Growth Hormone Promotes Hair Cell Regeneration in the Zebrafish (Danio rerio) Inner Ear following Acoustic Trauma

BACKGROUND: Previous microarray analysis showed that growth hormone (GH) was significantly upregulated following acoustic trauma in the zebrafish (Danio rerio) ear suggesting that GH may play an important role in the process of auditory hair cell regeneration. Our objective was to examine the effects of exogenous and endogenous GH on zebrafish inner ear epithelia following acoustic trauma. METHODOLOGY/PRINCIPAL FINDINGS: We induced auditory hair cell damage by exposing zebrafish to acoustic overstimulation. Fish were then injected intraperitoneally with either carp GH or buffer, and placed in a recovery tank for either one or two days. Phalloidin-, bromodeoxyuridine (BrdU)-, and TUNEL-labeling were used to examine hair cell densities, cell proliferation, and apoptosis, respectively. Two days post-trauma, saccular hair cell densities in GH-treated fish were similar to that of baseline controls, whereas buffer-injected fish showed significantly reduced densities of hair cell bundles. Cell proliferation was greater and apoptosis reduced in the saccules, lagenae, and utricles of GH-treated fish one day following trauma compared to controls. Fluorescent in situ hybridization (FISH) was used to examine the localization of GH mRNA in the zebrafish ear. At one day post-trauma, GH mRNA expression appeared to be localized perinuclearly around erythrocytes in the blood vessels of the inner ear epithelia. In order to examine the effects of endogenous GH on the process of cell proliferation in the ear, a GH antagonist was injected into zebrafish immediately following acoustic trauma, resulting in significantly decreased cell proliferation one day post-trauma in all three zebrafish inner ear end organs. CONCLUSIONS/SIGNIFICANCE: Our results show that exogenous GH promotes post-trauma auditory hair cell regeneration in the zebrafish ear through stimulating proliferation and suppressing apoptosis, and that endogenous GH signals are present in the zebrafish ear during the process of auditory hair cell regeneration

Universal antenatal group B streptococcus screening? The opinions of obstetricians and neonatologists within Australia

Group B streptococcus (GBS) is the leading infectious cause of morbidity and mortality in Australian newborns. Although intrapartum chemoprophylaxis is recommended to reduce the risk of neonatal GBS transmission and disease, controversy exists as to the best method to select women 'at risk' for this treatment. Our study aimed to survey the opinions of obstetricians and neonatologists currently in practice in Australia on GBS screening and treatment. Of the 488 obstetricians and 68 neonatologists currently in practice who responded to the survey, 271 obstetricians (56%) and 40 neonatologists (61%) supported universal antenatal screening. Of those respondents who did not support a universal antenatal screening policy, 196 (93%) and 24 (92%) of the obstetricians and neonatologists respectively, supported antenatal screening based on risk factors. This diversity in practitioner opinion highlights the lack of certainty in the literature as to the best management strategy to prevent neonatal GBS sepsis

Early neonatal streptococcal infection

10.1007/BF02759920Indian Journal of Pediatrics737573-57