Development of Novel Management Tools for Phortica variegata (Diptera: Drosophilidae), Vector of the Oriental Eyeworm, Thelazia callipaeda (Spirurida: Thelaziidae), in Europe

Lachryphagous males of Phortica variegata (Fallén, 1823) are gaining increasing attention in Europe, as they act as vectors of the nematode Thelazia callipaeda Railliet & Henry, 1910, causal agent of thelaziosis, an emergent zoonotic disease. Currently, there are no effective control strategies against the vector, and surveillance and monitoring rely on time-consuming and nonselective sampling methods. Our aim was to improve the knowledge about the population dynamics and the chemical ecology of the species. A total of 5,726 P. variegata flies (96.4% males and 3.6% females, mostly gravid) were collected in field experiments during June-September of 2020 in an oak forest in northern Spain. Our results indicate that 1) by means of sweep netting a significantly higher number of captures were found both around the collector´s body and in the air than at ground level; 2) a positive relationship was detected between the abundance of Phortica flies and temperature, with two significant peaks of abundance at 24 and 33°C; 3) the blend of red wine and cider vinegar was the most attractive bait; 4) yellow traps captured fewer flies compared to black and transparent traps; and 5) a significant reduction toward vinegar and wine was detected in presence of the phenolic monoterpenoid carvacrol. In addition, all the males (n = 690) analyzed by both molecular detection and dissection resulted negative for the presence of T. callipaeda larvae. Overall, these findings provide a better understanding of the vector in terms of monitoring and management strategies.

Functionalized PLGA nanoparticles prepared by nano-emulsion templating interact selectively with proteins involved in the transport through the blood-brain barrier

During the last few decades, extensive efforts has been made to design nanocarriers to transport drugs into the central nervous system (CNS). However, its efficacy is limited due to the presence of the Blood-Brain Barrier (BBB) which greatly reduces drug penetration making Drug Delivery Systems (DDS) necessary. Polymeric nanoparticles (NPs) have been reported to be appropriate for this purpose and in particular, poly(lactic-co-glycolic acid) (PLGA) has been used for its ability to entrap small molecule drugs with great efficiency and the ease with which it functionalizes NPs. Despite the fact that their synthetic identity has been studied in depth, the biological identity of such manufactured polymers still remains unknown as does their biodistribution and in vivo fate. This biological identity is a result of their interaction with blood proteins, the so-called "protein corona" which tends to alter the behavior of polymeric nanoparticles in the body. The aim of the present research is to identify the proteins bounded to polymeric nanoparticles designed to selectively interact with the BBB. For this purpose, four different PLGA NPs were prepared and analyzed: (i) "PLGA@Drug," in which a model drug was encapsulated in its core; (ii) "8D3-PLGA" NPs where the PLGA surface was functionalized with a monoclonal anti-transferrin receptor antibody (8D3 mAb) in order to specifically target the BBB; (iii) "8D3-PLGA@Drug" in which the PLGA@Drug surface was functionalized using the same antibody described above and (iv) bare PLGA NPs which were used as a control. Once the anticipated protein corona NPs were obtained, proteins decorating both bare and functionalized PLGA NPs were isolated and analyzed. Apart from the indistinct interaction with PLGA NPs with the most abundant serum proteins, specific proteins could also be identified in the case of functionalized PLGA NPs. These findings may provide valuable insight into designing novel vehicles based on PLGA NPs for crossing the BBB.

A proteomic analysis of the statocyst endolymph in common cuttlefish (Sepia officinalis): an assessment of acoustic trauma after exposure to sound

Recent studies, both in laboratory and sea conditions, have demonstrated damage after sound exposure in the cephalopod statocyst sensory epithelium, which secretes endolymph protein. Here, the proteomic analysis of the endolymph was performed before and after sound exposure to assess the effects of exposure to low intensity, low frequency sounds on the statocyst endolymph of the Mediterranean common cuttlefish (Sepia officinalis), determining changes in the protein composition of the statocyst endolymph immediately and 24 h after sound exposure. Significant differences in protein expression were observed, especially 24 h after exposure. A total of 37 spots were significantly different in exposed specimens, 17 of which were mostly related to stress and cytoskeletal structure. Among the stress proteins eight spots corresponding to eight hemocyanin isoforms were under-expressed possible due to lower oxygen consumption. In addition, cytoskeletal proteins such as tubulin alpha chain and intermediate filament protein were also down-regulated after exposure. Thus, endolymph analysis in the context of acoustic stress allowed us to establish the effects at the proteome level and identify the proteins that are particularly sensitive to this type of trauma.

Using a polymer probe characterized by MALDI-TOF/MS to assess river ecosystem functioning: From polymer selection to field tests

Characterization of river ecosystems must take into consideration both structural and functional aspects. For the latter, a convenient and simple approach for routine monitoring is based on the decomposition of organic matter measured in terms of breakdown of natural organic substrates like leaf litter, wood sticks. Here we extended the method to a synthetic organic material using polymer probes characterized by MALDI-TOF/MS. We first characterized several commercial available polymers, and finally selected polycaprolactonediol 1250 (PCP 1250), a polyester oligomer, as the most convenient for further studies. PCP 1250 was first tested at mesocosms scale under conditions simulating those of the river, with and without nutrient addition for up to 4weeks. Differences to the starting material measured in terms of changes in the relative ion peak intensities were clearly observed. Ions exhibited a different pattern evolution along time depending on their mass. Greatest changes were observed at longest exposure time and in the nutrient addition treatment. At shorter times, the effect of nutrients (addition or not) was indistinguishable. Finally, we performed an experiment in 11 tributaries of the Ebro River during 97days of exposure. Principal Component Analysis confirmed the different behavior of ions, which were clustered according to their mass. Exposed samples were clearly different to the standard starting material, but could not be well distinguished among each other. Polymer mass loss rates, as well as some environmental variables such as conductivity, temperature and flow were correlated with some peak intensities. Overall, the interpretation of field results in terms of environmental conditions remains elusive, due to the influence of multiple concurrent factors. Nevertheless, breakdown of synthetic polymers opens an interesting field of research, which can complement more traditional breakdown studies to assess river ecosystem functioning.

Sexual communication in day-flying Lepidoptera with special reference to castniids or 'butterfly-moths'

Butterflies and moths are subject to different evolutionary pressures that affect several aspects of their behaviour and physiology, particularly sexual communication. Butterflies are day-flying insects (excluding hedylids) whose partner-finding strategy is mainly based on visual cues and female butterflies having apparently lost the typical sex pheromone glands. Moths, in contrast, are mostly night-flyers and use female-released long-range pheromones for partner-finding. However, some moth families are exclusively day-flyers, and therefore subject to evolutionary pressures similar to those endured by butterflies. Among them, the Castniidae, also called 'butterfly-moths' or 'sun-moths', behave like butterflies and, thus, castniid females appear to have also lost their pheromone glands, an unparallel attribute in the world of moths. In this paper, we review the sexual communication strategy in day-flying Lepidoptera, mainly butterflies (superfamily Papilionoidea), Zygaenidae and Castniidae moths, and compare their mating behaviour with that of moth families of nocturnal habits, paying particular attention to the recently discovered butterfly-like partner-finding strategy of castniids and the fascinating facts and debates that led to its discovery.

Behavior of processionary males (Thaumetopoea pityocampa) induced by sex pheromone and analogs in a wind tunnel

The behavioral response of processionary males (Thaumetopoea pityocampa) to the natural pheromone (Z)-13-hexadecen-11-ynyl acetate (1) and structurally related analogs in a wind tunnel is presented. Stereomerically pureZ-1 and a mixture with theE isomer in 80:20 ratio elicited similar attraction responses at 1 µg and higher. The activity was dose-dependent, being optimum at 1 µg with 90% and 80% of males contacting with the source in the presence of theZ-1 andZ/E-1, respectively. 11-Hexadecynyl acetate (2) functioned as a pheromone mimic, being able to induce the complete mate-finding behavioral sequence, although its activity was much lower than that of the pheromone. (Z)-13-Hexadecen-11-ynyl alcohol (3) and, particularly, (Z)-13-hexadecen-11-ynal (4) were potent inhibitors of the upwind flight response in mixtures withZ-1 in 99:1, 95:5, and 91:9 ratios. (Z)-1,1,1-Trifluoro-16-nonadecen-14-yn-2-one (5) also inhibited the response of males to pheromone, particularly in the source contact behavior. Comparison with activity displayed by analogs in field tests is also reported.

Behavioral responses ofSpodoptera littoralis males to sex pheromone components and virgin females in wind tunnel

The major component of the sex pheromone of femaleSpodoptera littoralis, (Z,E)-9,11-tetradecadienyl acetate (1), elicited all steps of the male behavioral sequence, i.e., wing fanning and taking flight, oriented upwind flight and arrival to the middle of the tunnel, close approach and contact with the source. The activity was equivalent to that elicited by virgin females. In the range of doses tested, the dosage of1 had no significant effect on the number of source contacts. Male response was significantly affected by light intensity, being optimum at 3 lux. Activity of the minor components (Z)-9-tetradecenyl acetate (2), (E)-11-tetradecenyl acetate (3), tetradecyl acetate (4), (Z)-11-tetradecenyl acetate (5), and (Z,E)-9,12-tetradecadienyl acetate (6) was significantly lower than that of the major component when assayed individually. In multicomponent blends compound4 appeared to strongly decrease the number of males arrested at the source, the effect being particularly important when compound5 was present in the blend. Results of single sensillum experiments confirmed the existence of two main physiologically distinct sensillar types. The most common type of sensilla contained a neuron that responded specifically to compound1. A second type of sensilla, located laterally on the ventral sensory surface, contained two receptor neurons responding to compound6 and to (Z)-9-tetradecenol. Among short sensilla, one hair responded to compound4 and could represent a minor sensillar type. No sensory neuron was found to detect the other minor pheromone compounds2, 3, and5.

Hypoxia-inducible factor (HIF) 1α and 2α as predictive markers of outcome to VEGFR tyrosine kinase inhibitors (TKI) in renal cell carcinoma (RCC)

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Background: Relevant biomarkers in RCC are needed to identify appropriate candidates for selected targeted therapies. Mutations in the von Hippel-Lindau (VHL) gene result in the accumulation of HIF and increased expression of proangiogenic factors, including VEGF. Methods: Metastatic clear RCC patients with available baseline tumor samples who received first-line oral VEGFR-TKI were included in this analysis. VHL mutation/hypermethylation status and HIF1α and HIF2α immunohistochemical staining were analyzed from paraffin-embedded tumors. Additionally, a panel of candidate VEGF and VEGFR2 genetic SNPs was determined from peripheral blood samples. HIF was scored as negative or positive based on staining intensity (0-10% and > 10%, respectively). Results were evaluated for associations with clinical outcome. Results: 80 patients were included: 71 evaluable for HIF expression, 63 for VHL status and 52 for SNPs. 73% received treatment with sunitinib and median follow-up was 21.5 months. Unlike VHL status, HIF1 and HIF2 positive expression showed a significant correlation with PFS and OS. HIF1α was also predictive for response rate (RR). On multivariate analysis adjusting for other prognostic factors, HIF1α and HIF2α remained the most significant independent predictive factors for survival (adjusted HR 0.09, 95% CI 0.03-0.28, p < 0.0001 and HR 0.13, 95% CI 0.04-0.37, p < 0.0001; respectively). We did not find any statistically significant differences based on the VEGF and VEGFR2 SNPs analyzed. Conclusions: HIF1α and HIF2α levels represent the most important independent predictive factors of outcome for VEGFR-TKI therapy in metastatic RCC. These findings may contribute to optimize treatment with targeted agents. [Table: see text]

Prognostic value of immunohistochemical phenotypes (IP) of 141 operable breast cancer patients (pts) included in phase III trials of adjuvant therapy

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Background: Gene expression arrays and IP studies classified breast cancer in three distinct subtypes: basal, HER2/neu and luminal that are associated with different clinical outcomes. Methods: In 141 pts with operable breast cancer, included in phase III trials of adjuvant therapy in our center, immunohistochemical staining was performed on 3μm sections of paraffin blocks, containing tissue-arrays of tumour tissue.A basal phenotype (BP) was defined by negative estrogen receptor (ER) and progesterone receptor (PR) and positive cytokeratin (CK) 5/6 or EGFR immunoreactivity. HER2/neu phenotype as positive c-erb B2 by HercepTest™ and luminal phenotype (LP) by positive ER, PR and CK 7/8 and negative HER-2. Survival curves were calculated by the Kaplan-Meier method. The differences between survivals were estimated using the log rank test. Multivariate Cox regression analysis was used to evaluate any independent prognostic effect of the variables on disease-free survival (DFS). Results: Complete clinical follow-up information was available for 141 pts. The median follow-up period was 52 months (range 1–103 months). During this period, 13.8% pts died from breast cancer and 27.7% pts relapsed. At the time of the primary diagnosis 10.4% of the pts had lymph node negative disease and 89.6% had positive lymph nodes. 50.8% pts received taxane chemotherapy, 7.7% Trastuzumab, 62.3% radiotherapy and 61% pts received hormonotherapy. Positivity for LP was 65.2%, BP 9.9% and Her-2 phenotype 8.5%. 16.3% didn't fit for any of the three subtypes. Median DFS for BP: 24 moths, for LP and Her-2 phenotypes median DFS was not reached. 5 years DFS were; BP: 19%, LP: 63% and Her-2: 56%. Kaplan-Meier survival analyses demonstrated that the presence of a detectable BP was highly significantly associated with a worse DFS compared with the presence of a LP, log rank test (p= 0.0001). Multivariate Cox regression analyses estimated that the prognostic effect of BP in relation to DFS was independent of lymph node, stage and tumor size, HR: 0.12 95% CI (0.05–0.2). Conclusions: We found that expression of BP was associated with poor prognostic in the context of randomized phase III trials.

No significant financial relationships to disclose.

Inheritance of olfactory preferences II. Olfactory receptor neuron responses from Heliothis subflexa x Heliothis virescens hybrid male moths

Single-cell electrophysiological recordings were obtained from olfactory receptor neurons (ORNs) in sensilla trichodea on male antennae of hybrids formed mainly by crossing female Heliothis subflexa with male Heliothis virescens ('SV hybrids'). We recorded from the A-, B-, and C-type sensilla trichodea, with the latter two types housing ORNs exhibiting response profiles to different pheromone components that we had previously found to be characteristic for each species. For both the B- and the C-type SV hybrid sensilla, most of the ORNs exhibited a spike amplitude and ORN co-compartmentalization within sensilla that more strongly resembled the ORNs of parental H. subflexa rather than those of H. virescens. The overall mean dose-response profiles of the ORNs in hybrid C- and B-type sensilla were intermediate between those of the H. virescens and H. subflexa parental type ORNs. However, not all hybrid ORNs were intermediate in their tuning spectra, but rather ranged from those that closely resembled H. subflexa or H. virescens parental types to those that were intermediate, even on the same antenna. The most noteworthy shift in ORN responsiveness in hybrid males was an overall increase in sensitivity to Z9-14:Ald exhibited by Z9-16:Ald-responsive ORNs. Heightened cross-responsiveness to Z9-14:Ald by hybrid ORNs correlates well with observed behavioral cross-responsiveness of hybrids in which Z9-14:Ald could substitute for Z9-16:Ald in the pheromone blend, a behavior not observed in parental types. The hybrid ORN shifts involving greater sensitivity to Z9- 14:Ald also correlate well with studies of hybrid male antennal lobe interneurons that exhibited a shift toward greater cross-responsiveness to Z9-14:Ald and Z9- 16:Ald. We propose that the differences between parental H. virescens, H. subflexa, and SV hybrid male pheromone ORN responsiveness to Z9-16:Ald and Z9-14:Ald are most logically explained by an increased or decreased co-expression of two different odorant receptors for each of these compounds on the same ORN.

ERK1/2 is activated in non-small-cell lung cancer and associated with advanced tumours

Activation of the ERK1/2 pathway is involved in malignant transformation both in vitro and in vivo. Little is known about the role of activated ERK1/2 in non-small cell lung cancer (NSCLC). The purpose of this study was to characterise the extent of the activation of ERK1/2 by immunohistochemistry in patients with NSCLC, and to determine the relationship of ERK1/2 activation with clinicopathological variables. Specimens from 111 patients with NSCLC (stages I-IV) were stained for P-ERK. Staining for epidermal growth factor receptor (EGFR) and Ki-67 was also performed. In all, 34% of the tumour specimens showed activation for ERK1/2, while normal lung epithelial tissue was consistently negative. There was a strong statistical correlation between nuclear and cytoplasmic P-ERK staining and advanced stages (P<0.05 and P<0.001, respectively), metastatic hilar or mediastinal lymph nodes (P<0.01, P<0.001), and higher T stages (P<0.01, P<0.001). We did not find correlation of nuclear or cytoplasmic P-ERK staining with either EGFR expression or Ki-67 expression. Total ERK1/2 expression was evaluated with a specific ERK1/2 antibody and showed that P-ERK staining was not due to ERK overexpression but rather to hyperactivation of ERK1/2. Patients with a positive P-ERK cytoplasmic staining had a significant lower survival (P<0.05). However, multivariate analysis did not show significant survival difference. Our study indicates that nuclear and cytoplasmic ERK1/2 activation positively correlates with stage, T and lymph node metastases, and thus, is associated with advanced and aggressive NSCLC tumours.

A comparison of responses from olfactory receptor neurons of Heliothis subflexa and Heliothis virescens to components of their sex pheromone

Single-cell electrophysiological recordings were obtained from olfactory receptor neurons in sensilla trichodea on male antennae of the heliothine species Heliothis subflexa and the closely related congener H. virescens. A large percentage of sensilla (72% and 81%, respectively, of all sensilla sampled) contained a single odor-responsive receptor neuron tuned to the major pheromone component of both species, Z-11-hexadecenal. A second population of sensilla on H. subflexa antennae (18%) housed receptor neurons that were tuned to Z-9-hexadecenal but also responded with less sensitivity to Z-9-tetradecenal. A similar population of sensilla (4%) on H. virescens male antennae housed receptor neurons that were shown to be tuned specifically only to Z-9-tetradecenal, with no response to even high dosages of Z-9-hexadecenal. A third population of sensilla (comprising 8% and 16% of the sensilla sampled in H. subflexa and H. virescens, respectively) housed two olfactory receptor neurons, one of which was tuned to Z-11-hexadecenyl acetate and the other tuned to Z-11-hexadecenol. In H. subflexa the Z-11-hexadecenyl acetate-tuned neuron also responded to Z-9-tetradecenal with nearly equivalent sensitivity. The behavioral requirements of males of these two species for distinct pheromonal blends was, therefore, reflected by the subtle differences in the tuning properties of antennal olfactory receptor neurons.

[Von Willebrand factor as an intermediate between hemostasis and angiogenesis of tumor origin]

Cancer patients often show an imbalance condition between coagulation system and fibrinolysis which causes a prothrombotic state. Different molecular factors like von Willebrand factor (vWf), presenting higher plasmatic rates in these patients, play an important role in this situation. During active angiogenesis taking place in tumor growth, the vascular endothelial growth factor (VEGF) and the fibroblast growth factor (FGF-2) contribute to the proliferation and differentiation of endothelial tissue, the main vWf producer, promoting increased rates of vWf in the serum of neoplastic patients. Recently vWf's contribution to tumor cells and platelet adhesion has been described. In this process, the discovery of platelet, endothelial and tumor cell membrane integrins and their implication in cellular adhesion has represented a major step in demonstrating how blood clotting and platelet aggregation are mediated by tumor cell and platelet linkage. Migration properties acquired by tumor cells as a result of this binding have been also pointed out. Clinical trials show higher rates of plasmatic vWf in cancer patients the more advanced clinical and radiological stage they present (metastasic versus localized). Moreover, higher pre-surgical serum vWf rates in patients can be used to predict poorer survival after resection surgery. vWf high molecular weight multimers have been also related to a cleavage protease deficiency in the serum of the oncologic population. The promising results of antiaggregation/anticoagulation therapies in these patients permit us to envisage new therapeutic targets.

Control of the biosynthetic pathway of Sesamia nonagrioides sex pheromone by the pheromone biosynthesis activating neuropeptide

(Z)-11-Hexadecenyl acetate, the main pheromone component of Sesamia nonagrioides sex pheromone, is biosynthesized from palmitic acid by Delta(11)-desaturation followed by reduction and acetylation. Production of (Z)-11-hexadecenyl acetate is regulated by the Pheromone Biosynthesis Activating Neuropeptide (PBAN). Transformation of (Z)-11-hexadecen-1-ol into the corresponding acetate is a target step for PBAN in the regulation of this biosynthetic sequence, thus being the first example of a PBAN-activated acetylation. The production of the minor component (Z)-11-hexadecenal is also stimulated by PBAN. The usefulness of pentafluorobenzyloxime-derivatives for the analysis of aldehyde pheromone constituents by gas chromatography coupled to mass spectrometry is also reported.

Ethyl-2-cyanoacrylate fixation of the cranial bone flap after craniotomy

BACKGROUND

This procedure was done in order to evaluate the efficacy and safety of ethylcyanoacrylate as an adhesive for fixation of the bone flap.

METHODS

One hundred consecutive craniotomies in patients older than 16 years in which the bone flap was fixed with ethyl-2-cyanoacrylate were studied. The osteosynthesis and any complications in all cases were followed clinically and radiologically for 3 months.

RESULTS

Clinical and radiographic observation demonstrated that osteosynthesis was produced in 100% of the cases with no complications related to this procedure.

CONCLUSION

This technique proved to be safe, fast, and easy to accomplish, with immediate stability of the bone flap and excellent cosmetic results.

Delayed clearance of serum HBsAg in compensated cirrhosis B: relation to interferon alpha therapy and disease prognosis. European Concerted Action on Viral Hepatitis (EUROHEP)

OBJECTIVE

The aim of this study was to evaluate the incidence, prognostic factors and clinical significance of delayed clearance of serum HBsAg in compensated cirrhosis B.

METHODS

This was a retrospective cohort study of 309 consecutive white patients with biopsy-proved compensated cirrhosis type B.

RESULTS

During a mean follow-up of 68 months, HBsAg loss occurred in 32 patients, including 16 (8%) of 196 untreated patients (mean annual incidence 0.8%), 8 (10%) of 82 interferon (IFN) alpha-treated patients and eight patients who had been treated with other antivirals or steroids. The 5-yr probability of HBsAg loss was 4% and 16% for untreated and IFN-treated patients, respectively (p = 0.0001). Cox's regression analysis identified hepatitis B e antigen-positivity at entry as the sole independent prognostic factor for HBsAg loss. Of the 32 patients who lost HBsAg, one (3%) subsequently developed hepatocellular carcinoma (HCC) and died, whereas, among the patients who remained HBsAg-positive, 11% developed HCC and 20% had died. The probability of HCC appearance was lower (p = 0.0137) and survival was longer (p = 0.0006) in patients who cleared HBsAg compared with patients with HBsAg persistence.

CONCLUSION

The incidence of HBsAg loss is about 0.8% in cirrhosis type B. Prognostic factors for clearance of HBsAg are initial HBeAg positivity and therapy with alpha interferon. Patients with cirrhosis type B, who lose HBsAg, have a low risk for liver cancer or liver-related death.

Effects of trifluoromethyl ketones and related compounds on the EAG and behavioural responses to pheromones in male moths

Trifluoromethyl ketones (TFMKs) and analogues affect pheromone detection and behaviour in male moths. 3-Octylthio-1,1,1-trifluoropropan-2-one (OTFP), one of the most effective antiesterase agents, decreased the EAG amplitude and increased the repolarization time in Spodoptera littoralis. It also modified EAG responses of Mamestra brassicae and Heliothis zea to their pheromones and analogues, containing an acetate, an alcohol or an aldehyde function. In addition, OTFP also reduced the amplitude of the EAG response to linalool, a monoterpenic alcohol, but not its kinetics. The responses of male S. littoralis to the pheromone in the wind tunnel were significantly reduced after pre-exposure to vapours of OTFP. Comparison of the activity of other TFMKs and analogues with that of OTFP revealed a good agreement on EAG and behaviour. The effects of TFMKs on the EAG kinetics are discussed considering the hypothesis of an inhibition of the pheromone deactivation in the antenna.

Different effects of amiodarone on transport of T4 and T3 into the perfused rat liver

Uptake and metabolism of thyroxine (T4) and 3,5,3'-triiodothyronine (T3) were studied in isolated perfused livers of control and amiodarone-treated rats (40 mg.kg body wt-1.day-1, 22 days). With the use of this perfusion system and a two-pool model describing thyroid hormone kinetics, total uptake was evaluated by the half-time (t1/2) of the fast component of the biphasic thyroid hormone disappearance from the medium and by the fractional influx rate constant (k21). Metabolism was assessed by the t1/2 of the slow component, by determination of breakdown products in medium and bile, and by thyroid hormone disposal according to the two-pool model. Disposal was corrected for differences in mass transfer into the metabolizing pool. In amiodarone-treated rats, both uptake and metabolism of T4 were decreased. Furthermore, it was shown that only transport into the metabolizing liver compartment and not uptake into the nonmetabolizing liver compartment was decreased. Both uptake and total metabolism of T3 were unaffected by amiodarone. The results showed that the different transport systems for T4 and T3 described in isolated rat hepatocytes may also be operative in the intact rat liver. Furthermore, it can be concluded that the low-T3 syndrome, caused by treatment with amiodarone, may be due to both impaired transport and impaired 5'-deiodination.