Inner ear insult suppresses the respiratory response to carbon dioxide

Compensated respiratory acidosis has been observed in a significant number of patients with active vestibular disease. We therefore hypothesized that the inner ear may play an unrecognized integral role in respiratory control. To test this premise, we investigated whether mice with induced inner ear injury demonstrated any alteration in their respiratory response to inhaled carbon dioxide (CO(2)). Experimental mice and control mice were included in two separate experiments. Intra-tympanic gentamycin injections were administered to induce inner ear damage in experimental animals. Hearing loss and vestibular dysfunction were tested 1-week after injections to confirm presence of inner ear insult, following which the animal's respiratory response to inhalation of 8% CO(2) was examined. Mice with inner ear injury (n=60) displayed a significantly diminished hypercapnic ventilatory response (HCVR). This contrasted with the normal HCVR seen in control mice that had not undergone tympanic injections (n=30), controls that received tympanic injections with saline (n=5), and controls that had gentamicin administered systemically (n=5). In response to inspired CO(2), the mean respiratory frequency of control mice increased by an average of 50% over their baseline values for both parts of the experiment. In contrast, the ear-damaged experimental group mean values increased by only three breaths per minute (bpm) (2%) in the first experiment and by 28 bpm (11%) in the second experiment. Inner ear damage significantly reduces the respiratory response to CO(2) inhalation. In addition to the established role of the inner ear organ in hearing and balance, this alludes to an unidentified function of the inner ear and its interconnecting neuronal pathways in respiratory regulation. This finding may offer valuable new clues for disease states with abnormal respiratory control where inner ear dysfunction may be present.

Readiness for organisational change among general practice staff

BACKGROUND

Increasing demands on general practice to manage chronic disease may warrant organisational change at the practice level. Staff's readiness for organisational change can act as a facilitator or barrier to implementing interventions aimed at organisational change.

OBJECTIVES

To explore general practice staff readiness for organisational change and its association with staff and practices characteristics.

METHODS

This is a cross-sectional study of practices in three Australian states involved in a randomised control trial on the effectiveness of an intervention to enhance the role of non-general practitioner staff in chronic disease management. Readiness for organisational change, job satisfaction and practice characteristics were assessed using questionnaires.

RESULTS

502 staff from 58 practices completed questionnaires. Practice characteristics were not associated with staff readiness for change. A multilevel regression analysis showed statistically significant associations between staff readiness for organisational change (range 1 to 5) and having a non-clinical staff role (vs general practitioner; B=-0.315; 95% CI -0.47 to -0.16; p<0.001), full-time employment (vs part-time; B=0.175, 95% CI 0.06 to 0.29; p<0.01) and lower job satisfaction (B=-0.277, 95% CI -0.40 to -0.15; p<0.001).

CONCLUSIONS

The results suggest that different approaches are needed to facilitate change which addresses the mix of practice staff. Moderately low job satisfaction may be an opportunity for organisational change.

A standard panel of microsatellites for Asian seabass (Lates calcarifer)

Microsatellites are the most popular markers for parentage assignment and population genetic studies. To meet the demand for international comparability for genetic studies of Asian seabass, a standard panel of 28 microsatellites has been selected and characterized using the DNA of 24 individuals from Thailand, Malaysia, Indonesia and Australia. The average allele number of these markers was 10.82 +/- 0.71 (range: 6-19), and the expected heterozygosity averaged 0.76 +/- 0.02 (range: 0.63-1.00). All microsatellites showed Mendelian inheritance. In addition, eight standard size controls have been developed by cloning a set of microsatellite alleles into a pGEM-T vector to calibrate allele sizes determined by different laboratories, and are available upon request. Seven multiplex PCRs, each amplifying 3-5 markers, were optimized to accurately and rapidly genotype microsatellites. Parentage assignment using 10 microsatellites in two crosses (10 x 10 and 20 x 20) demonstrated a high power of these markers for revealing parent-sibling connections. This standard set of microsatellites will standardize genetic diversity studies of Asian seabass, and the multiplex PCR sets will facilitate parentage assignment.

Body site colonization in patients with community-associated methicillin-resistant Staphylococcus aureus and other types of S. aureus skin infections

Efforts to control spread of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) are often based on eradication of colonization. However, the role of nasal and non-nasal colonization in the pathogenesis of these infections remains poorly understood. Patients with acute S. aureus skin and soft tissue infection (SSTI) were prospectively enrolled. Each subject's nasal, axillary, inguinal and rectal areas were swabbed for S. aureus and epidemiological risk factors were surveyed. Among the 117 patients enrolled, there were 99 patients who had an SSTI and for whom data could be analysed. Sixty-five patients had a CA-MRSA SSTI. Among these patients, MRSA colonization in the nares, axilla, inguinal area and rectum was 25, 6, 11 and 13%, respectively, and 37% overall were MRSA colonized. Most (96%) MRSA colonization was detected using nose and inguinal screening alone. Non-nasal colonization was 25% among CA-MRSA patients, but only 6% among patients with CA-methicillin-susceptible S. aureus (MSSA) or healthcare-associated MRSA or MSSA. These findings suggest that colonization patterns in CA-MRSA infection are distinct from those in non-CA-MRSA S. aureus infections. The relatively high prevalence of non-nasal colonization may play a key role in CA-MRSA transmission and acquisition of infection.

Ocular manifestations of mosaic trisomy 22: A case report and review of the literature

Mosaic trisomy 22 is rare, but can be compatible with prolonged life. Patients with mosaic trisomy 22 usually present with intrauterine growth retardation, mental retardation, failure to thrive, and craniofacial asymmetry. We report the case of a five-year-old boy who had a birth weight of 3.8 kg and normal developmental milestones. He presented with unilateral ocular manifestations of ptosis, double elevator palsy, high myopia, and choroidal coloboma involving the macula. Cytogenetic evaluation showed a low level of trisomy 22 in peripheral blood lymphocytes (1 in 100) and in cultured fibroblasts from a conjunctival biopsy of the affected eye (1 in 60). Our case demonstrates the value of chromosomal analysis of the tissues involved rather than just karyotyping of the blood lymphocytes to detect mosaicism in patients with localised and unilateral congenital malformations.