Lysosomal cholesterol overload in macrophages promotes liver fibrosis in a mouse model of NASH

Accumulation of lipotoxic lipids, such as free cholesterol, induces hepatocyte death and subsequent inflammation and fibrosis in the pathogenesis of nonalcoholic steatohepatitis (NASH). However, the underlying mechanisms remain unclear. We have previously reported that hepatocyte death locally induces phenotypic changes in the macrophages surrounding the corpse and remnant lipids, thereby promoting liver fibrosis in a murine model of NASH. Here, we demonstrated that lysosomal cholesterol overload triggers lysosomal dysfunction and profibrotic activation of macrophages during the development of NASH. β-cyclodextrin polyrotaxane (βCD-PRX), a unique supramolecule, is designed to elicit free cholesterol from lysosomes. Treatment with βCD-PRX ameliorated cholesterol accumulation and profibrotic activation of macrophages surrounding dead hepatocytes with cholesterol crystals, thereby suppressing liver fibrosis in a NASH model, without affecting the hepatic cholesterol levels. In vitro experiments revealed that cholesterol-induced lysosomal stress triggered profibrotic activation in macrophages predisposed to the steatotic microenvironment. This study provides evidence that dysregulated cholesterol metabolism in macrophages would be a novel mechanism of NASH.

Dietary Supplementation With Eicosapentaenoic Acid Inhibits Plasma Cell Differentiation and Attenuates Lupus Autoimmunity

Accumulating evidence suggests that cholesterol accumulation in leukocytes is causally associated with the development of autoimmune diseases. However, the mechanism by which fatty acid composition influences autoimmune responses remains unclear. To determine whether the fatty acid composition of diet modulates leukocyte function and the development of systemic lupus erythematosus, we examined the effect of eicosapentaenoic acid (EPA) on the pathology of lupus in drug-induced and spontaneous mouse models. We found that dietary EPA supplementation ameliorated representative lupus manifestations, including autoantibody production and immunocomplex deposition in the kidneys. A combination of lipidomic and membrane dynamics analyses revealed that EPA remodels the lipid composition and fluidity of B cell membranes, thereby preventing B cell differentiation into autoantibody-producing plasma cells. These results highlight a previously unrecognized mechanism by which fatty acid composition affects B cell differentiation into autoantibody-producing plasma cells during autoimmunity, and imply that EPA supplementation may be beneficial for therapy of lupus.

Macrophages rely on extracellular serine to suppress aberrant cytokine production

A growing body of evidence indicates that cellular metabolism is involved in immune cell functions, including cytokine production. Serine is a nutritionally non-essential amino acid that can be generated by de novo synthesis and conversion from glycine. Serine contributes to various cellular responses, but the role in inflammatory responses remains poorly understood. Here, we show that macrophages rely on extracellular serine to suppress aberrant cytokine production. Depleting serine from the culture media reduced the cellular serine content in macrophages markedly, suggesting that macrophages depend largely on extracellular serine rather than cellular synthesis. Under serine deprivation, macrophages stimulated with lipopolysaccharide showed aberrant cytokine expression patterns, including a marked reduction of anti-inflammatory interleukin-10 expression and sustained expression of interleukine-6. Transcriptomic and metabolomics analyses revealed that serine deprivation causes mitochondrial dysfunction: reduction in the pyruvate content, the NADH/NAD⁺ ratio, the oxygen consumption rate, and the mitochondrial production of reactive oxygen species (ROS). We also found the role of mitochondrial ROS in appropriate cytokine production. Thus, our results indicate that cytokine production in macrophages is tightly regulated by the nutritional microenvironment.

Dipeptidyl peptidase-4 inhibition prevents nonalcoholic steatohepatitis-associated liver fibrosis and tumor development in mice independently of its anti-diabetic effects

Nonalcoholic steatohepatitis (NASH) is a hepatic phenotype of the metabolic syndrome, and increases the risk of cirrhosis and hepatocellular carcinoma (HCC). Although increasing evidence points to the therapeutic implications of certain types of anti-diabetic agents in NASH, it remains to be elucidated whether their effects on NASH are independent of their effects on diabetes. Genetically obese melanocortin 4 receptor–deficient (MC4R-KO) mice fed Western diet are a murine model that sequentially develops hepatic steatosis, NASH, and HCC in the presence of obesity and insulin resistance. In this study, we investigated the effect of the dipeptidyl peptidase-4 (DPP-4) inhibitor anagliptin on NASH and HCC development in MC4R-KO mice. Anagliptin treatment effectively prevented inflammation, fibrosis, and carcinogenesis in the liver of MC4R-KO mice. Interestingly, anagliptin only marginally affected body weight, systemic glucose and lipid metabolism, and hepatic steatosis. Histological data and gene expression analysis suggest that anagliptin treatment targets macrophage activation in the liver during the progression from simple steatosis to NASH. As a molecular mechanism underlying anagliptin action, we showed that glucagon-like peptide-1 suppressed proinflammatory and profibrotic phenotypes of macrophages in vitro. This study highlights the glucose metabolism–independent effects of anagliptin on NASH and HCC development.

Upregulation of cancer-associated gene expression in activated fibroblasts in a mouse model of non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH), characterized by chronic inflammation and fibrosis, is predicted to be the leading cause of cirrhosis and hepatocellular carcinoma (HCC) in the next decade. Although recent evidence suggests the importance of fibrosis as the strongest determinant of HCC development, the molecular mechanisms underlying NASH-induced carcinogenesis still remain unclear. Here we performed RNA sequencing analysis to compare gene expression profiles of activated fibroblasts prepared from two distinct liver fibrosis models: carbon tetrachloride–induced fibrosis as a model without obesity and HCC and genetically obese melanocortin 4 receptor–deficient (MC4R-KO) mice fed Western diet, which develop steatosis, NASH, and eventually HCC. Our data showed that activated fibroblasts exhibited distinct gene expression patterns in each etiology, and that the ‘pathways in cancer’ were selectively upregulated in the activated fibroblasts from MC4R-KO mice. The most upregulated gene in these pathways was fibroblast growth factor 9 (FGF9), which was induced by metabolic stress such as palmitate. FGF9 exerted anti-apoptotic and pro-migratory effects in fibroblasts and hepatoma cells in vitro and accelerated tumor growth in a subcutaneous xenograft model. This study reveals upregulation of cancer-associated gene expression in activated fibroblasts in NASH, which would contribute to the progression from NASH to HCC.

Obeticholic acid protects against hepatocyte death and liver fibrosis in a murine model of nonalcoholic steatohepatitis

Accumulating evidence has suggested that farnesoid X receptor (FXR) agonists, such as obeticholic acid (OCA) are therapeutically useful for non-alcoholic steatohepatitis (NASH). However, it is still unclear how FXR agonists protect against NASH and which cell type is the main target of FXR agonists. In this study, we examined the effects of OCA on the development of NASH using melanocortin 4 receptor-deficient (MC4R-KO) mice that progressively developed hepatic steatosis and NASH on Western diet (WD). Treatment with OCA effectively prevented chronic inflammation and liver fibrosis in WD-fed MC4R-KO mice with only marginal effect on body weight and hepatic steatosis. Hepatic crown-like structure (hCLS) is a unique histological structure characteristic of NASH, which triggers hepatocyte death-induced interstitial fibrosis. Intriguingly, treatment with OCA markedly reduced hCLS formation even after MC4R-KO mice developed NASH, thereby inhibiting the progression of liver fibrosis. As its mechanism of action, OCA suppressed metabolic stress-induced p53 activation and cell death in hepatocytes. Our findings in this study highlight the role of FXR in hepatocytes in the pathogenesis of NASH. Collectively, this study demonstrates the anti-fibrotic effect of OCA in a murine model of NASH with obesity and insulin resistance, which suggests the clinical implication for human NASH.

CD11c+ resident macrophages drive hepatocyte death-triggered liver fibrosis in a murine model of nonalcoholic steatohepatitis

Although recent evidence has pointed to the role of organ- and pathogenesis-specific macrophage subsets, it is still unclear which subsets are critically involved in the pathogenesis of nonalcoholic steatohepatitis (NASH). Using melanocortin-4 receptor-deficient (MC4R-KO) mice fed Western diet (WD), which exhibit liver phenotypes similar to those of human NASH, we found a histological structure, termed hepatic crown-like structure (hCLS), in which CD11c+ macrophages surround dead/dying hepatocytes, a prominent feature of NASH. Here, we demonstrate that hCLS-constituting macrophages could be a novel macrophage subset that drives hepatocyte death-triggered liver fibrosis. In an "inducible NASH model," hepatocyte death induces hCLS formation and liver fibrosis sequentially in the short term. In combination with the long-term WD feeding model, we also showed that resident macrophages are a major cellular source of CD11c+ macrophages constituting hCLS, which exhibited gene expression profiles distinct from CD11c- macrophages scattered in the liver. Moreover, depletion of CD11c+ macrophages abolished hCLS formation and fibrogenesis in NASH. Our clinical data suggest the role of CD11c+ macrophages in the disease progression from simple steatosis to NASH. This study sheds light on the role of resident macrophages, in addition to recruited macrophages, in the pathogenesis of NASH.

Synthetic "smart gel" provides glucose-responsive insulin delivery in diabetic mice

Although previous studies have attempted to create "electronics-free" insulin delivery systems using glucose oxidase and sugar-binding lectins as a glucose-sensing mechanism, no successful clinical translation has hitherto been made. These protein-based materials are intolerant of long-term use and storage because of their denaturing and/or cytotoxic properties. We provide a solution by designing a protein-free and totally synthetic material-based approach. Capitalizing on the sugar-responsive properties of boronic acid, we have established a synthetic polymer gel-based insulin delivery device confined within a single catheter, which exhibits an artificial pancreas-like function in vivo. Subcutaneous implantation of the device in healthy and diabetic mice establishes a closed-loop system composed of "continuous glucose sensing" and "skin layer"-regulated insulin release. As a result, glucose metabolism was controlled in response to interstitial glucose fluctuation under both insulin-deficient and insulin-resistant conditions with at least 3-week durability. Our "smart gel" technology could offer a user-friendly and remarkably economic (disposable) alternative to the current state of the art, thereby facilitating availability of effective insulin treatment not only to diabetic patients in developing countries but also to those patients who otherwise may not be strongly motivated, such as the elderly, infants, and patients in need of nursing care.

The H3K9 methyltransferase Setdb1 regulates TLR4-mediated inflammatory responses in macrophages

Proinflammatory cytokine production in macrophages involves multiple regulatory mechanisms, which are affected by environmental and intrinsic stress. In particular, accumulating evidence has suggested epigenetic control of macrophage differentiation and function mainly in vitro. SET domain, bifurcated 1 (Setdb1, also known as Eset) is a histone 3 lysine 9 (H3K9)-specific methyltransferase and is essential for early development of embryos. Here we demonstrate that Setdb1 in macrophages potently suppresses Toll-like receptor 4 (TLR4)-mediated expression of proinflammatory cytokines including interleukin-6 through its methyltransferase activity. As a molecular mechanism, Setdb1-deficiency decreases the basal H3K9 methylation levels and augments TLR4-mediated NF-κB recruitment on the proximal promoter region of interleukin-6, thereby accelerating interleukin-6 promoter activity. Moreover, macrophage-specific Setdb1-knockout mice exhibit higher serum interleukin-6 concentrations in response to lipopolysaccharide challenge and are more susceptible to endotoxin shock than wildtype mice. This study provides evidence that the H3K9 methyltransferase Setdb1 is a novel epigenetic regulator of proinflammatory cytokine expression in macrophages in vitro and in vivo. Our data will shed insight into the better understanding of how the immune system reacts to a variety of conditions.

Activating transcription factor 4 links metabolic stress to interleukin-6 expression in macrophages

Chronic inflammation is a molecular element of the metabolic syndrome and type 2 diabetes. Saturated fatty acids (SFAs) are considered to be an important proinflammatory factor. However, it is still incompletely understood how SFAs induce proinflammatory cytokine expression. Hereby we report that activating transcription factor (ATF) 4, a transcription factor that is induced downstream of metabolic stresses including endoplasmic reticulum (ER) stress, plays critical roles in SFA-induced interleukin-6 (Il6) expression. DNA microarray analysis using primary macrophages revealed that the ATF4 pathway is activated by SFAs. Haploinsufficiency and short hairpin RNA-based knockdown of ATF4 in macrophages markedly inhibited SFA- and metabolic stress-induced Il6 expression. Conversely, pharmacological activation of the ATF4 pathway and overexpression of ATF4 resulted in enhanced Il6 expression. Moreover, ATF4 acts in synergy with the Toll-like receptor-4 signaling pathway, which is known to be activated by SFAs. At a molecular level, we found that ATF4 exerts its proinflammatory effects through at least two different mechanisms: ATF4 is involved in SFA-induced nuclear factor-κB activation; and ATF4 directly activates the Il6 promoter. These findings provide evidence suggesting that ATF4 links metabolic stress and Il6 expression in macrophages.

Increased expression of macrophage-inducible C-type lectin in adipose tissue of obese mice and humans

OBJECTIVE

We have provided evidence that saturated fatty acids, which are released from adipocytes via macrophage-induced adipocyte lipolysis, serve as a naturally occurring ligand for the Toll-like receptor (TLR) 4 complex in macrophages, thereby aggravating obesity-induced adipose tissue inflammation. The aim of this study was to identify the molecule(s) activated in adipose tissue macrophages in obesity.

RESEARCH DESIGN AND METHODS

We performed a cDNA microarray analysis of coculture of 3T3-L1 adipocytes and RAW264 macrophages. Cultured adipocytes and macrophages and the adipose tissue of obese mice and humans were used to examine mRNA and protein expression.

RESULTS

We found that macrophage-inducible C-type lectin (Mincle; also called Clec4e and Clecsf9), a type II transmembrane C-type lectin, is induced selectively in macrophages during the interaction between adipocytes and macrophages. Treatment with palmitate, a major saturated fatty acid released from 3T3-L1 adipocytes, induced Mincle mRNA expression in macrophages at least partly through the TLR4/nuclear factor (NF)-κB pathway. Mincle mRNA expression was increased in parallel with macrophage markers in the adipose tissue of obese mice and humans. The obesity-induced increase in Mincle mRNA expression was markedly attenuated in C3H/HeJ mice with defective TLR4 signaling relative to control C3H/HeN mice. Notably, Mincle mRNA was expressed in bone-marrow cell (BMC)-derived proinflammatory M1 macrophages rather than in BMC-derived anti-inflammatory M2 macrophages in vitro.

CONCLUSIONS

Our data suggest that Mincle is induced in adipose tissue macrophages in obesity at least partly through the saturated fatty acid/TLR4/NF-κB pathway, thereby suggesting its pathophysiologic role in obesity-induced adipose tissue inflammation.

Activating transcription factor 3 constitutes a negative feedback mechanism that attenuates saturated Fatty acid/toll-like receptor 4 signaling and macrophage activation in obese adipose tissue

Obese adipose tissue is markedly infiltrated by macrophages, suggesting that they may participate in the inflammatory pathways that are activated in obese adipose tissue. Evidence has suggested that saturated fatty acids released via adipocyte lipolysis serve as a naturally occurring ligand that stimulates Toll-like receptor (TLR)4 signaling, thereby inducing the inflammatory responses in macrophages in obese adipose tissue. Through a combination of cDNA microarray analyses of saturated fatty acid-stimulated macrophages in vitro and obese adipose tissue in vivo, here we identified activating transcription factor (ATF)3, a member of the ATF/cAMP response element-binding protein family of basic leucine zipper-type transcription factors, as a target gene of saturated fatty acids/TLR4 signaling in macrophages in obese adipose tissue. Importantly, ATF3, when induced by saturated fatty acids, can transcriptionally repress tumor necrosis factor-alpha production in macrophages in vitro. Chromatin immunoprecipitation assay revealed that ATF3 is recruited to the region containing the activator protein-1 site of the endogenous tumor necrosis factor-alpha promoter. Furthermore, transgenic overexpression of ATF3 specifically in macrophages results in the marked attenuation of proinflammatory M1 macrophage activation in the adipose tissue from genetically obese KKA(y) mice fed high-fat diet. This study provides evidence that ATF3, which is induced in obese adipose tissue, acts as a transcriptional repressor of saturated fatty acids/TLR4 signaling, thereby revealing the negative feedback mechanism that attenuates obesity-induced macrophage activation. Our data also suggest that activation of ATF3 in macrophages offers a novel therapeutic strategy to prevent or treat obesity-induced adipose tissue inflammation.

Atorvastatin attenuates transplant-associated coronary arteriosclerosis in a murine model of cardiac transplantation

Accelerated coronary arteriosclerosis remains a major problem for the long-term survival of cardiac transplant recipients. However, the pathogenesis of transplant vasculopathy is poorly understood and there is no effective therapy. HMG-CoA reductase inhibitors, or statins, are widely prescribed to lower plasma cholesterol level. Accumulating evidence indicates that statins have various effects on vascular cells which are independent of their lipid-lowering effect. We investigated whether orally administered atorvastatin, one of the most potent statins, inhibits the development of intima hyperplasia in a mouse model of cardiac transplantation. Cardiac allografts from DBA mice were transplanted heterotopically into B10.D2 mice. Mice were administered either vehicle or atorvastatin everyday by gavage. Morphometrical analysis revealed that atorvastatin significantly reduced the development of coronary arteriosclerosis on the cardiac allografts harvested at one month. Immunohistochemical analysis revealed that atorvastatin attenuated infiltration of inflammatory cells with reduced expression of TGF-beta and adhesion molecules. These results suggest that atorvastatin may be effective in preventing transplant-associated arteriosclerosis along with other immunosuppressive agents.

Decision support system for the diagnosis of schizophrenia disorders

Clinical decision support systems are useful tools for assisting physicians to diagnose complex illnesses. Schizophrenia is a complex, heterogeneous and incapacitating mental disorder that should be detected as early as possible to avoid a most serious outcome. These artificial intelligence systems might be useful in the early detection of schizophrenia disorder. The objective of the present study was to describe the development of such a clinical decision support system for the diagnosis of schizophrenia spectrum disorders (SADDESQ). The development of this system is described in four stages: knowledge acquisition, knowledge organization, the development of a computer-assisted model, and the evaluation of the system's performance. The knowledge was extracted from an expert through open interviews. These interviews aimed to explore the expert's diagnostic decision-making process for the diagnosis of schizophrenia. A graph methodology was employed to identify the elements involved in the reasoning process. Knowledge was first organized and modeled by means of algorithms and then transferred to a computational model created by the covering approach. The performance assessment involved the comparison of the diagnoses of 38 clinical vignettes between an expert and the SADDESQ. The results showed a relatively low rate of misclassification (18-34%) and a good performance by SADDESQ in the diagnosis of schizophrenia, with an accuracy of 66-82%. The accuracy was higher when schizophreniform disorder was considered as the presence of schizophrenia disorder. Although these results are preliminary, the SADDESQ has exhibited a satisfactory performance, which needs to be further evaluated within a clinical setting.

The role of circulating precursors in vascular repair and lesion formation

The accumulation of smooth muscle cells (SMCs) plays a principal role in atherogenesis, post-angioplasty restenosis and transplantation-associated vasculopathy. Therefore, much effort has been expended in targeting the migration and proliferation of medial smooth muscle cells to prevent occlusive vascular remodeling. Recent evidence suggests that bone marrow-derived circulating precursors can also give rise to endothelial cells and smooth muscle cells that contribute to vascular repair, remodeling, and lesion formation under physiological and pathological conditions. This article overviews recent findings on circulating vascular progenitor cells and describes potential therapeutic strategies that target these cells to treat occlusive vascular diseases.

Effect of deuterium oxide on contraction characteristics and ATPase activity in glycerinated single rabbit skeletal muscle fibers

We studied the effect of deuterium oxide (D(2)O) on contraction characteristics and ATPase activity of single glycerinated muscle fibers of rabbit psoas. D(2)O increased the maximum isometric force P(0) by about 20%, while the force versus stiffness relation did not change appreciably. The maximum shortening velocity under zero load V(max) did not change appreciably in D(2)O, so that the force-velocity (P-V) curve was scaled depending on the value of P(0). The Mg-ATPase activity of the fibers during generation of steady isometric force P(0) was reduced by about 50% in D(2)O. Based on the Huxley contraction model, these results can be accounted for in terms of D(2)O-induced changes in the rate constants f(1) and g(1) for making and breaking actin-myosin linkages in the isometric condition, in such a way that f(1)/(f(1)+g(1)) increases by about 20%, while (f(1)+g(1)) remains unchanged. The D(2)O effect at the molecular level is discussed in connection with biochemical studies on actomyosin ATPase.

Electrical and mechanical properties and mode of innervation in scorpionfish sound-producing muscle fibres

To obtain information about the neural mechanism underlying sound production in teleost fish, we studied the electrical and mechanical properties and mode of innervation in the swimbladder muscle (SBM) fibres of scorpionfish Sebastiscus marmoratus. Action potentials of the SBM fibres in response to direct electrical stimulation neither exhibited overshoot nor propagated along the fibre. Stimulation of the motor nerve,however, uniformly evoked action potentials along the fibre. When neuromuscular transmission was blocked by curare, motor nerve stimulation uniformly evoked endplate potentials along the fibre. These results indicate that action potentials propagate along the nerve branches but not along the SBM fibre membrane. In accordance with the above results, histochemical studies showed that motor nerve branches run along the SBM fibres to form many endplates with cholinesterase activity, indicating multiterminal innervation. The SBM consisted of about 600 fibres, while its motor nerve contained about 100 axons, giving an innervation ratio of about 1:6. Like mammalian fast muscle fibres, the SBM fibres exhibited a low succinic dehydrogenase activity and a high ATPase activity. These results are discussed in connection with the function of the SBM fibres in producing sound.

Marked load-bearing ability of Mytilus smooth muscle in both active and catch states as revealed by quick increases in load

The anterior byssal retractor muscle (ABRM) of the bivalve Mytilus edulis shows a prolonged tonic contraction, called the catch state. To investigate the catch mechanism, details of which still remain obscure, we studied the mechanical responses of ABRM fibres to quick increases in load applied during maximum active isometric force (P(0)) generation and during the catch state. The mechanical response consisted of three components: (1) initial extension of the series elastic component (SEC), (2) early isotonic fibre lengthening with decreasing velocity, and (3) late steady isotonic fibre lengthening. The ABRM fibres could bear extremely large loads up to 10-15P(0) for more than 30-60 s, while being lengthened extremely slowly. If, on the other hand, quick increases in load were applied during the early isometric force development, the ABRM fibres were lengthened rapidly ('give') under loads of 1.5-2P(0). These findings might possibly be explained by two independent systems acting in parallel with each other; one is the actomyosin system producing active shortening and active force generation, while the other is the load-bearing system responsible for the extremely marked load-bearing ability as well as the maintenance of the catch state.

In vitro actomyosin motility in deuterium oxide

Actin filament velocities in an in vitro motility assay system were measured both in heavy water (deuterium oxide, D2O) and water (H2O) to examine the effect of D2O on the actomyosin interaction. The dependence of the sliding velocity on pD of the D2O assay solution showed a broad pD optimum of around pD 8.5 which resembled the broad pH optimum (pH 8.5) of the H2O assay solution, but the maximum velocity (4.1 +/- 0.5 microm/sec, n=11) at pD 8.5 in D2O was about 60% of that (7.1 +/- 1.1 microm/sec, n=11) at pH 8.5 in H2O. The Km values of 95 and 80 microM and Vmax values of 3.2 and 5.1 microm/sec for the D2O and H2O assay were obtained by fitting the ATP concentration dependence of the velocity (at pD and pH 7.5) to the Michaelis-Menten equation. The Km value of actin-activated Mg-ATPase activity of myosin subfragment 1(S1) was decreased from 50 microM[actin] in H2O to 33 microM[actin] in D2O without any significant changes in Vmax (9.4 s(-1) in D2O and 9.3 s(-1) in H2O). The rate constants of ADP release from the acto-S1-ADP complex measured by the stopped flow method were 361 +/- 26 s(-1) (n=27) in D2O and 512 +/- 39 s(-1) (n=27) in H2O at 6 degrees C. These results suggest that the decrease in the in vitro actin-myosin sliding velocity in D2O results from a slowing of the release of ADP from the actomyosin-ADP complex and the increase in the affinity of actin for myosin in the presence of ATP in D2O.

Recovery of action potentials and twitches after K-contractures in frog skeletal muscle

To give information about intracellular Ca2+ translocation during and after K-contractures in vertebrate skeletal muscle fibers, we examined recovery of action potentials and twitches after interruption and spontaneous relaxation of K-contractures at low temperature (3 degrees C) that greatly reduced the rate of Ca2+ reuptake by the sarcoplasmic reticulum. On membrane repolarization interrupting K-contractures, the amplitude of both action potentials and twitches recovered quickly, while the falling phase of action potential was markedly slowed at first to prolong its refractory period, so that repetitive stimulation (20 Hz) did not produce a complete tetanus. Meanwhile, on membrane repolarization after spontaneous relaxation of K-contractures, the action potentials were markedly reduced in amplitude and prolonged in duration at first, also resulting in prolonged refractory period. These results are discussed in connection with Ca2+ absorption to the surface and transverse tubule membranes, producing changes in action potential kinetics.

Effect of deuterium oxide on actomyosin motility in vitro

Actin filament velocities in an in vitro motility assay system were measured both in heavy water (deuterium oxide, D(2)O) and water (H(2)O) to examine the effect of D(2)O on the actomyosin interaction. The dependence of the sliding velocity on pD of the D(2)O assay solution showed a broad pD optimum of around pD 8.5 which resembled the broad pH optimum (pH 8.5) of the H(2)O assay solution, but the maximum velocity (4.1+/-0.5 microm/s, n=11) at pD 8.5 in D(2)O was about 60% of that (7.1+/-1.1 microm/s, n=11) at pH 8.5 in H(2)O. The K(m) values of 95 and 80 microM and V(max) values of 3.2 and 5.1 microm/s for the D(2)O and H(2)O assay were obtained by fitting the ATP concentration dependence of the velocity (at pD and pH 7.5) to the Michaelis-Menten equation. The K(m) value of actin-activated Mg-ATPase activity of myosin subfragment 1 (S1) was decreased from 50 microM [actin] in H(2)O to 33 microM [actin] in D(2)O without any significant changes in V(max) (9.4 s(-1) in D(2)O and 9.3 s(-1) in H(2)O). The rate constants of ADP release from the acto-S1-ADP complex measured by the stopped flow method were 361+/-26 s(-1) (n=27) in D(2)O and 512+/-39 s(-1) (n=27) in H(2)O at 6 degrees C. These results suggest that the decrease in the in vitro actin-myosin sliding velocity in D(2)O results from a slowing of the release of ADP from the actomyosin-ADP complex and the increase in the affinity of actin for myosin in the presence of ATP in D(2)O.

Measurement of nucleotide exchange rate constants in single rabbit soleus myofibrils during shortening and lengthening using a fluorescent ATP analog

The kinetics of displacement of a fluorescent nucleotide, 2'(3')-O-[N[2-[[Cy3]amido]ethyl]carbamoyl]-adenosine 5'-triphosphate (Cy3-EDA-ATP), bound to rabbit soleus muscle myofibrils were studied using flash photolysis of caged ATP. Use of myofibrils from this slow twitch muscle allowed better resolution of the kinetics of nucleotide exchange than previous studies with psoas muscle myofibrils (, Biophys. J. 73:2033-2042). Soleus myofibrils in the presence of Cy3-EDA-nucleotides (Cy3-EDA-ATP or Cy3-EDA-ADP) showed selective fluorescence staining of the A-band. The K(m) for Cy3-EDA-ATP and the K(d) for Cy3-EDA-ADP binding to the myofibril A-band were 1.9 microM and 3.8 microM, respectively, indicating stronger binding of nucleotide to soleus cross-bridges compared to psoas cross-bridges (2.6 microM and 50 microM, respectively). After flash photolysis of caged ATP, the A-band fluorescence of the myofibril in the Cy3-EDA-ATP solution under isometric conditions decayed exponentially with a rate constant of 0.045 +/- 0.007 s(-1) (n = 32) at 10 degrees C, which was about seven times slower than that for psoas myofibrils. When a myofibril was allowed to shorten with a constant velocity, the nucleotide displacement rate constant increased from 0.066 s(-1) (isometric) to 0.14 s(-1) at 20 degrees C with increasing shortening velocity up to 0.1 myofibril length/s (V(max), the shortening velocity under no load was approximately 0. 2 myofibril lengths/s). The rate constant was not significantly affected by an isovelocity stretch of up to 0.1 myofibril lengths/s. These results suggest that the cross-bridge kinetics are not significantly affected at higher strain during lengthening but depend on the lower strain during shortening. These data also indicate that the interaction distance between a cross-bridge and the actin filament is at least 16 nm for a single cycle of the ATPase.

Measurement of ATP turnover during shortening and lengthening of rabbit psoas myofibrils using a fluorescent ATP analog

In order to study ATP turnover during shortening and lengthening of rabbit psoas myofibrils, we have used fluorescence microscopy in which the displacement of a fluorescent nucleotide analog, 2'(3')-O-[N-[2-[[Cy3] amido] ethyl] carbamoyl]-adenosine 5' triphosphate (Cy3-EDA-ATP) bound to cross-bridge on flash photolysis of caged ATP was measured [Chaen et al. (1997) Biophys. J. 73, 2033-2042]. In the previous paper, we reported that when a myofibril was imposed to shorten with a constant velocity by a piezo-electric actuator, the nucleotide displacement rate constant initially increased to 0.7 s-1 with increasing shortening velocity and then declined with a further increase in shortening velocity. The rate constant during lengthening measured in the present experiment was found to be not significantly affected. These results suggest that the cross-bridge kinetics show a asymmetrical dependence on the mechanical strain in the cross-bridges, namely, the rate constants are not significantly affected at higher strain during lengthening but depend on the lower strain during shortening.

Evidence for the essential role of myosin subfragment-2 in the ATP-dependent actin-myosin sliding in muscle contraction

The role of myosin subfragment-2 (myosin S-2) in muscle contraction was studied by using an in vitro motility assay system in which the ATP-dependent sliding between myosin-coated polystyrene beads and actin filament arrays (actin cables) of giant algal cells were recorded under constant external loads provided with a centrifuge microscope. With antibody to myosin S-2 below 0.3 mg/ml, the maximum "isometric" force generated by myosin molecules on the bead decreased markedly, but the unloaded bead-sliding velocity along actin cables did not change appreciably, indicating a decrease in the number of myosin molecules interacting with actin cables. The antibody at 0.3-1.5 mg/ml decreased not only the maximum isometric force, but also the unloaded bead-sliding velocity in a dose-dependent manner. With the antibody at 1.5-3 mg/ml, the beads eventually stopped moving to remain attached to actin cables. These beads could be readily detached from actin cables with very small centrifugal forces, indicating very weak actin-myosin linkages. The antibody had no effect on rigor actin-myosin linkages formed before the antibody application. These results are consistent with the view that myosin S-2 plays an essential role in muscle contraction.

Validity study of the Brazilian version of the Calgary Depression Scale for Schizophrenia

INTRODUCTION

Although depression is a well-established feature of schizophrenia, it is difficult to measure, because it overlaps with negative symptoms and extrapyramidal symptoms (EPS). Routinely adopted depression scales were not designed to be used in--cases of schizophrenia, and are known to perform poorly when trying to distinguish depression from other symptoms.

OBJECTIVE

The aim of this study was to evaluate the validity of the Brazilian version of the Calgary Depression Rating Scale for Schizophrenia (CDSS).

METHOD

Outpatients from four mental health units in the city of São Paulo, diagnosed as having schizophrenia by DSM-IV criteria, were evaluated by two independent raters who applied the DSM-IV depression criteria. All patients were assessed by means of the CDSS, the Positive and Negative Syndrome Scale (PANSS), and the Extrapyramidal Symptom Rating Scale (ESRS).

RESULTS

Eighty patients were recruited for the study. The analysis was carried out by comparing the DSM-IV criteria of depression with the CDSS scores, by means of the receiver operating characteristic (ROC) curves. The area under the ROC curve for major depression was 0.95 (SD = 0.02), and at a cut-off point of 6/7 the validity coefficients were as follows: sensibility 77%, specificity 92%, positive predictive value 67% and negative predictive value 95%. The area under the ROC curve for minor depression was 0.95 (SD = 0.02), and at a cut-off point of 4/5 the validity coefficients were as follows: sensibility 95%, specificity 88%, positive predictive value 75% and negative predictive value 98%. The correlation coefficients between the CDSS scores, the PANSS negative and positive subscale scores, and the ESRS scores were all below 0.50.

CONCLUSION

It can be concluded that the Brazilian version of the CDSS is a valid research tool to assess depressive episodes for stabilized patients with schizophrenia.

Force-velocity relation of sliding of skeletal muscle myosin, arranged on a paramyosin filament, on actin cables

To investigate in vitro ATP-dependent sliding of regularly arranged myosin molecules on actin filaments, we prepared thick hybrid filaments in which myosin molecules isolated from rabbit skeletal muscle were arranged around the paramyosin core (length, 10-20 micron; diameter, </=0.2 micron) obtained from a molluscan smooth muscle. A single to a few thick hybrid filaments were attached to a polystyrene bead (diameter, 4.5 micron; specific gravity, 1.5) and made to slide on actin filament arrays (actin cables) in the internodal cell of an alga, mounted on the rotor of a centrifuge microscope. The bead was subjected to centrifugal forces serving as external loads to the ATP-dependent actin-myosin sliding. The maximum unloaded sliding velocity of the thick filament attached-bead (mean, 3.4 micron/s; 20-23 degrees C) was significantly higher than that of the bead coated with randomly oriented myosin molecules reported previously. The steady-state force-velocity (P-V) relations obtained were qualitatively similar to those in intact skeletal muscle fibers. These results indicate that this in vitro motility assay system retains the basic characteristics of contracting skeletal muscle fibers, and that it may be effectively used to study mechanisms underlying the steady-state P-V characteristics of ATP-dependent actin-myosin sliding using various recombinant myosins produced in nonmuscle cells.

Measurement of nucleotide release kinetics in single skeletal muscle myofibrils during isometric and isovelocity contractions using fluorescence microscopy

Rabbit psoas muscle myofibrils, in the presence of the fluorescent nucleotide analog 2'(3')-O-[N-[2-[[Cy3]amido]ethyl]carbamoyl]-adenosine 5' triphosphate (Cy3-EDA-ATP), showed selective fluorescence staining of the A-band with a reduced fluorescence at the M-line. Addition of Cy3-EDA-ATP to a myofibril in the presence of Ca2+ caused auxotonic shortening against a compliant glass microneedle. These results indicate that Cy3-EDA-ATP is a substrate for myosin in the myofibril system. The kinetics of nucleotide release from a single myofibril, held isometrically between two needles, were measured by the displacement of prebound Cy3-EDA-ATP on flash photolysis of caged ATP. The A-band fluorescence of the myofibril decayed exponentially with a rate constant of 0.3 s(-1) at 8 degrees C, an order of magnitude faster than that for isolated thick filaments in the absence of actin. When a myofibril was imposed to shorten with a constant velocity by a piezoelectric actuator, the nucleotide displacement rate constant initially increased to 0.7 s(-1) with increasing shortening velocity and then declined with a further increase in shortening velocity. These results demonstrate that the displacement rates of Cy3-EDA-nucleotides bound to the cross-bridges in the contracting myofibril reflect a process that shows strain dependence.

Family expectation, social adjustment and gender differences in a sample of schizophrenic patients

A case series to study factors related to family expectation regarding schizophrenic patients was conducted in an out-patient setting in the city of S. Paulo, Brazil. Patients diagnosed as presenting schizophrenia by the ICD 9th Edition and having had the disease for more than four years were included in the study. Family Expectation was measured by the difference between the Katz Adjustment Scale (R2 and R3) scores based on the relative's expectation and the socially expected activities of the patient (Discrepancy Score), and social adjustment was given by the DSM-III-R Global Assessment Scale (GAS). Outcome assessments were made independently, and 44 patients comprised the sample (25 males and 19 females). The Discrepancy mean score was twice as high for males as for females (p < 0.02), and there was an inverse relationship between the discrepancy score and social adjustment (r = -0.46, p < 0.001). Moreover, sex and social adjustment exerted independent effects on the discrepancy score when age, age at onset and number of psychiatric admissions were controlled by means of a multiple regression technique. There was an interaction between sex and social adjustment, the inverse relationship between social adjustment and discrepancy score being more pronounced for males. These findings are discussed in the light of the potential association between the family environment, gender and social adjustment of schizophrenic patients, and the need for further research, i.e. ethnographic accounts of interactions between patient and relatives sharing households particularly in less developed countries.

The mode of ATP-dependent microtubule-kinesin sliding in the auxotonic condition

Kinesin is a motor protein that converts chemical energy derived from ATP hydrolysis into mechanical work to transport cellular components along microtubules. We studied the properties of ATP-dependent microtubule-kinesin sliding with two different in vitro assay systems. In one assay system, a kinesin-coated glass microneedle (elastic coefficient, 1-2.5 pN microns -1) was made to slide along an axoneme. Using this system, we obtained the relationship between the force (= load) on the microneedle and the velocity of microneedle-kinesin sliding in the auxotonic condition, in which the load on the microtubule-kinesin contacts increased as sliding progressed. The force-velocity curve was upwardly convex (maximum velocity Vmax, 0.58 +/- 0.15 microns s-1; maximum isometric force P0, 5.0 +/- 1.6 pN) and was similar to that of in vitro actin-myosin sliding in the auxotonic condition, suggesting that the two motor protein systems have fundamental kinetic properties in common. In the other assay system, an axoneme attached to a glass microneedle (elastic coefficient, 4-5 pN microns -1) was made to slide on a kinesin-coated glass surface (Vmax, 0.68 +/- 0.17 microns s-1; P0, 46.1 +/- 18.6 pN). The change in shape of the axoneme indicated an enormous flexibility of randomly oriented kinesin molecules.

[Transvaginal ultrasonographic assessment of endometrium during hMG-hCG cycles]

Daily changes in the thickness and texture of the endometrium were assessed by transvaginal sonography in 15 natural (cycles 'cycle-A) and 24 stimulated cycles (cycle-B: hMG-hCG cycles; hCG 10,000 IU was injected on the day after the dominant follicle reached 18mm in three-directional radius, n = 7) (cycle-C: hCG 3,000 IU injections on the 5th, 9th and 13th day after hCG 10,000 injection were added to cycle-B, n = 10) (cycle-D: hCG 1,000 IU instead of 3,000 IU of cycle-C, n = 7). The duration of the luteal phase was 15, 9, 17 and 18 days in cycle-A, cycle-B, cycle-C and cycle-D, respectively. The thickness of the endometrium increased lineally until ovulation day (D +/- 0) (thickness: 10.7mm) in cycle-A, but in stimulated cycles it revealed a significantly rapid increase until D-4 (10.9mm) and then reached a plateau. The ratio of the thickness of the hyperechoic area to the total thickness of the endometrium reached 100% (D + 9) in cycle-A. The ratio reached only 72% (Max, D + 4) in cycle-B, but the effect of luteal support was shown to reach 89% and 85% (Max, D + 7) in cycle-C and cycle-D. The serum progesterone level in stimulated cycles revealed a rapid increase until D + 5, but it had an unstable pattern in cycle-C and cycle-D. It was shown that luteal support was necessary to offset the luteal phase defect caused by stimulation with hMG.

Action of cannabidiol on the anxiety and other effects produced by delta 9-THC in normal subjects

The object of the experiment was to verify whether cannabidiol (CBD) reduces the anxiety provoked by delta 9-THC in normal volunteers, and whether this effect occurs by a general block of the action of delta 9-THC or by a specific anxiolytic effect. Appropriate measurements and scales were utilized and the eight volunteers received, the following treatments in a double-blind procedure: 0.5 mg/kg delta 9-THC, 1 mg/kg CBD, a mixture containing 0.5 mg/kg delta 9-THC and 1 mg/kg CBD and placebo and diazepam (10 mg) as controls. Each volunteer received the treatments in a different sequence. It was verified that CBD blocks the anxiety provoked by delta 9-THC, however this effect also extended to marihuana-like effects and to other subjective alterations induced by delta 9-THC. This antagonism does not appear to be caused by a general block of delta 9-THC effects, since no change was detected in the pulse-rate measurements. Several further effects were observed typical of CBD and of an opposite nature to those of delta 9-THC. These results suggest that the effects of CBD, as opposed to those of delta 9-THC, might be involved in the antagonism of effects between the two cannabinoids.

Metabolic fate of 1-hexylcarbamoyl-5-fluorouracil in rats

1. The metabolic fate of a new antitumour agent, 1-hexylcarbamoyl-5-fluoro [6-14C]uracil (14C-HCFU) in rats after oral administration was compared with that of 5-fluoro[6-14C]uracil (14C-FU). 2. Tissue radioactivity reached a max. 1 to 3 h after administration of 14C-HCFU and 0.5 h after 14C-FU. 3. Both drugs were excreted rapidly, mostly in urine. Expired 14CO2 from 14C-HCFU was significantly less than that from 14C-FU. 4. Unchanged FU was not detected in plasma 3 h after administration of 14C-FU, whereas FU was detected in plasma 5 h after 14C-HCFU. The pyrimidine ring of 14C-HCFU might be degradated more slowly than that of 14C-FU. 5. 1-(5-Carboxypentylcarbamoyl)-5-fluorouracil and 1-(3-carboxypropylcarbamoyl)-5-fluorouracil were identified as the major urinary metabolites of 14C-HCFU.

Enzyme-linked sandwich immunoassay of macromolecular antigens using the rabbit antibody-coupled glass rod as a solid phase

A highly sensitive sandwich immunoassay of macromolecular antigens using the rabbit antibody Fab' - beta-D-galactosidase complex and the rabbit antibody immunoglobulin-G-coupled glass rod as a solid phase is described. The Fab' fragments of rabbit antibody IgG are conjugated with beta-D-galactosidase from Escherichia coli using N,N'-o-phenylenedimaleimide. Rabbit antibody IgG is coupled to the aminoalkylsilyl glass rods (3 mm in diameter and 5 mm in length) using glutaraldehyde. A wide range of the concentrations of rabbit IgG fraction (20-2000 mug/ml) is effective for coupling, and the amount of rabbit immunoglobulin G coupled can be controlled. The smallest amounts of ornithine delta-aminotransferase from rat liver, human immunoglobulin G and 2,4-dinitrophenyl human immunoglobulin G that can be determined are 0.03, 0.3 and 0.04 fmol, respectively. The sensitivity of the assay for these antigens is affected mainly by the non-specific binding of the complexes to the solid phase and the ability of antigen molecules, adsorbed on the solid phase, to bind specifically the complexes. The assay with the rabbit antibody immunoglobulin-G-coupled glass rods is simpler and more sensitive than that with the rabbit antibody immunoglobulin-G-coupled Sepharose 4B.

Enzyme-linked sandwich immunoassay of ornithine delta-aminotransferase from rat liver using antibody-coupled glass rods as solid phase

A macromolecular antigen, ornithine delta-aminotransferase [EC 2.6.1.13] from rat liver (OAT) was assayed by the sandwich procedure using rabbit (anti-OAT) Fab'-beta-D-galactosidase complex and rabbit (anti-OAT) IgG-coupled glass rods as a solid phase. The Fab' fragments of the rabbit (anti-OAT) IgG were conjugated with beta-D-galactosidase [EC 3.2.1.23] from Escherichia coli using N, N'-o-phenylenedimaleimide. The rabbit (anti-OAT) IgG was coupled to the aminoalkylsilyl glass rods using glutaraldehyde. The rabbit (anti-OAT) IgG-coupled glass rods were incubated with OAT and then with the rabbit (anti-OAT) Fab'-beta-D-galactosidase complex. The amount of OAT was determined from the activity of beta-D-galactosidase bound to the glass rods. A minimum of 0.03 fmoles of OAT could be determined by this method and use of the glass rods gave greater reproducibility, and was more sensitive and simpler than use of Sepharose 4B.

Effects of delta9-tetrahydrocannabinol and cannabinol in man

The interaction of delta9-tetrahydrocannabinol (delta9-THC) and cannabinol (CBN) was studied in man. Five male volunteers were given placebo, 50 mg CBN, 25 mg delta9-THC, 12.5 mg delta9-THC + 25 mg CBN, and 25 mg delta9-THC + 50 mg CBN (orally). Administrations were spaced 1 week apart. With physiological measures, delta9-THC produced an increase in heart rate while CBN did not. When combined, no change of the delta9-THC effect occurred. No changes occurred on the electrocardiogram, blood pressure, or body temperature. With psychophysical measures no changes occurred in pain thresholds or skin sensitivity as a function of drug treatment. In time estimates of the passage of 1 minute, delta9-THC alone produced underestimates of the passage of 1 minute and CBN alone had no effect. In combination the two drugs had a tendency to produce significant overestimates and underestimates of the passage of 1 minute. On a 66-item adjective-pair drug reaction scale, the volunteers reported feeling drugged, drunk, dizzy, and drowsy under the delta9-THC condition, but not under the CBN condition. With combined drug treatment, volunteers reported feeling more drugged, drunk, dizzy, and drowsy than under the delta9-THC condition alone. None of the drug treatments produced significant changes on other items which included items on perception, emotion, cognition and sociability. It appears that CBN increases the effect of delta9-THC on some aspects of physiological and psychological processes, but that these effects are small and cannot account for the greater potency which has been reported when plant material is used.