Impact of coronavirus disease 2019 on medical practice in endocrine and metabolic diseases in Japan: a nationwide surveillance study conducted by the Japan Endocrine Society.

We investigated the impact of the Coronavirus disease 2019 (COVID-19) pandemic on the management of endocrine and metabolic disorders in Japan. We conducted a cross-sectional nationwide questionnaire survey targeting board-certified endocrinologists under the auspices of the Japan Endocrine Society. The questionnaire consisted of multiple-choice questions and open-ended responses. Out of approximately 2,700 specialists, 528 (19.5%) opted to participate, suggesting a high level of interest in COVID-19 management among endocrinologists. The study found that almost half of participants had encountered cases of endocrine and metabolic disorders following COVID-19 infection or vaccination. Conditions related to thyroid diseases, glucose metabolism disorders/diabetes, and hypothalamic-pituitary disorders were particularly prevalent. Diabetes and obesity were identified as having high rates of severe cases or fatalities due to COVID-19. The study also highlighted challenges in routine diagnosis and treatment, emphasizing the potential benefits of combining remote consultations with in-person visits to optimize the frequency of examinations and check-ups during infectious disease outbreak which disrupts access to healthcare providers. The insights obtained from this survey are expected to contribute to ensuring appropriate healthcare provision for patients with endocrine and metabolic disorders by using flexible consultation formats, particularly even in the conditions where medical access may be limited due to future outbreaks of emerging or re-emerging infectious diseases.

Terminal differentiation of keratinocytes was damaged in type 2 diabetic mice.

AIMS: Although skin manifestations are common in diabetic patients, its characteristics are poorly identified. This study explored the differentiation process of keratinocytes in type 2 diabetes mellitus (T2DM) in vivo. METHODS: Back skin of T2DM model KKAy/TaJcl mice (KKAy) and C57BL/6JJcl mice (control) aged 8 and 12 weeks was used. The mRNA expression of differentiation markers of keratinocytes was measured by quantitative real-time polymerase chain reaction (qRT-PCR). The expression of each marker in situ was examined immunohistochemically. RESULTS: KKAy mice showed hyperglycemia versus control mice. The histological findings showed increased thickness and structural impairment of epidermal tissue in KKAy mice. The qRT-PCR revealed that the expression of integrin beta 1 and keratin 14 in KKAy and control mice was identical. However, the expression of involucrin at 8 weeks, keratin 10 at 12 weeks, and filaggrin and loricrin at 8 and 12 weeks was decreased in KKAy mice. Immunohistochemical findings showed that filaggrin was markedly decreased in KKAy mice, though Ki-67 remained unchanged. CONCLUSION: The terminal differentiation process was impaired in the diabetic skin, while keratinocyte proliferation was preserved. Damaged terminal differentiation of keratinocytes may contribute to impairment of the skin barrier function in diabetic dermatoses.

A pregnant woman with thymoma-associated pure red cell aplasia.

BACKGROUND: Pure red cell aplasia (PRCA) is a hematological disorder characterized by anemia with severe reticulocytopenia caused by a marked reduction in erythroid precursors in the bone marrow. PRCA is known to be associated with pregnancy, but thymoma-associated PRCA during pregnancy is very rare, and its successful management has not been reported. CASE PRESENTATION: A 37-year-old primiparous woman with severe anemia was referred to our center at 27 weeks' gestation. She was diagnosed with PRCA based on bone aspiration findings at 33 weeks' gestation. Magnetic resonance imaging (MRI) revealed an anterior mediastinal mass 4 cm in size suspected of being thymoma. She was therefore diagnosed with thymoma-associated PRCA during pregnancy. Surgery for thymoma was planned after delivery, since the imaging findings were suggestive of early-stage thymoma (Masaoka stage I or II). With transfusion of a total 3,360 ml of red blood cells (RBCs) during pregnancy, the patient gave birth to a baby girl weighing 2,548 g at 40 weeks' gestation. The baby showed transient congenital cutaneous candidiasis. The placental pathology revealed subamniotic inflammation with a fungal structure. Treatment with topical anti-fungal cream immediately ameliorated the baby's skin lesion. Maternal anemia did not improve after delivery; however, the thymoma did not increase in size. At five months after delivery, the mother underwent thymectomy with oral cyclosporine A. A pathological examination revealed Masaoka stage II-a thymoma. She completely had recovered from anemia at six months after surgery. Cyclosporine A treatment was discontinued three years after surgery. Remission has been sustained for four years since surgery. CONCLUSIONS: A very rare case of thymoma-associated PRCA during pregnancy was diagnosed without any subjective symptoms and was expectantly managed, resulting in a good prognosis. Although bone marrow aspiration during pregnancy is an invasive test, it is important to confirm the diagnosis. Conservative management with blood transfusion was possible for early-stage thymoma-associated PRCA during pregnancy. Active surveys, including MRI, for PRCA during pregnancy led to the detection of thymoma at an early stage and the achievement of a preferable pregnancy outcome.

Spontaneously conceived heterotopic pregnancy with abdominal pregnancy implanted on the vesicouterine pouch: A case report and literature review.

We report the case of a 36-year-old woman with spontaneously conceived heterotopic pregnancy with abdominal pregnancy. She visited the hospital at 5 weeks and 4 days of gestation and transvaginal ultrasonography revealed a normal intrauterine pregnancy. Two days later, she was urgently transported to the hospital due to extreme abdominal pain. Emergent laparotomy was performed to investigate the cause of massive intraperitoneal bleeding, which was confirmed to have been due to an abdominal pregnancy that implanted on the vesicouterine pouch. The hematic mass, including chorionic villi, was successfully removed from the peritoneum. The subsequent course of the intrauterine pregnancy was uneventful and a healthy baby was born at term. To the best of our knowledge, this is an extremely rare case report of a spontaneously conceived heterotopic abdominal pregnancy, in which the intrauterine pregnancy showed a successful outcome despite the collapse of the abdominal pregnancy at a very early stage.

TDP-43 transports ribosomal protein mRNA to regulate axonal local translation in neuronal axons.

Mislocalization and abnormal deposition of TDP-43 into the cytoplasm (TDP-43 proteinopathy) is a hallmark in neurons of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). However, the pathogenic mechanism of the diseases linked to TDP-43 is largely unknown. We hypothesized that the failure of mRNA transport to neuronal axons by TDP-43 may contribute to neurodegeneration in ALS and FTLD, and sought to examine the function of TDP-43 by identifying its target mRNA for axonal transport. We found that mRNAs related to translational function including ribosomal proteins (RPs) were decreased by shRNA-based TDP-43 knock-down in neurites of cortical neurons. TDP-43 binds to and transports the RP mRNAs through their 5' untranslated region, which contains a common 5' terminal oligopyrimidine tract motif and a downstream GC-rich region. We showed by employing in vitro and in vivo models that the RP mRNAs were translated and incorporated into native ribosomes locally in axons to maintain functionality of axonal ribosomes, which is required for local protein synthesis in response to stimulation and stress to axons. We also found that RP mRNAs were reduced in the pyramidal tract of sporadic ALS cases harboring TDP-43 pathology. Our results elucidated a novel function of TDP-43 to control transport of RP mRNAs and local translation by ribosomes to maintain morphological integrity of neuronal axons, and proved the influence of this function of TDP-43 on neurodegeneration in ALS and FTLD associated with TDP-43 proteinopathy.

Pregnant women's preferences for prenatal genetic testing: A single-center study in Japan.

AIM: To evaluate how many pregnant women would prefer to undergo prenatal genetic testing (GT) if they received adequate information during early gestation. METHODS: We examined the preferences for prenatal GT among pregnant women visiting our general outpatient clinic before 16 weeks' gestation between September 2014 and September 2017. We provided them with informational brochures about prenatal GT at their first visit. Women always received genetic counseling (GC) before undergoing GT of their own choice. RESULTS: Among 5700 pregnant women, 2077 (36.4%) received GC, and 1983 (34.8%) underwent some form of prenatal GT. The percentage undergoing GT was 9.4% (50/531) for women <30 years old, 19.0% (309/1623) for those 30-34 years old, 43.1% (989/2294) for those 35-39 years old, and 50.7% (635/1252) for those ≥40 years old. Older pregnant women tended to receive GC and GT more often than younger women (P < 0.001). The most common reason for receiving GC was advanced maternal age (79.7%). The most common prenatal GT was noninvasive prenatal testing (NIPT) (50%), followed by the combined test (29.0%) and quadruple test (11.2%). Pregnant women ≥35 years old tended to choose NIPT (60.5%), while those <35 years old tended to choose the combined test (52.9%). CONCLUSION: About one-third of the pregnant women preferred to receive prenatal GT by their own choice. Women's preferences for prenatal GT increased with maternal age; however, half of pregnant women with an advanced maternal age preferred not to undergo GT, even if they were well informed.

Chronic histiocytic intervillositis in three consecutive pregnancies in a single patient: Differing clinical results and pathology according to treatment used.

Chronic histiocytic intervillositis (CHI) is an extremely rare pathological condition but is strongly associated with severe obstetric complications and has a high recurrence rate. The management of this condition has not yet been established. We describe herein the occurrence of CHI in the late second-third trimester in each of three consecutive pregnancies in a single patient with four previous consecutive early miscarriages. In this patient, each of the three complicated pregnancies was managed with one of the following, respectively: low-dose aspirin; heparin plus low-dose aspirin; and prednisolone plus low-dose aspirin. CHI was histologically confirmed in all three pregnancies, but the clinical results and pathology (e.g. extent of histiocytic infiltration) in each pregnancy clearly differed with treatment. Both combination treatments eventuated in a live birth. Immunosuppressive therapy seemed to produce better clinical results by restricting the extent of the affected areas. The elevated alkaline phosphatase associated with the CHI was assumed to have no clinical prognostic value.

Level of urinary liver-type fatty acid-binding protein is associated with cardiac markers and electrocardiographic abnormalities in type-2 diabetes with chronic kidney disease stage G1 and G2.

Urinary liver-type fatty acid-binding protein (L-FABP) reflects the degree of stress in proximal tubules of the kidney. We examined the level of L-FABP in type-2 diabetes mellitus (T2DM) patients with chronic kidney disease (CKD) stage G1 and G2, and its relationship with cardiac markers and electrocardiographic (ECG) abnormalities. T2DM patients whose estimated glomerular filtration rate (eGFR) was ≥60 mL/min/1.73 m(2) were recruited [n = 276 (165 males), mean age 64 years]. The median level of urinary L-FABP was 6.6 µg/gCr. Urinary L-FABP showed significant correlation with urinary albumin-to-creatinine ratio (ACR) (r = 0.51, p < 0.0001). Median (25th-75th percentile) eGFR was 82 (72-95) mL/min/1.73 m2. We divided patients into four subgroups (group 1, L-FABP ≤8.4 µg/gCr and ACR ≤30 mg/gCr; group 2, L-FABP ≤8.4 µg/gCr and ACR >30 mg/gCr; group 3, L-FABP >8.4 µg/gCr and ACR ≤30 mg/gCr; group 4, L-FABP >8.4 µg/gCr and ACR >30 mg/gCr). Compared with group 1, group 4 was significantly higher in systolic blood pressure, and eGFR using standardized serum cystatin C, high-sensitivity troponin T, and N-terminal pro-brain natriuretic peptide (NT-proBNP). Group 4 had significantly higher level of NT-proBNP than group 3. Groups 2, 3 and 4 showed more ECG abnormalities than group 1. These findings suggest that simultaneous measurement of urinary L-FABP and ACR should be useful to assess cardiovascular damage reflecting on the elevation of cardiac markers and ECG abnormalities in T2DM with CKD G1 and G2.

Neuronal Excitation Induces Tau Protein Dephosphorylation via Protein Phosphatase 1 Activation to Promote Its Binding with Stable Microtubules.

The tau protein is a microtubule-associated protein that promotes microtubule stabilization. The phosphorylation of the tau protein has been linked to its dissociation from microtubules. Here, we examined the relationship between neuronal depolarization activity and tau protein phosphorylation by employing model systems in culture as well as in vivo. The KCl-evoked depolarization of cultured neurons has often been used to investigate the effects of neuronal activity. We found dephosphorylation at AT8 sites (S202, T205), T212, AT180 sites (T231, S235), and S396 in KCl-simulated cultured neurons. We also found that the KCl-induced tau protein dephosphorylation increases the level of the tau protein fractionated with stable microtubules. In an in vivo experiment, we demonstrated that the exposure of mice to a new environment activates protein phosphatase 1 in the mouse hippocampus and induces tau protein dephosphorylation. We also found an increased amount of the tau protein in a stable microtubule fraction, suggesting that the dephosphorylation of the tau protein may lead to its increased microtubule association in vivo. These results suggest that the association of microtubules with tau proteins may be regulated by the tau protein phosphorylation status affected by neuronal electrical activity.

Transient sleep apnea results in long-lasting increase in ß-amyloid generation and tau hyperphosphorylation.

Sleep apnea is regarded as an important risk factor in the pathogenesis of Alzheimer disease (AD). Chronic intermittent hypoxia treatment (IHT) given during the sleep period of the circadian cycle in experimental animals is a well-established sleep apnea model. Here we report that transient IHT for 4 days on AD model mice causes Aß overproduction 2 months after IHT presumably via upregulation of synaptic BACE1, side-by-side with tau hyperphosphorylation. These results suggest that even transient IHT may be sufficient to cause long-lasting changes in the molecules measured as AD biomarkers in the brain.

Oral alendronate can suppress bone turnover but not fracture in kidney transplantation recipients with hyperparathyroidism and chronic kidney disease.

Post-transplantation bone diseases negatively affect the quality of life of solid organ recipients. Secondary or tertiary hyperparathyroidism is a frequent complication in kidney transplantation (KTx) recipients. Treatment with immunosuppressive agents including glucocorticoids can lead to deterioration in bone metabolism in these patients. In the present study, we explored the effects of a three-year treatment period with oral alendronate (ALN) in long-term KTx recipients. Post-KTx recipients were recruited (n = 24, M/F = 12/12, mean age 52.0 ± 7.8 years) into this study. All patients were prescribed methylprednisolone (4.07 ± 0.86 mg/day) with various immunosuppressive agents. Before treatment with oral ALN (35 mg/week), the mean concentrations of intact parathyroid hormone (iPTH) and 25-hydroxyvitamin D were 139.2 ± 71.4 pg/mL and 20.8 ± 4.1 ng/mL, respectively. After 36 months of ALN treatment, mean iPTH levels increased slightly (+20.9 %). Treatment with ALN reduced bone-specific alkaline phosphatase (-35.4 %), serum type I collagen N-terminal telopeptide (-31.2 %) and osteocalcin (-55.6 %) levels. ALN did not increase bone mass after 24 months. Four patients with the highest baseline iPTH levels suffered a clinical osteoporotic fracture during the 36-month ALN treatment period. Higher iPTH levels with chronic kidney disease (CKD) at baseline were associated with the incidence of new clinical fractures during ALN treatment. In conclusion, anti-resorptive therapy with ALN can suppress bone turnover even when iPTH concentration is elevated in long-term KTx recipients. However, hyperparathyroidism with CKD seems to be associated with new clinical fractures during ALN treatment.

Impact of B Cell Depletion on COVID-19 in Kidney Transplant Recipients.

Kidney transplant recipients are patients at high risk for coronavirus disease 2019 (COVID-19) due to being on immunosuppressive therapy. B cell depletion therapy, including rituximab, is an important strategy for ABO-incompatible transplants. However, knowledge about the effect of B cell depletion therapy on COVID-19 is lacking. Thirty kidney transplant recipients who developed COVID-19 were included in this study. To examine the impact of B cell depletion therapy, we retrospectively investigated the relationship between the background of the patients and the clinical outcome. Of the 30 patients, 13 received B cell depletion therapy. The median time between transplant and onset of COVID-19 was 6.1 years after transplantation; however, nine cases remained markedly depleted of CD19(+) cells (<4.0%). The patients were assigned to the normal (n = 21) and depletion groups (n = 9). Progression rates in the depletion and normal groups were 55.6% and 9.5%, respectively (p = 0.014). Furthermore, the survival rate was significantly lower in the depletion group (100% in the normal group vs. 66.7% in the depletion group; p = 0.021). B cell depletion therapy may have long-term effects and increase the risk of COVID-19 in kidney transplant recipients.

Outcomes of Pancreas Transplantation for Lower-Ranked Candidates.

BACKGROUND: To perform more pancreas transplantation (PTx), our center sometimes performs pancreas transplantation for candidates ranked sixth place or lower. In this study, we analyzed the outcomes of PTx performed in our center to compare the outcomes of higher- and lower-ranked candidates. METHODS: Seventy-two cases in which PTx was performed at our center were divided into 2 groups according to the candidate's rank. Cases in which PTx was performed for candidates up to fifth place were classified into the higher rank candidate group (HRC group; n = 48), whereas PTx for candidates who were ranked sixth place or lower were classified into the lower rank candidate group (LRC group; n = 24). The outcomes of PTx were retrospectively compared. RESULTS: Although the LRC group included a greater number of older donors (age ≥60 years), a greater number of donors with deteriorated renal function, and a greater number of HLA mismatches, the 1- and 5-year patient survival rates in the HRC group were 91.6% and 91.6%, respectively, compared with 95.8% and 87.0%, respectively, in the LRC group (P = .755). In terms of both pancreas and kidney graft survival, there were no significant differences between the 2 groups. Additionally, there were no significant differences between the 2 groups regarding the glucagon stimulation test and 75 g OGTT results, insulin independence rate, HbA1c, or serum creatinine level after transplantation. CONCLUSIONS: In Japan, where there is a severe donor shortage, the performance of transplantation for lower-ranked candidates would increase the number of opportunities for patients to receive PTx.

Pancreas transplantation improves the quality of life of Japanese type 1 diabetes patients with diabetic kidney disease.

Objectives: Type 1 diabetes mellitus (T1DM) patients with diabetic kidney disease-induced kidney failure have a significantly impaired quality of life (QOL), resulting in a high level of physical, mental, and social anxiety. In this study, we evaluated the QOL of T1DM patients on the list for pancreas transplantation (PTx) at their registration, and determined whether PTx improved their QOL. Methods: There were 58 patients (men/women, 22/36; mean age, 42.8±8.0 years) with T1DM and who were registered on the waiting list for PTx. Quantitative QOL assessment was performed using the Medical Health Survey Short Form (SF-36) version 2. Changes in the QOL before and after PTx were also examined in 24 of these patients. Results: The mean value of each endpoint and the summary score of the SF-36 physical (PCS), mental (MCS), and role (RCS) components were all below the national normal level at PTx registration. No significant difference in QOL scores was observed in the intergroup comparison of 35 patients on dialysis, 13 patients without dialysis, and ten patients after kidney transplantation. The 24 patients who underwent PTx showed improvement in PCS, MCS, and most SF-36 scores. Conclusion: T1DM patients waiting for PTx had a decreased QOL, regardless of dialysis, and PTx improved their QOL.

Blockade of glucagon increases muscle mass and alters fiber type composition in mice deficient in proglucagon-derived peptides.

AIMS/INTRODUCTION: Glucagon is secreted from pancreatic α-cells and plays an important role in amino acid metabolism in liver. Various animal models deficient in glucagon action show hyper-amino acidemia and α-cell hyperplasia, indicating that glucagon contributes to feedback regulation between the liver and the α-cells. In addition, both insulin and various amino acids, including branched-chain amino acids and alanine, participate in protein synthesis in skeletal muscle. However, the effect of hyperaminoacidemia on skeletal muscle has not been investigated. In the present study, we examined the effect of blockade of glucagon action on skeletal muscle using mice deficient in proglucagon-derived peptides (GCGKO mice). MATERIALS AND METHODS: Muscles isolated from GCGKO and control mice were analyzed for their morphology, gene expression and metabolites. RESULTS: GCGKO mice showed muscle fiber hypertrophy, and a decreased ratio of type IIA and an increased ratio of type IIB fibers in the tibialis anterior. The expression levels of myosin heavy chain (Myh) 7, 2, 1 and myoglobin messenger ribonucleic acid were significantly lower in GCGKO mice than those in control mice in the tibialis anterior. GCGKO mice showed a significantly higher concentration of arginine, asparagine, serine and threonine in the quadriceps femoris muscles, and also alanine, aspartic acid, cysteine, glutamine, glycine and lysine, as well as four amino acids in gastrocnemius muscles. CONCLUSIONS: These results show that hyperaminoacidemia induced by blockade of glucagon action in mice increases skeletal muscle weight and stimulates slow-to-fast transition in type II fibers of skeletal muscle, mimicking the phenotype of a high-protein diet.

Selective phosphorylation of serine 345 on p47-phox serves as a priming signal of ROS-mediated axonal degeneration.

Oxidative stress is a well-known inducer of two major neurodegenerative pathways, neuronal cell death and neurite degeneration. We previously reported that reactive oxygen species (ROS) generated by NADPH oxidases induces EGFR-dependent phosphorylation and activation of ZNRF1 ubiquitin ligase in neurons, which promotes neuronal cell death and neurite degeneration. While these findings provide a potential therapeutic avenue for neurodegeneration, a deeper understanding of the molecular mechanisms of this pathway have emerged as key points of interest. Here, we show that a NADPH oxidase subunit p47-phox/neutrophil cytosolic factor 1 regulates ZNRF1 activity. Using an in vitro neurite degeneration model, we demonstrate that transection-induced phosphorylation of p47-phox at the 345th serine residue by p38 MAPK serves as an initiating signal to activate ZNRF1. The phosphorylated p47 (pS345) or a phospho-mimetic mutant p47-phox binds directly to ZNRF1 whereas a phosphorylation-resistant mutant p47-phox cannot bind to ZNRF1 and its overexpression in neurites significantly suppresses ZNRF1 activation, AKT ubiquitination, and degeneration after transection, suggesting that pS345 might enhance the EGFR-mediated phosphorylation-dependent activation of ZNRF1. These results suggest that pS345 might represent an important checkpoint to initiate the ZNRF1-mediated neurite degeneration. Our findings provide novel insights into the mechanism of ROS-mediated neurodegeneration.

Evaluation of the Efficacy and Effects of Common Hepatic Artery Reconstruction in Pancreas Transplantation: A Randomized Controlled Trial.

Maintenance of postoperative graft flow is important in pancreas transplantation. In Japan, reconstruction of the common hepatic artery is performed primarily to increase perfusion in the pancreatic head. We investigated the effects of common hepatic artery reconstruction on patient and graft survival and endocrine functions. Twenty-nine cases of pancreas transplantation were registered in the clinical trial. Of the 29 cases, four were excluded because of the risk of ischemia without reconstruction or complicated reconstruction due to a narrow artery. A total of 25 cases were randomized into two groups: 13 in the non-reconstructed group and 12 in the reconstructed group. The 1-year patient survival and graft survival rates of the non-reconstructed and reconstructed groups were 92.3% and 83.3%, and 91.7% and 82.5%, respectively. The incidence of complications in the two groups was comparable, with 38.5% (5/13 cases) in the non-reconstructed group and 33.3% (4/12 cases) in the reconstructed group. The results of the glucagon stimulation test and oral glucose tolerance test at 1 month and 1 year post-transplantation were comparable. Common hepatic artery reconstruction is not essential unless there is risk of ischemia. This study was registered at the University Hospital Medical Information Network Clinical Trials Registry under UMIN000027213.

An Examination of Donor Factors That Impact the Results of the Glucagon Stimulation Test as an Assessment of the Pancreatic Graft Endocrine Function.

OBJECTIVES: Delta C-peptide derived by the glucagon stimulation test is a reliable value for the evaluation of the pancreatic endocrine function after pancreas transplantation. We examined the associations between delta C-peptide as pancreatic graft endocrine function and donor background factors. METHODS: Sixty-five cases of pancreatic transplantation from brain-dead donors, which were performed in our facility, were enrolled in this study. Enrolled recipients underwent a glucagon stimulation test within 1 to 3 months after transplantation to evaluate the pancreatic graft endocrine function with delta C-peptide to compare donor background factors. RESULTS: The following factors were associated with significant deterioration of the delta C-peptide: age of 50 years or greater, death from cerebrovascular accident, hemoglobin A1c level of 5.6% or greater, creatinine level of 1.0 mg/dL or greater, C-reactive protein level of 25 mg/dL or greater, and sodium level of 150 mmol/L or greater. In addition, increased numbers of these donor factors indicated significantly greater deterioration of the posttransplant pancreatic endocrine function ( P < 0.001). CONCLUSIONS: To secure insulin independence after pancreas transplantation, which means maintaining a delta C-peptide level of 1.0 ng/mL or greater on a glucagon stimulation test, the utilization of donors, who possesses more than equal to 3 of the donor factors identified in this study, should be carefully considered.

High Protein Diet Feeding Aggravates Hyperaminoacidemia in Mice Deficient in Proglucagon-Derived Peptides.

(1) Background: Protein stimulates the secretion of glucagon (GCG), which can affect glucose metabolism. This study aimed to analyze the metabolic effect of a high-protein diet (HPD) in the presence or absence of proglucagon-derived peptides, including GCG and GLP-1. (2) Methods: The response to HPD feeding for 7 days was analyzed in mice deficient in proglucagon-derived peptides (GCGKO). (3) Results: In both control and GCGKO mice, food intake and body weight decreased with HPD and intestinal expression of Pepck increased. HPD also decreased plasma FGF21 levels, regardless of the presence of proglucagon-derived peptides. In control mice, HPD increased the hepatic expression of enzymes involved in amino acid metabolism without the elevation of plasma amino acid levels, except branched-chain amino acids. On the other hand, HPD-induced changes in the hepatic gene expression were attenuated in GCGKO mice, resulting in marked hyperaminoacidemia with lower blood glucose levels; the plasma concentration of glutamine exceeded that of glucose in HPD-fed GCGKO mice. (4) Conclusions: Increased plasma amino acid levels are a common feature in animal models with blocked GCG activity, and our results underscore that GCG plays essential roles in the homeostasis of amino acid metabolism in response to altered protein intake.

Phosphate overload induces podocyte injury via type III Na-dependent phosphate transporter.

Uptake of P(i) at the cellular membrane is essential for the maintenance of cell viability. However, phosphate overload is also stressful for cells and can result in cellular damage. In the present study, we investigated the effects of the transgenic overexpression of type III P(i) transporter Pit-1 to explore the role of extracellular P(i) in glomerular sclerosis during chronic renal disease. Pit-1 transgenic (TG) rats showed progressive proteinuria associated with hypoalbuminemia and dyslipidemia. Ultrastructural analysis of TG rat kidney by transmission electron microscopy showed a diffuse effacement of the foot processes of podocytes and a thickening of the glomerular basement membrane, which were progressively exhibited since 8 wk after birth. TG rats died at 32 wk of age due to cachexia. At this time, more thickening of the glomerular basement membrane and segmental sclerosis were observed in glomeruli of the TG rats. Immunohistochemical examination using anti-connexin 43 and anti-desmin antibodies suggested the progressive injury of podocytes in TG rats. TG rats showed higher P(i) uptake in podocytes than wild-type rats, especially under low P(i) concentration. When 8-wk-old wild-type and TG rats were fed a 0.6% normal phosphate (NP) or 1.2% phosphate (HP) diet for 12 wk, HP diet-treated TG rats showed more progressive proteinuria and higher serum creatinine levels than NP diet-treated TG rats. In conclusion, our findings suggest that overexpression of Pit-1 in rats induces phosphate-dependent podocyte injury and damage to the glomerular barrier, which result in the progression of glomerular sclerosis in the kidney.