Relationship between nailfold capillaroscopy parameters and the severity of diabetic retinopathy.

PURPOSE: To determine whether non-invasive measurements of the nailfold capillaries (NCs) are associated with the presence and severity of diabetic retinopathy (DR) in patients with type 2 diabetes. METHODS: Eighty-three eyes of 83 patients with type 2 diabetes were enrolled. Sixty-three age-matched non-diabetic subjects served as controls. Diabetic patients were classified by the severity of their DR: non-DR (NDR), non-proliferative DR (NPDR), and proliferative DR (PDR). We used nailfold capillaroscopy to measure NC parameters, including number, length, width, and turbidity. RESULTS: Four NC parameters in the diabetic patients were significantly lower than in the controls (all P < 0.001). There was a statistically significant decrease in the NC parameters along with the increasing severity of DR (number: P = 0.02; all others: P < 0.001). Logistic regression analysis revealed that combining the systemic characteristics of age, sex, systolic blood pressure, estimated glomerular filtration rate, hemoglobin A1c level, and history of hypertension and dyslipidemia could indicate the presence of DR and PDR (the area under the receiver operating characteristic curve [AUC] = 0.81, P = 0.006; AUC = 0.87, P = 0.001, respectively). Furthermore, the discriminative power of DR was significantly improved (P = 0.03) by adding NC length to the systemic findings (AUC = 0.89, P < 0.001). CONCLUSION: NC measurement is a simple and non-invasive way to assess the risk of DR and its severity.

Implications of the Onset of Sweating on the Sweat Lactate Threshold.

The relationship between the onset of sweating (OS) and sweat lactate threshold (sLT) assessed using a novel sweat lactate sensor remains unclear. We aimed to investigate the implications of the OS on the sLT. Forty healthy men performed an incremental cycling test. We monitored the sweat lactate, blood lactate, and local sweating rates to determine the sLT, blood LT (bLT), and OS. We defined participants with the OS during the warm-up just before the incremental test as the early perspiration (EP) group and the others as the regular perspiration (RP) group. Pearson's correlation coefficient analysis revealed that the OS was poorly correlated with the sLT, particularly in the EP group (EP group, r = 0.12; RP group, r = 0.56). Conversely, even in the EP group, the sLT was strongly correlated with the bLT (r = 0.74); this was also the case in the RP group (r = 0.61). Bland-Altman plots showed no bias between the mean sLT and bLT (mean difference: 19.3 s). Finally, in five cases with a later OS than bLT, the sLT tended to deviate from the bLT (mean difference, 106.8 s). The sLT is a noninvasive and continuous alternative to the bLT, independent of an early OS, although a late OS may negatively affect the sLT.

Constant Load Pedaling Exercise Combined with Electrical Muscle Stimulation Leads to an Early Increase in Sweat Lactate Levels.

A novel exercise modality combined with electrical muscle stimulation (EMS) has been reported to increase cardiovascular and metabolic responses, such as blood lactate concentration. We aimed to examine the effect of constant load pedaling exercise, combined with EMS, by non-invasively and continuously measuring sweat lactate levels. A total of 22 healthy young men (20.7 ± 0.8 years) performed a constant load pedaling exercise for 20 min at 125% of the pre-measured ventilatory work threshold with (EMS condition) and without (control condition) EMS stimulation. Blood lactate concentration was measured by blood samples obtained from the earlobe every minute. Sweat lactate was monitored in real time using a sensor placed on the forearm. The sweat lactate threshold (sLT) was defined as the point of increase in sweat lactate. sLT occurred significantly earlier in the EMS condition than in the control condition. In the single regression analysis, the difference in sLT between the two conditions, as the independent variable, was a significant predictor of the difference in blood lactate concentrations at the end of the exercise (p < 0.05, r = −0.52). Sweat lactate measurement may be a noninvasive and simple alternative to blood lactate measurement to determine the effectiveness of exercise combined with EMS.

Realtime Monitoring of Local Sweat Rate Kinetics during Constant-Load Exercise Using Perspiration-Meter with Airflow Compensation System.

Epidermal wearable sweat biomarker sensing technologies are likely affected by sweat rate because of the dilution effect and limited measurement methods. However, there is a dearth of reports on the local sweat rate (LSR) monitored in real-time during exercise. This explorative study investigated the feasibility of real-time LSR monitoring and clarified LSR kinetics on the forehead and upper arm during constant-load exercise using a perspiration meter with an airflow compensation system. This observational cross-sectional study included 18 recreationally trained males (mean age, 20.6 ± 0.8 years). LSR on the forehead and upper arm (mg/cm2/min) were measured during a constant-load exercise test at 25% of their pre-evaluated peak power until exhaustion. The LSR kinetics had two inflection points, with a gradual decrease in the incremental slope for each section. After the second flexion point, the LSR slope slightly decreased and was maintained until exhaustion. However, the degree of change varied among the participants. Although the ratio of forehead LSR to upper arm LSR tended to decrease gradually over time, there was little change in this ratio after a second flexion point of LSR in both. These findings suggest possible differences in LSR control between the forehead and upper arm during constant-load exercise to prolonged exhaustion.

Kinetic changes in sweat lactate following fatigue during constant workload exercise.

It is useful to investigate various physiological responses induced by fatigue in athletes. Moreover, wearable noninvasive sensors, including sweat sensors, are compatible with fatigue evaluation because of their ease of use, and ability to measure repeatedly and continual data. This cross-sectional study aimed to clarify how sweat lactate elimination curves obtained during constant workload exercise changed following fatigue. Seventeen recreationally trained males (average age, 20.6 ± 0.8 years) completed two consecutive constant workload exercise tests (at 25% peak power) with rest intervals; the participants were encouraged to perform Test 1 until exhaustion and Test 2 only for 10 min. Subjective fatigue (numerical rating scale with face rating scale), sweat lactate, and sweat rate were measured for 10 min in each test. Subjective fatigue was compared using the Wilcoxon signed-rank test and time to each constant value between Tests 1 and 2 was compared using paired t-test. Subjective fatigue significantly increased during Test 2 compared with that during Test 1. After Test 1, the sweat lactate elimination curve demonstrated a leftward shift, as proved by the significantly sooner observation of the peak and constant values of sweat lactate (2, 3, and 4 µA) (p < 0.01). Our preliminary results suggest that the sweat lactate elimination curve is different in the fatigue state. Further research may provide insight in the application of this curve to the evaluation for fatigue.

[Influence of the Each Correction Method for the Specific Binding Ratio and Standardized Uptake Value in the Dopamine Transporter SPECT].

This study was to reveal the characteristics for each correction effect of specific binding ratio (SBR) and standardized uptake value (SUV) in the dopamine transporter (DAT) single photon emission computed tomography (SPECT). We created the 123I solution of five radioactive concentrations, which was filled with two types of striatum phantom such as separated or integrated caudate and putamen. We created 10 striatum accumulation models by combining the 123I solution. Images were reconstructed using ordered subset expectation maximization (OSEM) incorporating attenuation correction (AC), scatter correction (SC) or resolution recovery (RR) for the collected data of 10 striatum accumulation models and 66 patients. Correction combinations were AC, ACSC, ACRR and ACSCRR. The SBR, SUVmean and SUVmax were evaluated correlation and relative error between SBR, SUVmean and SUVmax by each correction method. The SBR and SUV had a significant positive correlation with all correction methods. The minimum values of relative error for SBR, SUVmean and SUVmax were 39.7% with ACSCRR, 18.4% with AC and 16.5% with ACSC, respectively. In addition, the ACSC of SBR and SUVmean was almost same value. The SBR showed significantly higher values by incorporating SC, while the SUV was significantly higher values by incorporating RR. It was suggested that SUV could be used for the quantitative index of DAT SPECT. Furthermore, we demonstrated the characteristic among each correction for SBR and SUV.

Monitoring eruption activity using temporal stress changes at Mount Ontake volcano.

Volcanic activity is often accompanied by many small earthquakes. Earthquake focal mechanisms represent the fault orientation and slip direction, which are influenced by the stress field. Focal mechanisms of volcano-tectonic earthquakes provide information on the state of volcanoes via stresses. Here we demonstrate that quantitative evaluation of temporal stress changes beneath Mt. Ontake, Japan, using the misfit angles of focal mechanism solutions to the regional stress field, is effective for eruption monitoring. The moving average of misfit angles indicates that during the precursory period the local stress field beneath Mt. Ontake was deviated from the regional stress field, presumably by stress perturbations caused by the inflation of magmatic/hydrothermal fluids, which was removed immediately after the expulsion of volcanic ejecta. The deviation of the local stress field can be an indicator of increases in volcanic activity. The proposed method may contribute to the mitigation of volcanic hazards.

Okadaic acid is taken-up into the cells mediated by human hepatocytes transporter OATP1B3.

Okadaic acid is known as a diarrheal shellfish poison. It is thought that there is no specific target organ for okadaic acid after it has been absorbed into the body. However, the details of its pharmacokinetics are still unknown. In this study, we demonstrated that okadaic acid was more toxic to the hepatocyte-specific uptake transporter OATP1B1- or OATP1B3-expressing cells than control vector-transfected cells. In addition, PP2A activity, which is a target molecule of okadaic acid, was more potently inhibited by okadaic acid in OATP1B1- or OATP1B3-expressing cells compared with control vector-transfected cells. The cytotoxicity of okadaic acid in OATP1B1- or OATP1B3-expressing cells was attenuated by known substrates of OATP1B1- and OATP1B3, but not in control vector-transfected cells. Furthermore, after uptake inhibition study using OATP1B3-expressing cells, Dixon plot showed that okadaic acid inhibited the uptake of hepatotoxin microcystin-LR, which is a substrate for OATP1B1 and OATP1B3, in a competitive manner. These results strongly suggested that okadaic acid is a substrate for OATP1B3 and probably for OATP1B1, and could be involved in unknown caused liver failure and liver cancer. Since okadaic acid possesses cytotoxicity and cell proliferative activity by virtue of its known phosphatase inhibition activity.

p53 Plays an important role in cell fate determination after exposure to microcystin-LR.

BACKGROUND: Microcystin-LR, a cyclic heptapeptide, possesses the ability to inhibit the serine/threonine protein phosphatases PP1 and PP2A and, consequently, exhibits acute hepatocytotoxicity. Moreover, microcystin-LR induces cellular proliferation, resulting in tumor-promoting activity in hepatocytes. However, mechanisms that regulate the balance between cell death and proliferation after microcystin-LR treatment remain unclear. OBJECTIVE: We examined the contribution of the transcription factor p53, as well as that of the hepatic uptake transporter for microcystin-LR, organic anion transporting polypeptide 1B3 (OATP1B3), to the cellular response to microcystin-LR exposure. METHODS: We analyzed intracellular signaling responses to microcystin-LR by immunoblotting and real-time reverse-transcriptase polymerase chain reaction techniques using HEK293 human embryonic kidney cells stably transfected with SLCO1B3 (HEK293-OATP1B3). In addition, we analyzed the effect of attenuation of p53 function, via the p53 inhibitor pifithrin-alpha, and knockdown of p53 mRNA on the cytotoxicity of microcystin-LR using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. RESULTS: Microcystin-LR induced the phosphorylation and accumulation of p53 in HEK293-OATP1B3 cells, which resulted in up-regulation of the expression of p53 transcript targets, including p21 and seven in absentia homolog 1 (siah-1). In addition, microcystin-LR activated Akt signaling through the phosphorylation of Akt and glycogen synthase kinase 3beta. Although Akt signaling was activated, the accumulation of p53 led cells to apoptosis after treatment with 50 nM microcystin-LR for 24 hr. Both pharmacological inhibition of transcription factor activity of p53 by pifithrin-alpha and knockdown of p53 with small hairpin RNA attenuated the susceptibility of HEK293-OATP1B3 cells to microcystin-LR. CONCLUSIONS: This study demonstrates the importance of p53 in the regulation of cell fate after exposure to microcystin-LR. Our results suggest that, under conditions of p53 inactivation (including p53 mutation), chronic exposure to low doses of microcystin-LR may lead to cell proliferation through activation of Akt signaling. Results of this study may contribute to the development of chemoprevention and chemotherapeutic approaches to microcystin-LR poisoning.

Pharmacokinetics of human immunodeficiency virus protease inhibitor, nelfinavir, in poloxamer 407-induced hyperlipidemic model rats.

The effect of hyperlipidemia (HL) on the pharmacokinetics of nelfinavir (NFV), a human immunodeficiency virus protease inhibitor, was investigated, focusing on the change of NFV distribution in plasma using poloxamer 407-induced HL model rats (HL rats). The plasma unbound fraction (f(u)) in HL rats (0.20-0.39%) was significantly lower than the control (0.92-1.47%). Lipoprotein level in HL rats was about 5 times higher and low- and very low-density liproteins ratio were 1.7-4.5 times higher than the control. NFV recovery in the triglyceride-rich lipoprotein such as chylomicron, low- and very low-density liproteins fractions of HL rats were significantly higher. The area under the plasma concentration-time curve (AUC) of NFV after intravenous (i.v.: 5 mg/kg) and intraduodenal (i.d.: 30 mg/kg) administration to HL rats (i.v.: 6.12+/-0.48, i.d.: 24.4+/-2.2 microg x h/ml) were higher than the control (i.v.: 1.62+/-0.21, i.d.: 5.00+/-0.36 microg x h/ml). The steady state volume of distribution (Vd(ss)) in HL rats (0.60+/-0.07 l/kg) was lower than the control (6.25+/-0.55 l/kg). Systemic availability (F) in HL rats (66.6%) was higher than the control (51.4 %). Directly absorbed NFV from the gastrointestinal tract to the lymphatic system in HL rats was about 2 times higher than the control. From the results of this study, it was concluded that the increase of AUC was caused by decreasing f(u) and Vd(ss) due to the increase of the triglyceride-rich lipoprotein level. In addition, it was suggested that the increase of absorbed NFV through the lymphatic system, which did not receive the first-pass effect, was one reason for the increase of F in HL rats.

Effect of streptozotocin-induced diabetes mellitus on the pharmacokinetics of nelfinavir in rats.

The HIV protease inhibitor, nelfinavir (NFV), has been used widely for HIV infection. The drug exhibits high binding characteristics to serum protein (unbound fraction: 0.01). The effect of experimentally induced diabetes mellitus on the pharmacokinetics of NFV was investigated, focusing on the change of protein-binding due to the glycosylation of albumin in streptozotocin-induced diabetes mellitus rats (diabetic rats). The unbound fraction of NFV in diabetic rats (0.04) was greater than that in the control (0.015). In diabetic rats, although the AUC of NFV was decreased after both intravenous (control: 1.75+/-0.08, diabetic: 1.36+/-0.17 microg h/ml) and intraduodenal (control: 1.69+/-0.25, diabetic: 1.19+/-0.39 microg h/ml) administrations, the unbound AUC was increased significantly (intravenous, control: 0.026+/-0.001, diabetic: 0.054+/-0.007 microg h/ml, intraduodenal, control: 0.025+/-0.004, diabetic: 0.048+/-0.016 microg h/ml). The unbound total clearance (control: 131.3+/-6.0, diabetic: 64.3+/-8.0 l/h/kg) and the unbound steady state distribution volume (control: 274.0+/-18.0, diabetic: 123.0+/-14.0 l/kg) were decreased significantly; therefore, greater pharmacological effects can be expected in diabetes mellitus. The contribution of increasing the unbound fraction to these results was significantly higher. In addition, there were no significant differences in the systemic and hepatic availability, peak time and mean absorption time between the diabetic and control rats, suggesting that diabetes mellitus did not affect the absorption of NFV.

Study of the nanoscopic deformation of an annealed nafion film by using atomic force microscopy and a patterned substrate.

We demonstrated the repetitive imaging of the same area of a nafion film before and after annealing by using atomic force microscopy (AFM). In order to find the exact same area of the same sample after changing the cantilever and reattaching the sample, a micropatterned substrate was developed. A micropattern with a 250-500 microm pitch was prepared on the backside of a transparent glass substrate. This pattern includes various signs such as colored letters and numbers at the center of each lattice of the pattern. The nanostructures fabricated by AFM nanolithography on a nafion film using this new method were successfully characterized before and after annealing (over 100 degrees C). The AFM images clearly showed that the nanostructures on a nafion film were dramatically changed by annealing. The data indicated an evidence to understand why the nafion fuel cell does not work well at high temperatures. Our method is probably effective for the study of nanoscopic dynamics in various surface structures.

Regulated growth of diatom cells on self-assembled monolayers.

We succeeded in regulating the growth of diatom cells on chemically modified glass surfaces. Glass surfaces were functionalized with -CF3, -CH3, -COOH, and -NH2 groups using the technique of self-assembled monolayers (SAM), and diatom cells were subsequently cultured on these surfaces. When the samples were rinsed after the adhesion of the diatom cells on the modified surfaces, the diatoms formed two dimensional arrays; this was not possible without the rinsing treatment. Furthermore, we examined the number of cells that grew and their motility by time-lapse imaging in order to clarify the interaction between the cells and SAMs. We hope that our results will be a basis for developing biodevices using living photosynthetic diatom cells.