Quantifying Target Occupancy of Small Molecules Within Living Cells.

The binding affinity and kinetics of target engagement are fundamental to establishing structure-activity relationships (SARs) for prospective therapeutic agents. Enhancing these binding parameters for operative targets, while minimizing binding to off-target sites, can translate to improved drug efficacy and a widened therapeutic window. Compound activity is typically assessed through modulation of an observed phenotype in cultured cells. Quantifying the corresponding binding properties under common cellular conditions can provide more meaningful interpretation of the cellular SAR analysis. Consequently, methods for assessing drug binding in living cells have advanced and are now integral to medicinal chemistry workflows. In this review, we survey key technological advancements that support quantitative assessments of target occupancy in cultured cells, emphasizing generalizable methodologies able to deliver analytical precision that heretofore required reductionist biochemical approaches.

Acute tryptophan depletion alters the effective connectivity of emotional arousal circuitry during visceral stimuli in healthy women.

OBJECTIVE: Alterations in serotonin signalling within the brain-gut axis have been implicated in the pathophysiology of irritable bowel syndrome (IBS) and is a treatment target. Acute tryptophan depletion (ATD) decreases brain serotonin (5-hydroxytryptamine; 5-HT) levels, and increases visceral perception and negative emotional bias in patients with IBS. The aim of the present study was to determine the effect of ATD on brain activity and connectivity during visceral stimuli in healthy women, and to compare the ATD-induced brain connectivity of an arousal circuit in female patients with IBS without ATD. METHODS: 12 healthy females (19-25 years) were studied under placebo (PLA) conditions and ATD. Functional MRI measurements were performed during a rectal barostat protocol, consisting of random non-painful and maximal tolerable distensions. Partial least squares analyses and structural equation modelling were used to evaluate the effect of ATD on functional and effective brain connectivity during distension. Results in healthy controls under ATD were compared with the effective connectivity of brain responses to 45 mm Hg rectal distension in 14 female patients with constipation-predominant IBS (IBS-C) (24-50 years). RESULTS: In healthy controls, ATD resulted in increased response of an extensive brain network to balloon distension, including the amygdala and nodes of emotional arousal and homeostatic afferent networks. The effect was greater during high inflation, suggesting greater engagement of the central serotonion system with more aversive visceral stimuli. Effective connectivity analysis revealed a profound effect of ATD on coupling between emotional arousal network nodes, resulting in loss of negative feedback inhibition of the amygdala. A near-identical pattern was identified in the patients with IBS-C. CONCLUSIONS: The findings are consistent with an ATD-induced disinhibition of and increased connectivity within an emotional arousal network during aversive stimulation. Together with the previous demonstration of ATD-induced visceral hyperalgesia in healthy controls, and the near-identical effective connectivity pattern observed in patients with IBS-C, these findings suggest that dysregulation of this brain network may play a role in central pain amplification and IBS pathophysiology.

Adeno-associated virus-mediated gene delivery into the scala media of the normal and deafened adult mouse ear.

Murine models are ideal for studying cochlear gene transfer, as many hearing loss-related mutations have been discovered and mapped within the mouse genome. However, because of the small size and delicate nature, the membranous labyrinth of the mouse is a challenging target for the delivery of viral vectors. To minimize injection trauma, we developed a procedure for the controlled release of adeno-associated viruses (AAVs) into the scala media of adult mice. This procedure poses minimal risk of injury to structures of the cochlea and middle ear, and allows for near-complete preservation of low and middle frequency hearing. In this study, transduction efficiency and cellular specificity of AAV vectors (serotypes 1, 2, 5, 6 and 8) were investigated in normal and drug-deafened ears. Using the cytomegalovirus promoter to drive gene expression, a variety of cell types were transduced successfully, including sensory hair cells and supporting cells, as well as cells in the auditory nerve and spiral ligament. Among all five serotypes, inner hair cells were the most effectively transduced cochlear cell type. All five serotypes of AAV vectors transduced cells of the auditory nerve, though serotype 8 was the most efficient vector for transduction. Our findings indicate that efficient AAV inoculation (via the scala media) can be performed in adult mouse ears, with hearing preservation a realistic goal. The procedure we describe may also have applications for intra-endolymphatic drug delivery in many mouse models of human deafness.

History of early life adversity is associated with increased food addiction and sex-specific alterations in reward network connectivity in obesity.

BACKGROUND: Neuroimaging studies have identified obesity-related differences in the brain's resting state activity. An imbalance between homeostatic and reward aspects of ingestive behaviour may contribute to obesity and food addiction. The interactions between early life adversity (ELA), the reward network and food addiction were investigated to identify obesity and sex-related differences, which may drive obesity and food addiction. METHODS: Functional resting state magnetic resonance imaging was acquired in 186 participants (high body mass index [BMI]: ≥25: 53 women and 54 men; normal BMI: 18.50-24.99: 49 women and 30 men). Participants completed questionnaires to assess ELA (Early Traumatic Inventory) and food addiction (Yale Food Addiction Scale). A tripartite network analysis based on graph theory was used to investigate the interaction between ELA, brain connectivity and food addiction. Interactions were determined by computing Spearman rank correlations, thresholded at q < 0.05 corrected for multiple comparisons. RESULTS: Participants with high BMI demonstrate an association between ELA and food addiction, with reward regions playing a role in this interaction. Among women with high BMI, increased ELA was associated with increased centrality of reward and emotion regulation regions. Men with high BMI showed associations between ELA and food addiction with somatosensory regions playing a role in this interaction. CONCLUSIONS: The findings suggest that ELA may alter brain networks, leading to increased vulnerability for food addiction and obesity later in life. These alterations are sex specific and involve brain regions influenced by dopaminergic or serotonergic signalling.

Resilience is decreased in irritable bowel syndrome and associated with symptoms and cortisol response.

BACKGROUND: Irritable bowel syndrome (IBS) is a stress-sensitive disorder associated with early adverse life events (EALs) and a dysregulated hypothalamic-pituitary-adrenal (HPA) axis. Resilience is the ability to recover and adapt positively to stress but has not been well studied in IBS. The aims of this study are to compare resilience in IBS and healthy controls (HCs) and to assess its relationships with IBS symptom severity, quality of life (QOL), EALs, and HPA axis response. METHODS: Two hundred fifty-six subjects (154 IBS, 102 HCs) completed questionnaires for resilience (Connor-Davidson Resilience Scale [CD-RISC] and Brief Resilience Scale [BRS]), IBS symptoms, IBS-QOL, and EALs. Ninety-six of these subjects had serial serum adrenocorticotropic hormone (ACTH) and cortisol levels to exogenous corticotrophin-releasing hormone (CRH) and ACTH measured. The relationship between IBS status, resilience, and other variables of interest was assessed by regression analysis after adjusting for demographics and neuroticism, a predictor of resilience. KEY RESULTS: Resilience was significantly lower in IBS compared to HCs (CD-RISC: 72.16±14.97 vs 77.32±12.73, P=.003; BRS: 3.29±0.87 vs 3.93±0.69, P<.001); however, only BRS was significant after controlling for neuroticism (P=.001). Lower BRS scores were associated with greater IBS symptom severity (P=.002), poorer IBS-QOL (P<.001), and a higher number of EALs (P=.01). There was a significant interaction between BRS resilience and IBS status for ACTH-stimulated cortisol response (P=.031); more resilient IBS subjects had lower cortisol response, and more resilient HCs had higher cortisol response. CONCLUSIONS AND INFERENCES: Lower resilience is associated with IBS status, worse IBS symptom severity, lower IBS-QOL, greater EALs, and stress hyperresponsiveness.

Ca2+ responses to interleukin 1 and tumor necrosis factor in cultured human skin fibroblasts. Possible implications for Reye syndrome.

Elevated concentrations of cytokines were found in the plasma of patients acutely ill with Reye syndrome (RS) but not in control subjects or recovered RS patients. To determine whether this disorder involves a genetically determined abnormal response to cytokines, the effects of tumor necrosis factor (TNF) and IL-1 on intracellular free Ca2+ were compared in cultured skin fibroblasts from control subjects and patients with RS. IL-1 and TNF caused rapid, transient, and concentration-dependent increases in cytosolic free Ca2+. The peak cytosolic free Ca2+ was greater and occurred at higher concentrations of IL-1 and TNF in patient cells than in cells from age-matched controls. In control cells, the Ca2+ transient diminished sharply with increasing amounts of IL-1 or TNF above the maximum stimulatory concentration. In contrast, in patient fibroblast this bell-shaped curve of concentration dependency was much less apparent. Bradykinin-stimulated Ca2+ transients were similar in the two groups and did not exhibit the bell-shaped concentration dependency. Thus, plasma cytokine levels are elevated in RS patients and the Ca2+ response to cytokines is increased in cells derived from these patients. We propose that the increased response reflects a genetic defect in cytokine receptor-modulated signal transduction.

Relationship between unusual hepatic acyl coenzyme A profiles and the pathogenesis of Reye syndrome.

This study examines the relationship between impaired fatty acid oxidation and the pathogenesis of Reye syndrome. We present a hypothesis proposing that many clinical signs of this childhood disease are caused by accumulation of unusual acyl CoA esters, precursors to deacylated metabolites found in the patients' blood and urine. A new method was developed to measure acyl CoA compounds in small human liver biopsy samples, offering several advantages over previous techniques. A major finding was an accumulation in Reye syndrome patients of short- and medium-chain acyl CoA intermediates of fatty acid and branched-chain amino acid oxidation. These metabolites included octanoyl, isovaleryl, butyryl, isobutyryl, propionyl, and methylmalonyl CoA esters. The findings were explained in a model of hepatic fatty acid oxidation involving three interrelated pathways: mitochondrial beta-oxidation, peroxisomal beta-oxidation, and omega-oxidation in the endoplasmic reticulum. The results suggest that pathogenesis in Reye syndrome stems from generalized mitochondrial damage resulting in accumulation of acyl CoA esters. High levels of these compounds lead to inhibition of mitochondrial pathways for ureogenesis, gluconeogenesis, and fatty acid oxidation. The inhibited pathways, in turn, could cause the hyperammonemia, hypoglycemia, and hypoketonemia observed in patients. The model also explains underlying biochemical differences between patients with Reye syndrome and medium-chain acyl CoA dehydrogenase deficiency, another disorder of fatty acid metabolism. Acetyl CoA levels, in the latter disease, were dramatically decreased, compared with both human controls and Reye syndrome patients.

Impaired metabolic function and signaling defects in phagocytic cells in glycogen storage disease type 1b.

Patients with glycogen storage disease (GSD) type 1b (1b), in contrast to patients with GSD type 1a (1a), are susceptible to recurrent bacterial infections suggesting an impairment in their immune system. In this study, phagocytic cell (neutrophil and monocyte) respiratory burst activity, as measured by superoxide anion generation, oxygen consumption, and hexose monophosphate shunt activity, was markedly reduced in both neutrophils and monocytes from GSD 1b patients as compared with either GSD 1a patients or healthy adult control cells. Degranulation, unlike respiratory burst activity, was not significantly different in neutrophils from GSD 1b patients as compared with controls. Both neutrophils and monocytes from GSD 1b patients showed decreased ability to elevate cytosolic calcium in response to the chemotactic peptide f-Met-Leu-Phe. In addition, calcium mobilization in response to ionomycin was also attenuated suggesting decreased calcium stores. Thus, reduced phagocytic cell function in GSD 1b is associated with diminished calcium mobilization and defective calcium stores. Defective calcium signaling is associated with a selective defect in respiratory burst activity but not degranulation.

Brain networks associated with cognitive and hedonic responses to a meal.

BACKGROUND: We recently reported interrelated digestive, cognitive, and hedonic responses to a meal. The aim of this study was to identify brain networks related to the hedonic response to eating. METHODS: Thirty-eight healthy subjects (20-38 age range) were evaluated after a 5-hour fast and after ingestion of a test meal (juice and warm ham and cheese sandwich, 300 mL, 425 kcal). Perceptual and affective responses (satiety, abdominal fullness, digestive well-being, and positive mood), and resting scans of the brain using functional MRI (3T Trio, Siemens, Germany) were evaluated immediately before and after the test meal. A high-order group independent component analysis was performed to investigate ingestion-related changes in the intrinsic connectivity of brain networks, with a focus on thalamic and insular networks. KEY RESULTS: Ingestion induced satiation (3.3±0.4 score increase; P<.001) and abdominal fullness (2.4±0.3 score increase; P<.001). These sensations included an affective dimension involving digestive well-being (2.8±0.3 score increase; P<.001) and positive mood (1.8±0.2 score increase; P<.001). In general, thalamo-cortical connectivity increased with meal ingestion while insular-cortical connectivity mainly decreased. Furthermore, larger meal-induced changes (increase/decrease) in specific thalamic connections were associated with smaller changes in satiety/fullness. In contrast, a larger meal-induced decrease in insular-anterior cingulate cortex connectivity was associated with increased satiety, fullness, and digestive well-being. CONCLUSIONS AND INFERENCES: Perceptual and emotional responses to food intake are related to brain connectivity in defined functional networks. Brain imaging may provide objective biomarkers of subjective effects of meal ingestion.

Gene expression profiles in peripheral blood mononuclear cells correlate with salience network activity in chronic visceral pain: A pilot study.

BACKGROUND: Distinct gene expression profiles in peripheral blood mononuclear cells (PBMCs) consistent with increased sympathetic nervous system activity have been described in different populations under chronic stress. Neuroinflammatory brain changes, possibly related to the migration of primed monocytes to the brain, have been implicated in the pathophysiology of chronic pain. Irritable bowel syndrome (IBS) is a stress-sensitive gastrointestinal disorder associated with altered brain-gut interactions and increased sympathetic/vagal tone and anxiety. Reports about immune alterations in IBS are conflicting. This pilot study aimed to test how PBMC gene expression inflammatory profiles are correlated with altered brain signatures in the salience system. METHODS: Sixteen IBS and 16 healthy controls (HCs) completed resting state MRI scans. Gene expression profiles in PBMCs were assessed using human transcriptome array-2. Bioinformatic analyses determined differential expression of PBMCs between IBS and HCs. Partial least squares, a multivariate analysis technique, was used to identify disease correlations between PBMC gene expression profiles and functional activity in the brain's salience network. KEY RESULTS: Regions of the salience network, including the mid cingulate cortex, and mid and superior temporal gyrus were positively correlated with several pro-inflammatory genes (interleukin 6, APOL2) in IBS, but negatively correlated with several anti-inflammatory genes (KRT8, APOA4) in HCs. CONCLUSIONS & INFERENCES: Based on rodent studies, one may speculate that chronically activated stress signaling pathways in IBS maintain a pro-inflammatory state in the periphery. Alternatively, primed monocytes may migrate to the brain during stress, inducing regional neuroinflammatory changes in salience regions involved in the modulation of visceral sensitivity.

The effect of the GLP-1 analogue Exenatide on functional connectivity within an NTS-based network in women with and without obesity.

Objective: The differential effect of GLP-1 agonist Exenatide on functional connectivity of the nucleus tractus solitaries (NTS), a key region associated with homeostasis, and on appetite-related behaviours was investigated in women with normal weight compared with women with obesity. Methods: Following an 8-h fast, 19 female subjects (11 lean, 8 obese) participated in a 2-d double blind crossover study. Subjects underwent functional magnetic resonance imaging at fast and 30-min post subcutaneous injection of 5 µg of Exenatide or placebo. Functional connectivity was examined with the NTS. Drug-induced functional connectivity changes within and between groups and correlations with appetite measures were examined in a region of interest approach focusing on the thalamus and hypothalamus. Results: Women with obesity reported less hunger after drug injection. Exenatide administration increased functional connectivity of the left NTS with the left thalamus and hypothalamus in the obese group only and increased the correlation between NTS functional connectivity and hunger scores in all subjects, but more so in the obese. Conclusions: Obesity can impact the effects of Exenatide on brain connectivity, specifically in the NTS and is linked to changes in appetite control. This has implications for the use of GLP-1 analogues in therapeutic interventions.

Altered brain responses in subjects with irritable bowel syndrome during cued and uncued pain expectation.

BACKGROUND: A majority of the subjects with irritable bowel syndrome (IBS) show increased behavioral and brain responses to expected and delivered aversive visceral stimuli during controlled rectal balloon distension, and during palpation of the sigmoid colon. We aimed to determine if altered brain responses to cued and uncued pain expectation are also seen in the context of a noxious somatic pain stimulus applied to the same dermatome as the sigmoid colon. METHODS: A task-dependent functional magnetic resonance imaging technique was used to investigate the brain activity of 37 healthy controls (18 females) and 37 IBS subjects (21 females) during: (i) a cued expectation of an electric shock to the abdomen vs a cued safe condition; and (ii) an uncued cross-hair condition in which the threat is primarily based on context vs a cued safe condition. KEY RESULTS: Regions within the salience, attention, default mode, and emotional arousal networks were more activated by the cued abdominal threat condition and the uncued condition than in the cued safe condition. During the uncued condition contrasted to the cued safe condition, IBS subjects (compared to healthy control subjects) showed greater brain activations in the affective (amygdala, anterior insula) and attentional (middle frontal gyrus) regions, and in the thalamus and precuneus. These disease-related differences were primarily seen in female subjects. CONCLUSIONS & INFERENCES: The observed greater engagement of cognitive and emotional brain networks in IBS subjects during contextual threat may reflect the propensity of IBS subjects to overestimate the likelihood and severity of future abdominal pain.

Mitochondrial respiratory chain of Tetrahymena pyriformis. The thermodynamic and spectral properties.

The mitochondria isolated from the ciliate protozoon Tetrahymena pyriformis carry an oxidative phosphorylation with P/O ratio of 2 for succinate oxidation and P/O ratio of 3 for the oxidation of the NAD-linked substrates. The respiration is more than 90% inhibited with 1 mM cyanide while antimycin A and rotenone inhibit at concentrations of 1000-fold higher than those effective in mammalian mitochondria. Using a combination of spectral studies and potentiometric titrations, the components of the respiratory chain were identified and characterized with respect to the values of their half-reduction potentials. In the cytochrome bc1 region of the chain a cytochrome c was present with an Em7.2 of 0.225 V and two components with absorption maxima at 560 nm and the half-reduction potential values of -0.065 and -0.15 V at pH 7.2. The cytochrome with the more positive half-reduction potential was identified as the analogue of the cytochrome(s) b present in mitochondria of higher organisms, while the cytochrome with the more negative half-reduction potential was tentatively identified as cytochrome o. In addition ubiquinone was present at a concentration of approx. 4 nmol per mg mitochondrial protein. In the spectral region where cytochromes a absorb at least three cytochromes were found. A cytochrome with an absorption maximum at 593 nm and a midpoint potential of -0.085 V at pH 7.2 was identified as cytochrome a1. The absorption change at 615-640 nm, attributed usually to cytochrome a2, was resolved into two components with Em7,2 values of 0,245 and 0.345 V. It is concluded that the terminal oxidase in Tetrahymena pyriformis mitochondria is cytochrome a2 which in its two component structure resembles cytochrome aa3.

Mitochondrial respiratory chain of Tetrahymena pyriformis: the properties of submitochondrial particles and the soluble b and c type pigments.

Submitochondrial particles isolated from Tetrahymena pyriformis contain essentially the same redox carriers as those present in parental mitochondria: at pH 7.2 and 22 degree C there are two b-type pigments with half-reduction potentials of --0.04 and --0.17 V, a c-type cytochrome with a half reduction potential of 0.215 V, and a two-component cytochrome a2 with Em7.2 of 0.245 and 0.345 V. EPR spectra of the aerobic submitochondrial particles in the absence of substrate show the presence of low spine ferric hemes with g values at 3.4 and 3.0, a high spin ferric heme with g =6, and a g=2.0 signal characteristic of oxidized copper. In the reduced submitochondrial particles signals of various iron-sulfur centers are observed. Cytochrome c553 is lost from mitochondria during preparation of the submitochondrial particles. The partially purified cytochrome c553 is a negatively charged protein at neutral pH with an Em7.2 of 0.25 V which binds to the cytochrome c-depleted Tetrahymena mitochondria in the amount of 0.5 nmol/mg protein with KD of 0.8.10(-6) M. Reduced cytochrome c553 serves as an efficient substrate in the reaction with its own oxidase. The EPR spectrum of the partially purified cytochrome c553 shows the presence of a low spin ferric heme with the dominant resonance signal at g=3.28. A pigment with an alpha absorption maximum at 560 nm can be solubilized from the Tetrahymena cells with butanol. This pigments has a molecular weight of approx. 18 000, and Em7.2 of--0.17 V and exhibits a high spin ferric heme signal at g=6.

Altered functional connectivity within the central reward network in overweight and obese women.

BACKGROUND/OBJECTIVES: Neuroimaging studies in obese subjects have identified abnormal activation of key regions of central reward circuits, including the nucleus accumbens (NAcc), in response to food-related stimuli. We aimed to examine whether women with elevated body mass index (BMI) show structural and resting state (RS) functional connectivity alterations within regions of the reward network. SUBJECTS/METHODS: Fifty healthy, premenopausal women, 19 overweight and obese (high BMI=26-38 kg m(-2)) and 31 lean (BMI=19-25 kg m(-2)) were selected from the University of California Los Angeles' Oppenheimer Center for Neurobiology of Stress database. Structural and RS functional scans were collected. Group differences in grey matter volume (GMV) of the NAcc, oscillation dynamics of intrinsic brain activity and functional connectivity of the NAcc to regions within the reward network were examined. RESULTS: GMV of the left NAcc was significantly greater in the high BMI group than in the lean group (P=0.031). Altered frequency distributions were observed in women with high BMI compared with lean group in the left NAcc (P=0.009) in a medium-frequency (MF) band, and in bilateral anterior cingulate cortex (ACC) (P=0.014, <0.001) and ventro-medial prefrontal cortex (vmPFC) (P=0.034, <0.001) in a high-frequency band. Subjects with high BMI had greater connectivity of the left NAcc with bilateral ACC (P=0.024) and right vmPFC (P=0.032) in a MF band and with the left ACC (P=0.03) in a high frequency band. CONCLUSIONS: Overweight and obese women in the absence of food-related stimuli show significant structural and functional alterations within regions of reward-related brain networks, which may have a role in altered ingestive behaviors.

Biosynthetic relationship between the major matrix proteins of adrenal chromaffin granules.

The matrix of the chromaffin granule contains a family of acidic proteins, collectively known as the chromogranins. It has been suggested that this family results from protease action on the major component, chromogranin A. Evidence for this has now been obtained from in vitro translation of adrenal medullary messenger RNA and immunoprecipitation of translation products using an antiserum directed against chromogranin A, but which also recognises other chromogranins.

Cytokines inhibit fatty acid oxidation in isolated rat hepatocytes: synergy among TNF, IL-6, and IL-1.

We have developed an in vitro rat hepatocyte model in which cytokines inhibit fatty acid oxidation. Cytokine administration resulted in decreased fatty acid oxidation, ketone body production and acetyl CoA/CoA ratios. The inhibitory effects of TNF on fatty acid oxidation were enhanced by either IL-1 or IL-6. TNF (20 U/ml) + IL-6 (30 ng/ml) produced maximal inhibition, whereas IL-1 enhanced inhibition at submaximal TNF concentrations. The key to our model is that substrate input into the tricarboxylic acid cycle in the form of either alanine or pyruvate was required for cytokine mediated inhibition of fatty acid oxidation. Alanine or pyruvate may serve as a source for increased production of malonyl CoA, a potent inhibitor of fatty acid oxidation. We hypothesize that cytokines cause an inappropriate switch from fatty acid oxidation to fatty acid synthesis which has serious consequences for energy levels in the liver and can lead to end organ failure.

Hepatic metabolic alterations in rats treated with low-dose endotoxin and aspirin: an animal model of Reye's syndrome.

The administration of a sublethal dose of endotoxin (LPS) followed one hour later by a low dose of aspirin (LPS + ASA) to fasted rats leads to biochemical perturbations similar to Reye's syndrome. In this study hepatic energy metabolism was assessed in freeze-clamped liver samples (12 hours posttreatment) obtained from (250 to 300 g Sprague-Dawley) rats. The administration of aspirin alone to fasted rats did not significantly alter the hepatic levels of adenine nucleotides, total ketones, or acyl-CoA thioesters as compared to controls. In contrast, in both LPS and LPS + ASA samples, there were declines in ATP/ADP ratio (P less than .005), total ketones (P less than .001) and acetyl CoA (P less than .005) compared to their respective controls. A striking alteration in acyl-CoA thioesters was observed in LPS + ASA-treated animals. Unlike control, aspirin, or LPS-treated animals, LPS + ASA-treated animals accumulated relatively large amounts of unusual CoA esters, including propionyl-CoA, (iso)butyryl-CoA, beta-methylcrotonyl-CoA, and isovaleryl-CoA, metabolites of the branch chain amino acid and odd-chain fatty acid oxidation pathways. The acyl-CoA profile is similar to that obtained in patients with Reye's syndrome. Like human patients with Reye's syndrome, these rats showed hyperammonemia, compromised fatty acid oxidation, and accumulation of branched chain amino acid oxidation metabolites. Accumulation of these intermediates with LPS + ASA is a possible mechanism for the potentiation of Reye's syndrome by aspirin. These findings provide biochemical evidence that sublethal doses of LPS + ASA administered to fasted rats produces an animal model of Reye's syndrome.

Atrial appendages and venoatrial connections in hearts from patients with visceral heterotaxy.

BACKGROUND: Venoatrial connections are important when choosing surgical options for patients with visceral heterotaxy. The precise morphology of the atriums, however, is often obfuscated by the term "visceral heterotaxy." This morphologic study aims to clarify the features of significance to the cardiac surgeon. METHODS: We investigated 183 hearts from patients known from postmortem inspection to have so-called visceral heterotaxy. The connections of the systemic and pulmonary veins to the atriums, and the detailed morphology of the atriums, were examined in each case. RESULTS: Pectinate muscles extended bilaterally to the crux in 125 hearts determined to have isomeric morphologically right appendages. The other 58 hearts all exhibited bilaterally smooth-walled vestibules, and were diagnosed as having isomeric left appendages. Bilateral superior caval veins were frequent in both groups. The inferior caval vein was right- or left-sided with equal frequency in both groups, but was interrupted only in hearts with isomeric left appendages. The pulmonary veins connected in extraatrial fashion in 48% of cases with isomeric right appendages, whereas, most commonly, pulmonary veins were connected bilaterally to the atriums in those with isomeric left appendages (60%). CONCLUSIONS: Both the morphology of the atrial appendages and the venoatrial connections need to be distinguished to establish precise diagnoses in patients with so-called visceral heterotaxy ("splenic syndromes").