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The Arctic's sea ice cover has been receding rapidly in recent years, and global climate models typically predict a further decline over the next century. It is an open question whether a possible loss of Arctic sea ice is reversible. We study the stability of Arctic model sea ice in a conceptual, two-dimensional energy-based regular network model of the ice-ocean layer that considers ARM's longwave radiative budget data and SHEBA albedo measurements. Seasonal ice cover, perennial ice and perennial open water are asymptotic states accessible by the model. We show that the shape of albedo parameterization near the melting temperature differentiates between reversible continuous sea ice decrease under atmospheric forcing and hysteresis behavior. Fixed points induced solely by the surface energy budget are essential for understanding the interaction of surface energy with the radiative forcing and the underlying body of ice/water, particularly close to a bifurcation point. Future studies will explore ice edge stability and reversibility in this lattice model, generalized to a latitudinal transect with spatiotemporal lateral atmospheric heat transfer and high spatial resolution.

Access to high quality weather and climate data is crucial for a wide range of societal and economic issues. It allows optimising industrial processes, supports the identification of potential risks related to climate change or allows the development of corresponding adaptation and mitigation strategies. Although such data is freely available through Germany’s national meteorological service DWD (Deutscher Wetterdienst) since 2017, the application potential in industry and society has certainly not yet been fully unlocked. Major obstacles are the complexity of the raw data, as well as missing tools for their simple integration into existing industrial applications. The goal of the research project FAIR is to simplify the information exchange between the DWD and economical players. In order to reach this goal a requirement analysis with end-users of weather data from three different sectors was conducted. A central requirement regarding the site assessment of wind plants is quick and easy access to historical wind-series at specific sites. Preferably downloadable in formats like CSV or via an API. Event planning partners are interested in a quick access to health relevant weather information at their event location, and the E-mobility sector in temperature data along planned routes. In this paper, we summarize the results of the requirement analysis and present the deduced technical architecture and FAIR services aiming at a user-friendly exchange of weather data.

Background: Isavuconazole is a triazole antifungal agent for treatment of invasive aspergillosis and mucormycosis. At present, it is unclear whether a therapeutic drug monitoring (TDM) of isavuconazole would be necessary. The aim of the investigation was to validate a high-performance liquid chromatography (HPLC) assay for routine applications., Methods: An HPLC assay for routine determination of isavuconazole in plasma has been adapted and validated. The assay used the reagents and HPLC column provided by the ChromSystems HPLC Kit for TDM of itraconazole, posaconazole, and voriconazole. Isocratic flow rate was set at 1.0 mL/min. Detection was performed using a fluorescence detector with excitation wavelength set at 261 nm and emission wavelength set at 366 nm., Results: The assay was linear between 0.15 and 10 mg/L with intraday and interday imprecision and accuracy <10% (<20% at lower limit of quantification). The method was applied to routine TDM of 7 patients after hematopoietic stem cell transplantation (n = 31 samples). In these patients, trough levels ranged from 0.45 to 3.06 mg/L (median 1.44 mg/L)., Conclusions: A robust and simple HPLC assay of isavuconazole in plasma for routine TDM applications is presented.

The mammalian target of rapamycin inhibitor everolimus (RAD001) is a successfully used immunosuppressant in solid-organ transplantation. Several studies have already used RAD001 in combination with calcineurin inhibitors after hematopoietic stem cell transplantation (HSCT). We investigated calcineurin inhibitor-free pre- and post-transplantation immunosuppression of RAD001 combined with mycophenolate mofetil (MMF) in a nonmyeloablative HSCT setting. After nonmyeloablative conditioning with 2 Gy total body irradiation, 8 dogs received HSCT from dog leukocyte antigen-identical siblings. Immunosuppressives were given at doses of 1.5 mg RAD001 twice daily from day -1 to +49, then tapered until day +56, and 20 mg/kg MMF from day 0 to +28, then tapered until day +42. An historical cyclosporin A (CsA)/MMF regimen was used in the control group. All dogs engrafted. Median platelet nadir amounted in all dogs to 0 × 10(9)/L (median, day +10; duration <50 × 10(9)/L, 22 days) and median leukocyte nadir was 1.0 × 10(9)/L (range, .1 to 2.5 × 10(9)/L; median, day +13). Eventually, 5 of 8 (63%) animals rejected their grafts. Two dogs died of infections on day +19 and +25. Pharmacokinetics of RAD001 and MMF showed median trough levels of 19.1 (range, 10.5 to 43.2) μg/L and .3 (.1 to 1.3) mg/L, respectively. The median area under the curve was 325 (range, 178 to 593) μg/L × hour for RAD001 and 29.6 (range, 7.9 to 40.5) ng/L × hour for MMF. All dogs developed clinically mucosal viral infections during the clinical course. Compared with the control group, the level of toxicities for RAD001/MMF increased in all qualities. Combined immunosuppression of RAD001 and MMF after nonmyeloablative HSCT is associated with significant toxicities, including a prolonged platelet recovery time as well as increased infections compared to the CsA/MMF regimen., (Copyright © 2014 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.)

Everolimus (RAD001) is an mTOR inhibitor that has been successfully used as an immunosuppressant in solid-organ transplantation. Data in allogeneic hematopoietic stem cell transplantation (HSCT) is limited. This study aimed to investigate pharmacokinetics, safety, and efficacy of RAD001 in a canine allogeneic HSCT model. First, pharmacokinetics of RAD001 were performed in healthy dogs in order to determine the appropriate dosing. Doses of 0.25 mg RAD001 twice daily in combination with 15 mg/kg cyclosporin A (CsA) twice daily were identified as appropriate starting doses to achieve the targeted range of RAD001 (3-8 μg/L) when orally administered. Subsequently, 10 dogs were transplanted using 2 Gy total body irradiation (TBI) for conditioning and 0.25 mg RAD001 twice daily plus 15 mg/kg CsA twice daily for pre- and posttransplantation immunosuppression. Seven of the 10 transplanted dogs were maintained at the starting RAD001 dose throughout the study. For the remaining 3 dogs, dose adjustments were necessary. RAD001 accumulation over time did not occur. All dogs initially engrafted. Five dogs eventually rejected the graft (weeks 10, 10, 13, 27, and 56). Two dogs died of pneumonia (weeks 8 and 72) but were chimeric until then. Total cholesterol rose from median 4.1 mmol/L (3.5-5.7 mmol/L) before HSCT to 6.0 mmol/l (5.0-8.5 mmol/l) at day 21 after HSCT, but remained always within normal range. Changes in creatinine and triglyceride values were not observed. Long-term engraftment rates were inferior to sirolimus/CsA and mycophenolate mofetil (MMF)/CsA regimen, respectively. RAD001/CsA caused a more pronounced reduction of platelet counts to median 2 × 10(9)/L (range: 0-21 × 10(9)/L) and longer time to platelet recovery of 21 days (range: 14-24 days) compared with MMF/CsA. CsA c(2h) levels were significantly enhanced in the RAD001/CsA regimen, but c(0h) and area under the curve from 0 to 12 hours (AUC(0-12h)) values did not differ compared with an MMF/CsA immunosuppression. In summary, immunosuppression consisting of RAD001 and CsA is well tolerated but not as efficient as with other established immunosuppressants in a canine nonmyeloablative HSCT regimen. Hence, our study does not support the application of RAD001/CsA as standard practice in this setting., (Copyright © 2012 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.)

Objective: High-hydrophilic osmotic self-inflating hydro gel expanders are well-accepted for implantation to achieve tissue expansion in defined parts of the body like skin, breast and orbital soft tissue. To prevent post-implantation infections effective antibiotic prophylaxis might be helpful. The suitability of this hydro gel consisting of a co-polymer of N-vinyl-pyrolidone and methyl-methacrylate as a drug delivery system for antibiotics was investigated in a laboratory setting simulating the orbit in a newborn., Methods: In a first setting the dry expanders were incubated in a 0.3% solution (5 ml) of tobramycin and ofloxacin for 24 h (n = 10 for each substance, adsorbing 2.4 ml of the 0.3% solution, i.e. 7,200 μg antibiotic). Addressing the release of both antibiotics, the concentrations in 15 ml elution medium (0.9% sodium chloride, renewed after every sampling) were measured after 0.25, 1, 2, 6, 24, 48 and 72 h of elution. To simulate the clinical use in a second setting the expanders were dried after incubation in a 0.3% and 0.03% solution of tobramycin (n = 5 for each concentration) before measuring the release., Results: The cumulative amount of tobramycin released after 72 h reached 7,157 μg, i.e. 99% of the initially loaded antibiotic. The cumulatively released amount of ofloxacin was 5,505 μg (76% of loading dose). Main fraction of release (about two thirds) was detected for both antibiotics for a elution period 0 - 24 h. In the periods 24 - 48 and 48 - 72 h the released amount of tobramycin was significantly higher than for ofloxacin. The release from expander dried after loading tobramycin was comparable: The cumulatively released amount of 0.3% and 0.03% incubation solution was 99% and 79% of loading dose, respectively., Conclusions: The investigated hydro gel expanders soaked in antibiotic solution can store and further on release sufficient amounts of tobramycin or ofloxacin to produce antimicrobial effective concentrations in vitro in the surrounding environment according to the breakpoints reported by EUCAST [14]. This principle, when used in a clinical setting, might help to eliminate post-implantation infection, which is one of the major complications in clinical use.

Background: Graft pancreatitis is induced by ischemia/reperfusion injury in which neutrophil infiltration is believed to be a crucial early event. This observation suggests the presence of adhesion molecules already at the time of reperfusion. Therefore, this study was performed to evaluate the pattern of ICAM-1 and P-Selectin expression on human pancreas allografts following cold ischemia and reperfusion., Patients and Methods: We performed an analysis of pancreas biopsy specimens taken from 13 patients undergoing pancreas transplantation compared with pancreas specimens from 10 patients following resection. Cryostat sections were stained with monoclonal antibodies against CD11b, a neutrophil marker, and the adhesion molecules ICAM-1 and P-Selectin., Results: Extensive infiltration of CD11b-positive cells was detected in venules and capillaries of pancreas allografts after reperfusion (18.38 +/- 0.87) compared with controls (T1 4.22 +/- 0.55) or with tissue specimens at about 10 hours of cold ischemia (2.60 +/- 0.35; P < .001). Similarly, the pattern of P-Selectin showed a moderate expression before organ harvest (1.54 +/- 0.21) and in samples during cold ischemia (1.46 +/- 0.24) followed by a significantly greater number of P-Selectin-positive cells after reperfusion (2.54 +/- 0.18; P = .005). ICAM-1 was only weakly expressed on the surface of the venular endothelium in all controls (0.77 +/- 0.12). In contrast to P-Selectin, ICAM-1 showed prominent up-regulation during cold ischemia (2.23 +/- 0.23; P < .001) with no further increase after reperfusion (2.23 +/- 0.17)., Conclusion: The data suggested that ICAM-1 was already up-regulated during cold ischemia, possibly representing the mechanism of early neutrophil infiltration observed in human pancreatic ischemia/reperfusion injury.

Objectives: Failure to prevent secondary infectious complications in acute necrotizing pancreatitis (ANP) is attributable in part to the limited penetration of antimicrobial drugs. As newer quinolones are particularly attractive owing to their antimicrobial activity, for the first time we studied the penetration of moxifloxacin into pancreatic tissue in patients., Patients and Methods: In this prospective, non-comparative clinical trial, 60 patients undergoing elective pancreas resection received a single oral or intravenous (iv) dose of 400 mg moxifloxacin for perioperative antimicrobial prophylaxis. The concentration of moxifloxacin was measured in samples taken from blood and from pancreatic tissue at the beginning and at the end of resection., Results: Mean moxifloxacin concentrations in pancreatic tissue following iv or oral administration were 3.1+/-0.9 and 2.7+/-1.4 mg/kg at 3-3.7 h post-dose (first sampling) and 3.6+/-1.5 and 3.1+/-1.8 mg/kg at 4.3-5.3 h post-dose (second sampling), respectively. Corresponding mean plasma concentrations of moxifloxacin were 1.8+/-0.5 and 1.2+/-0.6 mg/L (first sampling) and 1.5+/-0.4 and 1.0+/-0.5 mg/L (second sampling), respectively. From first to second sampling, the mean tissue-to-plasma ratios varied from 1.8+/-0.6 to 2.6+/-1.2 (iv) and from 2.4+/-0.8 to 3.1+/-1.2 (oral). Pancreatic tissue concentrations of moxifloxacin exceeded the MIC90 for the relevant pathogens covered by moxifloxacin for at least 5 h after dosing., Conclusions: Moxifloxacin has been demonstrated to penetrate efficiently into human pancreatic tissue following iv or oral administration. From a pharmacological perspective, moxifloxacin appears to be promising for prophylaxis and treatment of local pancreas infections. Whether it is beneficial in the prevention and therapy of infectious complications in patients with ANP should be investigated in a controlled clinical trial.

The optimal effect of therapy with cyclosporine (CsA) seeks to minimize undesirable side effects while maximizing immunosuppression. This balance, depends on CsA exposure, which may be characterized by the area under the concentration-time-curve (AUC). Therefore, we tested the pharmacokinetic profile of microemulsion CsA as a superior approach to guide clinical immunosuppression after de novo simultaneous pancreas-kidney transplantations. We examined 10 consecutive pancreas-kidney recipients with type 1 diabetes and end-stage renal disease. All patients were treated with a regimen consisting of CsA, mycophenolate mofetil (MMF), and prednisone. Full (9-point) pharmacokinetic studies (C0, C1, C2, C3, C4, C6, C8, C10, C12) were performed on week 1 and during week 3 to examine CsA pharmacokinetic profiles. Mean AUC0-12 of 4431 +/- 2400 microg x h/L at week 1 remained stable at week 3 (5119 +/- 1190 microg x h/L). The C6 sampling time displayed the best correlation with AUC0-12 (r2 = 0.881), followed by C3 (r2 = 0.758). Our preliminary data after simultaneous pancreas-kidney transplantation support the hypothesis that C3 or C6 sampling is a more accurate predictor of the AUC0-12 than C0. The combination of two samplings, namely C3 + C6 (r2 = 0.938) or C2 + C6 (r2 = 0.955) proved excellent prediction of exposure after simultaneous pancreas-kidney transplantation.

Background and Aims: The expression of the ABC-transporters MDR-1, MRP1, and MRP-2 was investigated in healthy pancreas and in chronic pancreatitis tissue samples in rats and humans to evaluate their possible involvement in a multidrug resistance of the pancreas with consequences for the pharmacologic treatment of pancreatic diseases., Methods: Human pancreatic tissue samples of healthy tissue and chronic pancreatitis were collected during pancreas surgery. In rats, the time-course of the expression of transporter proteins was studied 14, 28, and 56 days after experimental induction of chronic pancreatitis. The expression of MDR-1, MRP-1, MRP-2, and furthermore, LRP and PAP was investigated by RT-PCR, Real Time TaqManPCR, and immunohistochemistry., Results: In rat pancreas, MDR-1 (P-gp) and MRP-1 but in human pancreas MDR-1 (P-gp), MRP-1 and MRP-2 were found to be expressed. Chronic pancreatitis lead to an increased transcription of mRNA of MDR-1 (rat and human) and much lower, MRP-2 (human)., Conclusions: The expression of P-gp and related transporters could have impact on the metabolism, distribution, and availability of various compounds, including drugs, in the pancreas. The results indicate that this could be more pronounced in chronic pancreatitis.

Infectious complications of acute necrotizing pancreatitis (ANP) determine the extent of multiorgan failure and account for 80% of deaths. Prophylactic use of antibiotics can reduce the incidence of these complications. However, the actual indication as well as choice of drug remains a controversial matter. We examined the penetration of moxifloxacin, a new broad-spectrum fluoroquinolone, in healthy and inflamed pancreatic tissue in rats after inducing ANP. The concentration of moxifloxacin in pancreatic tissue and serum was determined 10, 30, 60 and 240 min after the administration of moxifloxacin (5 mg/kg, i.v.). Mean serum concentrations 10 min after administration in rats with ANP were 1,886 ng/ml versus 1,805 ng/ml in healthy controls, and these values decreased to 350 versus 222 ng/ml, respectively, after 240 min. Corresponding concentrations in pancreatic tissue were in the mean 2-3 times higher., (Copyright 2003 S. Karger AG, Basel)

A juvenile, female renal transplant recipient suffered two acute rejection episodes: the first on posttransplant day 31 while taking cyclosporine, prednisone, and mycophenolate mofetil (MMF); and the second on posttransplant day 67, when she was taking tacrolimus, prednisone, and MMF. Dosage of MMF was initially started at 2 g/d (corresponding to 600 mg MMF/m(2) twice daily.), but was reduced to 250 mg/d to 500 mg/d after severe diarrhea and a paralytic ileus on posttransplant day 16. During therapy with tacrolimus, prednisone, and MMF, predose plasma mycophenolic acid (MPA) concentrations varied from 1.1 mg/L to 8.2 mg/L (median 3.0 mg/L). On posttransplant day 91, a 12-hour pharmacokinetic profile was obtained. The concentrations of MPA and its metabolites were determined with a validated high-performance liquid chromatography (HPLC) procedure. After oral MMF (250 mg) administration, the MPA concentration showed an atypical decline from a predose concentration of 6.0 mg/L to a value of 3.8 mg/L at 75 minutes postdose, and 3.4 mg/L at 6 hours postdose, before returning to 6.0 mg/L after 12 hours. The 12-hour area under the concentration-time curve (AUC) values for MPA and its major metabolite the phenolic glucuronide MPAG were 55.1 mg.h/L and 800 mg.h/L, respectively. An unusually high concentration (12-h AUC, 165 mg.h/L) of the phenolic glucose conjugate of MPA was found. The apparent renal clearance of MPAG was only 2.2 mL/min. Her creatinine clearance was 30 mL/min. MPAG clearances have been reported to range from approximately. 5.5 mL/min to 35 mL/min at a creatinine clearance of approximately 30 mL/min in renal transplant recipients. The authors' findings suggest that conjugation and clearance of MPA through the kidney is strongly impaired in this patient. The relatively high predose MPA concentrations could result from an enhanced enterohepatic circulation of MPA and its metabolites.

Improvement of non-surgical strategies is a pivotal task in the treatment of pancreatic cancer. Response to treatment with most anticancer agents has been very poor, probably due to insufficient drug concentration in tumor tissue. Increased response rates during chemotherapy might be achieved by dose escalation; however, this approach is often hampered by severe side effects. One strategy to overcome these adverse effects is application of nontoxic glucuronide prodrugs from which the active moiety is released by beta-glucuronidase within or near the tumor. The use of glucuronide prodrugs in pancreatic cancer requires increased expression of the enzyme in the diseased tissue, a problem that has not been addressed so far. We therefore investigated function and expression of beta-glucuronidase in tissue samples from human healthy pancreas (n=7) and pancreatic adenocarcinoma (n=8), respectively. Comparing the ability of tissue homogenates to cleave the standard substrate 4-methylumbelliferyl-beta-D-glucuronide, we found a significantly increased specific beta-glucuronidase activity (P<0.05) in pancreatic cancer (median: 133; 75% percentile: 286; 25% percentile: 111 nmol/mg per h) as compared to healthy pancreas (median: 74; 75% percentile: 113; 25% percentile: 71 nmol/mg per h). Enzyme kinetic experiments with the model prodrug N-[4-beta-glucuronyl-3-nitrobenzyloxycarbonyl] doxorubicin (HMR 1826) demonstrated bioactivation of HMR 1826 by pancreatic beta-glucuronidase. Enzymatic activity was found to be closely related to enzyme contents (r=0.87) as assessed by Western blot analysis. Our data indicate that increased beta-glucuronidase activity in pancreatic cancer seems to be due to an elevated steady-state level of the protein. This may be the basis for new therapeutic strategies in treatment of pancreatic carcinoma by using glucuronide prodrugs of anticancer agents.

Objective: The clinical outcome of patients after organ transplantation is correlated with cyclosporin A (CyA) exposure. It is generally accepted that the area under the concentration-time curve (AUC) provides a reliable means for drug exposure. However, in routine therapeutic drug monitoring (TDM) of CyA, trough levels are mostly used. Currently, a number of different new concepts of CyA-TDM, including approaches such as single, double or triple time-point and abbreviated AUC determinations, have been introduced. The purpose of this study was to compare the predictive value of the different strategies of TDM., Methods: Calculations were based on 40 individual concentration time profiles after oral administration of CyA to patients who had been included into an ongoing prospective clinical trial. Non-compartmental analysis was used to calculate the AUC0-12h. Multiple linear regression was performed to describe the relationship between the different sets of blood concentrations and the respective AUC0-12h as well as to evaluate their predictive value regarding AUC. Predictive performance was assessed by prediction bias and prediction precision, which were estimated as the mean prediction error and root mean squared error, respectively., Results: When comparing the various combinations of time points, it was found that one-point approaches showed the strongest differences with regard to the predictive value; the associated r2 values differed from 0.203 to 0.792. The two and three time-point approaches showed lower differences - r2 0.802-0.972. The four-point and five-point approaches (r2 0.942-0.982) were the strongest predictors for CyA AUC0-12h. Relative bias ranged from -27.7% to 63.8% and changed significantly when multiple-point predictors were used. In those cases, the predictive performance improved. Considering the predictive performance as well as the smallest bias and highest prediction precision, C3, C1 + C3, C1 + C3 + C6 and C1 + C2 + C3 + C6 were the best predictors., Conclusion: The results of this study indicate that in kidney transplant patients a clinically sufficient precise estimation of the CyA AUC is possible using two or three concentration time points.

The oxidative metabolism of xenobiotics is effected mainly by cytochrome P450 enzymes (CYP), which are expressed as a family of genetically related enzymes primarily in hepatocytes. The pancreas is among the extrahepatic tissues expressing CYP, and it has been suggested that intermediates generated by them might be of pathogenetic significance for diseases of the pancreas such as chronic pancreatitis. We studied 10 surgical resection specimens by immunohistochemistry with polyclonal antibodies against recombinant human CYP 1A1, 1A2, 2C9, 2E1, and 3A and used tissues from 11 normal pancreata as controls. In addition, we assayed microsomal preparations for their capacity to metabolize verapamil. In normal pancreata weak to moderate expression of all enzymes was demonstrated immunohistochemically in up to 50% of duct epithelia, acinar cells, and islet cells. In contrast, in chronic pancreatitis an up-regulation was observed, with immunohistochemical positivity in some cases in up to 100% of duct epithelia and acinar cells. The oxidative capacity of microsomal preparations from chronic pancreatitis was higher than that of preparations obtained from control tissues; compared to liver microsomes, however, it was low. The up-regulation of CYP may have pathogenetic significance for chronic pancreatitis. Yet considering the pancreas' capacity for conjugation reactions, conceivably low levels of reactive intermediates could effectively undergo inactivation.

Emphasis on drug safety is increasing as newly developed drugs become more potent. Interest in the prediction and description of drug interactions is growing accordingly. The study of potential interactions at a very early stage of drug development requires suitable in vitro models that describe drug interactions both qualitatively and quantitatively. The purpose of the work described here was to help assess the predictive value of in vitro drug interaction tests with liver microsomes and hepatocytes by means of the interaction between verapamil and cimetidine. The in vitro inhibition of verapamil metabolism by cimetidine observed during the studies was quantitatively similar to the results reported in published clinical studies after intravenous application. Studies using liver microsome fractions showed that the intrinsic clearances for the formation of various metabolites could be used to predict drug interactions. In addition, work with hepatocyte cultures revealed that an in vitro system covering both phase I and phase II reactions should be included in such studies to permit quantitative prediction of the various metabolic pathways. Both human hepatocyte cultures and human microsomes offer certain advantages for predicting the degree of drug metabolism and interactions in humans at the biotransformation level. Therefore, it seems likely that the simultaneous application of both systems will yield conclusions that most closely approximate the situation in humans.

An improved method using isocratic reversed phase HPLC is presented for the extraction and rapid determination of verapamil and its main metabolites in microsomal preparations and cell culture media. Possibilities for using the method to estimate cytochrome P450 enzymes in microsomal test systems and hepatocyte cultures are described. The studies show that primary hepatocyte cultures are suitable for studying the metabolism and interactions of pharmaceuticals in vitro and could be superior to microsomal systems in many cases.

1. The connection between feeding regime (food deprivation and restricted diet) and thermal acclimation (1-2, 6, 11 and 16 degrees C) was studied in rainbow trout held in diluted seawater (20% S). 2. At 1 degree C, food deprivation effects on all parameters are slight, and on RNA and certain enzymes they are masked by thermal acclimation effects. 3. At a salinity of 20% rainbow trout on a restricted diet and held at 11 degrees C have the highest growth rate. 4. Owing to increasing RNA levels, the RNA/DNA quotient is significantly higher than normal in rainbow trout held at 1 degree C although the fishes do not grow at this temperature. 5. Temperature and feeding both affect the enzymes we studied (liver: G1DH, AspT, arginase, G6PDH, and 6PGDH; kidney: G1DH, AspT, arginase, and Na/K-ATPase; white muscle: AspT and A1T; gill: Na/K-ATPase) differently. Interactions between these two factors also occur in some cases.

Glutamate dehydrogenase activity in the liver of the rainbow trout increases when the animals are starved for four weeks. Glutamate dehydrogenase, alanine aminotransferase and aspartate aminotransferase activity in the kidney of rainbow trout kept in sea water (20% S) is significantly higher than in the kidney of rainbow trout kept in fresh water. Gill Na/K-ATPase activity in the rainbow trout is reduced significantly (44%) by starvation for four weeks. Most of the free amino acids investigated in the white muscle of the rainbow trout were present in significantly higher concentrations in animals fed in sea water than in animals fed in fresh water. The concentrations of these amino acids are even higher in the muscle of starved animals held in sea water than in fed animals held in sea water.