GR-KLF15 pathway controls hepatic lipogenesis during fasting

During periods of fasting, the body undergoes a metabolic shift from carbohydrate utilization to the use of fats and ketones as an energy source, as well as the inhibition of de novo lipogenesis and the initiation of gluconeogenesis in the liver. The transcription factor sterol regulatory element-binding protein-1 (SREBP-1), which plays a critical role in the regulation of lipogenesis, is suppressed during fasting, resulting in the suppression of hepatic lipogenesis. We previously demonstrated that the interaction of fasting-induced Kruppel-like factor 15 (KLF15) with liver X receptor serves as the essential mechanism for the nutritional regulation of SREBP-1 expression. However, the underlying mechanisms of KLF15 induction during fasting remain unclear. In this study, we show that the glucocorticoid receptor (GR) regulates the hepatic expression of KLF15 and, subsequently, lipogenesis through the KLF15-SREBP-1 pathway during fasting. KLF15 is necessary for the suppression of SREBP-1 by GR, as demonstrated through experiments using KLF15 knockout mice. Additionally, we show that GR is involved in the fasting response, with heightened binding to the KLF15 enhancer. It has been widely known that the hypothalamic-pituitary-adrenal (HPA) axis regulates the secretion of glucocorticoids and plays a significant role in the metabolic response to undernutrition. These findings demonstrate the importance of the HPA-axis-regulated GR-KLF15 pathway in the regulation of lipid metabolism in the liver during fasting.

Hepatic FASN deficiency differentially affects nonalcoholic fatty liver disease and diabetes in mouse obesity models

Nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes are interacting comorbidities of obesity, and increased hepatic de novo lipogenesis (DNL), driven by hyperinsulinemia and carbohydrate overload, contributes to their pathogenesis. Fatty acid synthase (FASN), a key enzyme of hepatic DNL, is upregulated in association with insulin resistance. However, the therapeutic potential of targeting FASN in hepatocytes for obesity-associated metabolic diseases is unknown. Here, we show that hepatic FASN deficiency differentially affects NAFLD and diabetes depending on the etiology of obesity. Hepatocyte-specific ablation of FASN ameliorated NAFLD and diabetes in melanocortin 4 receptor-deficient mice but not in mice with diet-induced obesity. In leptin-deficient mice, FASN ablation alleviated hepatic steatosis and improved glucose tolerance but exacerbated fed hyperglycemia and liver dysfunction. The beneficial effects of hepatic FASN deficiency on NAFLD and glucose metabolism were associated with suppression of DNL and attenuation of gluconeogenesis and fatty acid oxidation, respectively. The exacerbation of fed hyperglycemia by FASN ablation in leptin-deficient mice appeared attributable to impairment of hepatic glucose uptake triggered by glycogen accumulation and citrate-mediated inhibition of glycolysis. Further investigation of the therapeutic potential of hepatic FASN inhibition for NAFLD and diabetes in humans should thus consider the etiology of obesity.

Inflammation as an exacerbation marker and target for prophylaxis against Coronavirus Disease 2019-related thrombosis

Objectives: There are currently no appropriate markers and target for prophylaxis against COVID-19-related thrombosis, especially in the not-severe cases. We tested the hypothesis that inflammation is a suitable marker and target for prophylaxis against COVID-19-related thrombosis. Methods: Data of all 32 COVID-19 patients admitted to Saitama Medical Center between January 1 and March 30, 2021, were analyzed. Patients were divided into severe (requiring oxygen, n=12) and non-severe (no requirement for oxygen, n=20), and also those with high C-reactive protein (CRP) level (cutoff value: 30 mg/L, n=21) and low-CRP (n=11). We also compared the clinical and laboratory data of a 46-year-old post-liver transplant male patient, who was treated with a combination of immunosuppressants (methylprednisolone, fludrocortisone, cyclosporine, and everolimus) with those of other COVID-19 patients, using the Smirnoff-Grubbs and Box plots tests. Results: The levels of CRP, ferritin, lactate dehydrogenase, aspartate aminotransferase, and thrombin-antithrombin complex (TAT) were significantly higher in the high-severity group than the low-severity group; while other coagulation parameters were comparable. The time between onset of illness and blood levels of lactate dehydrogenase, fibrinogen, D-dimer, TAT, and plasmin alpha2-plasmin inhibitor complex (PIC) were significantly higher whereas lymphocyte count was significantly lower in the high-CRP group. Extremely low levels of TAT, PIC, and plasminogen activator inhibitor-1 (PAI-1) were recorded in the liver transplant patient treated with immunosuppressants. The TAT, PIC, and PAI-1 levels were deemed outliers. Conclusions: Inflammation is a potentially suitable marker and target for prophylaxis against COVID-19-related thrombosis.

FoxO-KLF15 pathway switches the flow of macronutrients under the control of insulin

KLF15 is a transcription factor that plays an important role in the activation of gluconeogenesis from amino acids as well as the suppression of lipogenesis from glucose. Here we identified the transcription start site of liver-specific KLF15 transcript and showed that FoxO1/3 transcriptionally regulates Klf15 gene expression by directly binding to the liver-specific Klf15 promoter. To achieve this, we performed a precise in vivo promoter analysis combined with the genome-wide transcription-factor-screening method "TFEL scan", using our original Transcription Factor Expression Library (TFEL), which covers nearly all the transcription factors in the mouse genome. Hepatic Klf15 expression is significantly increased via FoxOs by attenuating insulin signaling. Furthermore, FoxOs elevate the expression levels of amino acid catabolic enzymes and suppress SREBP-1c via KLF15, resulting in accelerated amino acid breakdown and suppressed lipogenesis during fasting. Thus, the FoxO-KLF15 pathway contributes to switching the macronutrient flow in the liver under the control of insulin.

High protein diet-induced metabolic changes are transcriptionally regulated via KLF15-dependent and independent pathways

High protein diet (HPD) is an affordable and positive approach in prevention and treatment of many diseases. It is believed that transcriptional regulation is responsible for adaptation after HPD feeding and Kruppel-like factor 15 (KLF15), a zinc finger transcription factor that has been proved to perform transcriptional regulation over amino acid, lipid and glucose metabolism, is known to be involved at least in part in this HPD response. To gain more insight into molecular mechanisms by which HPD controls expressions of genes involved in amino acid metabolism in the liver, we performed RNA-seq analysis of mice fed HPD for a short period (3 days). Compared to a low protein diet, HPD feeding significantly increased hepatic expressions of enzymes involved in the breakdown of all the 20 amino acids. Moreover, using KLF15 knockout mice and in vivo Ad-luc analytical system, we were able to identify Cth (cystathionine gamma-lyase) as a new target gene of KLF15 transcription as well as Ast (aspartate aminotransferase) as an example of KLF15-independent gene despite its remarkable responsiveness to HPD. These findings provide us with a clue to elucidate the entire transcriptional regulatory mechanisms of amino acid metabolic pathways.

Understanding the experiences of long-term maintenance of self-worth in persons with type 2 diabetes in Japan: a qualitative study

OBJECTIVE

Persons with type 2 diabetes are often stigmatised for having what is considered a lifestyle-related disease. Accordingly, some blame themselves for their condition, resulting in feelings of low self-worth that ultimately impact their self-management behaviours. However, there are no studies examining why some do not blame themselves for their condition and manage to maintain their self-worth in relation to their illness. This study aimed to explore an understanding of how such persons experience the maintenance of self-worth in relation to their illness over the lifelong course of treatment.

DESIGN

A cross-sectional qualitative study. Face-to-face semistructured interviews were conducted with a purposive sampling strategy. The data was analysed using a qualitative descriptive method that involved concurrent data collection and constant comparative analysis.

SETTING

Two tertiary-level hospitals in Japan.

PARTICIPANTS

Thirty-three outpatients with type 2 diabetes who currently had good glycaemic control but had previously had poor glycaemic control.

RESULTS

Three themes explaining the maintenance of self-worth were identified: (1) Participants gained 'control' over their illness by living a 'normal life.' They found a way to eat preferred foods, dine out with family and friends, travel and work as usual; (2) Participants discovered the positive aspects of type 2 diabetes, as they felt 'healthier' from the treatment and felt a sense of security and gratitude for the care they received from healthcare professionals; (3) Participants discovered a new sense of self-worth by moving towards goals for type 2 diabetes treatment and experienced inner growth through positive lifestyle choices.

CONCLUSIONS

The process of restoring and maintaining self-worth should be brought to the attention of healthcare professionals in diabetes care. These professionals could help patients discover positive self-representations through diabetes treatment (eg, a realisation that one does not lack self-control) and could aid in increasing patient engagement in diabetes self-management.

Insulin- and Lipopolysaccharide-Mediated Signaling in Adipose Tissue Macrophages Regulates Postprandial Glycemia through Akt-mTOR Activation

The physiological role of immune cells in the regulation of postprandial glucose metabolism has not been fully elucidated. We have found that adipose tissue macrophages produce interleukin-10 (IL-10) upon feeding, which suppresses hepatic glucose production in cooperation with insulin. Both elevated insulin and gut-microbiome-derived lipopolysaccharide in response to feeding are required for IL-10 production via the Akt/mammalian target of rapamycin (mTOR) pathway. Indeed, myeloid-specific knockout of the insulin receptor or bone marrow transplantation of mutant TLR4 marrow cells results in increased expression of gluconeogenic genes and impaired glucose tolerance. Furthermore, myeloid-specific Akt1 and Akt2 knockout results in similar phenotypes that are rescued by additional knockout of TSC2, an inhibitor of mTOR. In obesity, IL-10 production is impaired due to insulin resistance in macrophages, whereas adenovirus-mediated expression of IL-10 ameliorates postprandial hyperglycemia. Thus, the orchestrated response of the endogenous hormone and gut environment to feeding is a key regulator of postprandial glycemia.

The association between health literacy levels and patient-reported outcomes in Japanese type 2 diabetic patients

OBJECTIVES

The aim of this study is to empirically examine a full pathway model of health literacy, and health and well-being outcomes among patients with type 2 diabetes.

METHODS

A three-wave longitudinal survey was administered to 148 patients with diabetes. Covariance structure analysis was conducted to create a path diagram, with health literacy and burden of medical expenses included as independent variables and with psychosocial factors, behaviors, and health and well-being outcomes included as dependent variables.

RESULTS

The model fit indices showed a comparative fit index of 0.985 at baseline, 0.959 after 3 months, and 0.948 after 6 months, with a root mean square error of approximation of 0.040 at baseline, 0.079 after 3 months, and 0.085 after 6 months. There were 14 significant paths across the three time points between health literacy and understanding of diabetes care, self-efficacy, communication with doctors, and medication adherence.

CONCLUSION

The model fitness index showed an adequate result. Health literacy was significantly positively associated with understanding of diabetes care, self-efficacy, communication with doctors, and medication adherence. Health literacy had a direct positive influence on medication adherence and possibly an indirect positive influence on exercise/diet via self-efficacy. The results were generally consistent across the three time points, suggesting good reliability of the models. Improving health literacy may lead to better self-management of diabetes and favorable health outcomes.

Glucocorticoid receptor suppresses gene expression of Rev-erbα (Nr1d1) through interaction with the CLOCK complex

Glucocorticoids have various medical uses but are accompanied by side effects. The glucocorticoid receptor (GR) has been reported to regulate the clock genes, but the underlying mechanisms are incompletely understood. In this study, we focused on the suppressive effect of the GR on the expression of Rev-erbα (Nr1d1), an important component of the clock regulatory circuits. Here we show that the GR suppresses Rev-erbα expression via the formation of a complex with CLOCK and BMAL1, which binds to the E-boxes in the Nr1d1 promoter. In this GR-CLOCK-BMAL1 complex, the GR does not directly bind to DNA, which is referred to as tethering. These findings provide new insights into the role of the GR in the control of circadian rhythm.

Survey on patients with undiagnosed diseases in Japan: potential patient numbers benefiting from Japan's initiative on rare and undiagnosed diseases (IRUD)

Background

There is now an international partnership to establish global programs for patients with rare and undiagnosed diseases, involving interdisciplinary expert panels and phenotype-driven genetic analyses utilizing next-generation sequencing and analytics. Whereas it is crucial to have data such as the actual number of undiagnosed patients, to help inform the implementation plan with such programs, there have been no systematic studies to quantitate the numbers of patients principally because of the inherent difficulty in most health systems to identify patients whose condition has not yet been diagnosed and coded. Our national experience with a rare disease program, Nan-Byo which was established in 1972, and the more recently expanded Initiative on Rare and Undiagnosed Diseases (IRUD), provided a unique opportunity to design a cross-sectional study to ascertain the undiagnosed patients in Japan based on the IRUD referral criteria.

Results

Two rounds of online surveys were performed: one survey targeting physicians affiliated with general hospitals (GH) and family clinics (FC) (the response rate: 30.6% (242/792)) and one nationwide survey targeting university hospitals (UH) in Japan (47.1% (839/1781)). A high percentage of doctors needing IRUD was seen in pediatrics at GH, FC, while there was a clear demand for IRUD in most departments at UH. We calculated the number of undiagnosed patients in Japan, as the “percentage of doctors needing IRUD” × “number of patients who would be referred to IRUD per doctor needing IRUD (cases/person)” × “total number of doctors in the relevant facilities in Japan (persons)”, resulting in 3681 cases in pediatrics/pediatric surgery and 33,703 cases in other departments, for a total of 37,384 cases.

Conclusions

Our study revealed the extant demand for IRUD in most departments and 37,000+ potential patients with undiagnosed diseases in the Japanese health system. These data inform the establishment of an equitable, sustainable, efficient and effective outpatient-based IRUD. These findings would serve as a valuable reference for undiagnosed diseases programs in different international jurisdictions and for countries and regions who also share vision(s) for societal implementation that help to advance international efforts to support patients with rare diseases who are direly waiting for diagnosis, subsequent treatment and care.

A candidate functional SNP rs7074440 in TCF7L2 alters gene expression through C-FOS in hepatocytes

The SNP rs7903146 at the transcription factor 7-like 2 (TCF7L2) locus is established as the strongest known genetic marker for type 2 diabetes via genome-wide association studies. However, the functional SNPs regulating TCF7L2 expression remain unclear. Here, we show that the SNP rs7074440 is a candidate functional SNP highly linked with rs7903146. A reporter plasmid with rs7074440 normal allele sequence exhibited 15-fold higher luciferase activity compared with risk allele sequence in hepatocytes, demonstrating a strong enhancer activity at rs7074440. Additionally, we identified C-FOS as an activator binding to the rs7074440 enhancer using a TFEL genome-wide screen method. Consistently, knockdown of C-FOS significantly reduced TCF7L2 expression in hepatocytes. Collectively, a novel enhancer regulating TCF7L2 expression was revealed through searching for functional SNPs.

Effect of sodium-glucose cotransporter 2 (SGLT2) inhibition on weight loss is partly mediated by liver-brain-adipose neurocircuitry

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have both anti-diabetic and anti-obesity effects. However, the precise mechanism of the anti-obesity effect remains unclear. We previously demonstrated that the glycogen depletion signal triggers lipolysis in adipose tissue via liver-brain-adipose neurocircuitry. In this study, therefore, we investigated whether the anti-obesity mechanism of SGLT2 inhibitor is mediated by this mechanism. Diet-induced obese mice were subjected to hepatic vagotomy (HVx) or sham operation and loaded with high fat diet containing 0.015% tofogliflozin (TOFO), a highly selective SGLT2 inhibitor, for 3 weeks. TOFO-treated mice showed a decrease in fat mass and the effect of TOFO was attenuated in HVx group. Although both HVx and sham mice showed a similar level of reduction in hepatic glycogen by TOFO treatment, HVx mice exhibited an attenuated response in protein phosphorylation by protein kinase A (PKA) in white adipose tissue compared with the sham group. As PKA pathway is known to act as an effector of the liver-brain-adipose axis and activate triglyceride lipases in adipocytes, these results indicated that SGLT2 inhibition triggered glycogen depletion signal and actuated liver-brain-adipose axis, resulting in PKA activation in adipocytes. Taken together, it was concluded that the effect of SGLT2 inhibition on weight loss is in part mediated via the liver-brain-adipose neurocircuitry.

A key role of nuclear factor Y in the refeeding response of fatty acid synthase in adipocytes

Fatty acid synthase (Fasn) is a key component of energy metabolism that is dynamically induced by food intake. Although extensive studies have revealed a number of transcription factors involved in the fasting/refeeding transition of Fasn expression in hepatocytes, much less evidence is available for adipocytes. Using the in vivo Ad-luc analytical system, we identified the inverted CCAAT element (ICE) around -100 nucleotides in the Fasn promoter as a critical cis-element for the refeeding response in adipocytes. Electrophoretic mobility shift assays and chromatin immunoprecipitation show that nuclear factor Y (NF-Y) binds to ICE specifically in refeeding states. Notably, the NF-Y binding to ICE is differently regulated between adipocytes and hepatocytes. These findings provide insights into the specific mechanisms controlling energy metabolism in adipocytes.

Willingness of patients with diabetes to use an ICT-based self-management tool: a cross-sectional study

OBJECTIVES

To examine the prevalence of the willingness of patients with diabetes to use a self-management tool based on information and communication technology (ICT) such as personal computers, smartphones, and mobile phones; and to examine the patient characteristics associated with that willingness.

RESEARCH DESIGN AND METHODS

We conducted a cross-sectional interview survey of 312 adults with diabetes at a university hospital in an urban area in Japan. Participants were classified into 2 groups: those who were willing to use an ICT-based self-management tool and those who were unwilling. Multiple logistic regression analysis was used to identify factors associated with the willingness, including clinical and social factors, current use of ICT, self-management practices, self-efficacy, and diabetes-related emotional distress.

RESULTS

The mean age of the 312 participants was 66.3 years (SD=11.5) and 198 (63%) were male. Most of the participants (93%) had type 2 diabetes. Although only 51 (16%) currently used ICT-based self-management tools, a total of 157 (50%) expressed the willingness to use such a tool. Factors associated with the willingness included: not having nephropathy (OR=2.02, 95% CI 1.14 to 3.58); outpatient visits once a month or more (vs less than once a month, OR=2.13, 95% CI 1.13 to 3.99); current use of personal computers and/or smartphones (OR=4.91, 95% CI 2.69 to 8.98); and having greater diabetes-related emotional distress (OR=1.10, 95% CI 1.01 to 1.20).

CONCLUSIONS

Approximately half of the patients showed interest in using an ICT-based self-management tool. Willing patients may expect ICT-based self-management tools to complement outpatient visits and to make self-management easier. Starting with patients who display the willingness factors might optimize programs based on such tools.

A case of insulin allergy successfully managed using multihexamer-forming insulin degludec combined with liraglutide

BACKGROUND

Insulin allergy, one of insulin's adverse effects, is rare, especially in patients with Type 2 diabetes, but management is difficult and no effective strategy has yet been established. We experienced an insulin allergy case successfully managed with a novel combination of insulins.

CASE REPORT

A 38-year-old woman started insulin therapy when diabetes was diagnosed at age 19 years. Despite poorly controlled diabetes because of poor adherence, she hoped to conceive a child and continuous subcutaneous insulin infusion was introduced using insulin aspart at age 32 years. One month thereafter, she developed skin reactions at the subcutaneous insulin infusion catheter insertion site. The patient was then tested for all rapid-acting insulin formulations, all of which triggered local reactions. She decided to continue the continuous subcutaneous infusion of human regular insulin, accompanied by oral cetirizine hydrochloride and betamethasone valerate ointment. The patient was admitted to our hospital at age 38 years with high HbA_1c levels. She was tested for all long-acting insulin analogues. All results, except for insulin degludec, were positive. She discontinued continuous subcutaneous insulin infusion and switched to insulin degludec combined with liraglutide. The allergic reactions had completely disappeared and her blood glucose was well controlled by the time of discharge.

CONCLUSION

Our patient was allergic to all insulin formulations except insulin degludec. Her allergic reactions completely disappeared after switching to insulin degludec. The crystallized structure of this insulin might mask its skin allergen antigenicity. Furthermore, her postprandial hyperglycaemia was successfully controlled with liraglutide. We propose multihexamer-forming ultra-long-acting insulin plus glucagon-like peptide-1 analogues as a therapeutic option for patients with insulin allergy.

KLF15 Enables Rapid Switching between Lipogenesis and Gluconeogenesis during Fasting

Hepatic lipogenesis is nutritionally regulated (i.e., downregulated during fasting and upregulated during the postprandial state) as an adaptation to the nutritional environment. While alterations in the expression level of the transcription factor SREBP-1c are known to be critical for nutritionally regulated lipogenesis, upstream mechanisms governing Srebf1 expression remain unclear. Here, we show that the fasting-induced transcription factor KLF15, a key regulator of gluconeogenesis, forms a complex with LXR/RXR, specifically on the Srebf1 promoter. This complex recruits the corepressor RIP140 instead of the coactivator SRC1, resulting in reduced Srebf1 and thus downstream lipogenic enzyme expression during the early and euglycemic period of fasting prior to hypoglycemia and PKA activation. Through this mechanism, KLF15 overexpression specifically ameliorates hypertriglyceridemia without affecting LXR-mediated cholesterol metabolism. These findings reveal a key molecular link between glucose and lipid metabolism and have therapeutic implications for the treatment of hyperlipidemia.

A qualitative study on the impact of internalized stigma on type 2 diabetes self-management

OBJECTIVE

To explore how patients with type 2 diabetes (T2DM) psychologically and behaviorally respond to internalized stigma through social stigma.

METHODS

A qualitative study with semi-structured interviews was recorded on audiotapes, transcribed verbatim, and analyzed using a grounded theory approach. Participants were adults aged 30-64 years and diagnosed with T2DM. A total of 26 patients participated.

RESULTS

The qualitative data revealed that participants' responses to social stigma, although varied, could be organized into a four-step process: Encountering Negative Experiences, Reevaluating the Self with Type 2 Diabetes, Reconstructing a Sense of Identity, and Maintaining Balance between Patient and Social Roles. When participants form a negative image of and relationship to their illness, they tend to internalize stigma, which can affect their sense of self-worth, attitude toward social participation, and compliance.

CONCLUSION

Participants who internalize stigma tend to have a lower sense of self-worth and their social participation falls somewhere between severely limited (Social Avoidance) and highly active (Role Conflict). This can hinder devotion to their treatment regimen and affect their degree of compliance with physicians.

PRACTICE IMPLICATIONS

Internalized stigma can be assessed by observing a patient's illness-related negative self-image.

Autonomic nervous system-mediated effects of galanin-like peptide on lipid metabolism in liver and adipose tissue

Galanin-like peptide (GALP) is a neuropeptide involved in the regulation of feeding behavior and energy metabolism in mammals. While a weight loss effect of GALP has been reported, its effects on lipid metabolism have not been investigated. The aim of this study was to determine if GALP regulates lipid metabolism in liver and adipose tissue via an action on the sympathetic nervous system. The respiratory exchange ratio of mice administered GALP intracerebroventricularly was lower than that of saline-treated animals, and fatty acid oxidation-related gene mRNA levels were increased in the liver. Even though the respiratory exchange ratio was reduced by GALP, this change was not significant when mice were treated with the sympatholytic drug, guanethidine. Lipolysis-related gene mRNA levels were increased in the adipose tissue of GALP-treated mice compared with saline-treated animals. These results show that GALP stimulates fatty acid β-oxidation in liver and lipolysis in adipose tissue, and suggest that the anti-obesity effect of GALP may be due to anorexigenic actions and improvement of lipid metabolism in peripheral tissues via the sympathetic nervous system.

Identification of human ELOVL5 enhancer regions controlled by SREBP

Fatty acid elongase 5 (ELOVL5) is an enzyme involved in the synthesis of polyunsaturated fatty acids. Sterol Regulatory Element-binding Protein (SREBP)-1 activates ELOVL5 and increases polyunsaturated fatty acid synthesis, which in turn negatively affects SREBP-1 expression. Thus, ELOVL5 has been established as an SREBP-1 target gene and an important component of the negative feedback loop of de novo lipogenesis. However, the human ELOVL5 promoter/enhancer has not been fully analyzed and the location of SREBP biding sites around the ELOVL5 gene has yet to be defined. Here we performed a detailed promoter/enhancer analysis of human ELOVL5 gene, and identified two new SREBP binding sites, one in the 10 kb upstream region and one in the exon 1. These two SRE motifs are conserved among mammals and the mechanism found in the present study by which SREBP activates ELOVL5 is considered to be common in mammals. Through these findings, we clarified the molecular mechanism how SREBP activates ELOVL5, an important regulator of de novo lipogenesis.

Heat devices in nonlinear irreversible thermodynamics

We present results obtained by using nonlinear irreversible models for heat devices. In particular, we focus on the global performance characteristics, the maximum efficiency and the efficiency at maximum power regimes for heat engines, and the maximum coefficient of performance (COP) and the COP at maximum cooling power regimes for refrigerators. We analyze the key role played by the interplay between irreversibilities coming from heat leaks and internal dissipations. We also discuss the relationship between these results and those obtained by different models.

Hepatocyte growth factor is constitutively produced by donor-derived bone marrow cells and promotes regeneration of pancreatic beta-cells

Recent studies have demonstrated that the transplantation of bone marrow cells following diabetes induced by streptozotocin can support the recovery of pancreatic b-cell mass and a partial reversal of hyperglycemia. To address this issue, we examined whether the c-Met/hepatocyte growth factor (HGF) signaling pathway was involved in the recovery of b-cell injury after bone marrow transplantation (BMT). In this model, donor-derived bone marrow cells were positive for HGF immunoreactivity in the recipient spleen, liver, lung, and pancreas as well as in the host hepatocytes. Indeed, plasma HGF levels were maintained at a high value.The frequency of c-Met expression and its proliferative activity and differentiative response in the pancreatic ductal cells in the BMT group were greater than those in the PBS-treated group, resulting in an elevated number of endogenous insulin-producing cells. The induction of the c-Met/HGF signaling pathway following BMT promotes pancreatic regeneration in diabetic rats.

Polyunsaturated fatty acids selectively suppress sterol regulatory element-binding protein-1 through proteolytic processing and autoloop regulatory circuit

Sterol regulatory element-binding protein (SREBP)-1 is a key transcription factor for the regulation of lipogenic enzyme genes in the liver. Polyunsaturated fatty acids (PUFA) selectively suppress hepatic SREBP-1, but molecular mechanisms remain largely unknown. To gain insight into this regulation, we established in vivo reporter assays to assess the activities of Srebf1c transcription and proteolytic processing. Using these in vivo reporter assays, we showed that the primary mechanism for PUFA suppression of SREBP-1 is at the proteolytic processing level and that this suppression in turn decreases the mRNA transcription through lowering SREBP-1 binding to the SREBP-binding element on the promoter ("autoloop regulatory circuit"), although liver X receptor, an activator for Srebf1c transcription, is not involved in this regulation by PUFA. The mechanisms for PUFA suppression of SREBP-1 confirm that the autoloop regulation for transcription is crucial for the nutritional regulation of triglyceride synthesis.

Successful desensitization by glargine administration in a patient with insulin allergy: a case report

The patient was a 56-year-old man with type 2 diabetes and insulin allergy. He was administered glargine, which did not produce any allergic reactions, except for a small non-pruritic wheal. Thereafter, other insulin preparation could be administered. We consider this the first case of successful insulin desensitization by glargine administration.

Microencapsule technique protects hepatocytes from cryoinjury

AIM

Hepatocyte transplantation is a potential alternative to whole organ liver transplantation. To realize this procedure, a hepatocyte bank system capable of supplying large numbers of hepatocytes must be established. We previously reported an easy method for cryopreserving hepatocytes using a microencapsulation technique. Here, we investigated how cryoinjury to microencapsulated hepatocytes could be avoided during cryopreservation.

METHODS

Hepatocytes from Sprague-Dawley rats were harvested in situ using a two-step ethylenediaminetetraacetic acid (EDTA)/collagenase digestion protocol. The cells were microencapsulated using alginate-poly L-lysine. The microencapsulated hepatocytes were put into vials and immediately immersed in liquid nitrogen. The growth of ice crystals in the vials containing the microencapsulated hepatocytes was observed using cryomicroscopy. The microencapsulated hepatocytes were sectioned for ultrastructural examination to investigate their intracellular conditions. Finally, total RNA was isolated from the cryopreserved microencapsulated hepatocytes and analyzed for hepatocyte nuclear factor (HNF) using reverse transcriptase polymerase chain reaction (RT-PCR) analysis.

RESULTS

Cryomicroscopy showed that the alginate microencapsulation technique protected the hepatocytes from physical damage caused by the growth of extracellular ice crystals. Ultrastructural examination revealed that the intracellular environment of the microencapsulated hepatocytes was maintained. The RT-PCR analysis additionally suggested that the alginate gel also maintained the HNF level.

CONCLUSION

Our microencapsulation technique protects hepatocytes from cryoinjury. This novel technique could be utilized by hepatocyte banks.

Long-term maintenance of the drug transport activity in cryopreservation of microencapsulated rat hepatocytes

Transplantation of isolated hepatocytes has been proposed to compensate for essential functions lacking in liver failure or for genetic defects that alter a specific liver metabolic pathway. Hepatocyte utilization for these purposes would be facilitated with a reliable, reproducible, and effective method of long-term hepatocyte storage. We have recently developed a simple new system for cryopreservation of hepatocytes that encapsulates alginate microspheres and maintains liver-specific function. The aim of this study was to elucidate the transport and drug-metabolizing enzyme activities of cryopreserved microencapsulated hepatocytes stored for a long time. Morphological examinations showed there is no apparent injury of the hepatocytes during cryopreservation processes. A drug-metabolizing enzyme (testosterone 6beta-hydroxylase, a specific probe for CYP3A2) and drug transport activities [salicylate, allopurinol, and prostaglandin E2 (PGE2), typical substrates of rOat2] in cryopreserved microencapsulated hepatocytes were maintained up to 120 days. Our results thus demonstrate for the first time that cryopreservation of primary rat hepatocytes by the encapsulation technique allows long-term retention of drug metabolism and drug transport activities.

A novel method of cryopreservation of rat and human hepatocytes by using encapsulation technique and possible use for cell transplantation

Encapsulated hepatocyte transplantation is a promising approach to cell transplantation without immunosuppression as an alternative to whole organ liver transplantation. However, the shortage of donor cells for hepatocyte transplantation has not been resolved, and at this critical point, it seems necessary to establish a method of hepatocyte cryopreservation to allow clinical application of hepatocyte transplantation and the development of a bioartificial liver system in the near future. In this study we demonstrated that cryopreserved microencapsulated rat and human hepatocytes can retain their hepatic function and that cryopreserved microencapsulated human hepatocytes transplanted into rat spleen remain viable without immunosuppression. Rat and human hepatocytes were isolated by a collagenase digestion method, and they were microencapsulated with poly-L-lysine. The microencapsulated rat hepatocytes were transferred to culture medium (DMEM containing 10% FBS and 10% DMSO) and immediately frozen in liquid nitrogen. A warm water bath (37 degrees C) was used to thaw the microencapsulated hepatocytes. Hepatic function, drug metabolism, and cell morphology were assessed after 90 days of cryopreservation. After 1 week of cryopreservation, microencapsulated hepatocytes were cultured for up to 2 weeks to assess their hepatic function and morphology. The morphology of human hepatocytes was assessed after 30 days of cryopreservation. Cryopreserved human hepatocytes were transplanted into rat spleen to assess their morphology. Cryopreserved microencapsulated hepatocytes retained their viability and were strongly positive for expression of albumin, OAT2, CYP3A2, and CYP3A9. Two weeks after cultivation, the cryopreserved microencapsulated rat hepatocytes had retained their hepatic function (urea synthesis). Cryopreserved microencapsulated human hepatocytes also mainly survived and retained their hepatic function for at least 30 days after cryopreservation. Moreover, entrapped cryopreserved human hepatocytes also survived and expressed albumin in rat spleen after transplantation. We demonstrated a novel method of long-term cryopreservation of rat and human hepatocytes by using an encapsulation technique, with retention of biological activity and excellent survival of the cryopreserved microencapsulated human hepatocytes transplanted into rat spleen. We believe that this novel approach to hepatocytes cryopreservation provides a new direction in encapsulated cell therapy with the goal of clinical application in the near future.

Elevation of serum albumin levels in nagase analbuminemic rats by allogeneic bone marrow cell transplantation

We investigated the feasibility of correcting the congenital absence of albumin in Nagase analbuminemic rats (NARs) by allogeneic bone marrow cell transplantation (BMT). Seven-week-old male NARs were used as recipients, and 6- to 8-week-old male Sprague-Dawley (SD) rats were used as allograft donors. NARs were divided into three groups: a BMT group (n=10) in which bone marrow cells were infused into the liver; a hepatocyte transplantation (HCT) group (n=8) in which hepatocytes were transplanted into the liver, and a control group (n=8) in which PBS was injected into the portal vein. Serum albumin levels were measured as an indicator of the function of the grafted cells, and the phenotypic characteristics of the engrafted cells in the recipient's liver were assessed with immunohistochemical and immunofluorescence techniques. At 8 weeks after cell transplantation, the serum albumin levels of the BMT group and HCT group were significantly higher than in the control group. The hepatocyte-like cells derived from bone marrow cells expressed albumin in liver of the NARs. According to this result, bone marrow cells can differentiate into hepatocyte-like cells in vivo. The results show that BMT is an effective treatment for congenital analbuminemia in a rat model and suggest that allogeneic BMT can be used as an efficient therapy for hereditary metabolic diseases.

Intrasplenic transplantation of encapsulated hepatocytes decreases mortality and improves liver functions in fulminant hepatic failure from 90% partial hepatectomy in rats

BACKGROUND

Encapsulated cell therapy might be a promising approach to enable cell transplantation without immunosuppression. This study investigates the viability and hepatic function of hepatocytes encapsulated with alginate/poly-L-lysine in vitro and the effect of the intrasplenic transplantation of cultured encapsulated hepatocytes on survival in 90% hepatectomized rats as a preliminary step toward allogeneic hepatocyte transplantation without immunosuppression.

MATERIALS AND METHODS

Rat hepatocytes were isolated and encapsulated using alginate/poly-L-lysine. Encapsulated hepatocytes were cultured for 28 days to measure cell viability, liver function, and morphology. Rats were treated with a 90% partial hepatectomy and then immediately underwent the intrasplenic transplantation of the cultured encapsulated hepatocytes, the capsule alone, or the allogeneic hepatocytes without the capsule. The survival rate, liver function, and cell morphology were assessed after transplantation.

RESULTS

The cultured encapsulated hepatocytes maintained their viability and showed better metabolic activity than day 0 cultured encapsulated hepatocytes. The encapsulated cells strongly expressed albumin and were positive for periodic acid-Schiff staining. Electron microscopy demonstrated that the microencapsulated hepatocytes retained the structural elements of hepatic cytoplasm and nuclei. Intrasplenic transplantation of the encapsulated hepatocytes increased the survival rate and improved the hepatic function. Encapsulated hepatocytes transplanted into rat spleen survived well and retained their hepatic function. Moreover, dramatic liver regeneration was observed 48 hr after transplantation in the group that received intrasplenic transplantations of encapsulated hepatocytes.

CONCLUSIONS

The intrasplenic transplantation of cultured encapsulated hepatocytes improved the survival rate of an acute liver failure rat model induced by a 90% partial hepatectomy.

Dose-dependent biphasic accumulation of TP53 protein in normal human embryo cells after X irradiation

The effects of various doses of X radiation on the kinetics of accumulation of TP53 protein (formerly known as p53) were examined in normal human embryo cells. We found that the rate of accumulation of TP53 protein was biphasic at X-ray doses between 1 and 4 Gy, while monophasic accumulation was observed after X irradiation with doses higher than 6 Gy. The first phase of accumulation was detected within 1 h after irradiation, and a second phase of accumulation was detected between 6 and 12 h after irradiation. The induction of CDKN1A (formerly known as p21(WAF1/CIP1)) and MDM2 proteins was also biphasic after doses of 4 Gy or less, while monophasic accumulation was observed after 6 Gy or higher. We found that the proteasome inhibitor ALLN increased the constitutive level of TP53 protein, and no change was observed in the TP53 level after X irradiation when cells were treated with ALLN. These results indicate that the dose-dependent accumulation of TP53 is due to an inhibition of TP53 degradation, and that the induction of MDM2 might be responsible in part for the different kinetics of accumulation of TP53.

Decreased deformability of red cells in refractory anemia and the abnormality of the membrane skeleton

Rheological characteristics of red cells in two patients with refractory anemia (with single chromosomal abnormality of 20q- or 13q-, respectively) were investigated with the hematological and biochemical properties. (1) Whole blood viscosity was remarkably increased, and the red cell deformability was greatly impaired (the impairments were prominent in patient with 20q-). (2) The hematocrit of both patients was about half of the normal value. Remarkable anisocytosis with elliptocytes and poikilocytes was observed in the patient with 20q-, but the anisocytosis was not so prominent in the patient with 13q-. (3) 2,3-diphosphoglycerate content in red cells was markedly increased in both patients, but adenylate content was not. (4) The red cells were slightly resistant to osmotic hemolysis, but they were not heat-labile. (5) Structural abnormality of spectrin was suggested from the impaired dimer-dimer association in red cell membrane and from the different susceptibility of spectrin to tryptic digestion. In conclusion, the rheological impairments and the abnormal shape of red cells in refractory anemia probably originated from the structural abnormality of cytoskeletal proteins in membrane, and the functional and structural abnormality may be different among patients.

Erythrocyte aggregation: bridging by macromolecules and electrostatic repulsion by sialic acid

Relation between aggregating force (of fibrinogen and IgG) and disaggregating force (due to electrostatic repulsion among erythrocytes) in erythrocyte aggregation was investigated with a rheoscope combining a video camera, an image analyzer and a computer. (i) Erythrocyte aggregation was augmented with the increase of molecular weight of bridging macromolecules as far as examined for fibrinogen and the degradation products and IgG and the related macromolecules, and the augmentation seemed to be dependent on the molecular length of macromolecules. In accelerating the erythrocyte aggregation, fibrinogen was more effective than IgG, and some interaction between fibrinogen and IgG in their coexistence was suggested. (ii) The decrease of sialic acid content on the erythrocyte surface accelerated IgG-induced erythrocyte aggregation much greater than fibrinogen-induced one. (iii) Counteraction between aggregating force and disaggregating force in leading to erythrocyte aggregation was discussed relating to molecular length of bridging macromolecule and electrostatic repulsive force by sialic acid.

Contribution of glycoproteins to fibrinogen-induced aggregation of erythrocytes

The contribution of membrane glycoproteins to the velocity of fibrinogen-induced erythrocyte aggregation was examined using a rheoscope combined with a video camera, an image analyzer and a computer. The structure of glycoproteins was modified with proteolytic enzymes, trypsin or alpha-chymotrypsin. (1) Mild enzymatic treatment of erythrocytes decreased the velocity of erythrocyte aggregation, but more intense treatment increased the velocity remarkably. (2) The erythrocyte aggregation was affected not only by the density of surface negative charge of erythrocytes, but also by the structural changes of glycoproteins. (3) Erythrocyte deformability and the morphological characteristics were not altered by these enzymatic treatments. The physiological significance of glycoproteins of erythrocyte surface for the survival of erythrocytes and for the suspension stability of blood was discussed.