception of rabbit cells, which were specifically resistant to the HIV-1 vector. The level of HIV-1 vector expression was very low in transduced cells of rodent, rabbit, cow, and pig origin. Early postentry restriction of primate immunodeficiency virus infection exhibits patterns largely coincident with species borders and applies to diverse cell types within an individual host, suggesting the involvement of species-specific, widely expressed cellular factors.

Regulated nuclear localization of stress-responsive factors: how the nuclear trafficking of protein kinases and transcription factors contributes to cell survival

The details of nuclear transport mechanisms are emerging rapidly, largely through work with model organisms. Here, we briefly describe these advances, with an emphasis on the remaining challenges. We then address the nuclear transport of some high profile cellular regulators, including p53 and the proto-oncogene PKB/Akt. We discuss the mechanisms that contribute to the differential subcellular localization of these proteins. Finally, we analyse the provocative patterns that emerge from our overview.

Elimination of replication block protein Fob1 extends the life span of yeast mother cells

A cause of aging in yeast is the accumulation of circular species of ribosomal DNA (rDNA) arising from the 100-200 tandemly repeated copies in the genome. We show here that mutation of the FOB1 gene slows the generation of these circles and thus extends life span. Fob1p is known to create a unidirectional block to replication forks in the rDNA. We show that Fob1p is a nucleolar protein, suggesting a direct involvement in the replication fork block. We propose that this block can trigger aging by causing chromosomal breaks, the repair of which results in the generation of rDNA circles. These findings may provide a novel link between metabolic rate and aging in yeast and, perhaps, higher organisms.

Anatomic correlates of painful tonic spasms in multiple sclerosis

Painful tonic spasms (PTS) are now regarded as a typical symptom of multiple sclerosis but pathologic or radiologic findings rarely have been described. We report clinical and magnetic resonance imaging records of five original cases. In all of them, lesions likely responsible for unilateral PTS involved the motor pathway at the level of the posterior limb of the internal capsule or the cerebral peduncle on the opposite side. Closeness of motor fibers seems to be the most important underlying anatomic factor because it enables involvement of a higher proportion of axons by a single demyelinating lesion and radial spread of ephaptic activation. In turn, preservation of the underlying pyramidal-spinal tract could make it easier for the pathologic discharge to reach the peripheral effectors and generate PTS.

Temporal differences in the appearance of NEP-B78 and an LBR-like protein during Xenopus nuclear envelope reassembly reflect the ordered recruitment of functionally discrete vesicle types

In this work, we have used novel mAbs against two proteins of the endoplasmic reticulum and outer nuclear membrane, termed NEP-B78 and p65, in addition to a polyclonal antibody against the inner nuclear membrane protein LBR (lamin B receptor), to study the order and dynamics of NE reassembly in the Xenopus cell-free system. Using these reagents, we demonstrate differences in the timing of recruitment of their cognate membrane proteins to the surface of decondensing chromatin in both the cell-free system and XLK-2 cells. We show unequivocally that, in the cell-free system, two functionally and biochemically distinct vesicle types are necessary for NE assembly. We find that the process of distinct vesicle recruitment to chromatin is an ordered one and that NEP-B78 defines a vesicle population involved in the earliest events of reassembly in this system. Finally, we present evidence that NEP-B78 may be required for the targeting of these vesicles to the surface of decondensing chromatin in this system. The results have important implications for the understanding of the mechanisms of nuclear envelope disassembly and reassembly during mitosis and for the development of systems to identify novel molecules that control these processes.

Regulated nucleo/cytoplasmic exchange of HOG1 MAPK requires the importin beta homologs NMD5 and XPO1

MAP kinase signaling modules serve to transduce extracellular signals to the nucleus of eukaryotic cells, but little is known about how signals cross the nuclear envelope. Exposure of yeast cells to increases in extracellular osmolarity activates the HOG1 MAP kinase cascade, which is composed of three tiers of protein kinases, namely the SSK2, SSK22 and STE11 MAPKKKs, the PBS2 MAPKK, and the HOG1 MAPK. Using green fluorescent protein (GFP) fusions of these kinases, we found that HOG1, PBS2 and STE11 localize to the cytoplasm of unstressed cells. Following osmotic stress, HOG1, but neither PBS2 nor STE11, translocates into the nucleus. HOG1 translocation occurs very rapidly, is transient, and correlates with the phosphorylation and activation of the MAP kinase by its MAPKK. HOG1 phosphorylation is necessary and sufficient for nuclear translocation, because a catalytically inactive kinase when phosphorylated is translocated to the nucleus as efficiently as the wild-type. Nuclear import of the MAPK under stress conditions requires the activity of the small GTP binding protein Ran-GSP1, but not the NLS-binding importin alpha/beta heterodimer. Rather, HOG1 import requires the activity of a gene, NMD5, that encodes a novel importin beta homolog. Similarly, export of dephosphorylated HOG1 from the nucleus requires the activity of the NES receptor XPO1/CRM1. Our findings define the requirements for the regulated nuclear transport of a stress-activated MAP kinase.

Visual evoked potentials in hypothyroidism: a long-term evaluation

Visual Evoked Potentials (VEP) were measured in 9 new-diagnosed hypothyroid female patients--mean age 46 +/- 12 ys--before treatment, during (with monthly evaluations) thyroid hormone replacement therapy and after long-term therapy, at the achievement as well as one year after having achieved and maintained euthyroidism. Three of the hypothyroids had abnormally prolonged latencies (m.v. 131.7 +/- 7.9 ms), while 7 had lower than normal amplitude (m.v. 2.3 +/- 2.8 microV). No remarkable change of amplitude was observed after the achievement of euthyroidism, after a mean time of 5.9 +/- 4.9 months (range 2-14 months). A significant shortening of latency (m 128.3 +/- 7.6 ms), even still higher than the control value (m 122.7 +/- 3.7 ms) was found. Significant correlation between P100 latency and thyroid hormone levels was found for TT4 (r = 0.3353; p = 0.005), TT3 (r = 0.2568; p = 0.032) and FT4 (r = 0.3572; p = 0.002). No further improvement in P100 latency (m 129.5 +/- 7.2 ms; p = 0.037) was found one year after the achievement of euthyroidism, while a remarkable amplitude increase (m 9.2 +/- 3.4 micro; p = 0.001) was observed. Our findings indicate that, as well as other studied parameters, VEP are reversibly alterated in hypothyroidism, probably in relation to metabolic rather than to structural alterations. Moreover, VEP can represent a useful neurophysiologic parameter for quantitation of SNC involvement in hypothyroidism.

Sclerosteosis: report of a case in a black African man

Sclerosteosis is a rare genetic disorder of bone modelling, similar to, but distinct from, van Buchem disease; it has been described almost exclusively in Afrikaners of South Africa, a white population of Dutch ancestry. Isolated cases have been reported in a girl in Japan, a boy in Spain, and in multiracial families in Brazil and USA. Here we report a case of sclerosteosis in a black man born in Senegal. He presented with the full features of the disease: tall stature; syndactyly: nail dysplasia; massive sclerosis of the long tubular bones, the ribs, the pelvis and the skull; multiple cranial nerve involvement: optic atrophy, facial palsy and trigeminal neuralgia. Radiologic examination, visual and brainstem auditory evoked potentials, computerized tomography and magnetic resonance imaging of the skull were performed. This seems to be the first case of the disease in a black African individual, with no known relationship with Dutch ancestry.

Contribution of central neuropathy to postural instability in IDDM patients with peripheral neuropathy

OBJECTIVE

To evaluate the contribution of central neuropathy on postural impairment observed in diabetic patients with peripheral neuropathy.

RESEARCH DESIGN AND METHODS

Central sensory and motor nervous propagation, nerve conduction velocity, and static posturography were assessed in the following age-matched subjects: 7 IDDM patients with peripheral neuropathy (group DN), 18 IDDM patients without peripheral neuropathy (group D), and 31 control subjects (group C). Somatosensory-evoked potentials (SEPs) during tibial nerve stimulation were recorded, and the spine-to-scalp sensory central conduction time (SCCT) was evaluated. Motor-evoked potentials (MEPs) were recorded from leg muscles during magnetic transcranial brain stimulation, and the scalp-to-spine motor central conduction time (MCCT) was evaluated. The following posturographic parameters were calculated from the statokinesigram: trace length, trace surface, velocity of body sway with its standard deviation, and VFY (a parameter derived from the velocity variance and the anteroposterior mean position of the body).

RESULTS

SCCT was significantly higher in the DN group than in the C and D groups (P < 0.001). MCCT was similar in all groups. Posturographic parameters were all significantly impaired in the DN group (P < 0.01). While posturographic parameters showed a direct relationship with some parameters of peripheral nerve conduction, no correlations were observed with SEP and MEP central conduction time. These results were also confirmed by logistic regression, which indicates peripheral neuropathy as the only implicating factor in postural instability (odds ratio 0.22, 95% CI 0.07-0.75) after data reduction by means of factor analysis.

CONCLUSIONS

Although diabetic patients with peripheral neuropathy show a delay in central sensory conduction, postural instability may be fully explained by the presence of peripheral neuropathy.

Genetic analysis of macromolecular transport across the nuclear envelope

Numerous factors that promote movement of macromolecules in and out of the nucleus have now been identified. These include both soluble cytoplasmic and nucleoplasmic proteins and proteins of the nuclear pore complex (NPC). Genetic analyses of the nuclear transport process in the model organism, the budding yeast Saccharomyces cerevisiae, have revealed remarkable conservation of all of these factors. In addition, important clues as to how these factors promote the unique bidirectional movement across the NPC have emerged from studies of yeast. We summarize the characterization and genetic interactions of the soluble transport factors and present data to illustrate how genetic experiments can be used to further define the import and export pathways.

Sensitivity and specificity of the EEG versus CT in acute cortical and subcortical stroke

122 patients with acute stroke were examined in order to demonstrate the sensitivity and the specificity of EEG versus CT findings, in distinguishing cortical from subcortical lesions. To do this the electroencephalographic diagnosis performed by two different electroencephalographers was compared with the neuroimaging diagnosis. The results showed a sensitivity of 77% and a specificity of 75%. Furthermore, the EEG findings can also provide physiopathological data, in that the cortical lesions are likely to be due to embolism, while the subcortical lesions are more likely to be due to the pathological process of the intracerebral blood-vessels and the lesions of the watershed territories to hemodynamic phenomena.

Drosophila mutants in the 55 kDa regulatory subunit of protein phosphatase 2A show strongly reduced ability to dephosphorylate substrates of p34cdc2

The 55 kDa regulatory subunit of Drosophila protein phosphatase 2A is located in the cytoplasm at all cell cycle stages, by the criterion of immunofluorescence. We are unable to detect significant change in protein phosphatase activity during the nuclear division cycle of syncytial embryos. However, cell cycle function of the enzyme is suggested by the mitotic defects exhibited by two Drosophila mutants, aar1 and twinsP, defective in the gene encoding the 55 kDa subunit. The reduced levels of the 55 kDa subunit correlate with the loss of protein phosphatase 2A-like, okadaic acid-sensitive phosphatase activity of brain extracts against caldesmon and histone H1 phosphorylated by p34cdc2/cyclin B kinase, but not against phosphorylase a. Thus the mitotic defects of aar1 and twinsP are likely to result from the lack of dephosphorylation of specific substrates by protein phosphatase 2A.

Protein phosphatase 2A1 is the major enzyme in vertebrate cell extracts that dephosphorylates several physiological substrates for cyclin-dependent protein kinases

Okadaic acid (2 nM) inhibited by 80-90% the protein phosphatase activities in diluted extracts of rat liver, human fibroblasts, and Xenopus eggs acting on three substrates (high mobility group protein-I(Y), caldesmon and histone H1) phosphorylated by a cyclin-dependent protein kinase (CDK) suggesting that a type-2A phosphatase was responsible for dephosphorylating each protein. This result was confirmed by anion exchange chromatography of rat liver and Xenopus extracts, which demonstrated that the phosphatases acting on these substrates coeluted with the two major species of protein phosphatase 2A, termed PP2A1 and PP2A2. When matched for activity toward glycogen phosphorylase, PP2A1 was five- to sevenfold more active than PP2A2 and 35-fold to 70-fold more active than the free catalytic subunit (PP2Ac) toward the three CDK-labeled substrates. Protein phosphatases 1, 2B, and 2C accounted for a negligible proportion of the activity toward each substrate under the assay conditions examined. The results suggest that PP2A1 is the phosphatase that dephosphorylates a number of CDK substrates in vivo and indicate that the A and B subunits that are associated with PP2Ac in PP2A1 accelerate the dephosphorylation of CDK substrates, while suppressing the dephosphorylation of most other proteins. The possibility that PP2A1 activity is regulated during the cell cycle is discussed.