GABA-B Agonist Baclofen Normalizes Auditory-Evoked Neural Oscillations and Behavioral Deficits in the Fmr1 Knockout Mouse Model of Fragile X Syndrome

Fragile X syndrome is a genetic condition resulting from FMR1 gene mutation that leads to intellectual disability, autism-like symptoms, and sensory hypersensitivity. Arbaclofen, a GABA-B agonist, has shown efficacy in some individuals with FXS but has become unavailable after unsuccessful clinical trials, prompting interest in publicly available, racemic baclofen. The present study investigated whether racemic baclofen can remediate abnormalities of neural circuit function, sensory processing, and behavior in Fmr1 knockout mice, a rodent model of fragile X syndrome. Fmr1 knockout mice showed increased baseline and auditory-evoked high-frequency gamma (30-80 Hz) power relative to C57BL/6 controls, as measured by electroencephalography. These deficits were accompanied by decreased T maze spontaneous alternation, decreased social interactions, and increased open field center time, suggestive of diminished working memory, sociability, and anxiety-like behavior, respectively. Abnormal auditory-evoked gamma oscillations, working memory, and anxiety-related behavior were normalized by treatment with baclofen, but impaired sociability was not. Improvements in working memory were evident predominantly in mice whose auditory-evoked gamma oscillations were dampened by baclofen. These findings suggest that racemic baclofen may be useful for targeting sensory and cognitive disturbances in fragile X syndrome.

[Granular cell tumors of the orbit: diagnostics and therapeutic aspects exemplified by a case report]

BACKGROUND

Granular cell tumors (Abrikossoff's tumor) are very rare, mostly benign tumors of neurogenic origin which preferentially occur in the upper aerodigestive tract. Granular cell tumors rarely originate in the orbit and are therefore a diagnostic and therapeutic challenge.

METHOD AND PATIENTS

A 42-year-old male patient presented to the Orthoptic Department of the University Eye Clinic in Salzburg with motility disturbances and diplopia in the right eye. The clinical examination revealed right-sided exophthalmos and shrinking of the choroid and retina due to a retrobulbar mass. The radiological examination showed an infiltrative tumor 1.7 × 1.3 cm in size in the lower temporal quarter of the orbit. Due to the localization a sonographically controlled fine needle puncture was carried out for preoperative diagnostics by a specialist in clinical cytology. The cytological examination confirmed the presence of a granular cell tumor. The tumor was excised via a conjunctival access route.

RESULTS

Motility testing in the postoperative course control showed an improvement in the findings and the exophthalmos was clearly regressive. Vision improved from 0.5 preoperatively to 1.0 postoperatively. During the postoperative observational period of 12 months no recurrences occurred. Clinical control examinations are planned every 3 months and imaging controls every 6 months.

CONCLUSION

Granular cell tumors of the orbit should be included in the differential diagnostics of orbital tumors despite the low incidence. A sonographically controlled fine needle puncture is an adequate procedure with respect to the diagnostics and further therapy for poorly differentiated tumors of the orbit with a suspicion of infiltrative growth and for which in toto resection is questionably possible. A complete surgical excision should be the aim of treatment of granular cell tumors. Continuous clinical and imaging control is necessary to enable early recognition of recurrences.

Antigenic competition in the immune response against protein mixtures: strain-specific non-immunogenicity of Escherichia coli antigens

Antigenic competition is argued to impair the immune response on the level of accessory cell-dependent antigen presentation to responsive T-cells (regulated by MHC encoded Ir gene products). A possible influence of these mechanisms on in vivo immunization with antigen mixtures was investigated by using cytoplasmic extracts of four different strains of Escherichia coli as antigen sources for immunizing rabbits. The immune response against these antigen mixtures was tested by crossed immune electrophoresis (CIE) and immunoblotting (IB) in a homologous system (a given antigen extract of one strain against the corresponding antisera) and in the heterologous system (antigen extract of one strain against the antisera of different other strains). Several proteins were non-immunogenic in the extract of one strain but elicited good antibody responses in other strains. One of the strain-specific non-immunogenic proteins was purified and revealed a normal immune response upon immunization. The data suggest that different antigenic competition effects are induced by different protein compositions of antigen mixtures. This strain-specific competition seems to determine the immunogenicity of certain molecules (and not only the immunogenic properties of the molecules themselves). Furthermore this method offers a practical approach to increase the antibody production against weak immunogens in antigen mixtures.