Optogenetic control of insulin secretion by pancreatic ß-cells in vitro and in vivo.

The present study assessed the ability of optogenetics techniques to provide a better understanding of the control of insulin secretion, particularly regarding pancreatic ß-cell function in homeostasis and pathological conditions such as diabetes mellitus (DM). We used optogenetics to investigate whether insulin secretion and blood glucose homeostasis could be controlled by regulating intracellular calcium ion concentrations ([Ca(2+)]i) in a mouse pancreatic ß-cell line (MIN6) transfected with the optogenetic protein channelrhodopsin-2 (ChR2). The ChR2-transfected MIN6 (ChR2-MIN6) cells secreted insulin following irradiation with a laser (470 nm). The increase in [Ca(2+)]i was accompanied by elevated levels of messenger RNAs that encode calcium/calmodulin-dependent protein kinase II delta and adenylate cyclase 1. ChR2-MIN6 cells suspended in matrigel were inoculated into streptozotocin-induced diabetic mice that were then subjected to a glucose tolerance test. Laser irradiation of these mice caused a significant decrease in blood glucose, and the irradiated implanted cells expressed insulin. These findings demonstrate the power of optogenetics to precisely and efficiently controlled insulin secretion by pancreatic ß-cells 'on demand', in contrast to techniques using growth factors or chemical inducers. Optogenetic technology shows great promise for understanding the mechanisms of glucose homeostasis and for developing treatments for metabolic diseases such as DM.

Maternal restraint stress during pregnancy in mice induces 11ß-HSD1-associated metabolic changes in the livers of the offspring.

In rats, maternal exposure to restraint stress during pregnancy can induce abnormalities in the cardiovascular and central nervous systems of the offspring. These effects are mediated by long-lasting hyperactivation of the hypothalamic-pituitary-adrenal axis. However, little is known about the potential effects of stress during pregnancy on metabolic systems. We examined the effect of restraint stress in pregnant mice on the liver function of their offspring. The offspring of stressed mothers showed significantly higher lipid accumulation in the liver after weaning than did the controls; this accumulation was associated with increased expression of lipid metabolism-related proteins such as alanine aminotransferase 2 diglyceride acyltransferase 1, peroxisome proliferator-activated receptor gamma and glucocorticoid receptor. Additionally, we observed increased levels of 11ß-hydroxysteroid dehydrogenase type 1, an intercellular mediator that converts glucocorticoid from the inactive to the active form, in the foetal and postnatal periods. These results indicate that restraint stress in pregnancy in mice induces metabolic abnormalities via 11ß-hydroxysteroid dehydrogenase type 1-related pathways in the foetal liver. It is therefore possible that exposure to stress in pregnant women may be a risk factor for metabolic syndromes (e.g. fatty liver) in children.

Endoscopic mucosal resection and endoscopic submucosal dissection for en bloc resection of superficial pharyngeal carcinomas.

BACKGROUND AND STUDY AIM: Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are being used increasingly to treat superficial oropharyngeal and hypopharyngeal carcinomas. The aim of this study was to clarify whether ESD provided better results than EMR for en bloc and complete resection of superficial pharyngeal carcinomas. PATIENTS AND METHODS: A total of 76 superficial pharyngeal carcinomas in 59 consecutively treated patients were included. Patients underwent either conventional EMR (using a transparent cap or strip biopsy) (n = 45 lesions) or ESD (n = 31 lesions) between October 2006 and January 2011. The rates of en bloc resection, complete resection (defined as en bloc resection with tumor-free margins), major complications, and local recurrence were evaluated retrospectively as the therapeutic outcomes. RESULTS: ESD yielded significantly higher rates of both en bloc and complete resection compared with EMR (en bloc 77.4 % [24/31] vs. 37.8 % [17/45], P = 0.0002; complete 54.8 % [17/31] vs. 28.9 % [13/45], P = 0.0379). ESD was more frequently complicated by severe laryngeal edema (4/21 [19.0 %] vs. 1/31 [3.2 %], P = 0.1446) and was also more time-consuming (124.9 ± 65.1 minutes vs. 57.2 ± 69.6 minutes; P = 0.0014). Local recurrence was observed more often after EMR than after ESD (3/45 [6.7 %] vs. 0/31 [0 %]), although this difference did not reach statistical significance (P = 0.2658). CONCLUSIONS: ESD appears to be a superior method of endoscopic resection of superficial pharyngeal carcinomas for achieving both en bloc and complete resection, although these benefits were also associated with a higher incidence of complications and a significantly longer procedure time. Large prospective studies are needed to compare ESD with conventional EMR for superficial pharyngeal carcinomas.

Long-term outcomes of endoscopic submucosal dissection for undifferentiated-type early gastric cancer.

BACKGROUND AND STUDY AIM: Endoscopic submucosal dissection (ESD) of undifferentiated-type early gastric cancer (UD-EGC) is technically feasible; however, the long-term clinical outcomes of the procedure have not yet been fully investigated. The aim of our study was to elucidate long-term outcomes of ESD for UD-EGC. PATIENTS AND METHODS: Between September 2003 and October 2009, a total of 153 patients were diagnosed endoscopically as having UD-EGC fulfilling the expanded criteria for ESD. After informed consent was obtained, 101 patients were selected to undergo ESD and 52 to undergo surgical operation. We assessed the clinical outcomes of ESD in 101 consecutive patients with 103 UD-EGC lesions who were undergoing ESD for the first time. The overall mortality and disease-free survival rates after ESD were evaluated as the long-term outcomes. RESULTS: The rates of en bloc and curative resection were 99.0% (102/103) and 82.5% (85/103), respectively. We encountered one patient with nodal metastasis detected by computed tomography before diagnostic ESD, although curative resection of the primary lesion was achieved based on routine histological examination. Among the 78 patients without a past history of malignancy within the previous 5 years in whom curative resection of the primary lesion was achieved, no cases of local recurrence or distant metastasis were observed during follow-up; however, 1 synchronous and 2 metachronous lesions were detected in 2 patients (2.6%) after primary ESD. Thus, estimated over a median follow-up period of 40.0 months (range 19-92 months) and 36.0 months (range 9-92 months), the 3-and 5-year overall mortality rates were 1.9% and 3.9%, respectively, and the 3-and 5-year overall disease-free survival rates were both 96.7%. CONCLUSIONS: Although our single-center retrospective study may be considered to be only preliminary, our data indicate that ESD for UD-EGC may yield good long-term outcomes.

Inhibition of N-methyl-D-aspartate receptor activity resulted in aberrant neuronal migration caused by delayed morphological development in the mouse neocortex.

Embryonic and neonatal neocortical neurons already express functional N-methyl-D-aspartate (NMDA) receptors before they form synapses. To elucidate the role of NMDA receptors in neuronal migration in the developing neocortex, we visualized radially migrating neurons by transferring the enhanced green fluorescent protein (EGFP) gene into the ventricular zone (VZ) of the mouse neocortex using in utero electroporation at E15.5. Two days later, we prepared neocortical slices and examined the EGFP-positive cells using time-lapse imaging in the presence of the NMDA receptor antagonist Cerestat. The EGFP-positive cells generated in the VZ in the control slices exhibited a multipolar morphology, but within several hours they became bipolar (with a leading process and an axon-like process) and migrated toward the pial surface. By contrast, many of the multipolar cells in the Cerestat-treated slices failed to extend either process and become bipolar, and frequently changed direction, although they ultimately reached their destination even after Cerestat-treatment. To identify the molecules responding for mediating NMDA signaling during neuronal migration and the changes in morphology observed above, we here focused on Src family kinases (SFKs), which mediate a variety of neuronal functions including migration and neurite extension. We discovered that the activity of Src and Fyn was reduced by Cerestat. These findings suggest that NMDA receptors are involved in neuronal migration and morphological changes into a bipolar shape, and in the activation of Src and Fyn in the developing neocortex.

Relationship between noise characteristics in protein expressions and regulatory structures of amino acid biosynthesis pathways.

Gene regulatory dynamics involves several stochastic chemical reactions. As a consequence, the copy number of given protein varies greatly among cells even in the case of isogeneic cells. Recently, the characteristics of noise in gene expressions were studied by using simple artificial gene networks. However, the noise characteristics in natural regulatory networks having complex interactions still remain unclear. In this study, we have focused on the noise in natural regulatory networks to understand the relationship between the characteristics of the noise and the structures of regulatory interactions. We targeted the expressions of genes related to amino acid biosynthesis (AAB) because of their well known regulatory structures. By measuring the noise of AAB genes in isogeneic Escherichia coli cells using flow cytometry, we found the noise amplitude in AAB genes to depend on the structure of the regulatory network. We categorised the regulatory networks with feedback regulation into two cases. In one case, the gene expression is negatively regulated by the final products of the AAB pathway known as feedback repression, whereas in another case, the gene expression is negatively regulated as a result of depletion of the substrate that is located upstream of the AAB pathway and activates the expression of the corresponding gene. Our data revealed that the noise amplitude of AAB genes in the former case is significantly smaller than the noise amplitude in the latter case. Furthermore, we found that the response time as a result of environmental changes is generally longer in the former case. This result provides a basis for understanding the role of natural regulatory networks better.

Association of T-cell receptor Vbeta haplotypes with dry skin in DS-Nh mice.

BACKGROUND: Although dry skin and T cell-dependent disease exacerbation are characteristic features of atopic dermatitis (AD), the involvement of T cells in the development of dry skin remains unclear. AIMS: We aimed to elucidate the role of T cells in the development of dry skin in DS-Nh mice as a model for AD, and to evaluate this skin condition pharmacologically. METHODS: We prepared DS-Nh mice harbouring a T-cell receptor (TCR)Vbeta(a) haplotype with a central deletion in the TCRBV gene segments, and mice harbouring a TCRVbeta(b) haplotype without any deletion. We analysed the TCRVbeta chain usage and cytokine response to antimouse CD3 monoclonal antibodies in the splenocytes from the two mouse substrains. Transepidermal water loss (TEWL) was measured, and histochemical examination of these mice was carried out. Finally, a pharmacological analysis using loratadine was also performed to evaluate the features of spontaneous dry skin in DS-Nh mice as a model of AD. RESULTS: Although the deletion of TCRBV gene segments in the TCRVbeta(a) haplotype yielded different representations of each TCRVbeta mRNA, this deletion did not evoke distinct cytokine profiles in the splenocytes compared with those of mice with the TCRVbeta(b) haplotype. Furthermore, our results indicated that the onset of dry skin occurred earlier in mice with TCRVbeta(b) than in those with TCRVbeta(a). Pharmacologically, AD-like dry skin in DS-Nh with TCRVbeta(b) mice is susceptible to an H1 blocker. CONCLUSIONS: A specific lymphocyte subpopulation bearing T-cell receptors may be responsible for loratadine-responsive dermatitis in DS-Nh mice.

Spontaneous scratching behaviour in DS-Nh mice as a possible model for pruritus in atopic dermatitis.

Itching is one of the major clinical symptoms in atopic dermatitis (AD) and complicates the management of this pathological condition. An animal model of AD-like pruritus would contribute to a better understanding of AD and could lead to the development of safe and effective antipruritic agents. DS non-hair (DS-Nh) mice raised under conventional conditions spontaneously develop pruritus, which is associated with a dermatitis similar to human AD. There is a significant positive correlation between disease severity and the period of scratching behaviour in DS-Nh mice. In the present study, we found that levels of histamine and nerve growth factor (NGF) in serum and/or skin tissue were higher in DS-Nh mice with AD-like dermatitis than in age-matched mice without dermatitis. The histopathological data indicated that nerve fibres extend into and mast cells infiltrate the surrounding area of the skin lesion. NGF production by XB-2 cells, which was derived from mouse keratinocytes, was enhanced by histamine via the H1 receptor. We also found that prolonged treatment with an H1-antagonist was effective against pruritus through depression of the production of NGF, which is thought to be generated by keratinocytes. We conclude that DS-Nh mice can serve as a suitable model for gaining a better understanding of pruritus in AD, and that prolonged treatment with an H1-antagonist may be beneficial in patients with AD-associated pruritus.

Whole-body positron emission tomography with F-18 fluorodeoxyglucose for the detection of recurrence in uterine sarcomas.

We evaluated the usefulness of whole-body positron emission tomography (PET) using F-18 fluorodeoxyglucose (FDG-PET) for the detection of recurrence in follow-up patients after primary treatment of uterine sarcoma. Eight patients with pathologically proven uterine sarcoma underwent FDG-PET, computed tomography (CT), and ultrasonography (US). Final diagnoses of recurrence were established in five cases (three carcinosarcomas and two leiomyosarcomas). PET revealed recurrent sites in the intraperitoneum, liver, lung, bone, and retroperitoneal lymph nodes. However, the minimum size of the tumor detected by PET depended on the sites of recurrence. CT and US images showed two false-negative cases of intraperitoneal tumors. PET was able to detect a solitary small intraperitoneal tumor, which was very difficult to detect by CT and US. Positive PET findings did not affect the prognosis in three of the five recurrent patients; however, the remaining two patients consequently underwent the combination therapy consisting of surgery and chemotherapy and survived for more than 1 year after the positive FDG-PET results. Application of PET imaging for the early detection of recurrent sites was useful for the decision of treatment strategy for patients with recurrent uterine sarcoma.

Comparative analysis of transcriptional responses to saline stress in the laboratory and brewing strains of Saccharomyces cerevisiae with DNA microarray.

To construct yeast strains showing tolerance to high salt concentration stress, we analyzed the transcriptional response to high NaCl concentration stress in the yeast Saccharomyces cerevisiae using DNA microarray and compared between two yeast strains, a laboratory strain and a brewing one, which is known as a stress-tolerant strain. Gene expression dynamically changed following the addition of NaCl in both yeast strains, but the degree of change in the gene expression level in the laboratory strain was larger than that in the brewing strain. The response of gene expression to the low NaCl concentration stress was faster than that to the high NaCl concentration stress in both strains. Expressions of the genes encoding enzymes involved in carbohydrate metabolism and energy production in both strains or amino acid metabolism in the brewing strain were increased under high NaCl concentration conditions. Moreover, the genes encoding sodium ion efflux pump and copper metallothionein proteins were more highly expressed in the brewing strain than in the laboratory strain. According to the results of transcriptome analysis, candidate genes for the creation of stress-tolerant strain were selected, and the effect of overexpression of candidate genes on the tolerance to high NaCl concentration stress was evaluated. Overexpression of the GPD1 gene encoding glycerol-3-phosphate dehydrogenase, ENA1 encoding sodium ion efflux protein, and CUP1 encoding copper metallothionein conferred high salt stress tolerance to yeast cells, and our selection of candidate genes for the creation of stress-tolerant yeast strains based on the transcriptome data was validated.

Comparison of hemostatic effects by route of H2 receptor antagonist administration following endoscopic mucosal resection in patients with neoplastic gastric lesions.

BACKGROUND: To date, there has not been an in-depth investigation to identify differences in the effects of bleeding prevention among different routes of administration of H2 receptor antagonists to treat gastric ulcers following endoscopic mucosal resection (EMR). AIM: To prospectively compare the frequency of bleeding following EMR between patients treated with intravenous (IV) famotidine and those with oral famotidine. METHODS: Fifty-three patients with neoplastic gastric lesions (33 carcinoma and 20 adenoma) treated by EMR were included. Subjects underwent EMR with circumferential mucosal incision assisted by submucosal injection of sodium hyaluronate (EMRSH), followed by IV or oral (PO) administration of famotidine at a dosage of 40 mg/day for 2 days. Patients with odd ID numbers were assigned to IV therapy (30 cases) while even numbers were given PO therapy (23 cases). Frequencies and endoscopic findings of bleeding during the first 2 days after EMR were examined. RESULTS: Frequency of bleeding within 2 days after EMR was 3 and 4% in IV and PO patients, respectively, showing no significant difference. No significant difference was seen in the endoscopic findings of bleeding and therapy, either, with respective IV and PO findings at 23 and 26%. CONCLUSIONS: No significant difference was observed in frequency of bleeding within 2 days after gastric EMR between IV and oral administrations of famotidine.

Visualization of microglia in living tissues using Iba1-EGFP transgenic mice.

Microglia are thought to play important roles not only in repairing injured tissue but in regulating neuronal activity, and visualizing the cells is very useful as a means of further investigating the function of microglia in vivo. We previously cloned the ionized calcium-binding adaptor molecule 1 (Iba1) gene, which is expressed selectively in microglia/microphages. To generate new transgenic mice to visualize microglia with enhanced green fluorescent protein (EGFP), we here constructed a plasmid carrying EGFP cDNA under control of the Iba1 promoter. This construct was injected into C57B/6 mouse zygotes, and the Iba1-EGFP transgenic line was developed. Fluorescent in-situ hybridization analysis revealed that the Iba1-EGFP transgene was located on chromosome 11D. No obvious defects were observed during development or in adulthood, and the EGFP fluorescence remained invariant over the course of at least four generations. Judging from the immunoreactivity with anti-Iba1 antibody, all EGFP-positive cells in the adult brain were ramified microglia. In the developing transgenic embryos, EGFP signals were detected as early as embryonic Day 10.5. The most prominent EGFP signals were found in forebrain, spinal cord, eye, foreleg, yolk sac, liver, and vessel walls. At postnatal Day 6, clear EGFP signals were observed in the supraventricular corpus callosum, known as "fountain of microglia", where ameboid microglia migrate into the brain parenchyma and mature into ramified microglia. Iba1-EGFP transgenic mice thus permit observation of living microglia under a fluorescence microscope and provide a useful tool for studying the function of microglia in vivo.

Effect of peripheral blood progenitor cell dose on hematopoietic recovery: identification of minimal progenitor cell requirements for rapid engraftment.

Repeated high-dose chemotherapy (HDC) with stem cell support is advocated for curative treatment of epithelial ovarian cancer patients, requiring large quantities of progenitor cell harvest. Although the switchover to peripheral blood stem cell transplantation has generally made possible the harvest of large quantities of progenitor cells, the minimum threshold is still pertinent for planning the safe conduct of HDC. However, as the minimum threshold for safe peripheral blood stem cell transplantation (PBSCT) is not yet established, this study was designed to clarify the minimum amount of progenitor cells required for prompt recovery of hematopoietic. Retrospective analysis was performed on 52 HDCs administered in 37 ovarian cancer patients. After autologous bone marrow aspiration (10 patients) or peripheral blood stem cell harvest (27 patients), colony-forming unit granulocyte macrophage (CFU-GM) were enumerated prior to cryopreservation. Numbers of CFU-GM were again calculated before reinfusion and the patients were divided into eight groups: 0.13-<0.4, 0.4-<0.7, 0.7-<1.0, 1.0-<3.5, 3.5-<5.0, 5.0-<10.0, 10.0-<20.0 and >20.0 (x 10(5)/kg). The minimum CFU-GM threshold (x 10(5)/kg) was found to be 1.0-<3.5 for platelets and 3.5-<5.0 for white blood cells. Higher infusion doses did not lead to significant benefits in hematopoietic reconstruction. These results indicate that preservation of a minimum of 7-10 x 10(5)/kg CFU-GM is recommended for the safe conduct of tandem HDCs.

DS-Nh as an experimental model of atopic dermatitis induced by Staphylococcus aureus producing staphylococcal enterotoxin C.

DS-Nh mice raised under conventional conditions spontaneously develop dermatitis similar to human atopic dermatitis (AD), which is associated with staphylococcal infection. In the present study, we show that Staphylococcus aureus producing staphylococcus exotoxin C (SEC) was recovered from the culture of the skin lesions of DS-Nh mice with AD-like dermatitis and that the serum levels of anti-SEC antibodies from these mice were elevated. We describe here how to promote experimental AD by epicutaneous injection with SEC-producing S. aureus to DS-Nh mice. In order to assess the role of SEC in the pathogenesis of AD, the mitogenic activity, TCRBV repertoire analysis and the production of IL-4 and IFN-gamma from spleen mononuclear cells (MNC) from DS-Nh stimulated by SEC were compared with those due to SEA, SEB and TSST. The weakest was the mitogenic activity of SEC, and higher IL-4 responses and lower IFN-gamma responses to SEC showed correlation with TCRBV8S2-positive T cells, which were selectively stimulated by SEC. We also demonstrate that SEC-producing S. aureus was able to survive in DS-Nh after intradermal injection. These results suggest a possible role for SEC in the pathogenesis of AD through host-S. aureus relationships.

kdsA mutations affect FtsZ-ring formation in Escherichia coli K-12.

No one has, as yet, addressed the relationship between the nature of the outer membrane and cell division. kdsA encodes 3-deoxy-D-manno-octulosonic acid (KDO) 8-phosphate synthetase which catalyses the first step in the synthesis of KDO, the linker between lipid A and oligosaccharide of lipopolysaccharide (LPS). Seven temperature-sensitive mutants containing missense mutations in kdsA were affected in the production of KDO and all mutants stopped dividing at 41 degrees C and formed filaments with either one or no FtsZ ring. All observed defects were reversed by the plasmid-borne wild-type kdsA gene. Western blotting analysis, however, demonstrated that the amount of FtsZ protein was not affected by the mutation. The mutants were more susceptible to various hydrophobic materials, such as novobiocin, eosin Y and SDS at 36 degrees C. Methylene blue, however, restored kdsA mutant growth. Plasmid-borne wild-type msbA, encoding a lipid A transporter in the ABC family, partially suppressed kdsA mutation. A mutation of lpxA, functioning at the first stage in lipid A biosynthesis, inhibited both cell division and growth, producing short filaments. These results indicate that the instability of the outer membrane, caused by the defect in KDO biosynthesis, affects FtsZ-ring formation.

L-glutamate production by lysozyme-sensitive Corynebacterium glutamicum ltsA mutant strains.

BACKGROUND: A non-pathogenic species of coryneform bacteria, Corynebacterium glutamicum, was originally isolated as an L-glutamate producing bacterium and is now used for fermentative production of various amino acids. A mutation in the C. glutamicum ltsA gene caused susceptibility to lysozyme, temperature-sensitive growth, and L-glutamate production. RESULTS: The characteristics of eight lysozyme-sensitive mutants which had been isolated after N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis were examined. Complementation analysis with the cloned wild-type ltsA gene and DNA sequencing of the ItsA region revealed that four mutants had a mutation in the ltsA gene. Among them, two mutants showed temperature-sensitive growth and overproduced L-glutamate at higher temperatures, as well as the previously reported ltsA mutant. Other two showed temperature-resistant growth: one missense mutant produced L-glutamate to some extent but the other nonsense mutant did not. These two mutants remained temperature-resistant in spite of introduction of ltsA::kan mutation that causes temperature-sensitive growth in the wild-type background. CONCLUSIONS: These results indicate that a defect caused by the ltsA mutations is responsible for temperature-sensitive growth and L-glutamate overproduction by C. glutamicum. The two temperature-resistant mutants seem to carry suppressor mutations that rendered cells temperature-resistance and abolished L-glutamate overproduction.

Hydraulic conductivity of rice roots.

A pressure chamber and a root pressure probe technique have been used to measure hydraulic conductivities of rice roots (root Lp(r) per m(2) of root surface area). Young plants of two rice (Oryza sativa L.) varieties (an upland variety, cv. Azucena and a lowland variety, cv. IR64) were grown for 31-40 d in 12 h days with 500 micromol m(-2) s(-1) PAR and day/night temperatures of 27 degrees C and 22 degrees C. Root Lp(r) was measured under conditions of steady-state and transient water flow. Different growth conditions (hydroponic and aeroponic culture) did not cause visible differences in root anatomy in either variety. Values of root Lp(r) obtained from hydraulic (hydrostatic) and osmotic water flow were of the order of 10(-8) m s(-1) MPa(-1) and were similar when using the different techniques. In comparison with other herbaceous species, rice roots tended to have a higher hydraulic resistance of the roots per unit root surface area. The data suggest that the low overall hydraulic conductivity of rice roots is caused by the existence of apoplastic barriers in the outer root parts (exodermis and sclerenchymatous (fibre) tissue) and by a strongly developed endodermis rather than by the existence of aerenchyma. According to the composite transport model of the root, the ability to adapt to higher transpirational demands from the shoot should be limited for rice because there were minimal changes in root Lp(r) depending on whether hydrostatic or osmotic forces were acting. It is concluded that this may be one of the reasons why rice suffers from water shortage in the shoot even in flooded fields.

Effect of 1alpha-hydroxyvitamin D3 and egg-shell calcium on bone metabolism in ovariectomized osteoporotic model rats.

Egg-shell calcium (Ca) is one of the effective Ca sources for bone metabolism. In the present study, we investigated whether egg-shell Ca had similar effects compared with calcium carbonate (CaCO3) when vitamin D3 (1alpha(OH)D3) treatment was given to an osteoporotic rat model. In both 1alpha(OH)D3-supplemented and -unsupplemented rats, the bone mineral density (BMD) of the lumber spine in the vitamin-supplemented group increased significantly compared with the unsupplemented group. In a Ca balance study, there were also significant differences in intestinal Ca absorption, urinary Ca and fecal Ca between the vitamin-supplemented and -unsupplemented groups. These results show that egg-shell Ca could have similar effects to CaCO3 on bone metabolism. In contrast with CaCO3, vitamin D3 supplementation did not significantly increase serum Ca levels in the egg-shell Ca group; however, the mechanism of Ca absorption is still unclear. Our results suggest that egg-shell Ca may be an effective nutrient in Ca metabolism for people treated with vitamin D3.

Effects of lanthanides on voltage-dependent potassium currents in bullfrog sympathetic neurons.

The effects of lanthanides (La(3+), Gd(3+), Lu(3+) and Sm(3+)) on voltage-dependent potassium currents were studied in dissociated bullfrog sympathetic neurons. A-type current (I(A)) and M-type current (I(M)) were blocked by lanthanides (0.1-30 microM) with I(M) being much less sensitive to these ions than I(A). The order of potency was Gd(3+)>/=Lu(3+) approximately La(3+) approximately Sm(3+) for I(A) and Gd(3+)&z.Gt;Lu(3+) approximately La(3+)>Sm(3+) for I(M). The I(M) block occurred independently of its activation kinetics while the I(A) block was associated with a positive shift of the activation and inactivation curves. Gd(3+) (100 microM) blocked the delayed rectifier-type current (I(K)) by less than 20%; Lu(3+), La(3+) and Sm(3+) (100 microM for each) were without effect on I(K). It is concluded that I(A) was the most sensitive to lanthanides, and Gd(3+) was the most potent for all the currents in amphibian autonomic neurons.