Abstract P6-11-11: Multistage Delivery of Paclitaxel: Increased Drug Stability and Sustained Release Results in Enhanced Efficacy in Breast Cancer

Background: A significant challenge for effectively treating cancer is overcoming biological barriers that reduce circulation times and increase degradation of possible treatments. We established an innovative approach to address this issue by embedding drug-containing nanoparticles within the pores of a larger mesoporous silicon particle (MSP) in order to optimize site-specific localization and release of therapeutic agents. The objective is to develop a nanotherapeutic-based multistage platform for breast cancer treatment, wherein paclitaxel, a mitotic inhibitor used in the treatment of breast tumors, will be loaded into polymeric micelles, which in turn will be loaded within MSPs. We hypothesize that this nested incorporation of drugs within MSPs, combined with enhanced tumor transport, will result in a more pronounced and sustained antitumor effect.

Materials and Methods: Micelles were assembled from amphiphilic block copolymers consisting of poly(ethylene glycol)-poly(∈-caprolactone) (PEG-PCL, MW = 5k-5k). Nanoparticle size, zeta potential, and morphology was determined, and PTX loading and release kinetics from micelles analyzed. Drug-containing micelles were incorporated into MSPs by a previously established dry-loading method, wherein nanoparticles were incorporated into pores via capillary action. Loading of fluorescent micelles was used to verify loading within MSPs via fluorescence microscopy and flow cytometry analysis. Sulforhodamine B assays were used to evaluate the in vitro antitumor efficacy of the platform in MCF-7 and MDA-MB-468 breast cancer cells. In vivo efficacy was evaluated in MDA-MB-468 breast tumors in female nu/nu mice.

Results: Resulting micelles had an average size of 20 nm, as confirmed through TEM, with paclitaxel loaded into micelles very effectively. Release kinetics showed that 50% of the drug was released within 4 hours and 80% released within 24 hours. Loading of micelles into MSPs depended largely on electrostatic interactions, with micelles loading better within pores of MSPs displaying increased positive charge. Micelle loading into MSPs was successful as demonstrated by flow cytometry, and release was significantly retarded (< 30% of drug released over 4 d). Incubation of micelle-containing MSPs with breast cancer cells in vitro showed that MSPs could be internalized by cells, after which a sustained and delayed release of the payload was observed in cells. Breast tumors treated with MSPs demonstrated sustained tumor suppression (169 mm3 compared to initial starting volume of 200 mm3) at day 35 following a single injection. It is important to note that sustained tumor efficacy was achieved with nanoparticle and free drug formulations, however, with the caveat of repeated administrations.

Discussion: A novel multistage approach to chemotherapy effectively allows a secondary payload to be loaded and preserved within the MSPs until reaching the tumor site. This prevents premature release of the drug and allows for a sustained release which may potentially result in fewer patient side effects. Future studies will involve loading of multiple nanoparticle types into MSPs and addition of targeting and diagnostic components.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-11-11.

Diet-dependent modulation of hippocampal expression of endocannabinoid signaling-related proteins in cannabinoid antagonist-treated obese rats

Diet-induced obesity produces changes in endocannabinoid signaling (ECS), influencing the regulation of energy homeostasis. Recently, we demonstrated that, in high-fat-diet-fed rats, blockade of CB1 receptor by AM251 not only reduced body weight but also increased adult neurogenesis in the hippocampus, suggesting an influence of diet on hippocampal cannabinoid function. To further explore the role of hippocampal ECS in high-fat-diet-induced obesity, we investigated whether the immunohistochemical expression of the enzymes that produce (diacylglycerol lipase alpha and N-acyl phosphatidylethanolamine phospholipase D) and degrade (monoacylglycerol lipase and fatty acid amino hydrolase) endocannabinoids may be altered in the hippocampus of AM251 (3 mg/kg)-treated rats fed three different diets: standard diet (normal chow), high-carbohydrate diet (70% carbohydrate) and high-fat diet (60% fat). Results indicated that AM251 reduced caloric intake and body weight gain, and induced a modulation of the expression of ECS-related proteins in the hippocampus of animals exposed to hypercaloric diets. These effects were differentially restricted to either the 2-arachinodoyl glycerol or anandamide signaling pathways, in a diet-dependent manner. AM251-treated rats fed the high-carbohydrate diet showed a reduction of the diacylglycerol lipase alpha : monoacylglycerol lipase ratio, whereas AM251-treated rats fed the high-fat diet showed a decrease of the N-acyl phosphatidylethanolamine phospholipase D : fatty acid amino hydrolase ratio. These results are consistent with the reduced levels of hippocampal endocannabinoids found after food restriction. Regarding the CB1 expression, AM251 induced specific changes focused in the CA1 stratum pyramidale of high-fat-diet-fed rats. These findings indicated that the cannabinoid antagonist AM251 modulates ECS-related proteins in the rat hippocampus in a diet-specific manner. Overall, these results suggest that the hippocampal ECS participates in the physiological adaptations to different caloric diets.

Peer review versus editorial review and their role in innovative science

Peer review is a widely accepted instrument for raising the quality of science. Peer review limits the enormous unstructured influx of information and the sheer amount of dubious data, which in its absence would plunge science into chaos. In particular, peer review offers the benefit of eliminating papers that suffer from poor craftsmanship or methodological shortcomings, especially in the experimental sciences. However, we believe that peer review is not always appropriate for the evaluation of controversial hypothetical science. We argue that the process of peer review can be prone to bias towards ideas that affirm the prior convictions of reviewers and against innovation and radical new ideas. Innovative hypotheses are thus highly vulnerable to being "filtered out" or made to accord with conventional wisdom by the peer review process. Consequently, having introduced peer review, the Elsevier journal Medical Hypotheses may be unable to continue its tradition as a radical journal allowing discussion of improbable or unconventional ideas. Hence we conclude by asking the publisher to consider re-introducing the system of editorial review to Medical Hypotheses.

Chronic immobilization in the malpar1 knockout mice increases oxidative stress in the hippocampus

The lysophosphatidic acid LPA₁ receptor has recently been involved in the adaptation of the hippocampus to chronic stress. The absence of LPA₁ receptor aggravates the chronic stress-induced impairment of both hippocampal neurogenesis and apoptosis that were accompanied with hippocampus-dependent memory deficits. Apoptotic death and neurogenesis in the hippocampus are regulated by oxidative stress. In the present work, we studied the involvement of LPA₁ receptor signaling pathway in the regulation of the hippocampal redox after chronic stress. To this end, we used malpar1 knockout (KO) and wild-type mice assigned to either chronic stress (21 days of restraint, 3 h/day) or control conditions. Lipid peroxidation, the activity of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX), as well as mitochondrial function stimulation, monitored through the activity of cytochrome c oxidase (COX), were studied in the hippocampus. Our results showed that chronic immobilization stress enhanced lipid peroxidation as well as the activity of the antioxidant enzymes studied (CAT, SOD, and GPX). This effect was only observed in absence of LPA₁ receptor. Furthermore, only malpar1 KO mice submitted to chronic stress exhibited a severe downregulation of the COX activity, suggesting the presence of mitochondrial damage. Altogether, these results suggest that malpar1 KO mice display enhanced oxidative stress in the hippocampus after chronic stress. This may be involved in the hippocampal abnormalities observed in this genotype after chronic immobilization, including memory, neurogenesis, and apoptosis.

Postnatal Growth Patterns in a Chilean Cohort: The Role of SES and Family Environment

Objective. This study examined how family environmental characteristics served as mediators in the relationship between socioeconomic conditions and infant growth in a cohort of Chilean infants. Methods. We studied 999 infants, born between 1991 and 1996, from a longitudinal cohort which began as an iron deficiency anemia preventive trial. SES (Graffar Index), the Life Experiences Survey, and the Home Observation for Measurement of the Environment (HOME) were assessed in infancy. Using path analysis, we assessed the relationships between the social factors, home environment, and infant growth. Results. During the first year, weight and length gain averaged 540 grams/month and 6.5 cm/month, respectively. In the path analysis model for weight gain, higher SES and a better physical environment were positively related to higher maternal warmth, which in turn was associated with higher average weight gain. Higher SES was directly related to higher average length gain. Conclusions. In our cohort, a direct relationship between SES and length gain developed during infancy. Higher SES was indirectly related to infant weight gain through the home environment and maternal warmth. As the fastest growing infants are at risk for later obesity, new strategies are needed to encourage optimal rather than maximal growth.

Attenuation of cocaine-induced conditioned locomotion is associated with altered expression of hippocampal glutamate receptors in mice lacking LPA1 receptors

RATIONALE

Lysophosphatidic acid is a phospholipid mediator that modulates neurodevelopment and neurogenesis in the hippocampus through its actions on LPA1 receptors. Emerging evidences support LPA(1) as a mediator of learning and emotional behaviour. There are no studies addressing its role on behaviours associated to drug abuse.

OBJECTIVES

We examined whether genetic deletion of LPA1 receptor in maLPA(1)-null mice affected either cocaine-induced conditioned locomotion (CL) or behavioural sensitization (BS) induced by repeated cocaine exposure. We also analysed whether cocaine induced changes in the expression of functional markers of both dopamine- and glutamate-related genes in the striatum and the dorsal hippocampus.

METHODS

We monitored cocaine-induced CL and BS in both genotypes of mice. Striatal dopamine and hippocampal glutamate-related genes were measured by real-time quantitative PCR, Western blot, and immunohistochemistry.

RESULTS

maLPA(1)-null mice exhibit an attenuated CL response after cocaine conditioning but a normal BS after repeated cocaine exposure. These behavioural changes were associated to alterations on the expression of metabotropic mGLUR3 glutamate receptors and on the actions of cocaine on the GLUR1 subunit of AMPA glutamate receptors in the hippocampus of maLPA(1) animals. Striatal dopaminergic markers (tyrosine hydroxylase, dopamine D1 receptor, and dopamine transporter DAT), were similar in both genotypes and were equally affected by cocaine exposure.

CONCLUSION

The present results indicate that the lack of LPA1 receptor affect cocaine-induced conditioned locomotion but not behavioural sensitization. The findings suggest that LPA1 receptor may be necessary for a normal associative contextual learning associated to cocaine, probably through the modulation of hippocampal glutamatergic circuits.

Chimeric calicivirus-like particles elicit specific immune responses in pigs

Virus-like particles (VLPs) have received considerable attention due to their potential application in veterinary vaccines and, in particular, VLPs from rabbit haemorrhagic disease virus (RHDV) have successfully shown to be good platforms for inducing immune responses against an inserted foreign epitope in mice. The aim of this study was to assess the immunogenicity of chimeric RHDV-VLPs as vaccine vectors in pigs. For this purpose, we have generated chimeric VLPs containing a well-known T epitope of 3A protein of foot-and-mouth disease virus (FMDV). Firstly, RHDV-VLPs were able to activate immature porcine bone marrow-derived dendritic cells (poBMDCs) in vitro. Secondly, pigs were inoculated twice in a two-week interval with chimeric RHDV-VLPs at different doses intranasally or intramuscularly. One intramuscularly treated group was also inoculated with adjuvant Montanide™ ISA 206 at the same time. Specific IgG and IgA antibodies against RHDV-VLPs were induced and such levels were higher in the adjuvanted group compared with other groups. Interestingly, anti-RHDV-VLP IgA responses were higher in groups inoculated intramuscularly than those that received the VLPs intranasally. Two weeks after the last immunisation, specific IFN-γ-secreting cells against 3A epitope and against RHDV-VLPs were detected in PBMCs by ELISPOT. The adjuvanted group exhibited the highest IFN-γ-secreting cell numbers and lymphoproliferative specific T cell responses against 3A epitope and RHDV-VLP. This is the first immunological report on the potential use of chimeric RHDV-VLPs as antigen carriers in pigs.

[Prevalence of neuropathic pain according to the NP4 test in primary care]

BACKGROUND

Primary Care Physicians are usually the first to see patients with neuropathic pain. The aim of this study is to assess the prevalence of neuropathic pain, its therapeutic management, and to clinically characterize these patients.

MATERIAL AND METHODS

An epidemiological, observational, cross-sectional study was carried out in Spanish Primary Care settings. The first 25 patients older than 18 years with any type of pain (a total of 16,115) were registered, and the first 5 with a high neuropathic pain component according to the NP4 test, and was clinically confirmed (n= 3,836) were included in the study. Pain intensity and impact on daily activities, as well as overall satisfaction with treatment were assessed.

RESULTS

A total of 45.7% of patients had neuropathic pain according to NP4 test. The median age was 59 years, and 60% were women. Patients took a mean of 2.4 drugs, with NSAIDs (53%) and non-opioid analgesics (51%) being the most common. The scores for Pain intensity and interference in daily activities were both 6.2. The overall opinion of the SATMED-Q test was 47.3/100, which was 1.4 points lower than the standardised score according to Spanish population.

CONCLUSIONS

Neuropathic pain according to NP4 test is highly prevalent in Spanish Primary Care settings. The management of these patients with NSAIDs and non-opioid analgesics is not appropriate, as they are not recommended for this kind of pain. Although they were being treated with more than 2 analgesics, they still referred to high pain intensity, interference in daily activities, and a low general opinion of the treatment.

Active and passive MDMA ('ecstasy') intake induces differential transcriptional changes in the mouse brain

3,4-Methylenedioxymethamphetamine (MDMA, 'ecstasy') is a recreational drug widely used by adolescents and young adults. Although its rewarding effects are well established, there is controversy on its addictive potential. We aimed to compare the consequences of active and passive MDMA administration on gene expression in the mouse brain since all previous studies were based on passive MDMA administration. We used a yoked-control operant intravenous self-administration paradigm combined with microarray technology. Transcriptomic profiles of ventral striatum, frontal cortex, dorsal raphe nucleus and hippocampus were analysed in mice divided in contingent MDMA, yoked MDMA and yoked saline groups, and several changes were validated by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The comparison of contingent MDMA and yoked MDMA vs. yoked saline mice allowed the identification of differential expression in several genes, most of them with immunological and inflammatory functions, but others being involved in neuroadaptation. In the comparison of contingent MDMA vs. yoked MDMA administration, hippocampus and the dorsal raphe nucleus showed statistically significant changes. The altered expression of several genes involved in neuroadaptative changes and synapse function, which may be related to learning self-administration behaviour, could be validated in these two brain structures. In conclusion, our study shows a strong effect of MDMA administration on the expression of immunological and inflammatory genes in all the four brain regions studied. In addition, experiments on MDMA self-administration suggest that the dorsal raphe nucleus and hippocampus may be involved in active MDMA-seeking behaviour, and show specific alterations on gene expression that support the addictive potential of this drug.

Distribution of diacylglycerol lipase alpha, an endocannabinoid synthesizing enzyme, in the rat forebrain

1,2-diacylglycerol lipase alpha (DAGLα) is responsible for the biosynthesis and release of 2-arachidonoyl-glycerol (2-AG), the most abundant endocannabinoid in the brain. Although its expression has been detected in discrete regions, we showed here an integrated description of the distribution of DAGLα mRNA and protein in the rat forebrain using in situ hybridization histochemistry and immunohistochemistry. As novelty, we described the distribution of DAGLα protein expression in the olfactory system, the rostral migratory stream, neocortex, septum, thalamus, and hypothalamus. Similar DAGLα immunostaining pattern was also found in the brain of wild-type, but not of DAGLα knockout mice. Immunohistochemical data were correlated by the identification of DAGLα mRNA expression, for instance, in the somata of specific cells in olfactory structures, rostral migratory stream and neocortex, cells in some septal-basal-amygdaloid areas and the medial habenula, and magnocellular cells of the paraventricular hypothalamic nucleus. This widespread neuronal distribution of DAGLα is consistent with multiple roles for endocannabinoids in synaptic plasticity, including presynaptic inhibition of neurotransmitter release. We discuss our comparative analysis of the forebrain expression patterns of DAGLα and other components of the endocannabinoid signaling system, including the CB(1) receptor, monoacylglyceride lipase (MAGL), and fatty acid amide hydrolase (FAAH), providing some insight into the potential physiological and behavioral roles of this system.

Abstract P6-14-10: Treatment of Breast Cancer Using Multistage Delivery of PI3K/mTOR Inhibitors

Background: Current chemotherapeutic strategies are not without substantial shortcomings, including non-specific drug distribution and toxicity to normal cells. Breakthroughs in the understanding of underlying molecular mechanisms of tumorigenesis has led to the discovery and design of several drugs capable of exerting effects on key targets essential for tumor propagation. Consider rapamycin and LY294002, drugs that target the PI3K/mammalian target of rapamycin (mTOR) signaling pathway, a pathway found to be dysregulated in breast cancer. The objective is to generate a nanoscale platform capable of site-specifically delivering a powerful payload of PI3K/mTOR inhibitors for the synergistic treatmentof breast tumors. The novel, injectable nanocarrier consists of three components: 1) mesoporous silicon particles (MSPs) that will be injected into the bloodstream and housing; 2) nanoparticles (polymer micelles) loaded with; 3) PI3K/mTOR inhibitors. We hypothesize that this platform will provide for enhanced bioavailability and drug synergy at tumor sites.

Materials and Methods: The amphiphilic block copolymers that comprise the micelles consist of a pegylated formulation of poly(ε-caprolactone) (PEG-PCL, MW = 5k-1k). Drug-containing micelles were fabricated using a film sonication technique. The yield, loading efficiency, and percentage of loaded drug was calculated. Nanoparticle size and zeta potential was determined using dynamic light scattering (DLS), while size and morphology was corroborated via TEM. Release studies of drugs from micellar formulations was performed to determine the kinetics of release. Dried APTES-modified MSPs were incubated with the micellar formulations for ∼3 h. Nanoparticle loading and release was analyzed via HPLC. The in vitro antitumor efficacy of the platform was evaluated in MCF-7 and MDA-MB-468 breast cancer cells via a sulforhodamine B assay.

Results: Micelles produced by the film sonication technique were found to have an average zeta potential of -9.29 mV, and an average diameter of 34.4 ± 2.7 nm. This size was confirmed via TEM. Drug loading densities of paclitaxel, rapamycin, and LY294002 within polymer micelles was shown to be 4.6 ± 0.4, 4.1 ± 0.6, and 3.2 ± 0.6 %, respectively. Factoring in a theoretical loading of 5% for all drugs, the loading efficiency using this procedure is very high. The release kinetics were shown to be slow for rapamycin and paclitaxel (20% release over 4 days) while very fast for LY294002 (>60%). Loading of micelles within the MSPs was shown to be approximately 40%. Upon incubation of the micelles with MCF-7 and MDA-MB-468 breast cancer cells, the multistage platform was effective at suppressing tumor growth after a 4 d incubation. Discussion: We have proposed herein a novel nanotherapeutic platform that aims to effectively target the PI-3K/mTOR pathway in breast tumors, bringing about tumor eradication by delivering drugs in a site-specific fashion in order to maximize drug synergy. We believe that the long blood circulation and the site-specific delivery afforded by the nanocarrier platform will translate in vitro synergy findings to the in vivo setting. Current work is underway to examine the in vivo efficacy of the platform.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-14-10.

On the role of spectral resolution in velocity shear layer measurements by Doppler reflectometry

The signal quality of a Doppler reflectometer depends strongly on its spectral resolution, which is influenced by the microwave beam properties and the radius of curvature of the cutoff layer in the plasma. If measured close to a strong perpendicular velocity shear layer, the spectrum of the backscattered signal is influenced by different velocities. This can give rise to two Doppler shifted peaks in the spectrum as observed in TJ-II H-mode plasmas. It is shown by two-dimensional full wave simulations that the two peaks are separable provided the spectral resolution of the system is sufficient. However, if the spectral resolution is poor, the two peaks blend into one and yield an intermediate and incorrect velocity.

Doppler reflectometer system in the stellarator TJ-II

A Doppler reflectometer system has recently been installed in the stellarator TJ-II. The system is optimized for the Q-band (33-50 GHz) and the high-curvature plasmas produced in TJ-II. The launch angle of the microwave beam can be controlled by a steerable mirror to obtain angles between +/-20 degrees enabling the measurement of perpendicular wave numbers in the range of 3-15 cm(-1). The available angular range allows for comparisons between positive and negative values and additionally for calibration of the system. Localization and k(perpendicular)-estimation is done via the three-dimensional ray/beam-tracing code TRUBA. First measured spectra and radial profiles of the perpendicular velocity of plasma density fluctuations are presented.

Maghemite-silica nanocomposites: sol-gel processing enhancement of the magneto-optical response

The preparation and processing of maghemite-silica gel nanocomposites have been investigated in order to maximize their magneto-optical response for magnetic field sensing applications. In situ precipitation of maghemite nanoparticles from an iron salt precursor during the sol-gel processing of the silica matrix has been carried out while controlling the time, temperature, and environment at each step of the whole process. In this paper, the nanostructural, magnetic, and magneto-optical properties of these materials are correlated with the processing path followed, from the starting sol to the partially densified monolith. Results demonstrate that introducing a washing treatment prevents the formation of hematite phase as well as an excessive particle agglomeration. Different processing conditions of identical sols may lead to nanocomposites with a Verdet constant at low magnetic fields (0.01 T) ranging from 200 to 950 rad T(-1) m(-1), which is the typical value of commercial terbium gallium garnets used in Faraday rotators.

A dynamic expression pattern of sGalpha(i2) protein during early period of postnatal rat brain development

The function of sGalphai2 protein in central nervous system is not well understood. Therefore to explore the possible role of this protein in postnatal brain development, we have analyzed the protein expression pattern of brain obtained from rats of postnatal day 0 (P0) to P90 by dot-blots and immunocytochemistry techniques. In dot-blots, both nuclear and membrane fractions showed a gradual decrease from P0 to P60. Highest protein level was observed at the age of P0. There was also a trend of decline in the sGalphai2 protein from P0 to P90 in brain sections stained by immunocytochemistry method. At P0, the protein labeling was highest in cerebral cortex, hippocampus, cerebellum and mitral cell layer. In cerebral cortex, a drop in the immunolabeling of sGalphai2 protein was observed at P3, which was significantly increased at the age of P5. However, in striatum and olfactory tubercle, it was maintained through P0-P10 and P0-P5, respectively. Thalamus was one of the areas where labeling was not as strong as cortex, hippocampus or striatum. In contrary to other areas, immunostaining of sGalphai2 in corpus-callosum and lacunosum-molecular was not seen at P0 and appeared in advanced postnatal ages. A detectable level of sGalphai2 protein was observed at P5 in carpus-callosum and at P20 in lacunosum-molecular. A high level of sGalphai2 protein in the period when cellular layer organization and synaptic innervations, synaptic connections and maturation take place, suggests for a potential role of this protein in the early postnatal brain development.

Saccular aneurysms of the extracranial internal carotid artery. Experience and review of the literature

The aim of this study was to describe the surgical technique employed and our results in the treatment of saccular aneurysms of the internal carotid artery at the extracranial level. We describe 3 cases of patients with saccular aneurysms of the extracranial internal carotid who underwent surgery at our unit within the last 3 years. We report on indications for treatment, surgical technique and results in terms of morbidity-mortality and also review the pertinent literature. Surgical treatment was indicated on the grounds of the patients being symptomatic: 2 had a history of cerebral ischemia, and 1 showed local compression symptoms. The surgical approach was presternocleidomastoid cervicotomy extended distally, and in 2 patients was accompanied by nasotracheal intubation to achieve adequate exposure. In 2 cases, we performed an aneurysmectomy with end-to-end anastomosis. In the third patient, the aneurysm neck was ligated from within the sac followed by aneurysmectomy. There was no mortality or neurological morbidity (local or general). The patients remain free from neurological symptoms with a patent carotid axis. Our clinical experience suggests that, despite the anatomically unfavorable location of this type of aneurysm and the greater complexity of the surgical technique, this patient group can be effectively treated. The frequent presence of an elongated carotid axis and an aneurysmal neck means the surgeon can easily restore arterial continuity by direct procedures.

Glucose metabolism and insulin secretion in a patient with ABCC8 mutation and Fanconi-Bickel syndrome caused by maternal isodisomy of chromosome 3

Fanconi-Bickel syndrome (FBS) is a rare disorder of glucose transport caused by autosomal recessive mutations in GLUT2. Clinically, FBS results in growth failure, hepatomegaly, renal Fanconi syndrome, and abnormal glucose homeostasis. We report a 23 month old female with FBS characterized by more severe and refractory hypoglycemia than typically seen in this disorder. Although previous reports indicate that FBS patients have diminished insulin secretion, our patient showed evidence of hyperinsulinism (HI). Sequence analysis showed that the patient was homozygous for a known null mutation in GLUT2, confirming the clinical diagnosis of FBS. Parental genotyping showed that the mother was heterozygous for the GLUT2 mutation, while the father was wild type. Tandem repeat marker analysis showed that the patient inherited the GLUT2 mutation via maternal isodisomy of chromosome 3. Further molecular testing showed that the patient was heterozygous for a mutation in ABCC8, a known cause of congenital HI. We discuss the patient's biochemical responses in light of the molecular findings.