Sex, salinity and sampling period dependent patterns of growth hormone mRNA expression in Mozambique tilapia

Tilapias comprise the second most aquacultured finfish group in the world. Such popularity stems in part from their tolerance to a wide range of environmental conditions and their sexually dimorphic nature, where males grow larger than females. As in other vertebrates, growth in tilapia is regulated by the growth hormone/ insulin like growth factor (GH/IGF) system. Moreover, environmental salinity has previously been shown to directly modulate growth in tilapia. Less is known, however, regarding how salinity may modulate sexually dimorphic growth. Utilizing a species of tilapia of high salinity tolerance, the Mozambique tilapia, Oreochromis mossambicus, we compared gh expression from the pituitary of male and female adults reared in fresh water (FW), seawater (SW), and a tidal regime (TR) characterized by dynamically changing salinities between FW and SW every six hours, over a 24 h period. We found significant effects of sex, salinity regime and whether fish were sampled during daylight or dark hours. In both sexes, gh expression was greater in fish reared in SW and TR compared with those in FW, and greater in fish sampled during dark hours, compared with those sampled in daylight hours. Pituitary gh expression was greater in males than in females reared in SW and TR, but not in FW. These results provide insight on the sex-specific modulation of gh expression by environmental factors in Mozambique tilapia.

Systemic versus tissue-level prolactin signaling in a teleost during a tidal cycle

Euryhaline Mozambique tilapia (Oreochromis mossambicus) are native to estuaries where they encounter tidal fluctuations in environmental salinity. These fluctuations can be dramatic, subjecting individuals to salinities characteristic of fresh water (FW < 0.5‰) and seawater (SW 35‰) within a single tidal cycle. In the current study, we reared tilapia under a tidal regimen that simulated the dynamic conditions of their native habitat. Tilapia were sampled every 3 h over a 24 h period to temporally resolve how prolactin (PRL) signaling is modulated in parallel with genes encoding branchial effectors of osmoregulation. The following parameters were measured: plasma osmolality, plasma PRL₁₇₇ and PRL₁₈₈ concentrations, pituitary prl₁₇₇ and prl₁₈₈ gene expression, and branchial prl receptor (prlr1 and prlr2), Na⁺/Cl^--cotransporter (ncc2), Na⁺/K⁺/2Cl^--cotransporter (nkcc1a), Na⁺/K⁺-ATPase (nkaα1a and nkaα1b), cystic fibrosis transmembrane regulator (cftr), and aquaporin 3 (aqp3) gene expression. Throughout the 24 h sampling period, plasma osmolality reflected whether tilapia were sampled during the FW or SW phases of the tidal cycle, whereas pituitary prl gene expression and plasma PRL levels remained stable. Branchial patterns of ncc2, nkcc1a, nkaα1a, nkaα1b, cftr, and aqp3 gene expression indicated that fish exposed to tidally changing salinities regulate the expression of these gene transcripts in a similar fashion as fish held under static SW conditions. By contrast, branchial prlr1 and prlr2 levels were highly labile throughout the tidal cycle. We conclude that local (branchial) regulation of endocrine signaling underlies the capacity of euryhaline fishes, such as Mozambique tilapia, to thrive under dynamic salinity conditions.

Predictors of Robotic Versus Laparoscopic Inguinal Hernia Repair

BACKGROUND

The advent of robotic-assisted surgery has added an additional decision point in the treatment of inguinal hernias. The goal of this study was to identify the patient, surgeon, and hospital demographic predictors of robotic inguinal hernia repair (IHR).

METHODS

We conducted a retrospective analysis of 102,241 IHRs (1096 robotic and 101,145 laparoscopic) from 2010 through 2015 with data collected in the Premier Hospital Database. The adjusted odds ratio (OR) of receiving a robotic IHR was calculated for each of several demographic factors using multivariable logistic regression.

RESULTS

The rate of robotic IHR increased from 2010 through 2015. Age <65 y and Charlson comorbidity index were not predictors of a robotic IHR. Females were more likely to receive a robotic IHR (OR 1.69, confidence interval [CI] 1.40-2.05, P < 0.0001). Compared with white patients, black patients were more likely (OR 1.33, CI 1.06-1.68, P = 0.0138), and other race patients were less likely (OR 0.47, CI 0.38-0.58, P < 0.0001) to receive a robotic IHR. Compared with Medicare insurance, patients with all other types of insurance were more likely to receive a robotic IHR (OR > 1.00, lower limit of CI > 1.00, P < 0.05). Higher volume surgeons were less likely to perform robotic IHR (OR < 1.00, upper limit of CI < 1.00, P < 0.05). Nonteaching (OR 1.81, CI 1.53-2.13, P < 0.0001), larger (OR > 1.00, lower limit of CI > 1.00, P < 0.05), and rural (OR 1.27, CI 1.03-1.57, P = 0.025) hospitals were more likely to perform robotic IHR. Significant regional variation in the rate of robotic IHR was identified (OR > 1.00, lower limit of CI > 1.00, P < 0.05).

CONCLUSIONS

The rate of robotic IHR is increasing exponentially. This study found that female gender, black race, insurance other than Medicare, lower surgeon annual volume, larger hospital size, nonteaching hospital status, rural hospital location, and hospital region were predictors of robotic IHR.

Predictors of laparoscopic versus open inguinal hernia repair

BACKGROUND

Inguinal hernia repair (IHR) is among the most common general surgery procedures. Multiple studies have examined costs and benefits of laparoscopic approach versus open repair. This study aimed to identify patient, surgeon, and hospital demographic predictors of laparoscopic versus open IHR.

METHODS

We conducted a retrospective analysis of 342,814 IHRs (241,669 open; 101,145 laparoscopic) performed in adults (age ≥ 18) from 2010 to 2015 using the Premier Hospital Database. Multivariate logistic regression was used to estimate the adjusted odds ratio of an IHR being laparoscopic versus open with respect to several demographic variables.

RESULTS

The odds of an IHR being laparoscopic increased from 2010 to 2015. A laparoscopic procedure was more likely in patients who were < age 65 (OR 1.29, CI 1.24-1.31, p < 0.0001), male (OR 1.31, CI 1.27-1.34, p < 0.0001), privately insured (OR 1.36, CI 1.33-1.40, p < 0.0001), and neither white, black, nor Hispanic (OR 1.11, CI 1.09-1.14, p < 0.0001). The likelihood of a procedure being laparoscopic decreased 13% with each one-unit increase in Charlson comorbidity index value (OR 0.88, CI 0.87-0.89, p < 0.0001). Surgeons were more likely to perform a laparoscopic procedure if they had larger annual IHR caseloads (≥ 45/year; OR 1.57, CI 1.53-1.60, p < 0.0001), and operated at large hospitals (> 500 beds; OR 1.36, CI 1.33-1.39, p < 0.0001) in New England (OR 2.38, CI 2.29-2.47, p < 0.0001). Non-predictors of a laparoscopic procedure included urban/rural hospital location (OR 1.02, CI 0.10-1.05, p = 0.06) and hospital teaching status (OR 1.01, CI 0.99-1.03, p = 0.2084).

CONCLUSIONS

Use of laparoscopic IHR is increasing. Patient age, gender, race, and insurance type, as well as surgeon annual volume, hospital size, and hospital region were predictors of a laparoscopic procedure. Further studies are needed to explain and remedy underlying differences impacting these predictors.

The effects of transfer from steady-state to tidally-changing salinities on plasma and branchial osmoregulatory variables in adult Mozambique tilapia

The Mozambique tilapia, Oreochromis mossambicus, is a teleost fish native to estuarine waters that vary in salinity between fresh water (FW) and seawater (SW). The neuroendocrine system plays a key role in salinity acclimation by directing ion uptake and extrusion in osmoregulatory tissues such as gill. While most studies with O. mossambicus have focused on acclimation to steady-state salinities, less is known about the ability of adult fish to acclimate to dynamically-changing salinities. Plasma osmolality, prolactin (PRL) levels, and branchial gene expression of PRL receptors (PRLR1 and PRLR2), Na⁺/Cl^- and Na⁺/K⁺/2Cl^- co-transporters (NCC and NKCC), Na⁺/K⁺-ATPase (NKAα1a and NKAα1b), cystic fibrosis transmembrane conductance regulator (CFTR), and aquaporin 3 (AQP3) were measured in fish reared in FW and SW steady-state salinities, in a tidal regimen (TR) where salinities changed between FW and SW every six hours, and in fish transferred from FW or SW to TR. Regardless of rearing regimen, plasma osmolality was higher in fish in SW than in FW fish, while plasma PRL was lower in fish in SW. Furthermore, branchial gene expression of effectors of ion transport in TR fish showed greater similarity to those in steady-state SW fish than in FW fish. By seven days of transfer from steady-state FW or SW to TR, plasma osmolality, plasma PRL and branchial expression of effectors of ion transport were similar to those of fish reared in TR since larval stages. These findings demonstrate the ability of adult tilapia reared in steady-state salinities to successfully acclimate to dynamically-changing salinities. Moreover, the present findings suggest that early exposure to salinity changes does not significantly improve survivability in future challenge with dynamically-changing salinities.

clc-2c is regulated by salinity, prolactin and extracellular osmolality in tilapia gill

Teleosts inhabiting fresh water (FW) depend upon ion-absorptive ionocytes to counteract diffusive ion losses to the external environment. A Clc Cl^- channel family member, Clc-2c, was identified as a conduit for basolateral Cl^- transport by Na⁺/Cl^- cotransporter 2 (Ncc2)-expressing ionocytes in stenohaline zebrafish (Danio rerio). It is unresolved whether Clc-2c/clc-2c is expressed in euryhaline species and how extrinsic and/or intrinsic factors modulate branchial clc-2c mRNA. Here, we investigated whether environmental salinity, prolactin (Prl) and osmotic conditions modulate clc-2c expression in euryhaline Mozambique tilapia (Oreochromis mossambicus). Branchial clc-2c and ncc2 mRNAs were enhanced in tilapia transferred from seawater (SW) to FW, whereas both mRNAs were attenuated upon transfer from FW to SW. Next, we injected hypophysectomized tilapia with ovine prolactin (oPrl) and observed a marked increase in clc-2c from saline-injected controls. To determine whether Prl regulates clc-2c in a gill-autonomous fashion, we incubated gill filaments in the presence of homologous tilapia Prls (tPrl₁₇₇ and tPrl₁₈₈). By 24 h, tPrl₁₈₈ stimulated clc-2c expression ~5-fold from controls. Finally, filaments incubated in media ranging from 280 to 450 mosmol/kg for 3 and 6 h revealed that extracellular osmolality exerts a local effect on clc-2c expression; clc-2c was diminished by hyperosmotic conditions (450 mosmol/kg) compared with isosmotic controls (330 mosmol/kg). Our collective results suggest that hormonal and osmotic control of branchial clc-2c contributes to the FW adaptability of Mozambique tilapia. Moreover, we identify for the first time a regulatory link between Prl and a Clc Cl^- channel in a vertebrate.