Substance P induces inositol 1,4,5-trisphosphate and intracellular free calcium increase in cultured normal human epidermal keratinocytes

Abstract Substance P is a neuropeptide which is present in peripheral C nerve endings and released from them. Free nerve endings of C nerve are present in human epidermis. The effects of substance P on the transmembrane signaling system of pig epidermal sheets were previously reported. In these studies, a small amount of cells other than keratinocytes contaminated the epidermal sheets and the species difference from human was also noticed. Therefore we investigated the effects of substance P on cultured normal human epidermal keratinocytes. Alteration of intracellular free calcium (Ca²⁺) in single living keratinocytes was studied using an inverted fluorescence microscope and Ca²⁺ -sensitive dye, Fura 2-AM. Treatment of normal human epidermal kertinocytes with substance P resulted in an increase in inositol 1,4,5-trisphosphate and in intracellular Ca²⁺. Substance P inhibited DNA synthesis of the keratinocytes in a dose-dependent manner. These results are consistent with the view that substance P stimulates phosphatidylinositol-4,5-bisphosphate hydrolysis of human keratinocytes, resulting in inositol 1,4,5-trisphosphate-Ca²⁺ signal.     

Changes in Glucose Metabolism in Cerebral Cortex and Cerebellum Correlate With Tremor and Rigidity Control by Subthalamic Nucleus Stimulation in Parkinson's Disease: A Positron Emission Tomography Study

Objective. Employing [¹⁸F]fluorodeoxyglucose (FDG) positron emission tomography (PET) to assess the correlation between the effect of deep brain stimulation (DBS) on the subthalamic nucleus (STN) and the regional cerebral metabolic rate of glucose (rCMRGlc) in advanced Parkinson's disease patients (N = 8). Materials and Methods. On the basis of patients’ diary records, we performed FDG‐PET during the off‐period of motor activity with on‐ or off‐stimulation by STN‐DBS on separate days and analyzed the correlation between changes in motor symptoms and alterations in the rCMRGlc. Result. When FDG‐PET was performed, the motor score on the unified Parkinson's disease rating scale (UPDRS) was 64% lower with on‐stimulation than with off‐stimulation (p < 0.001, Wilcoxon single‐rank test). STN‐DBS increased the rCMRGlc in the posterior part of the right middle frontal gyrus, which corresponded to the premotor area, and the right anterior lobe of the cerebellum (p < 0.005, paired t‐test). No region exhibited a decrease in rCMRGlc. Among the items of the UPDRS motor score, the changes in resting tremor and rigidity of the left extremities showed a significant correlation with the changes in rCMRGlc observed in the right premotor area (p < 0.02 and p < 0.05, respectively, Spearman's rank correlation). Conclusions. STN‐DBS either activates the premotor area or normalizes the deactivation of the premotor area. These FDG‐PET findings obtained are consistent with the idea that STN‐DBS modifies the activities of neural circuits involved in motor control.     

A novel action of stargazin as an enhancer of AMPA receptor activity

Stargazin (γ-2) is disrupted in the ataxic and epileptic mutant mouse, stargazer (stg). The striking defect in the stg cerebellum is the lack of functional AMPA receptors on granule cells. Recently, it has been reported that γ-2 and its related molecules are crucial for the surface expression, synaptic targeting and recycling of AMPA receptors, being termed collectively as the transmembrane AMPA receptor regulatory proteins (TARPs). However, it is still unclear whether TARPs directly modulate AMPA receptor activity. Here we report that coexpression of GluR1 (GluR1) with γ-2 using HEK293 cells and Xenopus oocytes markedly enhanced glutamate-induced currents. This effect was far beyond the increase of AMPA receptor surface expression and accompanied by increased glutamate affinity and subunit cooperativity. Other member of TARPs (γ-3, γ-4, and γ-8) also enhanced the current response through the AMPA receptors. The enhancing effect by γ-2 coexpression was further observed for homomeric GluR2 (GluR2) channels, which, when expressed alone, are known to produce only a small or negligible current response. These results suggest that γ-2 not only promotes AMPA receptor surface expression but also directly modulates AMPA receptor activity.     

Detection of skeletal muscle fatigue using an accelerometer in dynamic cardiomyoplasty

 An animal experiment was done using six mongrel dogs that weighed 28 ± 3 kg to show that an accelerometer could detect skeletal muscle fatigue in dynamic cardiomyoplasty. Through left-side thoracotomy, the heart was exposed and an electrode to sense the heartbeat was positioned on the left ventricle. A left latissimus dorsi muscle flap (LDMF) was inserted into the left chest cavity and rolled around the heart. An accelerometer was put on the rolled LDMF to sense the ventricular acceleration by contraction of the LDMF and the heart. The LDMF was stimulated under these settings: pulse width, 210 μs; stimulation output, 6 V; burst frequency, 30 Hz; burst duration, 200 ms; synchronous ratio, 1 : 4; and synchronous delay, 66 ms. Output voltage from the accelerometer was recorded 1, 3, 5, 10, and 15 min after the beginning of stimulation. Percentages of the amplitude in all dogs after 3, 5, 10, and 15 min were 81 ± 10%, 63 ± 12%, 48 ± 11%, and 45 ± 14% of the values after 1 min, respectively. Significant differences were found between the values after 1 min and those after 3 min, between the values after 3 min and those after 5 min, and between the values after 5 min and those after 10 min. This study suggests that muscle fatigue is detectable with an accelerometer in actual dynamic cardiomyoplasty. Received: May 11, 2001 / Accepted: September 10, 2002 Acknowledgments This work was financially supported in a part by a Grant in Aid for Scientific Research (05671113) from the Ministry of Education, Science, and Culture of Japan. Correspondence to:H. Kuroda     

Altered synthesis of interferon-γ and expression of interferon-γ receptor by peripheral blood mononuclear cells from patients with IgA nephropathy and non-IgA proliferative glomerulonephritis

Previously we reported disease-specific interaction between interferon- (IFN-) and interleukin-4 (IL-4) in patients with IgA nephropathy (IgAN), suggesting the existence of unusual T cell behavior in this disease. In the present study, we investigated characteristic synthesis of interferon- (IFN-) and expression of IFN- receptor (IFN-R) in the peripheral blood mononuclear cells (PBMC) from patients with IgAN and other chronic proliferative glomerulonephritis (PGN). Heparinized peripheral blood samples were obtained from 38 patients with chronic mesangial proliferative glomerulonephritis (CGN; including 24 with IgA nephropathy) and 20 healthy controls. PBMC were isolated by gradient centrifugation and fragments were cultured in Iscove's modified Dulbecco's medium (IMDM) supplemented with 10% fetal calf serum (FCS) for 72 hr. IFN- concentrations in supernatants were evaluated by the enzyme-linked immunosorbent assay (ELISA). Other parts of PBMC pellets were reacted with anti-human IFN-R monoclonal antibody and FITC-labeled anti-mouse second antibody for analysis of IFN-R expression on these cells by FACScan. The remaining PBMC were fractionated into CD4⁺ T cells, CD8⁺ T cells, B cells, NK, cells and macrophages using the MACS cell sorting system. The isolated cells were evaluated for IFN- or IFN-R mRNA expression by the semiquantitative RT-PCR method.In vitro IFN- synthesis was enhanced in patients with CGN, and NK cells were revealed to be responsible for such enhancement. On the other hand, the expression of IFN-R on macrophages was suppressed in CGN patients. These results suggest that impairment of regulation of the IFN- system might be involved in the development of CGN.     

A longitudinal study on social support and life satisfaction among Japanese elderly]

The purpose of this study was to examine the impact of social support on life satisfaction among Japanese elderly aged 60 and over (N = 1,285), using the longitudinal data of a national representative sample. An initial survey was carried out in 1987, and a follow-up was conducted in 1990. We measured life satisfaction by the Life Satisfaction Index A. Social support was measured from two aspects, providing support and receiving support. The impact of social support and changes in support during a period of three years on life satisfaction were assessed by sex after controlling for influences of socioeconomic status, physical functioning, and initial life satisfaction. Providing support predicted a high life satisfaction three years later only in females. Receiving support was not significantly associated with life satisfaction for either males or females. However changes in providing and receiving support had a significant impact on life satisfaction of the elderly. The findings of this study suggest that the effects of social support on life satisfaction differ by sex and the impacts of changes in support are strong determinant predicting life satisfaction of the elderly.