CHRONOBIOLOGY OF HIGH BLOOD PRESSURE

BIOCOS, the project aimed at studying BIOlogical systems in their COSmos, has obtained a great deal of expertise in the fields of blood pressure (BP) and heart rate (HR) monitoring and of marker rhythmometry for the purposes of screening, diagnosis, treatment, and prognosis. Prolonging the monitoring reduces the uncertainty in the estimation of circadian parameters; the current recommendation of BIOCOS requires monitoring for at least 7 days. The BIOCOS approach consists of a parametric and a non-parametric analysis of the data, in which the results from the individual subject are being compared with gender- and age-specified reference values in health.Chronobiological designs can offer important new information regarding the optimization of treatment by timing its administration as a function of circadian and other rhythms.New technological developments are needed to close the loop between the monitoring of blood pressure and the administration of antihypertensive drugs.

Effect of l-phenylalanine supplementation and a high-protein diet on pharmacokinetics of cefdinir in healthy volunteers: an exploratory study

BACKGROUND

Upregulation of oligopeptide transport activity by dietary protein, certain dipeptides and amino acids has been reported in the rat intestine and a human intestinal cell line.

OBJECTIVE

In this study, the pharmacokinetics of cefdinir were investigated after L-phenylalanine supplementation and a high-protein diet (HPD) in humans to explore changes in the activities of intestinal and renal oligopeptide transporters.

METHODS

A normal-protein diet (NPD, 73.2 +/- 2.6 g/day), NPD + l-phenylalanine (7.5 g/day), or HPD (141.3 +/- 3.7 g/day) was given to six male healthy volunteers for 12 days followed by a single dose of cefdinir after an overnight fast in a randomized three-way crossover study with a 22-day washout. Blood and urine were collected over a 12-h period after administration of cefdinir. Concentrations of cefdinir in plasma and/or urine were measured by high-performance liquid chromatography.

RESULTS

Plasma concentrations and urinary excretion of the drug did not change throughout the study. Physiological variables and laboratory values did not reveal any differences between the three periods except for serum and urinary nitrogen levels and serum triglyceride.

DISCUSSION

A reason for the unchanged pharmacokinetics of cefdinir may be due to lower doses of L-phenylalanine and protein in humans than in animals when converting animal effective doses to humans.

CONCLUSION

In humans, L-phenylalanine supplementation and HPD do not seem to upregulate intestinal and renal oligopeptide transport in the ranges of duration and dose examined.

Monomethylarsonous acid induced cytotoxicity and endothelial nitric oxide synthase phosphorylation in endothelial cells

Chronic arsenic poisoning is reported to be associated with peripheral and cardiovascular disease, arteriosclerosis, Raynaud's syndrome, hypertension, and Blackfoot disease. Monomethylarsonous acid (MMA(III)) is a reactive metabolite of inorganic arsenic and a potent inhibitor of endothelial nitric oxide synthase (eNOS). Arsenic is also reported to phosphorylate eNOS in cultured keratinocyte and Human T cell leukemia Jurkat cells, respectively. In the present study, we examined the cytotoxicity and eNOS phosphorylation by MMA(III) exposure in cultured bovine aortic endothelial cells (BAEC). Results showed that MMA(III) is more toxic than arsenite in BAEC cells. The IC(50) values for MMA(III) and arsenite were determined to be approximately 1.7 and 24.1 micromol/L, respectively. Exposure of BAEC to MMA(III) (0.75 micromol/L) caused a significant eNOS phosphorylation 15 min after MMA(III) exposure. However, a complex of MMA(III) with dithiothreitol (DTT) that lacks the reactivity with vicinal thiols unaffected eNOS phosphorylation. The present study shows that MMA(III )generated during biomethylation of arsenic is highly toxic in BAEC. Our study also suggests that MMA(III) could induce the eNOS phosphorylation through modification to cellular thiols of the eNOS enzyme. And the initial up-regulation of eNOS phosphorylation by MMA(III )seems to be an adaptive response against disruption of eNOS bioactivity during arsenic exposure.

Different effects of light food on pharmacokinetics and pharmacodynamics of three benzodiazepines, quazepam, nitrazepam and diazepam

OBJECTIVE

Quazepam, nitrazepam and diazepam are administered under fed or fasted conditions for insomnia or anxiety disorder. Light bedtime food may have clinically relevant effects on the plasma levels of those drugs and hence on psychomotor performance. This study assessed the effect of light food on the pharmacokinetics and pharmacodynamics of these drugs.

METHOD

Twenty-one eligible subjects were randomized to one of three groups of seven subjects: quazepam 20 mg, diazepam 5 mg or nitrazepam 5 mg. Each healthy subject took a single oral dose of the assigned drug after overnight fasting and after light food, on a separate occasion. Blood samples were collected until 72 h after dosing. The plasma samples were assayed using high-pressure liquid chromatography with spectrophotometric detection. Reaction time, critical flicker fusion test and visual analogue scales were conducted.

RESULTS

The peak plasma concentration (C(max)) and area under the concentration-time curve (AUC) of quazepam with light food were 1.2-fold [90% confidence interval (CI): 1.1-1.5; P < 0.05] and 1.5-fold (90% CI: 1.3-1.9; P < 0.05) higher than that without light food, respectively. For nitrazepam and diazepam, the time to peak was delayed about 1 h in fed condition (P > 0.05). However it had no effect on their C(max) and AUC. Reaction time of quazepam with light food was prolonged at 4 and 6 h after dosing and its area under the effect-time curve from 0 to 10 h was increased (P < 0.05).

CONCLUSION

Light food increased the bioavailability of quazepam and affected psychomotor performance. Light food delayed T(max) of nitrazepam and diazepam but had no effect on C(max) and AUC.

Naphthoquinone enhances antigen-related airway inflammation in mice

The current authors have previously demonstrated that diesel exhaust particles (DEP) enhance antigen-related airway inflammation in mice. Furthermore, a recent study has shown that organic chemicals in DEP, rather than their carbonaceous nuclei, are important contributors to the aggravating effects of airway inflammation. However, the components in DEP responsible for the enhancing effects on the model remain to be identified. The current authors investigated the effects of naphthoquinone (NQ), one of the extractable chemical compounds of DEP, on antigen-related airway inflammation, local expression of cytokine proteins, and antigen-specific immunoglobulin (Ig) production in mice. Pulmonary exposure to NQ dose-dependently aggravated antigen-related airway inflammation, as characterised by infiltration of eosinophils and lymphocytes around the airways and an increase in goblet cells in the bronchial epithelium. Combined exposure to NQ and antigen enhanced the local expression of interleukin (IL)-4, IL-5, eotaxin, macrophage chemoattractant protein-1 and keratinocyte chemoattractant, compared with exposure to antigen or NQ alone. Also, NQ exhibited adjuvant activity for the antigen-specific production of IgG(1) and IgG(2a). These results provide the first experimental evidence that naphthoquinone can enhance antigen-related airway inflammation in vivo, and that naphthoquinone can, to some extent, partly play a role in the pathogenesis of diesel exhaust particle toxicity on the condition.

Cutting Edge: Role of TANK-Binding Kinase 1 and Inducible IκB Kinase in IFN Responses against Viruses in Innate Immune Cells

TANK-binding kinase 1 (TBK1) and inducible IkappaB kinase (IKK-i) are involved in the activation of transcription factors inducing the production of type I IFNs. Although TBK1, but not IKK-i, is critical for LPS-induced IFN induction, the role of these kinases in the responses against viral infection is yet to be determined. In this study, we show that type I IFN production against various RNA viruses was completely abrogated in conventional dendritic cells (DCs) and macrophages induced from fetal liver cells lacking both TBK1 and IKK-i, whereas considerable amounts of IFN were produced in cells lacking either of them. Microarray analysis revealed that various IFN-inducible genes were also regulated by the kinases. In contrast, Fms-like tyrosine kinase 3 ligand-induced DCs produced IFN-alpha even in the absence of both TBK1 and IKK-i. Thus, these two kinases are essential and compensate each other for the regulation of IFN responses in innate immune cells except plasmacytoid DCs.

VP1686, a Vibrio type III secretion protein, induces toll-like receptor-independent apoptosis in macrophage through NF-kappaB inhibition

Vibrio parahaemolyticus, causative agent of human gastrointestinal diseases, possesses several virulent machineries including thermostable direct hemolysin and type III secretion systems (TTSS1 and -2). In this report, we establish that TTSS1-dependent secretion and translocation of a V. parahaemolyticus effector protein VP1686 into the cytosol induces DNA fragmentation in macrophages. We performed yeast two-hybrid screening to identify the molecules involved in VP1686-mediated cell death pathways and showed that nuclear factor RelA p65/NF-kappaB physically interacts with VP1686. To understand the impact of this interaction on the NF-kappaB DNA binding activities in infected macrophages, we analyzed a series of deletion mutants for the TTSS and its secreted proteins. Induction of DNA binding activity of NF-kappaB was significantly suppressed, and increased macrophage apoptosis has been associated with V. parahaemolyticus strain, which contains both VP1686 and TTSS1. Macrophages lacking Toll-like receptor adaptor molecules MyD88 (myeloid differentiation primary response protein 88) or TRIF (TIR domain-containing adapter-inducing interferon beta) showed similar sensitivity to VP1686. As a consequence of NF-kappaB suppression, microarray analysis has revealed that VP1686 translocation alerted the expression of many genes that have known functions in cellular responses to apoptosis, cell growth, and transcriptional regulation. Our results suggest an important role for Vibrio effector protein VP1686 that activate a conserved apoptotic pathway in macrophages through suppression of NF-kappaB activation independent of Toll-like receptor signaling.

Detection of pathogenic intestinal bacteria by Toll-like receptor 5 on intestinal CD11c+ lamina propria cells

Toll-like receptors (TLRs) recognize distinct microbial components and induce innate immune responses. TLR5 is triggered by bacterial flagellin. Here we generated Tlr5-/- mice and assessed TLR5 function in vivo. Unlike other TLRs, TLR5 was not expressed on conventional dendritic cells or macrophages. In contrast, TLR5 was expressed mainly on intestinal CD11c+ lamina propria cells (LPCs). CD11c+ LPCs detected pathogenic bacteria and secreted proinflammatory cytokines in a TLR5-dependent way. However, CD11c+ LPCs do not express TLR4 and did not secrete proinflammatory cytokines after exposure to a commensal bacterium. Notably, transport of pathogenic Salmonella typhimurium from the intestinal tract to mesenteric lymph nodes was impaired in Tlr5-/- mice. These data suggest that CD11c+ LPCs, via TLR5, detect and are used by pathogenic bacteria in the intestinal lumen.

Effect of MKC-733, a 5-HT receptor partial agonist, on bowel motility and symptoms in subjects with constipation: an exploratory study

BACKGROUND

MKC-733, a 5-HT(3) receptor partial agonist, is a novel enteroprokinetic compound.

OBJECTIVE

The aim of this study was to explore the effects of MKC-733 on bowel motility and symptoms in a small group of subjects with constipation. Tolerability was also examined.

METHODS

The study was conducted in a single-blind and dose-escalation manner on 14 male and female subjects with constipation aged 22-67 years. After a 1 week run-in period, subjects were treated with placebo (b.i.d.) for 1 week, and 0.2 and 0.5 mg of MKC-733 (b.i.d.) for 2 weeks sequentially. Geometric mean and per cent elimination of surrogate markers of bowel motility were measured by a radio-opaque marker technique at the end of each treatment period. They were analysed on the whole group and subgroups with low (n = 6) and high (n = 8) bowel motility based upon the geometric mean value after placebo treatment. Subjects kept diaries of their bowel habits and gastrointestinal symptoms.

RESULTS

Percent elimination increased after treatment with 0.5 mg MKC-733 compared with placebo treatment in the whole group (70.4 +/- 33.5% vs. 47.1 +/- 36.6%, mean +/- SD, P < 0.05). In the low bowel motility group, both geometric mean and percent elimination increased after treatment with 0.5 mg MKC-733 compared with placebo (7.1 +/- 0.9 vs. 5.9 +/- 0.5, P < 0.05; 60.0 +/- 35.8% vs. 13.3 +/- 19.4%, P < 0.05). Stool frequency increased after the first-week treatment with MKC-733 compared with placebo (P < 0.05). Numbers of sensation of incomplete evacuation and gastrointestinal symptoms decreased to half and less after the treatment with MKC-733. No serious adverse effect was noted.

CONCLUSION

Multiple doses of 0.5 mg MKC-733 improve bowel motility, which was clearly demonstrated in the subjects with decreased bowel motility. MKC-733 at the doses studied might be effective in increasing stool frequency and reduce gastrointestinal symptoms related to constipation. MKC-733 was well tolerated. Further studies will be needed to clarify efficacy and safety of MKC-733 on a larger population.

Fluorescent phospholipid analogs as microscopic probes for detection of the mycolic acid-containing layer in Corynebacterium glutamicum: detecting alterations in the mycolic acid-containing layer following ethambutol treatment

Corynebacterium glutamicum belongs to the mycolic acid-containing actinomycetes, which also include Mycobacterium, Nocardia, and Rhodococcus. The cells of this group possess a cell wall with a thick outer layer composed primarily of mycolic acid, which functions as a permeability barrier. To investigate the mechanism of mycolic acid-containing layer (mycolate layer) formation, we have developed a fluorescence microscopic technique detecting the mycolate layer in situ. The staining specificity of fluorescence-labeled phospholipid analogs was determined by simultaneous staining with the hydrophobic fluorescent dye Nile Red and peptidoglycan-staining fluorescence-conjugated vancomycin. We found that fluorescence-labeled phospholipid analogs preferentially stain the mycolate layer. Using this technique, we observed the effect of the anti-mycobacterial drug ethambutol on C. glutamicum mycolate-layer formation. Ethambutol interfered specifically with mycolate-layer formation on the division planes and cell poles, while the side-wall mycolate layer was not severely affected. This indicates that mycolate-layer formation occurs mainly on division planes and cell poles in C. glutamicum, where the peptidoglycan layer is actively synthesized.

Gallbladder adenoma: report of a case with emphasis on contrast-enhanced US findings

There is a marked paucity of contrast-enhanced ultrasound (US) findings of gallbladder disease in the literature, and there is only one previous case of gallbladder adenoma. We report such a case. US showed a 2-cm polypoid lesion at the gallbladder body. Color Doppler US showed the hypervascular nature of the lesion, and contrast-enhanced US revealed the lesion to be homogeneously enhanced, suggesting that the lesion was composed of the same pathology. The lesion was surgically resected, and was found to be an adenoma without cancer foci. This case suggests that contrast-enhanced US is an effective tool in diagnosing a gallbladder adenoma.

Effects of phenanthraquinone on allergic airway inflammation in mice

BACKGROUND

Diesel exhaust particles (DEP) enhance allergic airway inflammation in mice (Takano et al., Am J Respir Crit Care Med 1997; 156: 36-42). DEP consist of carbonaceous nuclei and a vast number of organic chemical compounds. However, it remains to be identified which component(s) from DEP are responsible for the enhancing effects. 9,10-Phenanthraquinone (PQ) is a quinone compound involved in DEP.

OBJECTIVE

To investigate the effects of PQ inoculated intratracheally on allergic airway inflammation related to ovalbumin (OVA) challenge.

MATERIALS AND METHODS

We evaluated effects of PQ on airway inflammation, local expression of cytokine proteins, and allergen-specific immunoglobulin production in mice in the presence or absence of OVA. Results In the presence of OVA, PQ (2.1 ng/animal) significantly increased the numbers of eosinophils and mononuclear cells in bronchoalveolar lavage fluid as compared with OVA alone. In contrast, the numbers of these cells around the airways were not significantly different between OVA challenge and OVA plus PQ challenge in lung histology. PQ exhibited adjuvant activity for the allergen-specific production of IgG1 and IgE. OVA challenge induced significant increases in the lung expression of IL-4, IL-5, eotaxin, macrophage chemoattractant protein-1, and keratinocyte chemoattractant as compared with vehicle challenge. However, the combination of PQ with OVA did not alter the expression levels of these proteins as compared with OVA alone.

CONCLUSION

These results indicate that PQ can enhance the immunoglobulin production and the infiltration of inflammatory cells into alveolar spaces that are related to OVA, whereas PQ seems to be partially responsible for the DEP toxicity on the allergic airway inflammation.

Duodenal adenoma with production of massive mucus: report of a case with emphasis on US findings

Duodenal adenoma with massive mucus production is very rare. We report such a case. Ultrasonography (US) showed the presence of massive mucus, and contrast- enhanced US revealed the thickened wall to be homogeneously enhanced, suggesting that the lesion was composed of the same pathology. The US results were confirmed histologically by endoscopically guided biopsy. Thus, contrast-enhanced US helps determine the biopsy point and determine good diagnostic strategies.

Microarray analysis identifies apoptosis regulatory gene expression in HCT116 cells infected with thermostable direct hemolysin-deletion mutant of Vibrio parahaemolyticus

The thermostable direct hemolysin (TDH) is considered as a major virulence factor of Vibrio parahaemolyticus. We observed this potential in several human cancer cell lines by using the TDH-producing wild-type (RIMD2210633) as well as tdh-deletion mutant of V. parahaemolyticus and found that the deletion of tdh did not affect cytotoxicity to any of the cell lines tested. DNA fragmentation and annexin V staining showed that both wild-type and tdh-mutant trigger apoptosis in these cells. To understand the molecular basis of cell death in the absence of TDH, gene expression profile of human colon cancer cell line HCT116 infected with tdh-deletion mutant was carried out using human cDNA microarrays consisting of 33,000 known genes. In infected cells, differentially expressed genes including genes for early growth response, growth arrest and DNA damage, and activating transcription factor that affect programmed cell death pathways were detected. Interestingly, mutant strains having a deletion in type III secretion system 1 (TTSS1) failed to elicit DNA fragmentation in HCT116 cells. Our results strongly suggest that apoptosis requires functional TTSS1 and TTSS1-dependent translocation factor(s) to be associated with the host cell death, and thus pathogenesis of V. parahaemolyticus.

A fragment of the hypophosphatemic factor, MEPE, requires inducible cyclooxygenase-2 to exert potent anabolic effects on normal human marrow osteoblast precursors

MEPE, 56.6 kDa protein isolated from tumors associated with hypophosphatemic osteomalacia, increases renal phosphate excretion and is expressed in normal human bone cells. AC-100, a central 23-amino acid fragment of MEPE, contains motifs that are important in regulating cellular activities in the bone microenvironment. Thus, we assessed in vitro effects of AC-100 on multipotential normal human marrow stromal (hMS) cells that have the capacity to differentiate into mature osteoblasts. Proliferation was quantified by [H3]thymidine uptake and cell counting and differentiation by the levels of mRNA for the alpha2-chain of type I procollagen (COL1A2), alkaline phosphatase (AP), and osteocalcin (OC) measured using real time reverse transcriptase PCR (RT-PCR) and by the formation of mineralized nodules. AC-100 increased proliferation by 257 +/- 89% (P < 0.005), increased gene expression of COL1A2 by 339 +/- 85% (P < 0.005), AP by 1,437 +/- 40% (P < 0.001), and OC by 1,962 +/- 337% (P < 0.001). In addition, it increased mineralized nodule formation by 81 +/- 14% (P < 0.001) in a dose- and time-dependent fashion. In equimolar dosages, the parent compound, MEPE, had the full activity of the AC-100 fragment. AC-100 elicited a comparable response to both IGF-I and BMP-2 with respect to proliferation and differentiation of hMS cells. Using gene expression microarray analysis, we demonstrated that AC-100 increased (by approximately 3-fold) the mRNA for cyclooxgenase-2 (COX-2), an inducible enzyme required for prostaglandin synthesis. Moreover, NS-398, a specific inhibitor of COX-2 action completely blocked AC-100-induced increases in proliferation and differentiation. Thus, AC-100 has potent anabolic activity on osteoblast precursor cells in vitro and these effects require the induction of COX-2.

Regulation of lipopolysaccharide-inducible genes by MyD88 and Toll/IL-1 domain containing adaptor inducing IFN-β

Macrophages recognize lipopolysaccharide (LPS) by Toll-like receptor 4 and activate inflammatory responses by inducing expression of various genes. TLR4 activates intracellular signaling pathways via TIR domain containing adaptor molecules, MyD88, and Toll/IL-1 domain containing adaptor inducing IFN-beta (TRIF). Although macrophages lacking MyD88 or TRIF showed impaired cytokine production, activation of intracellular signaling molecules still occurred in response to LPS in these cells. In the present study, we implemented cDNA microarrays to investigate the contribution of MyD88 and TRIF in gene expression induced by LPS stimulation. Whereas wild-type macrophages induced 148 genes in response to LPS, macrophages lacking both MyD88 and TRIF did not upregulate any genes in response to LPS. Surprisingly, 80 LPS-inducible genes were redundantly regulated by either MyD88 or TRIF. In contrast, proinflammatory cytokines and chemokines were critically regulated by MyD88 or TRIF alone. Genes critically regulated by MyD88 alone tend to be induced quickly after LPS stimulation and regulated by mRNA stability as well as transcription. Genes known to be induced by type I interferons were simply dependent on TRIF for their expression. Taken together, MyD88 and TRIF play both redundant and distinct roles in LPS-induced gene expression.

A Corynebacterium glutamicum rnhA recG double mutant showing lysozyme-sensitivity, temperature-sensitive growth, and UV-sensitivity

Corynebacterium glutamicum mutant KY9707 was originally isolated for lysozyme-sensitivity, and showed temperature-sensitive growth. Two DNA fragments from a wild-type C. glutamicum chromosomal library suppressed the temperature-sensitivity of KY9707. These clones also rescued the lysozyme-sensitivity of KY9707, although partially. One of them encodes a protein of 382 amino acid residues, the N-terminal domain of which was homologous to RNase HI. This gene suppressed the temperature-sensitive growth of an Escherichia coli rnhA rnhB double mutant. We concluded that this gene encodes a functional RNase HI of C. glutamicum and designated it as rnhA. The other gene encodes a protein of 707 amino acid residues highly homologous to RecG protein. The C. glutamicum recG gene complemented the UV-sensitivity of E. coli recG258::kan mutant. KY9707 showed increased UV-sensitivity, which was partially rescued by either the recG or rnhA gene of C. gluamicum. Point mutations were found in both recG and rnhA genes in KY9707. These suggest that temperature-sensitive growth, UV-sensitivity, and probably lysozyme-sensitivity also, of KY9707 were caused by mutations in the genes encoding RNase HI and RecG.

Dentonin, a fragment of MEPE, enhanced dental pulp stem cell proliferation

Matrix extracellular phosphoglycoprotein (MEPE) is a SIBLING protein, found in bone and dental tissues. The purpose of this study was to determine whether a 23-amino-acid peptide derived from MEPE (Dentonin or AC-100) could stimulate dental pulp stem cell (DPSC) proliferation and/or differentiation. DPSCs were isolated from erupted human molars, and the mitogenic potential of Dentonin in DPSCs was measured by BrdU immunoassay and cell-cycle gene SuperArray. Differentiation of DPSCs with Dentonin was characterized by Western blot and by osteogenesis gene SuperArray. Dentonin enhanced DPSC proliferation by down-regulating P16, accompanied by up-regulation of ubiquitin protein ligase E3A and human ubiquitin-related protein SUMO-1. Enhanced cell proliferation required intact RGD and SGDG motifs in the peptide. This study shows that Dentonin can promote DPSC proliferation, with a potential role in pulp repair. Further studies are required to determine the usefulness of this material in vivo.

Magnifying chromoendoscopy of the esophagus: in-vivo pathological diagnosis using an endocytoscopy system

BACKGROUND AND STUDY AIMS

The aim of the present study was to observe the endoscopic characteristics of cells on the surface layer of superficial esophageal carcinomas in vivo using an endocytoscopy system and to compare the findings with those in normal squamous epithelium.

PATIENTS AND METHODS

Superficial esophageal cancers in 12 patients were examined with methylene blue staining using an endocytoscopy system.

RESULTS

The endocytoscopy system and methylene blue staining made it possible to observe cells on the surface of the squamous epithelium in normal esophageal mucosa. Normal cells were arranged homogeneously, and the nucleus cytoplasm ratio was uniform and low. In esophageal cancers, the density of cells was found to be much greater than that in normal squamous epithelium. The cell distribution was also irregular and the cells were extremely heterogeneous, with the nuclei having different staining, size, and shape characteristics. The nucleus cytoplasm ratio was also very irregular.

CONCLUSIONS

Examining esophageal tissue using the endocytoscopy system described here makes it possible to observe detailed histological alterations in esophageal lesions in vivo.

MEPE has the properties of an osteoblastic phosphatonin and minhibin

Matrix extracellular phosphoglycoprotein (MEPE) is expressed exclusively in osteoblasts, osteocytes and odontoblasts with markedly elevated expression found in X-linked hypophosphatemic rickets (Hyp) osteoblasts and in oncogenic hypophosphatemic osteomalacia (OHO) tumors. Because these syndromes are associated with abnormalities in mineralization and renal phosphate excretion, we examined the effects of insect-expressed full-length human-MEPE (Hu-MEPE) on serum and urinary phosphate in vivo, (33)PO(4) uptake in renal proximal tubule cultures and mineralization of osteoblast cultures. Dose-dependent hypophosphatemia and hyperphosphaturia occurred in mice following intraperitoneal (IP) administration of Hu-MEPE (up to 400 microg kg(-1) 31 h(-1)), similar to mice given the phosphaturic hormone PTH (80 microg kg(-1) 31 h(-1)). Also the fractional excretion of phosphate (FEP) was stimulated by MEPE [65.0% (P < 0.001)] and PTH groups [53.3% (P < 0.001)] relative to the vehicle group [28.7% (SEM 3.97)]. In addition, Hu-MEPE significantly inhibited (33)PO(4) uptake in primary human proximal tubule renal cells (RPTEC) and a human renal cell line (Hu-CL8) in vitro (V(max) 53.4% inhibition; K(m) 27.4 ng/ml, and V(max) 9.1% inhibition; K(m) 23.8 ng/ml, respectively). Moreover, Hu-MEPE dose dependently (50-800 ng/ml) inhibited BMP2-mediated mineralization of a murine osteoblast cell line (2T3) in vitro. Inhibition of mineralization was localized to a small (2 kDa) cathepsin B released carboxy-terminal MEPE peptide (protease-resistant) containing the acidic serine-aspartate-rich motif (ASARM peptide). We conclude that MEPE promotes renal phosphate excretion and modulates mineralization.

Cold induces shifts of voltage dependence in mutant SCN4A, causing hypokalemic periodic paralysis

BACKGROUND

The authors reported a mutation, P1158S, of the human skeletal muscle sodium channel gene (SCN4A) in a family with cold-induced hypokalemic periodic paralysis (hypoKPP) and myotonia.

OBJECTIVE

To identify mechanisms of temperature dependency in this channelopathy.

METHODS

Using the amphotericin B perforated patch clamp method, sodium currents were recorded at 22 and 32 degrees C from the wild-type (WT) and P1158S mutant SCN4A expressed in tsA201 cells. Computer simulation was performed, incorporating the gating parameters of the P1158S mutant SCN4A.

RESULTS

P1158S mutant SCN4A exhibited hyperpolarizing shifts in voltage dependence of both activation and inactivation curves at a cold temperature and a slower rate of inactivation than the WT. Computer simulation reproduced the abnormal skeletal muscle electrical activities of both paralysis at a low potassium concentration in the cold and myotonia at a normal potassium concentration.

CONCLUSIONS

Both paralysis and myotonia are attributable to the biophysical properties of the SCN4A mutation associated with hypoKPP. This is the first report of an SCN4A mutation that exhibits temperature-dependent shifts of voltage dependence in sodium channel gating.

Enhancement of acute lung injury related to bacterial endotoxin by components of diesel exhaust particles

BACKGROUND

Diesel exhaust particles (DEP) synergistically aggravate acute lung injury related to lipopolysaccharide (LPS) in mice, but the components in DEP responsible for this have not been identified. A study was undertaken to examine the effects of the organic chemicals (DEP-OC) and residual carbonaceous nuclei (washed DEP) derived from DEP on LPS related lung injury.

METHODS

ICR mice were divided into experimental groups and vehicle, LPS, washed DEP, DEP-OC, washed DEP+LPS, and DEP-OC+LPS were administered intratracheally. The cellular profile of the bronchoalveolar lavage (BAL) fluid, pulmonary oedema, lung histology, and expression of proinflammatory molecules and Toll-like receptors in the lung were evaluated.

RESULTS

Both DEP-OC and washed DEP enhanced the infiltration of neutrophils into BAL fluid in the presence of LPS. Washed DEP combined with LPS synergistically exacerbated pulmonary oedema and induced alveolar haemorrhage, which was concomitant with the enhanced lung expression of interleukin-1beta, macrophage inflammatory protein-1alpha, macrophage chemoattractant protein-1, and keratinocyte chemoattractant, whereas DEP-OC combined with LPS did not. Gene expression of Toll-like receptors 2 and 4 was increased by combined treatment with washed DEP and LPS. The enhancement effects of washed DEP on LPS related changes were comparable to those of whole DEP.

CONCLUSIONS

These results suggest that the residual carbonaceous nuclei of DEP rather than the extracted organic chemicals predominantly contribute to the aggravation of LPS related lung injury. This may be mediated through the expression of proinflammatory cytokines, chemokines, and Toll-like receptors.