•Recurrent short-term hypo- and hyper-glycemia reduced Schwann cells viabilities.•Cleaved caspase-3 and CHOP levels increased and Bcl-2 decreased in hypo- and hyper-glycemic groups.•TBARS levels ...increased by hypo- and hyperglycemia.•Recurrent short-term hypoglycemia induced apoptosis and oxidative stress in Schwann cells.•4-PBA treatment ameliorated cell death and oxidative stress in both groups.
Hypoglycemia and fluctuating high or low glucose conditions are under-appreciated sources of oxidative stress contributing to diabetic neuropathy. We investigated the effects of recurrent short-term hypoglycemia and hyperglycemia, on apoptosis and oxidative stress in Schwann cells. Immortalized adult mouse Schwann (IMS32) cells were exposed to five different glucose treatments over 3 days: 1) normal glucose (NG), 2) constant low glucose (LG), 3) constant high glucose (HG), 4) intermittent low glucose (ILG; 1 h three times per day), 5) intermittent high glucose (IHG; 1 h three times per day). Cell viability was decreased by all treatment variants, in comparison to NG. Thiobarbituric acid reactive substance (TBARS) levels were increased by HG, LG, IHG, and ILG. High glucose (HG and IHG) and low glucose (LG and ILG) increased the expression of cleaved caspase-3 and reduced that of Bcl-2. In addition, endoplasmic reticulum (ER) stress-responsive transcription factor C/EBP homologous protein (CHOP) expression was increased under low and high glucose conditions. Cell death and oxidative stress induced by HG, LG, IHG, and ILG were significantly reduced by 4-phenyl butyric acid (4-PBA), an ER stress inhibitor. These findings indicate that recurrent short-term hypoglycemia and hyperglycemia induce apoptosis and oxidative stress via the ER stress response in Schwann cells.
Aims/Introduction
Recent studies advocate that omega‐3 polyunsaturated fatty acids (ω‐3 PUFAs) have direct anti‐oxidative and anti‐inflammatory effects in the vasculature; however, the role of ω‐3 ...PUFAs in Schwann cells remains undetermined.
Materials and methods
Immortalized mouse Schwann (IMS32) cells were incubated with the ω‐3 PUFAs docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). The messenger ribonucleic acid levels of several anti‐oxidant enzymes (heme oxygenase‐1 Ho‐1, nicotinamide adenine dinucleotide phosphate H quinone oxidoreductase 1, catalase, superoxide dismutase and glutathione peroxidase) were identified using real‐time reverse transcription polymerase chain reaction. Ho‐1 and nicotinamide adenine dinucleotide phosphate H quinone oxidoreductase 1 protein levels were evaluated using Western blotting. Nuclear factor (erythroid‐derived 2)‐related factor 2 (Nrf2) of the nuclear fraction was also quantified using western blotting. Catalase activity and glutathione content were determined by colorimetric assay kits. Nrf2 promoter‐luciferase activity was evaluated by a dual luciferase assay system.
Results
Treatment with tert‐butyl hydroperoxide decreased cell viability dose‐dependently. DHA or EPA pretreatment significantly alleviated tert‐butyl hydroperoxide‐induced cytotoxicity. DHA or EPA increased the messenger ribonucleic acid levels of Ho‐1, nicotinamide adenine dinucleotide (phosphate) H quinone oxidoreductase 1 and catalase dose‐dependently. Ho‐1 protein level, catalase activity, Nrf2 promoter‐luciferase activity and intracellular glutathione content were significantly increased by DHA and EPA.
Conclusions
These findings show that DHA and EPA can induce Ho‐1 and catalase through Nrf2, thus protecting Schwann cells against oxidative stress. ω‐3 PUFAs appear to exert their neuroprotective effect by increasing defense mechanisms against oxidative stress in diabetic neuropathies.
We demonstrated that both DHA and EPA could prevent cell death by inducing numerous antioxidants in IMS32 cells. Our findings suggest that enhancements of antioxidative defenses might have therapeutic value in the treatment of diabetic neuropathy.
Aims
We investigated the impact of actual waiting time and perceived waiting time on treatment satisfaction in patients with diabetes receiving outpatient care.
Methods
Three hundred and thirty-six ...outpatients diagnosed with diabetes mellitus or impaired glucose tolerance were selected and the time they spent in reception, blood collection, consultation, and accounting were recorded to measure the time they spent waiting in the hospital (actual waiting time). Simultaneously, we conducted a questionnaire survey that included questions on their perceptions of the waiting time (perceived waiting time) and satisfaction with treatment (DTSQ).
Results
No significant relationship was found between actual waiting time and DTSQ score, although associations were observed with perceived waiting time. The patients who felt the overall waiting time was long scored 23.0, those who felt it was short scored 26.0, and those who felt it was very short scored 34.0, with those who felt the waiting time was long having a significantly lower score (
p
= 0.004,
p
< 0.001, respectively) and those who felt it was short having a significantly lower score than those who felt it was very short (
p
= 0.008). In addition, more patients who felt the waiting time was long expressed dissatisfaction with the responses of doctors and staff than those who felt the waiting time was short.
Conclusions
These results suggest that in addition to reducing actual waiting times, shortening perceived waiting times by improving the responses of medical staff could help to increase patient satisfaction.
Autophagy is the process by which intracellular components are degraded by lysosomes. It is also activated by oxidative stress; hence, autophagy is thought to be closely related to oxidative stress, ...one of the major causes of diabetic neuropathy. We previously reported that docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) induced antioxidant enzymes and protected Schwann cells from oxidative stress. However, the relationship between autophagy and oxidative stress-induced cell death in diabetic neuropathy has not been elucidated. Treatment with tert-butyl hydroperoxide (tBHP) decreased the cell survival rate, as measured by an MTT assay in immortalized Fischer rat Schwann cells 1 (IFRS1). A DHA pretreatment significantly prevented tBHP-induced cytotoxicity. tBHP increased autophagy, which was revealed by the ratio of the initiation markers, AMP-activated protein kinase, and UNC51-like kinase phosphorylation. Conversely, the DHA pretreatment suppressed excessive tBHP-induced autophagy signaling. Autophagosomes induced by tBHP in IFRS1 cells were decreased to control levels by the DHA pretreatment whereas autolysosomes were only partially decreased. These results suggest that DHA attenuated excessive autophagy induced by oxidative stress in Schwann cells and may be useful to prevent or reduce cell death in vitro. However, its potentiality to treat diabetic neuropathy must be validated in in vivo studies.
Individuals suffering from diabetic polyneuropathy (DPN) experience debilitating symptoms such as pain, paranesthesia, and sensory disturbances, prompting a quest for effective treatments. ...Dipeptidyl-peptidase (DPP)-4 inhibitors, recognized for their potential in ameliorating DPN, have sparked interest, yet the precise mechanism underlying their neurotrophic impact on the peripheral nerve system (PNS) remains elusive. Our study delves into the neurotrophic effects of DPP-4 inhibitors, including Diprotin A, linagliptin, and sitagliptin, alongside pituitary adenylate cyclase-activating polypeptide (PACAP), Neuropeptide Y (NPY), and Stromal cell-derived factor (SDF)-1a—known DPP-4 substrates with neurotrophic properties. Utilizing primary culture dorsal root ganglia (DRG) neurons, we meticulously evaluated neurite outgrowth in response to these agents. Remarkably, all DPP-4 inhibitors and PACAP demonstrated a significant elongation of neurite length in DRG neurons (PACAP 0.1 μM: 2221 ± 466 μm, control: 1379 ± 420, p < 0.0001), underscoring their potential in nerve regeneration. Conversely, NPY and SDF-1a failed to induce neurite elongation, accentuating the unique neurotrophic properties of DPP-4 inhibition and PACAP. Our findings suggest that the upregulation of PACAP, facilitated by DPP-4 inhibition, plays a pivotal role in promoting neurite elongation within the PNS, presenting a promising avenue for the development of novel DPN therapies with enhanced neurodegenerative capabilities.
Objective and Methods An SGLT2 inhibitor (ipragliflozin, dapagliflozin, luseogliflozin, tofogliflozin, or canagliflozin) was administered to 132 outpatients with type 2 diabetes mellitus with or ...without other antidiabetic drugs for 6 months to evaluate its efficacy, the incidence of adverse events, and its influence on the renal function. Results The patient's mean glycated hemoglobin level significantly improved from 7.52±1.16% to 6.95±0.98% (p<0.001). The body weight of the patients was significantly reduced from 78.0±15.3 kg to 75.6±15.1 kg (p<0.001). The estimated visceral fat area was also significantly reduced from 108.4±44.6 cm2 to 94.5±45.3 cm2 (p<0.001). The waist circumference, blood pressure, serum alanine aminotransferase, γ-glutamyl transpeptidase, and uric acid levels also showed a significant decrease. The urinary albumin/creatinine ratio (U-ACR) was significantly reduced in the patients whose U-ACR levels were 30-300 mg/gCr at the baseline. The mean eGFR significantly decreased in the patients with a pre-treatment eGFR value of ≥90 mL/min/1.73 m2 but remained unchanged in the patients with a pre-treatment value of <90 mL/min/1.73 m2. A total of 13 adverse events were noted, including systemic eruption (n=1), cystitis (n=2), pudendal pruritus (n=2), nausea (n=1), malaise (n=1), a strong hunger sensation and increased food ingestion (n=1), and non-serious hypoglycemia (n=5). Conclusion SGLT2 inhibitors seemed to be useful in the treatment of obese type 2 diabetes mellitus patients. Furthermore, these data suggest that SGLT2 inhibitors may protect the renal function.
Multicentric Castleman disease (MCD) is an atypical lymphoproliferative disorder characterized by systemic lymphadenopathy and constitutional inflammatory symptoms. Dysregulated overproduction of ...interleukin-6 is responsible for the clinical abnormalities. This multicenter prospective study was undertaken to evaluate the safety and efficacy of a humanized anti–human interleukin-6 (IL-6) receptor monoclonal antibody (MRA) in patients with MCD. We report here results of the first 60 weeks of the study enrolling 28 patients. The initial dosing period consisted of 8 infusions of 8 mg/kg MRA administered biweekly. Adjustments in the dose and treatment interval were allowed for each patient in an extension phase after 16 weeks. Within 16 weeks, treatment with MRA consistently alleviated lymphadenopathy and all the inflammatory parameters. Hemoglobin, albumin, and total cholesterol levels, high-density lipoprotein cholesterol values, and body mass index all increased significantly. In addition, fatigue diminished. Chronic inflammatory symptoms were successfully managed over 60 weeks. In 8 (28.6%) patients, the MRA dose was decreased or the treatment interval was extended without exacerbation. Eleven (73.3%) of 15 patients who had received oral corticosteroids before study entry were able to do well on a reduced corticosteroid dose. Most adverse events were mild to moderate in severity. MRA was tolerated well and significantly alleviated chronic inflammatory symptoms and wasting in patients with MCD.
Aims/Introduction
Transplantation of stem cells promotes axonal regeneration and angiogenesis in a paracrine manner. In the present study, we examined whether the secreted factors in conditioned ...medium of stem cells from human exfoliated deciduous teeth (SHED‐CM) had beneficial effects on diabetic polyneuropathy in mice.
Materials and Methods
Conditioned medium of stem cells from human exfoliated deciduous teeth was collected 48 h after culturing in serum‐free Dulbecco's modified Eagle's medium (DMEM), and separated into four fractions according to molecular weight. Dorsal root ganglion neurons from C57BL/6J mice were cultured with SHED‐CM or DMEM to evaluate the effect on neurite outgrowth. Streptozotocin‐induced diabetic mice were injected with 100 μL of SHED‐CM or DMEM into the unilateral hindlimb muscles twice a week over a period of 4 weeks. Peripheral nerve functions were evaluated by the plantar test, and motor and sensory nerve conduction velocities. Intraepidermal nerve fiber densities, capillary number‐to‐muscle fiber ratio, capillary blood flow and morphometry of sural nerves were also evaluated.
Results
Conditioned medium of stem cells from human exfoliated deciduous teeth significantly promoted neurite outgrowth of dorsal root ganglion neurons compared with DMEM. Among four fractions of SHED‐CM, the only fraction of <6 kDa promoted the neurite outgrowth of dorsal root ganglion neurons. In addition, SHED‐CM significantly prevented decline in sensory nerve conduction velocities compared with DMEM in diabetic mice. Although SHED‐CM did not improve intraepidermal nerve fiber densities or morphometry of sural nerves, SHED‐CM ameliorated the capillary number‐to‐muscle fiber ratio and capillary blood flow.
Conclusions
These results suggested that SHED‐CM might have a therapeutic effect on diabetic polyneuropathy through promoting neurite outgrowth, and the increase in capillaries might contribute to the improvement of neural function.
In this study, we examined whether the secreted factors could be collected from conditioned medium of stem cells from human exfoliated deciduous teeth had beneficial effects on diabetic polyneuropathy. Conditioned medium of stem cells from human exfoliated deciduous teeth might have a therapeutic effect on diabetic polyneuropathy through promoting neurite outgrowth, and the increase in capillaries might contribute to the improvement of neural function.
We present a case of a 32‐year‐old diabetic woman with Prader–Willi syndrome who developed severe ketoacidosis caused by a sodium‐glucose cotransporter 2 (SGLT2) inhibitor, a novel class of ...antihyperglycemic agents, during a strict low‐carbohydrate diet. At admission, a serum glucose level of 191 mg/dL was relatively low, though laboratory evaluations showed severe ketoacidosis. This is the first report of ketoacidosis caused by a SGLT2 inhibitor. It is necessary to not only pay attention when using a SGLT2 inhibitor in patients following a low‐carbohydrate diet, but also to start a low‐carbohydrate diet in patients treated with a SGLT2 inhibitor because of a high risk for developing ketoacidosis.
This is the first report of ketoacidosis caused by a SGLT2 inhibitor. It is necessary to pay attention not only to use a SGLT2 inhibitor in the patients during a low‐carbohydrate diet but also to start a low‐carbohydrate diet in the patients treated with a SGLT2 inhibitor because of a high risk for developing ketoacidosis.
Aims/Introduction
A gold standard in the diagnosis of diabetic polyneuropathy (DPN) is a nerve conduction study. However, as a nerve conduction study requires expensive equipment and well‐trained ...technicians, it is largely avoided when diagnosing DPN in clinical settings. Here, we validated a novel diagnostic method for DPN using a point‐of‐care nerve conduction device as an alternative way of diagnosis using a standard electromyography system.
Materials and Methods
We used a multiple regression analysis to examine associations of nerve conduction parameters obtained from the device, DPNCheck™, with the severity of DPN categorized by the Baba classification among 375 participants with type 2 diabetes. A nerve conduction study using a conventional electromyography system was implemented to differentiate the severity in the Baba classification. The diagnostic properties of the device were evaluated using a receiver operating characteristic curve.
Results
A multiple regression model to predict the severity of DPN was generated using sural nerve conduction data obtained from the device as follows: the severity of DPN = 2.046 + 0.509 × ln(age years) − 0.033 × (nerve conduction velocity m/s) − 0.622 × ln(amplitude of sensory nerve action potential µV), r = 0.649. Using a cut‐off value of 1.3065 in the model, moderate‐to‐severe DPN was effectively diagnosed (area under the receiver operating characteristic curve 0.871, sensitivity 70.1%, specificity 87.7%, positive predictive value 83.0%, negative predictive value 77.3%, positive likelihood ratio 5.67, negative likelihood ratio 0.34).
Conclusions
Nerve conduction parameters in the sural nerve acquired by the handheld device successfully predict the severity of DPN.
Currently, most diagnostic criteria for diabetic polyneuropathy consist of physical examinations; for example, Achilles tendon reflex or vibration sensation with a tuning fork. Therefore, the low diagnostic sensitivity of these criteria should be improved. Although the gold standard for quantitative evaluation of diabetic polyneuropathy is an electromyography system, these have not become widely used due to their high cost and necessity of an advanced examination technique. The current work verified the efficacy of a handheld nerve conduction device. If clinicians recognize the validity and reliability of the device, this simplified nerve conduction study could be carried out in various clinical settings, including clinics or hospitals in developing or developed countries. The worldwide utilization of the device would improve diagnostic sensitivity for diabetic polyneuropathy in the future.
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