Osmotic Pump Delivery Research Articles

Endothelial cell Orai1 is essential for endothelium-dependent contraction of mouse carotid arteries in normotensive and hypertensive mice.

Endothelium-dependent contraction (EDC) exists in blood vessels of normotensive animals, but is exaggerated in hypertension. An early signal in EDC is cytosolic Ca2+ rise in endothelial cells. In this study we investigated the functional role of Orai1, a major endothelial cell Ca2+ entry channel, in EDC. Hypertension model was established in WT mice by intake of L-NNA in the drinking water (0.5 g/L) for 4 weeks or osmotic pump delivery of Ang II (1.5 mg·kg-1·d-1) for 2 weeks. In TRPC5 KO mice, the concentration of L-NNA and Ang II were increased to 1 g/L or 2 mg·kg-1·d-1, respectively. Arterial segments were prepared from carotid arteries and aortas, andEDC was elicited by acetylcholine in the presence of Nω-nitro-L-arginine methyl ester. We showed that low concentration of acetylcholine (3-30 nM) initiated relaxation in phenylephrine-precontracted carotid arteries of both normotensive and hypertensive mice, while high concentration of acetylcholine (0.1-2 μM) induced contraction. Application of selective Orai1 inhibitors AnCoA4 (100 μM) or YM58483 (400 nM) had no effect on ACh-induced relaxation but markedly reduced acetylcholine-induced EDC. We found that EDC was increased in hypertensive mice compared with that of normotensive mice, which was associated with increased Orai1 expression in endothelial cells of hypertensive mice. Compared to TRPC5 and TRPV4, which were also involved in EDC, endothelial cell Orai1 had relatively greater contribution to EDC than either TRPC5 or TRPV4 alone. We identified COX-2, followed by PGF2α, PGD2 and PGE2 as the downstream signals of Orai1/TRPC5/TRPV4. In conclusion, Orai1 coordinates together with TRPC5 and TRPV4 in endothelial cells to regulate EDC responses. This study demonstrates a novel function of Orai1 in EDC in both normotensive and hypertensive mice, thus providing a general scheme about the control of EDC by Ca2+-permeable channels.

A nano-enabled biotinylated anti-LDL theranostic system to modulate systemic LDL cholesterol

Cardiovascular diseases (CVDs) remain one of the leading causes of death with an estimated 17.9 million lives lost each year. Circulating high levels of low-density lipoproteins (LDL), are susceptible to various modifications such as oxidation and glycosylation (diabetics). This leads to development of atherosclerosis, which can impair quality of life and death. There is a growing need for detection and subsequent treatment of high LDL cholesterol, which could be achieved through design of a system for detection of LDL with subsequent drug release for disease management. Fenofibrate-loaded solid lipid nanoparticles (SLNs) were synthesized and coated with anti-oxidized LDL antibodies to form anti-LDL SLN. The nanoparticles were delivered via an osmotic pump delivery device implanted on the jugular vein of Large White pigs as an anti-LDL theranostic system, referred to as an Intra-Vascular Implantable Sensor and Drug Delivery Device (IVISDDD), for modulation of systemic LDL cholesterol levels. Modulatory fenofibrate release was observed from the IVISDDD following in vivo analysis in response to anti-LDL SLN-LDL complex uptake and degradation. This notably contributed to a 29.9% reduction in total cholesterol via a 37.4% reduction in LDL levels, and an increase in HDL levels. The observed effect on cholesterol levels indicated that the device could be employed for detection of circulating biomarkers and delivery of lipophilic drugs in CVDs.

Follistatin Protein Enhances Satellite Cell Counts in Reinnervated Muscle.

Background Muscle recovery following peripheral nerve repair is sup-optimal. Follistatin (FST), a potent muscle stimulant, enhances muscle size and satellite cell counts following reinnervation when administered as recombinant FST DNA via viral vectors. Local administration of recombinant FST protein, if effective, would be more clinically translatable but has yet to be investigated following muscle reinnervation. Objective The aim of this study is to assess the effect of direct delivery of recombinant FST protein on muscle recovery following muscle reinnervation. Materials and Methods In total, 72 Sprague-Dawley rats underwent temporary (3 or 6 months) denervation or sham denervation. After reinnervation, rats received FST protein (isoform FS-288) or sham treatment via a subcutaneous osmotic pump delivery system. Outcome measures included muscle force, muscle histomorphology, and FST protein quantification. Results Follistatin treatment resulted in smaller muscles after 3 months denervation ( p = 0.019) and reduced force after 3 months sham denervation ( p < 0.001). Conversely, after 6 months of denervation, FST treatment trended toward increased force output ( p = 0.066). Follistatin increased satellite cell counts after denervation ( p < 0.001) but reduced satellite cell counts after sham denervation ( p = 0.037). Conclusion Follistatin had mixed effects on muscle weight and force. Direct FST protein delivery enhanced satellite cell counts following reinnervation. The positive effect on the satellite cell population is intriguing and warrants further investigation.

Soluble Epoxide Hydrolase Inhibition by t-TUCB Promotes Brown Adipogenesis and Reduces Serum Triglycerides in Diet-Induced Obesity.

Brown adipose tissue (BAT) is an important target for obesity treatment and prevention. Soluble epoxide hydrolase (sEH) converts bioactive epoxy fatty acids (EpFAs) into less active diols. sEH inhibitors (sEHI) are beneficial in many chronic diseases by stabilizing EpFAs. However, roles of sEH and sEHI in brown adipogenesis and BAT activity in treating diet-induced obesity (DIO) have not been reported. sEH expression was studied in in vitro models of brown adipogenesis and the fat tissues of DIO mice. The effects of the sEHI, trans-4-{4-[3-(4-trifluoromethoxy-phenyl)-ureido]-cyclohexyloxy-benzoic acid (t-TUCB), were studied in vitro and in the obese mice via mini osmotic pump delivery. sEH expression was increased in brown adipogenesis and the BAT of the DIO mice. t-TUCB promoted brown adipogenesis in vitro. Although t-TCUB did not change body weight, fat pad weight, or glucose and insulin tolerance in the obese mice, it decreased serum triglycerides and increased protein expression of genes important for lipid metabolism in the BAT. Our results suggest that sEH may play a critical role in brown adipogenesis, and sEHI may be beneficial in improving BAT protein expression involved in lipid metabolism. Further studies using the sEHI combined with EpFA generating diets for obesity treatment and prevention are warranted.

Sustained and controlled release of herbal medicines: The concept of synchronized release

Synchronized release, defined as simultaneous release of multiple components while keeping the inter-component ratios steady, is crucial to the design and development of sustained- or controlled-release delivery systems of herbal medicines. A theory of infinite dose dividing is proposed to interpret the rationale behind synchronized release. The key point of the mechanisms is to curb diffusion so as to offset the release divergence caused by differences in physicochemical properties of multiple components. In practice, pH-dependent gradient-release, erosion-controlled and osmotic pump delivery systems have been adapted to attain synchronized release of model herbal medicines. Nevertheless, synchronized release is still in the proof-of-concept stages and should be corroborated by more evidence with more model herbal medicines.

Abstract TP137: Suppression of Microrna Let-7a Expression Promotes Neurogenesis in Arginine Decarboxylase-neural Stem Cells After Ischemia

Introduction: Neural stem cells (NSCs) have been studied as promising novel treatments for central nervous system (CNS) disorders due to the potential of differentiation into neuron. To increase the therapeutic efficiency of NSCs, we have focused on microRNA let-7a ( let-7a ), known as the regulator of diverse cellular mechanisms and agmatine, an endogenous primary amine synthesized from decarboxylation of L-arginine catalyzed by arginine decarboxylase (ADC) and a neurotransmitter reported to affect neuroprotection in CNS. The purpose of this study is to investigate the role of arginine metabolic enzyme which regulated let-7a in neural stem cell differentiation. Methods: Cortical NSCs were isolated from pregnant imprinting control region mice and used for experiments after 2-3 passages. After let-7a mimic and agmatine treatment, we performed by RT-PCR, western blot and immunocytochemistry. To confirm the effects of arginine metabolic enzyme and let-7a in vivo , mice were subjected to distal middle cerebral artery occlusion (dMCAO). Following dMCAO, mice were treated agmatine by intraperitoneal injection, let-7a mimic by osmotic pump and human ADC gene delivery into the NSCs using retroviral vector ( vh ADC)-NSCs via intracranial injection at the corpus callosum. Results: In vitro study suggested that high levels of let-7a promoted the expression of TLX and c-Myc, as well as repressed DCX and ERK expression. In addition, agmatine attenuated the expression of TLX and increased the expression of ERK by negatively regulating let-7a . Also, after dMCAO, we found that vh ADC-NSC and let-7a co-treatment group reduced the infarct volume, increased the expression of DCX, Neurogenin2, Olig2, and attenuated the expression of GFAP. Conclusion: In the present study, we found that agmatine can enhance NSC differentiation into neurons by modulating expression of let-7a . In vivo study showed that vh ADC-NSC and let-7a co-treatment promoted neurogenesis and inhibited glial differentiation in the treatment of neural stem cell transplantation in ischemic condition. Therefore, our study suggests that the therapeutic efficiency of the vh ADC-NSC on neural stem cell differentiation through suppression of let-7a of the CNS diseases.

Characterization of crosslinked hard gelatin capsules for a structural assembly of elementary osmotic pump delivery system

The objective of this study was to characterize the crosslinked hard gelatin capsules (HGCs) for use as a structural assembly of elementary osmotic pumps (EOP). HGCs were crosslinked in formaldehyde vapor for 6, 12, and 24 h. Weight loss after immersing in various mediums, water soluble protein fraction, loss on drying, and formaldehyde residue were investigated. Fourier transform infrared (FTIR) spectra were used to detect the crosslinking formation. The EOP capsules were prepared for delivery of diltiazem hydrochloride (DIL HCl) and ambroxol hydrochloride (AMB HCl), which are freely and sparingly water soluble drugs, respectively. Physicochemical stability of storage crosslinked HGC shells was investigated. All crosslinked HGC shells were water insoluble. FTIR spectra exhibited intermediate lysine methylol and arginine methylol peaks. Storage time increased, moisture content increased and formaldehyde residue decreased. The developing EOP capsules were more appropriate for delivery of high water soluble rather than low water soluble drug. EOP capsule contained 100 mg DIL HCl using HGCs crosslinked for 12 h provided release profiles for 12 h with a lag time of 2.6–3.1 h. It was also found that DIL HCl EOP capsules prepared using crosslinked HGC shells stored for 90 days maintained the similar drug release profiles. AMB HCl EOP capsules exhibited low drug release. In summary, the crosslinked HGCs were applicable as a structural assembly of the osmotic controlled drug delivery system.

Evidence for the role of β2* nAChR desensitization in regulating body weight in obese mice

Nicotine's effect on food intake and body weight has been well documented; however, the relevant receptors underlying these effects have not been firmly established. The purpose of the present study was to: (1) identify the nicotinic acetylcholine receptor (nAChR) subtype involved in food intake and body weight; (2) establish whether food intake and body weight reduction produced by nicotinic drugs are due to activation or desensitization of nAChRs; and, (3) assess the role of the melanocortin system in nicotinic drug effects on food intake and body weight. To identify the nAChR, we tested the effect of sazetidine-A (SAZ-A), a relatively selective ligand of β2-containing nAChRs, on food intake and body weight in obese mice. SAZ-A (3 mg/kg; SC) administered twice-daily significantly decreased food intake and body weight. To assess whether these effects involved desensitization, SAZ-A was administered to non-obese mice via osmotic pump, which, due to its slow sustained drug delivery method, causes prolonged desensitization. SAZ-A via osmotic pump delivery significantly decreased the gain in body weight and reduced food intake. In contrast, body weight was unaffected by SAZ-A in β2−/− mice or in mice lacking the melanocortin 4 receptor (MC4R). These results indicate that β2 containing nAChRs are essential to SAZ-A's inhibitory effect on body weight and food intake and engage the melanocortin system.

Nicotinamide Phosphoribosyltransferase Inhibitor Is a Novel Therapeutic Candidate in Murine Models of Inflammatory Lung Injury

We previously identified the intracellular nicotinamide phosphoribosyltransferase (iNAMPT, aka pre-B-cell colony enhancing factor) as a candidate gene promoting acute respiratory distress syndrome (ARDS) and ventilator-induced lung injury (VILI) with circulating nicotinamide phosphoribosyltransferase potently inducing NF-κB signaling in lung endothelium. iNAMPT also synthesizes intracellular nicotinamide adenine dinucleotide (iNAD) in response to extracellular oxidative stress, contributing to the inhibition of apoptosis via ill-defined mechanisms. We now further define the role of iNAMPT activity in the pathogenesis of ARDS/VILI using the selective iNAMPT inhibitor FK-866. C57/B6 mice were exposed to VILI (40 ml/kg, 4 h) or LPS (1.5 mg/kg, 18 h) after osmotic pump delivery of FK-866 (100 mg/kg/d, intraperitoneally). Assessment of total bronchoalveolar lavage (BAL) protein, polymorphonuclear neutrophil (PMN) levels, cytokine levels (TNF-α, IL-6, IL-1α), lung iNAD levels, and injury scores revealed that FK-866-mediated iNAMPT inhibition successfully reduced lung tissue iNAD levels, BAL injury indices, inflammatory cell infiltration, and lung injury scores in LPS- and VILI-exposed mice. FK-866 further increased lung PMN apoptosis, as reflected by caspase-3 activation in BAL PMNs. These findings support iNAMPT inhibition via FK-866 as a novel therapeutic agent for ARDS via enhanced apoptosis in inflammatory PMNs.

Randomized Trial of Continuous Subcutaneous Delivery of Exenatide by ITCA 650 Versus Twice-Daily Exenatide Injections in Metformin-Treated Type 2 Diabetes

OBJECTIVETo evaluate ITCA 650, a continuous subcutaneous miniature osmotic pump delivery system of exenatide versus twice-daily exenatide injections (Ex-BID) in subjects with type 2 diabetes.RESEARCH DESIGN AND METHODSWe conducted a randomized, two-stage, 24-week, open-label, phase 2 study in type 2 diabetes inadequately controlled with metformin. Stage I: 155 subjects were randomized to 20 or 40 μg/day of ITCA 650 or Ex-BID 5→10 μg. Stage II: 131 subjects were rerandomized to 20, 40, 60, or 80 μg/day of ITCA 650. Change from baseline for HbA1c, weight, and fasting plasma glucose were evaluated at weeks 12 and 24.RESULTSHbA1c was significantly lower in all groups after 12 and 24 weeks. Stage I: mean change in HbA1c from a mean baseline of 7.9–8.0% was −0.98, −0.95, and −0.72% for the 20 and 40 μg/day ITCA 650 and Ex-BID groups, respectively, with 63, 65, and 50% of subjects achieving HbA1c levels ≤7% (P < 0.05). Stage II: significant (P < 0.05) reductions in HbA1c (∼1.4% from baseline) were achieved with 60 and 80 μg/day ITCA 650, and 86 and 78% of subjects achieved HbA1c ≤7% at 24 weeks; respectively. Weight was reduced by 2.8–3.7 kg (P < 0.05) at 24 weeks in all except the 20→20 μg/day group. ITCA 650 was well tolerated; nausea was lower and transient with 20 μg/day relative to Ex-BID; and 60 μg/day had the best profile of tolerability and HbA1c lowering.CONCLUSIONSITCA 650 significantly reduced HbA1c and weight and was well tolerated. The 20→60 μg/day regimen was considered the best dose for further examination in phase 3.

Recent Patent in Controlled Porosity Osmotic Pump

The porous osmotic pump based drug delivery system for excellent controlled release of drug for 24 hrs. The porous osmotic pump contains pore forming water soluble additives in the coating membrane, which after coming in contact with water, dissolve, resulting in an in situ formation of a microporous structure. The porous osmotic pump delivery from this system is not influenced by the different physiological factors. The present review is concerned with the patent study of drug release through controlled porous osmotic pump. This patent review is useful in knowledge of controlled porous osmotic pump for its application.

Formulation and characterization of osmotic delivery of Levetiracetam

T present study deals with formulation and characterization of oral extended release elementary osmotic pump delivery system for the novel anti-epileptic drug-Levetiracetam. Levetiracetam is a highly water soluble drug over a wide range of pH 1 to 7.8. Therefore its release may be controlled by formulating it in the controlled release system like oral osmotic drug delivery. The present research work describes the controlled release osmotic delivery of levetiracetam. Here, core tablets were prepared after optimizing the type and amount of binder, the type and amount of osmogen and the type and amount of polymer. Binders like maize starch, PVP K-90, co-povidone-28 were used. Sodium chloride and mannitol were tried as osmogen while different grade of HPMC in different concentration were used to increase its dissolution possessing properties. Later on, the core tablets were coated with different types and amount of cellulose acetate. Further the coated tablets were drilled using laser drill. A 32 factorial design were applied by taking two variables – amount of osmogen and percentage weight gain of coat. The prepared tablets were evaluated for in vitro drug release and its mechanism of release. The optimized formula for oral elementary osmotic pump was found out and it was giving the desired drug release pattern for period of 12 hrs by zero order release mechanism.

Recent Patent in Controlled Porosity Osmotic Pump

The porous osmotic pump based drug delivery system for excellent controlled release of drug for 24 hrs. The porous osmotic pump contains pore forming water soluble additives in the coating membrane, which after coming in contact with water, dissolve, resulting in an in situ formation of a microporous structure. The porous osmotic pump delivery from this system is not influenced by the different physiological factors. The present review is concerned with the patent study of drug release through controlled porous osmotic pump. This patent review is useful in knowledge of controlled porous osmotic pump for its application. Keywords: Controlled porous osmotic pump (CPOP), osmotic pump, physiological factors

Formulation development and evaluation of controlled porosity osmotic pump delivery system for oral delivery of atenolol

In the present study, we developed and evaluated the controlled porosity osmotic pump (CPOP) based drug deliverysystem of sparingly water soluble drug atenolol (ATL).We selected target release profile and optimized different variables to help us achieve this. Formulation variables, such as, the levels of solubility enhancer (0-15% w/w of drug), ratio of the drug to the osmogents, coat thickness of the semipermeable membrane (SPM) and level of pore former (0-20% w/w of polymer) were found to effect the drug release from the developed formulations. Cellulose acetate (CA 398-10) was used as the semipermeable membrane containing polyethylene glycol 400 as the Cplasticizer. ATL release was directly proportional to the level of the solubility enhancer, osmotic pressure generated by osmotic agent and level of pore former; however, was inversely proportional to the coat thickness of SPM. Drug release from developed formulations was independent of the pH and agitation intensities of release media. Burst strength of the exhausted shells decreased with increase in the level of pore former. The optimized formulations were subjected to stability studies as per International Conference on Harmonisation (ICH) guidelines, and formulations were found to be stable after 3 months study. Steady-state plasma levels of drug were predicted by the method of superposition.

Formulation development and evaluation of controlled porosity osmotic pump delivery system for oral delivery of atenolol

Formulation development and evaluation of controlled porosity osmotic pump delivery system for oral delivery of atenolol

Granulocyte colony-stimulating factor enhances cellular proliferation and motor function recovery on rats subjected to traumatic brain injury

Objective: Traumatic brain injury (TBI) results in neurological dysfunction and death through primary or secondary mechanisms. Here, we evaluated the effect of osmotic pump delivery of granulocyte colony-stimulating factor (G-CSF) on the histopathology and motor function recovery of rats after experimental TBI.Methods: Sprague–Dawley rats were used as experimental model by fluid percussion device to cause brain injury on the motor cortex area. The rats were simultaneously subjected to TBI and were implanted of min-osmotic pump containing recombinant human G-CSF (300 μg/700 μl) via intraperitoneal injection. Motor function was assessed by rotarod test. 5-bromo-2'-deoxyuridine (BrdU) was used to label the proliferating cells and their differentiation was evaluated by histology and immunohistochemistry.Results: The G-CSF group showed significantly better motor function recovery than the control group, and the effect lasted up to 14 days after TBI. Moreover, the G-CSF group exhibited a greater increase in the number of BrdU-positive cells compared with the control group. The G-CSF group also had a significantly higher number of DCX-positive cells in the ipsilateral subventricular zone (SVZ) than the control group.Conclusions: These data suggest that the beneficial effect of delivering G-CSF via an osmotic pump may improve the motor function and enhance neurogenesis in the SVZ of the injured brain.

The phenotype and potential origin of nestin+cardiac myocyte-like cells following infarction

Nestin+ cardiac myocyte-like cells were detected in the peri-infarct/infarct region of the ischemically damaged heart. The present study was undertaken to elucidate the phenotype and potential origin of nestin+ cardiac myocyte-like cells and identify stimuli implicated in their appearance. In the infarcted human and rat heart, nestin+ cardiac myocyte-like cells were morphologically and structurally immature, exhibited a desmin-immunoreactive striated phenotype, expressed the beta(1)-adrenergic receptor, and associated with an aberrant pattern of connexin-43 expression and/or organization. Nestin+ cardiac myocyte-like cells were detected 24 h postischemic injury and persisted in the infarcted rat heart for 9 mo. In the normal rat heart, cardiac progenitor transcriptional factors Nkx2.5/GATA4 were detected in a subpopulation of nestin+ neural stem cells. Following an ischemic insult, nestin+/Nkx2.5+ neural stem cells migrated to the peri-infarct/infarct region and appeared to be in a primordial state of differentiation to a nestin+ cardiac myocyte-like cell. The exposure of adult male rats to normobaric hypoxia (12% O2) for 10 days failed to promote the appearance of nestin+ cardiac myocyte-like cells. Following osmotic pump delivery of isoproterenol to normal adult rats, nestin+ cardiac myocyte-like cells were detected, albeit the response was modest and secondary to tissue loss. Thus ischemia-induced appearance of nestin+ cardiac myocyte-like cells apparently represents an adaptive response to heal the infarcted heart. Nkx2.5/GATA4 expression in a subpopulation of resident neural stem cells provides the appropriate phenotype for their potential differentiation to a nestin+ cardiac myocyte-like cell.

Mechanisms of hearing loss from trauma and inflammation: otoprotective therapies from the laboratory to the clinic

This article reviews a series of in vitro and in vivo studies that examined the otoprotective efficacy of locally delivered dexamethasone and explored the mechanisms by which dexamethasone protects auditory hair cells. These studies used auditory threshold testing in response to pure tone stimuli, organ of Corti explant cultures, FITC-phalloidin-stained explants, and surface preparations to determine hair cell density, osmotic pump delivery of dexamethasone into the scala tympani, an animal model of electrode insertion trauma (EIT)-induced hearing loss, and real-time RT-PCR studies of gene expression levels. Local delivery of two different formulations of dexamethasone conserved hearing and protected hair cells in an animal model of cochlear implantation. Dexamethasone treatment protected hair cells in organ of Corti explants exposed to an ototoxic level of an inflammatory cytokine, and gene expression studies showed that this protection was accomplished by increased expression levels of anti-apoptosis genes (e.g. Bcl-2) and decreased levels of pro-apoptosis genes (e.g. Bax). We conclude that dexamethasone is an effective otoprotective drug for both the conservation of hearing and preservation of hair cells against trauma-induced losses. Locally delivered dexamethasone is a promising therapeutic approach for the conservation of hearing during the process of cochlear implantation.

Biologically inspired approaches to drug delivery for nerve regeneration

As the biological processes governing nerve regeneration have become elucidated over the past decades, interest has developed in manipulating these processes to improve nerve regeneration. Drug delivery to the regenerating nerve has the potential for major clinical applications in neurodegenerative diseases, spinal cord injury and peripheral nerve injury or sacrifice. This article reviews the evolution of the field of drug delivery to the regenerating nerve, from simple local applications of neurotrophic agents in solution and osmotic pump delivery, to the existing approaches involving novel biomaterials and genetically manipulated cell populations. A discussion of the various known nerve growth-promoting agents, and the chemical considerations involved in their delivery, is included. A perspective on the role of tissue engineering approaches for nerve regeneration in the future is offered.

Modifying Thyroidal Status in Atlantic Cod by Osmotic Pump Delivery of Thyroid and Antithyroid Agents

The objective of this study was to determine whether osmotic pump delivery of 3,5,3′-triiodo-L-thyronine (T3), thyroid inhibitors (potassium iodide, methimazole, and thiourea), or gonadal hormones (estradiol-17β and testosterone) could modify the thyroidal status of wild Atlantic cod Gadus morhua. Osmotic pumps implanted intraperitoneally delivered on average 3% (SE = 0.5%) of their initial volume per day under the experimental conditions (depth, 25 m; temperature, 5.2–7.6°C). The administration of T3 significantly increased serum levels of both T3 and L-thyroxine (T4). Treatment with either methimazole or thiourea significantly depressed serum T3 levels to about 55% of control values, whereas treatment with testosterone significantly reduced T4 levels to about 35%. We conclude that the delivery of thyroid or antithyroid agents by osmotic pumps is an effective means for creating experimental hyper- or hypothyroidism in wild Atlantic cod.