Protein grafting of p53TAD onto a leucine zipper scaffold generates a potent HDM dual inhibitor.

Reactivation of the p53 pathway by a potential therapeutic antagonist, which inhibits HDM2 and HDMX, is an attractive strategy for drug development in oncology. Developing blockers towards conserved hydrophobic pockets of both HDMs has mainly focused on small synthetic compounds; however, this approach has proved challenging. Here we describe an approach to generate a potent HDM dual inhibitor, p53LZ2, by rational protein grafting of the p53 transactivation domain onto a homodimeric leucine zipper. p53LZ2 shows tight binding affinity to both HDMs compared with wild-type p53 in vitro. X-ray crystallographic, comparative modelling and small-angle X-ray scattering studies of p53LZ2-HDM complexes show butterfly-shaped structures. A cell-permeable TAT-p53LZ2 effectively inhibits the cancer cell growth in wild-type but not mutant p53 by arresting cell cycle and inducing apoptosis in vitro. Thus, p53LZ2, designed by rational grafting, shows a potential therapeutic approach against cancer.

Bilateral vestibulopathy: clinical characteristics and diagnostic criteria.

OBJECTIVES: To define clinical and laboratory characteristics of bilateral vestibulopathy (BV) and to propose diagnostic criteria of this disorder based on clinical and laboratory findings. STUDY DESIGN: Retrospective case series review. MATERIALS AND METHODS: We recruited 108 patients with a clinical suspicion of BV based on presenting symptoms (unsteadiness or oscillopsia during locomotion) and bedside (dynamic visual acuity or head impulse tests) and laboratory (bithermal caloric or rotatory chair tests) findings after excluding the patients with other disorders that may explain the symptoms. Definite diagnosis of BV was made when the patients showed abnormal findings on both bedside and laboratory tests in addition to the symptoms, whereas probable diagnosis was obtained when either the bedside or laboratory findings were abnormal along with the symptoms. RESULTS: All patients had unsteadiness, and 36 (33%) reported oscillopsia. Diminished vestibulo-ocular responses to head impulse in both horizontal directions were present in 45 of the 100 patients evaluated. Dynamic visual acuity was impaired in 65 (95%) of the 68 patients who underwent testing. Fifty-one (57%) patients showed bilateral hyporesponsiveness during bithermal caloric tests. Forty-eight (53%) patients had reduced gain of the vestibulo-ocular reflex during rotatory chair test. By adopting our diagnostic criteria, 93 patients (86%) were diagnosed as having BV, definite in 49 (45%), and probable in 44 (41%). CONCLUSION: The proposed diagnostic criteria encompass the symptoms and findings of both bedside and laboratory evaluations and may provide a valuable tool for investigating BV.

Bimedial rectus hypermetabolism in convergence spasm as observed on positron emission tomography.

A 52-year-old man developed vertical gaze palsy, convergence spasm, and convergence-retraction nystagmus due to glioblastoma of the right thalamus. 18F-fluorodeoxyglucose positron emission tomography (PET) inadvertently demonstrated markedly increased metabolism in the medial rectus muscles. The hypermetabolism indicates active contraction of these extraocular muscles due to excessive convergence drive attributed to inappropriate activation or disrupted inhibition of convergence neurons by the diencephalic lesion.

Sequential bilateral hearing loss in multiple sclerosis.

OBJECTIVES: We describe a case of multiple sclerosis presenting with sequential bilateral hearing loss. METHODS: A 46-year-old woman underwent a series of audiological and neurologic evaluations for sequential bilateral hearing losses that occurred 6 months apart. RESULTS: Initially, the patient suffered from sudden left hearing loss, and magnetic resonance imaging documented an enhancing lesion in the left middle cerebellar peduncle. Six months later, another episode of sudden vertigo, right hearing loss, and right facial palsy developed. Magnetic resonance imaging disclosed a new lesion in the right middle cerebellar peduncle. CONCLUSIONS: Sequential bilateral hearing loss may be a manifestation of multiple sclerosis. In younger patients with sudden hearing loss, multiple sclerosis should be included in the differential diagnosis.

The mutation of a novel Saccharomyces cerevisiae SRL4 gene rescues the lethality of rad53 and lcd1 mutations by modulating dNTP levels.

The SRL4 (YPL033C) gene was initially identified by the screening of Saccharomyces cerevisiae genes that play a role in DNA metabolism and/or genome stability using the SOS system of Escherichia coli. In this study, we found that the srl4Delta mutant cells were resistant to the chemicals that inhibit nucleotide metabolism and evidenced higher dNTP levels than were observed in the wild-type cells in the presence of hydroxyurea. The mutant cells also showed a significantly faster growth rate and higher dNTP levels at low temperature (16 degrees C) than were observed in the wild-type cells, whereas we detected no differences in the growth rate at 30 degrees C. Furthermore, srl4Delta was shown to suppress the lethality of mutations of the essential S phase checkpoint genes, RAD53 and LCD1. These results indicate that SRL4 may be involved in the regulation of dNTP production by its function as a negative regulator of ribonucleotide reductase.

Double saccadic pulses and macrosaccadic oscillations from a focal brainstem lesion.

Double saccadic pulses (DSP) are saccadic intrusions that consist of an initial saccade away from a fixation followed immediately by a return saccade back to the fixation. DSP have been reported in patients with presumed multiple sclerosis and metabolic encephalopathy. However, DSP have not been described in a circumscribed brain lesion. We report a man who developed almost continuous DSP with intervening macrosaccadic oscillations from a circumscribed lesion in the dorsal pontine tegmentum which extended up to the midbrain level and spared the nucleus raphe interpositus where the pause cells reside. Damage to the projections from the superior colliculus to omnipause neurons and resultant dysfunction of omnipause neuron may be a mechanism of saccadic intrusions and oscillations observed in our patient with a circumscribed brainstem lesion.

Translation initiation factor eIF1A possesses RNA annealing activity in its oligonucleotide-binding fold.

Translation initiation factor eIF1A is highly conserved among all eukaryotes, and performs essential functions in the formation of 43S preinitiation complex and mRNA scanning. In this study, we found that RNA annealing activity is intrinsically associated with eIF1A. Schizosaccharomyces pombe, Saccharomyces cerevisiae, and human eIF1As were isolated in their recombinant forms in order to determine their RNA annealing activities. A truncated eIF1A devoid of both N- and C-terminal domains proved most active, indicating that the activity is localized in the OB-fold domain. Some N- or C-terminal His tag fusions were shown to make the proteins inactive. This is probably caused by shielding of the RNA binding surface, as the proteins were activated via partial proteolytic digestion. We also found that eIF1A formed a stable complex with a short double-stranded RNA in gel mobility shift assays. Our results indicate that eIF1A may function as an RNA chaperone, inducing conformational changes in rRNA in the 43S preinitiation complex.

Nystagmus during neck flexion in the pitch plane in benign paroxysmal positional vertigo involving the horizontal canal.

BACKGROUND: In benign paroxysmal positional vertigo involving the horizontal canal (HC-BPPV), nystagmus may be induced by neck flexion in the pitch plane while sitting (head-bending nystagmus). OBJECTIVE: To determine the characteristics and lateralizing value of head-bending nystagmus in HC-BPPV. METHODS: Using video-oculography, head-bending nystagmus was recorded in 54 patients with HC-BPPV (32 canalolithiasis and 22 cupulolithiasis). Lesion side was determined by comparing intensity of the nystagmus induced by lateral head turning (head-turning nystagmus) in supine. RESULTS: Head-bending nystagmus was observed in 39 patients (72.2%) and lying-down nystagmus in 41 (75.9%). Thirty three patients (61.1%) showed both types of nystagmus while six (11.1%) had only head-bending and another eight (14.8%) showed only lying-down nystagmus. In 45 patients with asymmetrical head-turning nystagmus, the direction of head-bending nystagmus was mostly toward the affected ear in canalolithasis (88.9%) and toward the intact ear in cupulolithasis (80.0%). In 9 (16.7%) patients whose affected ear could not be determined due to symmetrical head-turning nystagmus, the particle repositioning maneuver based on the direction of head-bending or lying-down nystagmus resulted in the resolution of symptom. Two patients showed a transition from canalo- to cupulolithiasis during head-bending posture. CONCLUSION: In HC-BPPV, neck flexion in the pitch plane while sitting may generate nystagmus by inducing ampullopetal migration of the otolithic debris in the horizontal canal or by ampullofugal deflection of the cupula by the attached otolithic debris. Head-bending nystagmus may be a valuable sign for lateralizing the involved canal in HC-BPPV, especially when patients show symmetrical head-turning nystagmus. Conversion of canalo- into cupulolithiasis by the neck flexion supports the current explanation of the mechanisms of HC-BPPV.