Construction of a map of chromosome 16 by using radiation hybrids.

A human-hamster cell hybrid carrying a single copy of chromosome 16 as the only human genetic material was irradiated with a single dose of gamma-rays (7000 rads; 1 rad = 0.01 Gy) and then fused with a thymidine kinase-deficient hamster cell line (RJKM) to generate radiation hybrids retaining unselected fragments of this human chromosome. In two experiments, 223 hybrids were isolated in hypoxanthine/aminopterine/thymidine (HAT) medium and screened with 38 DNA probes, corresponding to anonymous DNA or gene sequences localized on chromosome 16. The most likely order and location of the 38 DNA sequences were established by multiple pairwise analysis and scaled to estimate physical distance in megabases. The order and the distances thus obtained are mostly consistent with available data on genetic and physical mapping of these markers, illustrating the usefulness of radiation hybrids for mapping.     

Enhanced corticobulbar excitability in chronic smokers during visual exposure to cigarette smoking cues

Background

Neuroimaging studies of chronic smokers report altered activity of several neural regions involved in the processing of rewarding outcomes. Neuroanatomical evidence suggests that these regions are directly connected to the tongue muscle through the corticobulbar pathways. Accordingly, we examined whether corticobulbar excitability might be considered a somatic marker for nicotine craving.

Methods

We compared motor-evoked potential (MEP) amplitudes recorded from the tongue and the extensor carpi radialis (control muscle) of chronic smokers under drug withdrawal and intake conditions as well as a nonsmoker group. All participants were tested during passive exposure to pictures showing a smoking cue or a meaningless stimulus. In the intake condition, chronic smokers were asked to smoke a real cigarette (CSn: group 1) or a placebo (CSp: group 2).

Results

Results show that MEP amplitudes recorded from the tongues of participants in the CSn and CSp groups under the withdrawal condition were selectively enhanced during exposure to a smoking cue. However, this effect on tongue MEP amplitudes disappeared in the intake condition for both the CSn and CSp groups.

Limitations

Limitations include the fact that the study was conducted in 2 different laboratories, the small sample size, the absence of data on chronic smoker craving strength and the different tastes of the real and placebo cigarettes.

Conclusion

These results suggest that, in chronic smokers, tongue muscle MEP amplitudes are sensitive to neural processes active under the physiological status of nicotine craving. This finding implicates a possible functional link between neural excitability of the corticobulbar pathway and the reward system in chronic smokers.     

Expanding the indications for the bone anchored hearing system (BAHS) in patients with single sided deafness

PurposeProvide data to support expansion of FDA indications for the Bone anchored hearing system (BAHS).Materials and methodsThis retrospective study in a tertiary otologic referral center included106 consecutive subjects who were implanted with a Bone Anchored Hearing System (BAHS) between January 2009 and January 2015 for single sided deafness. Subjects were divided into three groups by bone conduction pure tone average (PTA) of the better hearing ear: 0–20 dB (group 1), 21–40 dB (group 2) and 41–55 dB (group 3). All patients underwent BAHS implantation. Speech perception data (Hearing In Noise Test and Consonant-Nucleus-Consonant testing) was collected before and after surgical intervention. Patient-reported quality of life measures were obtained at least 6 months after activation. These included the Abbreviated Profile of Hearing Aid Benefit and Glasgow Benefit Inventory.ResultsAll three groups of subjects demonstrated statistically significant improvement in outcome measures following BAHS. Subject reported quality of life outcome measures demonstrated significant improvement in disability from hearing loss and in quality of life.ConclusionsPatients with single sided deafness who have bone conduction thresholds worse than 20 dB in their contralateral ear are still able to benefit significantly from BAHS.