Bacteria can compensate the fitness costs of amplified resistance genes via a bypass mechanism.

Antibiotic heteroresistance is a phenotype in which a susceptible bacterial population includes a small subpopulation of cells that are more resistant than the main population. Such resistance can arise by tandem amplification of DNA regions containing resistance genes that in single copy are not sufficient to confer resistance. However, tandem amplifications often carry fitness costs, manifested as reduced growth rates. Here, we investigated if and how these fitness costs can be genetically ameliorated. We evolved four clinical isolates of three bacterial species that show heteroresistance to tobramycin, gentamicin and tetracyclines at increasing antibiotic concentrations above the minimal inhibitory concentration (MIC) of the main susceptible population. This led to a rapid enrichment of resistant cells with up to an 80-fold increase in the resistance gene copy number, an increased MIC, and severely reduced growth rates. When further evolved in the presence of antibiotic, these strains acquired compensatory resistance mutations and showed a reduction in copy number while maintaining high-level resistance. A deterministic model indicated that the loss of amplified units was driven mainly by their fitness costs and that the compensatory mutations did not affect the loss rate of the gene amplifications. Our findings suggest that heteroresistance mediated by copy number changes can facilitate and precede the evolution towards stable resistance.

Assessment of quality of life in thyroid cancer patients using the EORTC thyroid-specific questionnaire: a prospective cross-sectional study.

BACKGROUND: Many studies on the quality of life (QoL) among the thyroid cancer survivors have shown conflicting results. This may be since many of these studies have not used thyroid cancer-specific questionnaires. PATIENTS AND METHODS: In our study we have translated the EORTC THY-34, validated and served it in a cross-sectional study to the assess the QoL among thyroid cancer patients free of disease during their routine follow-up. Patients were categorized based on the duration from treatment completion, ATA risk stratification, treatment received, number of RAI sessions and thyroid function status during analysis. RESULTS: Overall, 220 thyroid cancer survivors were included in this study. In general, in the EORTC QLQ-C30, the global QoL of thyroid cancer patients were good with a mean score of 72.99. The highest score was that for social functioning (89.55). In the EORTC-THY34 all the patients in the cohort had relatively lower scores (on symptom scales). Overall, there was no difference in the QLQ-C30 and THY-34 QoL with respect to any of the categorization mentioned above. However, our thyroid cancer patients QoL scores were better and/or comparable to those in published literature and they were also better or comparable to the QoL of the general population those were available in literature. CONCLUSIONS: There was no difference in the QoL scores based on various categories. To better understand the quality of life of these patients a prospective longitudinal study with baseline values and values at regular intervals might give us a better insight.

Etiology of short stature in Indian children and an assessment of the growth hormone-insulin-like growth factor axis in children with idiopathic short stature.

Background Our objectives were to evaluate the etiology of short stature, assess the prevalence of idiopathic short stature (ISS) and assess the growth hormone (GH)-insulin-like growth factor (IGF) axis in children with ISS. Methods A stepwise diagnostic evaluation was done in 394 children aged 4-16 years with short stature. Children with no definitive etiology were labeled as ISS. In these children, baseline IGF-1, IGF binding protein-3 (IGFBP-3) and stimulated IGF-1 after administration of GH for 4 days were measured. Results Hypothyroidism (in 18.1%) and ISS (in 15.5%) were the commonest causes of short stature. In children with ISS (n=61), the mean baseline and stimulated IGF-1 standard deviation scores (SDSs) were -1.2±1.0 and -0.3±1.4, respectively, with levels below -2 SDS in 13 (21%) and six (10%) children, respectively. In 33 (54%) of the ISS patients, response to GH was suboptimal (increment in the IGF-1 level <40%). There was no difference in the mean peak GH, IGFBP-3 and baseline and stimulated IGF-1 levels between children with familial and non-familial ISS. A significant positive correlation of height SDS with baseline IGF-1 SDS (r=0.28, p=0.026), stimulated IGF-1 SDS (r=0.32, p=0.010) and ΔIGF-1 SDS (r=0.26, p=0.036) was observed in children with ISS. Conclusions Hypothyroidism and ISS were the commonest etiologies for short stature. The baseline IGF-1 was below -2 SDS in 21% and the increment after GH stimulation was suboptimal in 54% of children, indicating that a substantial proportion of children with ISS had an impaired GH-IGF axis.