Objective: Single-nephron glomerular filtration rate (SNGFR) is an important and valuable parameter for evaluating renal function. Previously, SNGFR measurements required radioactive labelling of isolated animal nephrons, which was a time-consuming and inefficient process. Owing to the development of laser confocal microscopy, in vivo renal visualisation became much simpler, facilitated by the use of fluorescent markers. In this study, the effects of C-peptide on hyperfiltration reversal were evaluated during the early stages of diabetes mellitus (DM). Methods: Wistar rats (n = 17) were divided into control and streptozotocin-induced DM groups. Analyses were performed at 2 and 6 weeks following induction. Lucifer Yellow was administered by bolus injection to visualise tubular urinary flow using a laser confocal microscope. Results: SNGFR increased in diabetic rats (p < 0.05) and decreased by approximately 40% following C-peptide administration (p < 0.05). Moreover, tubular luminal flow increased (p < 0.05), as previously reported, but decreased by 3–11% after C-peptide administration in 6-week diabetic rats without significance. Conclusion: Confocal microscopy demonstrated that C-peptide administration decreases SNGFR and tubular luminal flow in diabetic rats.

Intra- and inter-cellular Ca²⁺ waves play key roles in cellular functions. Focal stimulation triggers Ca²⁺ wave propagation from the stimulation point to neighboring cells through the cytoplasm, which involves localized metabolism reactions and specific diffusion processes. Briefly, inositol 1,4,5-trisphosphate (IP₃) is produced at membranes and diffuses into the cytoplasm, resulting in Ca²⁺ release from the endoplasmic reticulum (ER). Particularly, Ca²⁺ released from the ER is mediated by two principles, the IP₃-induced Ca²⁺ and Ca²⁺-induced Ca²⁺ releases. Ca²⁺ is diffused through the cytoplasm and, furthermore, transported into neighboring cells through gap junctions. These intra- and inter-cellular Ca²⁺ waves have been widely investigated using theoretical and experimental methods in various cell types. In this review we summarize the mathematical models used for the numerical simulation of intra- and inter-cellular Ca²⁺ wave propagations.

In this study, we investigated the spatial and temporal reorganization of actin filaments in living endothelial cells in response to shear stress by transfecting a fluorescent protein, Dronpa-Green-labeled actin, which was photoactivated microscopically by UV irradiation, and evaluating the time constants of fluorescence decay after photoactivation. The time constant in the upstream region decreased gradually after 30 min of shear stress and then increased. Particularly, the time constant in the downstream region tended to be higher than in the upstream region, suggesting that actin polymerization was more activated in the downstream region. Our results demonstrated the spatial and temporal heterogeneity of actin reorganization due to shear stress.

Polymerization accelerated by Pmel17, advanced within the mildly acidic conditions of melanosomes, plays a vital role during pigment deposition. The polymers closely resemble amyloid fibrils, associated with amyloidosis. Concerning the formation of the amyloidogenic cross-β structure, the initial mechanism in the conversion to a β-structure is critically important. To explore the core regions forming a stem of the amyloid, we prepared a series of fragment peptides of the C-terminal part of the the repeat domain (RPT, residues 315–444) and examined their ability to produce amyloids. Sequence alignment of the peptides bearing the ability to form amyloid structures revealed that β-consisting of ⁴⁰⁵VSIVVLSGTTAAQVTT⁴²⁰ are the core regions responsible for initiating the formation of cross-β structures and for further ordered aggregation.

The rheological response of bile (which is produced in the liver) was studied in steady-shear and creep-recovery measurements as a function of pH to promote clinical prediction and prevention of stone formation in the gallbladder. We used bile samples extracted from the gallbladders of pigs. Steady-shear rheological measurements reflected the shear-thinning behavior of bile, and the viscosity of bile increased to high values at high pH values. Therefore, an increase in pH could reduce the emptying process of the gallbladder, which would enhance the risk of gallstone formation risk. Creep-recovery measurements revealed that bile elicited a rapid elastic response and showed strong recovery behavior at high pH. Moreover, the elastic behavior of bile could be predicted by the Burger model.

The influence of fibrinogen concentration on blood dielectric properties has been analyzed by GHz electrical impedance spectroscopy (EIS). The complex impedances of native blood and blood with various fibrinogen concentrations Z*_blood,exp were measured by a coaxial sensor in the frequency range from 1 MHz to 3 GHz. The complex permittivity of native blood and blood with various fibrinogen concentrations ε*_blood were extracted from the Z*_blood,exp by equivalent circuit model based on the transmission line theory. The reactance X_blood,native and resistance Rs_blood,native of native blood have a peak called characteristic frequency f_c at around 300 MHz. At the time t = 0 min just after fibrinogen addition, the relative blood permittivity ε_blood decreases, conductivities σ_blood increases and f_c shifts to higher frequency with increase of fibrinogen concentrations c_fib in plasma. With increment of time, from t = 0 min to t = 12 min, ε_blood decreases while σ_blood slightly decreases to time because red blood cell (RBC) aggregation reaction. By comparing the ε_blood,native of native blood and blood with various c_fib, the fibrinogen dissolved in plasma rises the blood permittivity. However, fibrinogen is unable to rise the blood permittivity unlimitedly because of RBC aggregation reaction.