Effects of intra- and extracellular H+ and Na+ concentrations on Na+-H+ antiport activity in the lacrimal gland acinar cells

Kinetic properties of the Na⁺-H⁺ antiport in the acinar cells of the isolated, superfused mouse lacrimal gland were studied by measuring intracellular pH (pH_i) and Na⁺ activity (aNa_i) with the aid of double-barreled H⁺- and Na⁺-selective microelectrodes, respectively. Bicarbonate-free solutions were used throughout. Under untreated control conditions, pH_i was 7.12±0.01 and aNa_i was 6.7±0.6 mmol/l. The cells were acid-loaded by exposure to an NH ₄ ⁺ solution followed by an Na⁺-free N-methyl-d-glucamine (NMDG⁺) solution. Intracellular Na⁺ and H⁺ concentrations were manipulated by changing the duration of exposure to the above solutions. Subsequent addition of the standard Na⁺ solution rapidly increased pH_i. This Na⁺-induced increase in pH_i was almost completely inhibited by 0.5 mmol/l amiloride and was associated with a rapid, amiloride-sensitive increase in aNa_i. The rate of pH_i recovery induced by the standard Na⁺ solution increased in a saturable manner as pH_i decreased, and was negligible at pH_i 7.2–7.3, indicating an inactivation of the Na⁺-H⁺ antiport. The apparent K _m for intracellular H⁺ concentration was 105 nmol/l (pH 6.98). The rate of acid extrusion from the acid-loaded cells increased proportionally to the increase in extracellular pH. Depletion of aNa_i to less than 1 mmol/l by prolonged exposure to NMDG⁺ solution significantly increased the rate of Na⁺-dependent acid extrusion. The rate of acid extrusion increased as the extracellular Na⁺ concentration increased following Michaelis-Menten kinetics (V _max was 0.55 pH/min and the apparent K _m was 75 mmol/l at pH_i 6.88). The results clearly showed that the Na⁺-H⁺ antiport activity is dependent on the chemical potential gradient of both Na⁺ and H⁺ ions across the basolateral membrane, and that the antiporter is asymmetric with respect to the substrate affinity of the transport site. The data agree with the current model of activation and inactivation of the antiporter by an intracellular site through changes in the intracellular Na⁺ and H⁺ concentrations.     

A new method for assaying adhesion of cancer cells to the greater omentum and its application for evaluating anti-adhesion activities of chemically synthesized oligosaccharides

A new ex vivo method for assaying adhesion of cancer cells to the greater omentum has been developed using mouse greater omentum and [³H]labelled human gastric and mouse colorectal cancer cells. Since the adhesion rates were found to increase up to 18 h and labelled cells seemed to be stable during the period, the present method could be useful for investigating adhesion of cancer cells to the greater omentum, which must occur at the first step of the peritoneal dissemination. The adhesion of cancer cells to the greater omentum was inhibited by a series of chemically synthesized oligosaccharides and Galβ1,3[3OMeGalβ1,4GlcNAcβ1,6]αBn was found to be the best inhibitor. The anti-tumor effect of this novel tetrasaccharide in vivo was shown in preliminary experiments using Balb/c mice and colon26 cells.     

Restricted expression of transgenic HLA-DRA gene in thymic epithelial cells and its role in acquisition of T cell tolerance to self-superantigens and processed DRα-derived peptide

We have established a set of transgenic mouse lines in which the HLA-DRA gene was expressed in different cell types. In one line (DRα-24), DRαEβ^b molecules were expressed on thymic medullary and cortical epithelial cells and all lineages of bone marrow-derived antigen-presenting cells (APC) except for thymic macrophages. By contrast, expression of the molecules in another line (DRα-30) was found on thymic medullary and cortical epithelial cells but not on bone marrow-derived APC in the thymus and periphery. To evaluate the role of thymic epithelial cells in acquisition of T cell tolerance, comparative analysis of DRα-24 and DRα-30 was performed. In DRα-30, T cells expressing TcR Vβ5 and Vβ11 were eliminated to comparable levels to those in DRα-24, suggesting that expression of the DRαEβ^b molecules on thymic epithelial cells are sufficient for clonal deletion of the self-superantigen-reactive T cells. In addition, CD4⁺ T cells from DRa-30 as well as those from DRα-24 were tolerant to DRα-derived peptide/I-A^b complex expressed on spleen cells from DRα-24 even in the presence of exogenous interleukin-2. These observations suggest that expression of the DRα chain in thymic epithelial cells could induce T cell tolerance directed toward naturally processed DRα-derived peptide bound to I-A^b molecules, probably via clonal deletion of the self-reactive T cells.     

Na+-Ca2+ exchange in the isolated cochlear outer hair cells of the guinea-pig studied by fluorescence image microscopy

The outer hair cell isolated from the guinea-pig was superfused in vitro and the cytosolic calcium concentration ([Ca²⁺]_i) and sodium concentration ([Na⁺]_i) were measured using fluorescence indicators. Under the resting condition, [Ca²⁺]_i and [Na⁺]_i were 91±9 nM (n = 51) and 110±5 mM (n = 12), respectively. Removal of external Na⁺ by replacing with N-methyl-D-glucamine (NMDG⁺) increased [Ca²⁺]_i by 270±79% (n = 27) and decreased [Na⁺]_i by 23±4 mM (n = 6). Both changes in [Ca²⁺]_i and [Na⁺]_i were totally reversible on returning external Na⁺ to the initial value and were inhibited by addition of 0.1 mM La³⁺ or 100 M amiloride 5-(N,N-dimethyl) hydrochloride. Elevation of external Ca²⁺ ions to 20 mM reversibly decreased [Na⁺]_i by 8±6 mM (n = 5). Moreover, the chelation of the intracellular Ca²⁺ with 1,2-bis (2-aminophenoxy) ethane-N,N,N,N-tetraacetic acid (BAPTA) exerted an inhibitory action on the NMDG⁺-induced reduction in [Na⁺]_i. Exposure to 5 mM NaCN for 2 min significantly and reversibly increased [Ca²⁺]_i by 290±37% (n = 5), but did not affect the [Ca²⁺]_i elevation induced by the NMDG⁺ solution. The rise in [Ca²⁺]_i induced by the NMDG⁺ solution was not enhanced by ouabain pretreatment. Addition of ouabain did not alter the [Na⁺]_i. The present results are best explained by the presence of an Na⁺-Ca²⁺ exchanger in cell membrane and indicate that the activity of Na⁺/K⁺ pump is poor in outer hair cells.     

Association between childhood oral allergy syndrome and sensitization against four major pollens (Japanese cedar, orchard grass, short ragweed, alder)]

BACKGROUND/AIM: Although OAS (oral allergy syndrome) during childhood is believed to be rare, it seems to be increasing these days. METHODS, SUBJECTS: We here report 16 cases of childhood OAS, which were diagnosed, in our division. In addition to these reports, we investigated the rate of sensitization against four major pollens (Japanese cedar, orchard grass, short ragweed, alder) among 1067 pediatric patients with allergic diseases (median age: 4 years old) in our division. The sensitization was examined by IgE CAPRAST and above class 2 was judged as positive sensitization. RESULTS: OAS in childhood differs from that in adulthood in some ways. One is that childhood OAS does not always accompany with pollinosis. The most frequent allergen in our study was kiwi fruits followed by tomato, orange and melon among these patients. The sensitization rate against alder was equivalent as that against orchard grass and short ragweed, but less than that against Japanese cedar. CONCLUSION: Childhood OAS may have different mechanisms from adulthood OAS which almost always accompanies with pollinosis or latex allergy.     

The effects of repeated thermal therapy for patients with chronic pain

BACKGROUND: It has been reported that local thermal therapy with a hot pack or paraffin relieves pain. We hypothesized that systemic warming may decrease pain and improve the outcomes in patients with chronic pain. The purpose of this study was to clarify the effects of systemic thermal therapy in patients with chronic pain. METHODS: Group A (n = 24) patients with chronic pain were treated by a multidisciplinary treatment including cognitive behavioral therapy, rehabilitation, and exercise therapy, whereas group B (n = 22) patients were treated by a combination of multidisciplinary treatment and repeated thermal therapy. A far-infrared ray dry sauna therapy and post-sauna warming were performed once a day for 4 weeks during hospitalization. We investigated the improvements in subjective symptoms, the number of pain behavior after treatment and outcomes 2 years after discharge. RESULTS: The visual analog pain score, number of pain behavior, self-rating depression scale, and anger score significantly decreased after treatment in both groups. After treatment, the number of pain behavior was slightly smaller (p = 0.07) and anger score was significantly lower in group B than those in group A (p = 0.05). Two years after treatment, 17 patients (77%) in group B returned to work compared with 12 patients (50%) in group A (p < 0.05). CONCLUSION: These results suggest that a combination of multidisciplinary treatment and repeated thermal therapy may be a promising method for treatment of chronic pain.     

Long-term Natural Course of the Osteochondral Lesion of the Talus in a Child: A Case Report

Recent reports have described midterm natural courses of osteochondral lesion of the talus (OLT) and lack of progression of ankle osteoarthritis (OA) in adult patients. The relationship between the OLT managed with nonoperative treatment and development of OA in children remains unknown. We report the long-term course of medial OLT in a 12-year-old female who was treated nonoperatively for 10 years. Radiographically, no osteoarthritic changes were observed at the first examination. She initially returned to her basketball club after nonoperative treatment. Although daily activities were not restricted, limitation of recreational activities began to appear at 4 years of follow-up. Subsequently, plain radiographs revealed bone absorption around the osteochondral fragment and osteophyte formation at the medial gutter, then ankle OA was advanced at the final follow-up.     

Effects of participatory workplace improvement program on stress-related biomarkers and self-reported stress among university hospital nurses: a preliminary study

Although participatory workplace improvement programs are known to provide favorable effects on high stress occupations like nursing, no studies have confirmed its effect using biomarkers. The aim of this study was to determine whether a participatory workplace improvement program would decrease stress-related symptoms as evaluated by biomarkers and self-reported stress among hospital nurses. Three actions to alleviate job stress, which were determined through focus group interviews and voting, were undertaken for two months. A total of 31 female Japanese nurses underwent measurement of inflammatory markers, autonomic nervous activity (ANA), and perceived job stress (PJS) at three-time points; before the program (T1), within a week after the completion of the program (T2), and three months after the program (T3). A series of inflammatory markers (Interferon-γ, Interleukin (IL)-6, and IL-12/23p40) decreased significantly at T2, and IL-12/23p40 and IL-15 significantly decreased at T3 compared to T1, while ANA and PJS remained unchanged. Our participatory program exerted beneficial effects in reducing inflammatory responses, but not for ANA and PJS. Further investigations with a better study design, i.e., a randomized controlled trial, and a larger sample size are warranted to determine what exerted beneficial effects on inflammatory markers and why other outcomes remained unchanged.