Safety Assessment of L-ß-Aminoisobutyric Acid (L-BAIBA): Subchronic Toxicity Study in Sprague Dawley Rats.

L-3-Aminoisobutyric acid (L-BAIBA) is an endogenous compound in human metabolism when thymine and valine undergo catabolism. L-BAIBA represents one of the two isomers of BAIBA in biological systems. BAIBA has been shown to reduce body fat percentage via an increase in fatty acid oxidation and a decrease in hepatic lipogenesis. However, no toxicological effects of L-BAIBA in animals or humans have been established. The present study was designed to evaluate the safety and toxic potentials of this compound, where L-BAIBA was administered orally to Sprague Dawley rats at 100, 300, and 900 mg/kg/day for 90 days. No treatment-related adverse effects were observed in any of the treatment groups. Based on the results, the No-Observed-Adverse-Effect Level (NOAEL) of L-BAIBA was 900 mg/kg/day.

Non-pharmacologic direct cost of a simplified strategy with glecaprevir/pibrentasvir for 8 weeks in naïve non-cirrhotic patients with hepatitis C implemented in clinical practice. The Just SIMPLE Study.

BACKGROUND AND OBJECTIVE: The emergence of highly tolerable, effective, and shorter duration direct-acting antivirals (DAAs) regimens offers the opportunity to simplify hepatitis C virus management but medical costs are unknown. Thus, we aimed to determine the direct medical costs associated with a combo-simplified strategy (one-step diagnosis and low monitoring) to manage HCV infection within an 8-week glecaprevir/pibrentasvir (GLE/PIB) regimen in clinical practice in Spain. PATIENTS AND METHODS: Healthcare resources and clinical data were collected retrospectively from medical charts of 101 eligible patients at 11 hospitals. Participants were adult, treatment naïve subjects with HCV infection without cirrhosis in whom a combo-simplified strategy with GLE/PIB for 8 weeks were programmed between Apr-2018 and Nov-2018. RESULTS: The GLE/PIB effectiveness was 100% (CI95%: 96.2-100%) in the mITT population and 94.1% (CI95%: 87.5-97.8%) in the ITT population. Three subjects discontinued the combo-simplified strategy prematurely, none of them due to safety reasons. Five subjects reported 8 adverse events, all of mild-moderate intensity. Combo-simplified strategy mean direct costs were 754.35±103.60€ compared to 1689.42€ and 2007.89€ of a theoretical 12-week treatment with 4 or 5 monitoring visits, respectively; and 1370.95€ and 1689.42€ of a theoretical 8-week with 3 or 4 monitoring visits, respectively. Only 4.9% of the subjects used unexpected health care resources. CONCLUSIONS: 8-week treatment with GLE/PIB combined with a combo simplified strategy in real-life offers substantial cost savings without affecting the effectiveness and safety compared to traditional approaches.

Cost-effectiveness analysis of glecaprevir/pibrentasvir regimen for treating Chinese patients with chronic hepatitis C genotype 1 and genotype 2 infection.

BACKGROUND: Hepatitis C virus (HCV) infection is an important health threat in China to which direct acting antivirals (DAAs) are very effective. In 2019, another novel DAA glecaprevir/pibrentasvir (GLE/PIB) was officially approved. Knowledge of its cost-effectiveness would be informative for clinical decision-making but has not been evaluated. This study aims to evaluate the cost-effectiveness of GLE/PIB to inform policy-making on drug reimbursement and HCV eradication. METHODS: Markov models were developed from the payers' perspective and simulated the lifetime experience of adult patients chronically infected with HCV genotype 1 or genotype 2. Two regimens, GLE/PIB and pegylated interferon (pegIFN) plus ribavirin (RBV), were compared in cost and quality adjusted life years (QALY) with both outcomes being discounted to 2020 values. The incremental cost-effectiveness ratio (ICER) was computed to reflect the incremental benefit of GLE/PIB versus pegIFN + RBV. The robustness of the model outcomes was examined using deterministic and probabilistic sensitivity analysis (PSA) to identify influential parameters and to assess the probability of GLE/PIB being cost-effective. The GDP per capita in China in 2019 ($10,275) was used as the threshold for cost-effectiveness. RESULTS: For the entire target population, GLE/PIB was the dominant regimen attaining a cost-saving of $255 and 1.17 more QALYs relative to pegIFN + RBV. The finding was more pronounced for HCV genotype 1 infection by saving $1,656 and creating 1.37 more QALYs. At the $10,275 threshold, the probability of GLE/PIB being cost-effective was 99.32% overall and 99.85% for HCV genotype 1 infection. The age of starting DAA treatment, price of pegIFN + RBV, cost of cirrhosis treatment and duration of the GLE/PIB regimen were the five most influential factors. For the patients with HCV genotype 2 infection, the ICER of GLE/PIB was $12,914/QALY with 95% confidence interval of $4,047/QALY to $37,640/QALY. The GLE/PIB regimen statistically cannot be ruled out as a cost-effective option for HCV genotype 2 infection. CONCLUSIONS: GLE/PIB is a cost-effective strategy to treat chronic HCV genotype 1 and HCV genotype 2 infection in China. This regimen should be initiated at a younger age to maximize its value. To achieve national eradication, it may be timely to consider replacing pegIFN + RBV with DAAs, such as GLE/PIB, as the first-line treatment.

A Cost-Effectiveness Analysis of Glecaprevir/Pibrentasvir Versus Existing Direct-Acting Antivirals to Treat Chronic Hepatitis C in Japan.

INTRODUCTION: The objective of the study was to evaluate the cost-effectiveness of glecaprevir/pibrentasvir versus other direct-acting antivirals (DAAs) for treating chronic hepatitis C virus (HCV) infections in Japan. METHODS: We developed a health state transition model to capture the natural history of HCV. A cost-effectiveness analysis of DAAs from the perspective of a public healthcare payer in Japan with a lifetime horizon over annual cycles was performed. Treatment attributes, baseline demographics, transition probabilities, health-state utilities, and costs data were extracted from publications. Costs and outcomes were discounted at 2% per annum. In the base case we focused on genotype 1 (GT1) treatment-naïve patients without cirrhosis. The scenario analysis examined a pan-genotype treatment in GT1-3 (i.e., portfolio), treatment-naïve, and treatment-experienced patients. The portfolio cost-effectiveness of DAAs was derived by calculating a weighted average of patient segments defined by treatment history, cirrhosis status, and genotype. RESULTS: The base case results indicated that glecaprevir/pibrentasvir was dominant (i.e., generating higher quality-adjusted life years [QALYs] and lower lifetime costs) compared to all other DAAs. The predicted lifetime risk of hepatocellular carcinoma was 3.66% for glecaprevir/pibrentasvir and sofosbuvir/ledipasvir, 4.99% for elbasvir/grazoprevir, and 5.27% for daclatasvir/asunaprevir/beclabuvir. In scenario analysis the glecaprevir/pibrentasvir (GLE/PIB) portfolio dominated the sofosbuvir (SOF)-based portfolio (namely sofosbuvir/ledipasvir in GT1-2 and sofosbuvir + ribavirin in GT3). The base case probabilistic sensitivity analysis (PSA) showed that glecaprevir/pibrentasvir was cost-effective in 93.4% of the simulations for a willingness-to-pay/QALY range of Japanese yen (JPY) 1.6-20 million. The PSA for the portfolio scenario indicated that the GLE/PIB portfolio was cost-effective in 100% of simulations until the willingness-to-pay/QALY reached JPY 5.2 million; this proportion decreased to 69.4% at a willingness-to-pay/QALY of JPY 20 million. Results were also robust in deterministic sensitivity analyses. CONCLUSION: In GT1 treatment-naïve non-cirrhotic patients GLE/PIB was a cost-effective strategy compared to other DAAs. When a pan-genotypic framework was used, the GLE/PIB portfolio dominated the SOF-based portfolio.

A Cost-Effectiveness Analysis of Shortened Direct-Acting Antiviral Treatment in Genotype 1 Noncirrhotic Treatment-Naive Patients With Chronic Hepatitis C Virus.

BACKGROUND: Direct-acting antivirals are successful in curing hepatitis C virus infection in more than 95% of patients treated for 12 weeks, but they are expensive. Shortened treatment durations, which may have lower cure rates, have been proposed to reduce costs. OBJECTIVES: To evaluate the lifetime cost-effectiveness of different shortened treatment durations for genotype 1 noncirrhotic treatment-naive patients. METHODS: Assuming a UK National Health Service perspective, we used a probabilistic decision tree and Markov model to compare 3 unstratified shortened treatment durations (8, 6, and 4 weeks) against a standard 12-week treatment duration. Patients failing shortened first-line treatment were re-treated with a 12-week treatment regimen. Parameter inputs were taken from published studies. RESULTS: The 8-week treatment duration had an expected incremental net monetary benefit of £7737 (95% confidence interval £3242-£11 819) versus the standard 12-week treatment, per 1000 patients. The 6-week treatment had a positive incremental net monetary benefit, although some uncertainty was observed. The probability that the 8- and 6-week treatments were the most cost-effective was 56% and 25%, respectively, whereas that for the 4-week treatment was 17%. Results were generally robust to sensitivity analyses, including a threshold analysis that showed that the 8-week treatment was the most cost-effective at all drug prices lower than £40 000 per 12-week course. CONCLUSIONS: Shortening treatments licensed for 12 weeks to 8 weeks is cost-effective in genotype 1 noncirrhotic treatment-naive patients. There was considerable uncertainty in the estimates for 6- and 4-week treatments, with some indication that the 6-week treatment may be cost-effective.

Glecaprevir/pibrentasvir expands reach while reducing cost and duration of hepatitis C virus therapy.

Hepatitis C virus (HCV) treatments have dramatically progressed from poorly tolerated, moderately successful interferon-based therapies to highly effective all-oral interferon-free regimens. While sustained virologic responses have significantly improved with fixed-dose combinations (FDC) of these direct-acting antivirals (DAA), cost remains high and certain populations of patients remain difficult to treat. Glecaprevir (GLE, an NS3/4A protease inhibitor) and pibrentasvir (PIB, NS5A inhibitor) were recently approved as a FDC therapy for HCV, and have expanded reach, reduced cost, and in certain populations, reduced HCV treatment duration. GLE/PIB is effective across all genotypes, and has been shown to be effective in HIV-infected patients, patients with chronic kidney disease, and Child-Pugh A-compensated cirrhosis. GLE/PIB is also effective for a shortened duration of 8 weeks in treatment-naive non-cirrhotic patients.

Benefit-risk assessment for sofosbuvir/velpatasvir/voxilaprevir based on patient population and hepatitis C virus genotype: U. S. Food and Drug Administration's evaluation.

On July 18, 2017, the U.S. Food and Drug Administration (FDA) approved sofosbuvir/velpatasvir/voxilaprevir (SOF/VEL/VOX) (Vosevi) fixed-dose combination (FDC), an interferon-free, complete regimen for adult patients with chronic hepatitis C virus (HCV) infection without cirrhosis or with compensated cirrhosis (Child-Pugh A) who have: • genotype 1, 2, 3, 4, 5, or 6 infection and have previously been treated with an HCV regimen containing a nonstructural protein 5A (NS5A) inhibitor; and • genotype 1a or 3 infection and have previously been treated with an HCV regimen containing sofosbuvir without an NS5A inhibitor. Approval was based on an acceptable safety profile and high sustained virological response rates 12 weeks after the end of treatment (SVR12) in two phase 3 clinical trials in subjects previously treated with a direct-acting antiviral (DAA) regimen. In POLARIS-1, 96% of SOF/VEL/VOX-treated subjects achieved SVR12. In POLARIS-4, 98% of SOF/VEL/VOX-treated subjects achieved SVR12. A key and challenging question in evaluating the data was determining the contribution of VOX to SOF/VEL and how this differed depending on the genotype and patient population. In this article, we provide our perspective on the issues considered in making these determinations, especially regarding the POLARIS-4 data in subjects who have previously been treated with a chronic HCV regimen containing sofosbuvir without an NS5A inhibitor. Conclusion: We seek to provide context as to why a broad indication was given for NS5A inhibitor-experienced patients (HCV genotypes 1-6) while the indication for NS5A inhibitor- naïve patients was limited to HCV genotypes 1a and 3 only. (Hepatology 2018;67:482-491).

HCV management in resource-constrained countries.

With the arrival of all-oral directly acting antiviral (DAA) therapy with high cure rates, the promise of hepatitis C virus (HCV) eradication is within closer reach. The availability of generic DAAs has improved access to countries with constrained resources. However, therapy is only one component of the HCV care continuum, which is the framework for HCV management from identifying patients to cure. The large number of undiagnosed HCV cases is the biggest concern, and strategies to address this are needed, as risk factor screening is suboptimal, detecting <20% of known cases. Improvements in HCV confirmation through either reflex HCV RNA screening or ideally a sensitive point of care test are needed. HCV notification (e.g., Australia) may improve diagnosis (proportion of HCV diagnosed is 75%) and may lead to benefits by increasing linkage to care, therapy and cure. Evaluations for cirrhosis using non-invasive markers are best done with a biological panel, but they are only moderately accurate. In resource-constrained settings, only generic HCV medications are available, and a combination of sofosbuvir, ribavirin, ledipasvir or daclatasvir provides sufficient efficacy for all genotypes, but this is likely to be replaced with pangenetypic regimens such as sofosbuvir/velpatasvir and glecaprevir/pibrentaasvir. In conclusion, HCV management in resource-constrained settings is challenging on multiple fronts because of the lack of infrastructure, facilities, trained manpower and equipment. However, it is still possible to make a significant impact towards HCV eradication through a concerted effort by individuals and national organisations with domain expertise in this area.

Multidimensional Langevin Modeling of Nonoverdamped Dynamics.

Based on a given time series, data-driven Langevin modeling aims to construct a low-dimensional dynamical model of the underlying system. When dealing with physical data as provided by, e.g., all-atom molecular dynamics simulations, effects due to small damping may be important to correctly describe the statistics (e.g., the energy landscape) and the dynamics (e.g., transition times). To include these effects in a dynamical model, an algorithm that propagates a second-order Langevin scheme is derived, which facilitates the treatment of multidimensional data. Adopting extensive molecular dynamics simulations of a peptide helix, a five-dimensional model is constructed that successfully forecasts the complex structural dynamics of the system. Neglect of small damping effects, on the other hand, is shown to lead to significant errors and inconsistencies.

Experimental assessment of gold nanoparticle-mediated dose enhancement in radiation therapy beams using electron spin resonance dosimetry.

In this work, we aim to experimentally assess increments of dose due to nanoparticle-radiation interactions via electron spin resonance (ESR) dosimetry performed with a biological-equivalent sensitive material.We employed 2-Methyl-Alanine (2MA) in powder form to compose the radiation sensitive medium embedding gold nanoparticles (AuNPs) 5 nm in diameter. Dosimeters manufactured with 0.1% w/w of AuNPs or no nanoparticles were irradiated with clinically utilized 250 kVp orthovoltage or 6 MV linac x-rays in dosimetric conditions. Amplitude peak-to-peak (App) at the central ESR spectral line was used for dosimetry. Dose-response curves were obtained for samples with or without nanoparticles and each energy beam. Dose increments due to nanoparticles were analyzed in terms of absolute dose enhancements (DEs), calculated as App ratios for each dose/beam condition, or relative dose enhancement factors (DEFs) calculated as the slopes of the dose-response curves.Dose enhancements were observed to present an amplified behavior for small doses (between 0.1-0.5 Gy), with this effect being more prominent with the kV beam. For doses between 0.5-5 Gy, dose-independent trends were observed for both beams, stable around (2.1 ± 0.7) and (1.3 ± 0.4) for kV and MV beams, respectively. We found DEFs of (1.62 ± 0.04) or (1.27 ± 0.03) for the same beams. Additionally, we measured no interference between AuNPs and the ESR apparatus, including the excitation microwaves, the magnetic fields and the paramagnetic radicals.2MA was demonstrated to be a feasible paramagnetic radiation-sensitive material for dosimetry in the presence of AuNPs, and ESR dosimetry a powerful experimental method for further verifications of increments in nanoparticle-mediated doses of biological interest. Ultimately, gold nanoparticles can cause significant and detectable dose enhancements in biological-like samples irradiated at both kilo or megavoltage beams.

Preclinical assessment of early tumor response after irradiation by positron emission tomography with 2-amino-[3-¹¹C]isobutyric acid.

The positron emission tomography (PET) probe, 2-amino-[3-¹¹C]isobutyric acid ([3-¹¹C]AIB), is reported to accumulate less in inflammatory lesions than 2-deoxy-2-[¹8F]fluoro-D-glucose ([¹8F]FDG) and has the potential for evaluation of the efficacy of radiotherapy. To determine whether [3-¹¹C]AIB is useful to monitor early metabolic change in tumors after radiotherapy, we evaluated the temporal change in [3-¹¹C]AIB tumor uptake, tumor volume, histological features and expression of amino acid transporters early after radiotherapy in a mouse tumor model. PET with [3-¹¹C]AIB was conducted in mice bearing a subcutaneous tumor (SY, derived from small cell lung cancer) in two schedules: schedule 1, before (day -1) and after (days 1 and 3) 15 Gy of radiation and schedule 2, days -1, 1 and 5. [3-¹¹C]AIB tumor uptake tended to increase on day 1 after irradiation and decreased thereafter. Tumor uptake was not correlated with tumor volume in schedule 1. Although tumor uptake was correlated with tumor volume in schedule 2, this correlation was lost when the day 5 data of greatly reduced tumor volumes were excluded. In a separate group of tumor-bearing mice, excised tumor sections were stained with terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) or anti-Ki-67 antibody. There was no correlation between tumor uptake and percentages of TUNEL- or Ki-67-positive cells. Expression of amino acid transporters, SLC38A1, SLC38A2 and SLC38A4, was determined by real-time RT-PCR. SLC38A1 and SLC38A2 were expressed in SY tumors, and a significant correlation was observed between [3-¹¹C]AIB tumor uptake and SLC38A1 expression. In conclusion, early change in [3-¹¹C]AIB tumor uptake after irradiation reflected the temporal change in amino acid transporter expression, while it was independent of change in tumor volume, apoptosis and cell proliferation. PET with [3-¹¹C]AIB has the potential for use in non-invasive evaluation of early metabolic change after irradiation before morphological change of tumors.

Clinical assessment of potential drug interactions of faldaprevir, a hepatitis C virus protease inhibitor, with darunavir/ritonavir, efavirenz, and tenofovir.

BACKGROUND: Faldaprevir is a potent, once-daily hepatitis C virus (HCV) NS3/4A protease inhibitor. Studies were performed to investigate potential drug interactions between faldaprevir and the commonly used antiretrovirals darunavir/ritonavir, efavirenz, and tenofovir to guide the coadministration of faldaprevir with these agents in human immunodeficiency virus/HCV-coinfected patients. METHODS: In 3 open-label, phase 1 pharmacokinetic (PK) studies, healthy adult volunteers received (1) darunavir/ritonavir (800 mg/100 mg once daily) with and without faldaprevir (240 mg once daily); (2) faldaprevir (240 mg twice daily) with and without efavirenz (600 mg once daily); or (3) faldaprevir (240 mg twice daily) or tenofovir (300 mg once daily) alone and in combination. To assess potential drug interactions, geometric mean ratios and 90% confidence intervals for PK parameters were calculated. Safety was evaluated. RESULTS: Efavirenz decreased faldaprevir area under the concentration-time curve (AUC) by 35%, Cmax by 28%, and Cmin by 46%, consistent with induction of CYP3A by efavirenz. Tenofovir decreased faldaprevir AUC by 22%, which was not considered to be clinically relevant. Faldaprevir had no clinically relevant effects on darunavir or tenofovir PK (15% and 22% AUC increase, respectively). Adverse events were consistent with the known safety profiles of faldaprevir and the antiretrovirals being examined. CONCLUSIONS: No clinically significant interactions were observed between faldaprevir and darunavir/ritonavir or tenofovir. A potentially clinically relevant decrease in faldaprevir exposure was observed when coadministered with efavirenz; this decrease can be managed using the higher of the 2 faldaprevir doses tested in phase 3 trials (240 mg once daily as opposed to 120 mg once daily).

Minimum costs for producing hepatitis C direct-acting antivirals for use in large-scale treatment access programs in developing countries.

BACKGROUND: Several combinations of 2 or 3 direct-acting antivirals (DAAs) can cure hepatitis C virus (HCV) in the majority of treatment-naive patients. DAAs for HCV infection have similar mechanisms of action and chemical structures to antiretrovirals for human immunodeficiency virus (HIV) infection. Generic antiretrovirals are currently manufactured at very low prices, to treat 10 million people with HIV/AIDS in developing countries. METHODS: Four HCV DAAs, currently either in phase 3 development or recent approval (daclatasvir, sofosbuvir, simeprevir, faldaprevir), and ribavirin were classified by chemical structure, molecular weight, total daily dose, and complexity of synthesis. The likely range of manufacturing costs per gram of DAA were then projected as formulated product cost, based upon treating a minimum of 1 million patients annually (to arrive at volume demand) combined with an analysis of the complexity of synthesis and a 40% margin for formulation. Projections were then compared with actual costs of antiretrovirals with similar structures. RESULTS: Minimum manufacturing costs of antiretrovirals were US$0.2-$2.1 per gram. The complexity of chemical synthesis for HCV DAAs was ranked from lowest to highest: ribavirin, daclatasvir, sofosbuvir, faldaprevir, and simeprevir. Predicted manufacturing costs (US dollars) for 12-week courses of HCV DAAs were $21-$63 for ribavirin, $10-$30 for daclatasvir, $68-$136 for sofosbuvir, $100-$210 for faldaprevir, and $130-$270 for simeprevir. CONCLUSIONS: Within the next 15 years, large-scale manufacture of 2 or 3 drug combinations of HCV DAAs is feasible, with minimum target prices of $100-$250 per 12-week treatment course. These low prices could make widespread access to HCV treatment in low- and middle-income countries a realistic goal.

HCV F1/F2 patients: treat now or continue to wait.

The treatment of chronic HCV is evolving rapidly. In 2014, three new oral antiviral agents, simeprevir, faldeprevir and sofosbuvir will become available for patients with HCV genotype 1. These agents have far less side effects than the first generation protease inhibitors telaprevir and boceprevir. Treatment will therefore be easier for patients to tolerate but still require peginterferon and ribavirin (PEGINF/RBV). The first IFN free therapy, sofosbuvir (SOF) and ribavirin (RBV), will also become available in 2014. This treatment is highly effective for patients with HCV genotype 2. However, SVR rates with SOF/RBV appear to be similar to that achieved with PEGINF/RBV in patients with HCV genotype 3. The first IFN-free all oral antiviral therapy combination for patients with HCV genotype 1 may be available late in 2014 or early 2015. The factors which should be considered when deciding whether to treat a patient with HCV now or to delay treatment until IFN free therapies are available is discussed.

An assessment of the role of ethylene in mediating lettuce (Lactuca sativa) root growth at high temperatures.

Growth of temperate lettuce (Lactuca sativa) plants aeroponically in tropical greenhouses under ambient root-zone temperatures (A-RZTs) exposes roots to temperatures of up to 40 degrees C during the middle of the day, and severely limits root and shoot growth. The role of ethylene in inhibiting growth was investigated with just-germinated (24-h-old) seedlings in vitro, and 10-d-old plants grown aeroponically. Compared with seedlings maintained at 20 degrees C, root elongation in vitro was inhibited by 39% and root diameter increased by 25% under a temperature regime (38 degrees C/24 degrees C for 7 h/17 h) that simulated A-RZT in the greenhouse. The effects on root elongation were partially alleviated by supplying the ethylene biosynthesis inhibitors aminooxyacetic acid (100-500 microM) or aminoisobutyric acid (5-100 microM) to the seedlings. Application of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid to seedlings grown at 20 degrees C mimicked the high temperature effects on root elongation (1 microM) and root diameter (1 mM). Compared with plants grown at a constant 20 degrees C root-zone temperature, A-RZT plants showed decreased stomatal conductance, leaf relative water content, photosynthetic CO(2) assimilation, shoot and root biomass, total root length, the number of root tips, and root surface area, but increased average root diameter. Addition of 10 microM ACC to the nutrient solution of plants grown at a constant 20 degrees C root-zone temperature mimicked the effects of A-RZT on these parameters but did not influence relative water content. Addition of 30 microM aminoisobutyric acid or 100 microM aminooxyacetic acid to the nutrient solution of A-RZT plants increased stomatal conductance and relative water content and decreased average root diameter, but had no effect on other root parameters or root and shoot biomass or photosynthetic CO(2) assimilation. Although ethylene is important in regulating root morphology and elongation at A-RZT, the failure of ethylene biosynthesis inhibitors to influence shoot carbon gain limits their use in ameliorating the growth inhibition induced by A-RZT.

Autoradiographic assessment of pineal gland glucose utilization and capillary permeability in the unanesthetized rat.

Pineal gland glucose utilization (GU) and capillary permeability (CP) were measured in unanesthetized rats, using complementary quantitative autoradiographic techniques. GU values within the pineal tissue were homogeneously distributed around 70 mumol of glucose/100 g each min, i.e., they were approximately 30% lower than in the cortical gray structures. The blood-to-brain transfer constant of [14C]-alpha-aminoisobutyric acid, as an index of CP, was up to ten orders of magnitude higher than that for the rest of the brain. These measurements were carried out at that point in the circadian rhythm that corresponds to the minimum level of neurosecretory activity of the pineal gland.