False-positive findings on lumbar discography. Reliability of subjective concordance assessment during provocative disc injection

STUDY DESIGN

Experimental disc injections in subjects with no history of low back symptoms.

OBJECTIVE

To determine in an experimental model the reliability of patients' subjective interpretation of pain concordancy during provocative disc injection.

BACKGROUND

Discography in the evaluation of low back pain relies on a patient's subjective assessment of pain magnitude and quality during disc injection. Reproduction of significant pain on disc injection, which is similar to patients' usual pain, is believed to prove that the disc injected is the source of the patient's low back pain. In the current study, this hypothesis was tested in a controlled setting on patients with known nonspinal pain in a common referral area of discogenic pain.

METHODS

Patients with no history of low back pain were recruited to participate in a study of discography. Patients scheduled to undergo posterior iliac crest bone graft harvesting for nonthoracolumbar procedures were evaluated with lumbar radiography, magnetic resonance imaging, and psychometric testing. Two to 4 months after bone graft harvesting, patients underwent lumbar discography by strict blinded protocol. Patients were asked to compare the sensations elicited at discography to their usual back/buttock pain since bone graft harvesting. Pain was rated as 0-5 on a pain thermometer and concordancy was rated as none, dissimilar, similar, or exact.

RESULTS

Eight subjects completed the study, and 24 discs were injected. Of the 14 disc injections causing some pain response, 5 were believed to be "different" (nonconcordant) pains (35.7%); 7 were "similar" (50.0%), and 2 were "exact" pain reproductions (14.3%). The presence of anular disruption predicted concordant pain reproduction (P < 0.05). Of 10 discs with anular tears, injection of 5 elicited pain that was similar to or an exact reproduction of pain at the iliac crest bone graft harvest sites. By the usual criteria for positive discography, 4 of the 8 patients (50%) would have been classified as positive. In these patients, the pain on a single disc injection was very painful, and the pain quality was noted to be exact or similar to the usual discomfort. All subjects had a negative control disc.

CONCLUSIONS

The findings of this study demonstrate that patients with no history of low back pain who had undergone posterior iliac bone graft harvesting for nonlumbar procedures often experienced a concordant painful sensation on lumbar discography with their usual gluteal area pain. Thus, the ability of a patient to separate spinal from nonspinal sources of pain on discography is questioned, and a response of concordant pain on discography may be less meaningful than often assumed.

Mutations of the calcium-sensing receptor (CASR) in familial hypocalciuric hypercalcemia, neonatal severe hyperparathyroidism, and autosomal dominant hypocalcemia

The calcium-sensing receptor (CASR) is a plasma membrane G protein coupled receptor that is expressed in the parathyroid hormone (PTH) producing chief cells of the parathyroid gland and the cells lining the kidney tubule. By virtue of its ability to sense small changes in circulating calcium concentration ([Ca(2+)](o)) and to couple this information to intracellular signaling pathways that modify PTH secretion or renal cation handling, the CASR plays an essential role in maintaining mineral ion homeostasis. Inherited abnormalities of the CASR gene located on chromosome 3p13.3-21 can cause either hypercalcemia or hypocalcemia depending upon whether they are inactivating or activating, respectively. Heterozygous loss-of-function mutations give rise to familial (benign) hypocalciuric hypercalcemia (FHH) in which the lifelong hypercalcemia is asymptomatic. The homozygous condition manifests itself as neonatal severe hyperparathyroidism (NSHPT), a rare disorder characterized by extreme hypercalcemia and the bony changes of hyperparathyroidism which occur in infancy. The disorder autosomal dominant hypocalcemia (ADH) is due to gain-of-function mutations in the CASR gene. ADH may be asymptomatic or present with neonatal or childhood seizures. A common polymorphism in the intracellular tail of the CASR, Ala to Ser at position 986, has a modest effect on the serum calcium concentration in healthy individuals.

Vulvar intraepithelial neoplasia of the simplex (differentiated) type: a clinicopathologic study including analysis of HPV and p53 expression

The simplex (differentiated) variant of vulvar intraepithelial neoplasia (VIN) has not been well characterized. The authors studied the clinicopathologic features of 12 cases of simplex VIN and obtained follow-up data to assess its relationship to vulvar invasive squamous cell carcinoma (InvSCC). Expression of p53 protein was analyzed immunohistochemically and compared with adjacent non-neoplastic epidermal lesions. Assessment of human papilloma virus (HPV) deoxyribonucleic acid was done by polymerase chain reaction amplification and in situ hybridization. All patients were of postmenopausal age (mean age, 66.8 years). Three patients had a history of prior vulvar InvSCC and one had a separate synchronous vulvar InvSCC. Squamous hyperplasia was present in the adjacent epidermis in 10 patients and lichen sclerosus (LS) was present in four patients. Histologically, simplex VIN differed from "classic" VIN by its highly differentiated features. The characteristic features included parakeratosis, thickened epidermis with elongated and anastomosing rete ridges, enlarged abnormal keratinocytes with premature eosinophilic cytoplasmic differentiation extending deeply within the epidermis, whorling of enlarged keratinocytes or keratin pearl formation within rete ridges, prominent intercellular bridges, and dysplastic basilar cells. One patient had minimal microinvasion (0.6 mm). Ten of 12 patients had positive p53 immunostaining staining with suprabasilar extension of p53 positive cells in each patient. The labeling index (LI) of basilar cells ranged from 0% to 99% (median, 94.5%). Non-neoplastic lesions in the adjacent epidermis had p53-positive basal cells in nine of 11 evaluable cases. The LI was significantly lower in these lesions, with a median of 4% in squamous hyperplasia and 7.5% in LS; none had suprabasilar extension of p53-positive cells. HPV (type 31/35/51) was identified in only one simplex VIN--a p53-negative lesion. Staining for p53 often delineated sharply the junction between simplex VIN and squamous hyperplasia. Four patients subsequently developed vulvar InvSCC at 5, 6, 9, and 55 months. All four InvSCCs were of the conventional keratinizing type and were HPV negative, as were the one synchronous and two prior InvSCCs. The authors conclude that (1) simplex VIN has a strong association with vulvar InvSCC and is a probable precursor lesion of HPV-negative vulvar InvSCCs, (2) HPV is very uncommon in simplex VIN and probably does not play an important role in its genesis, (3) alteration of the p53 gene appears to be involved in the development of simplex VIN, and (4) immunostaining for p53 protein may be helpful in the differential diagnosis of simplex VIN.

Three novel proteins of the syntaxin/SNAP-25 family

Intracellular membrane traffic is thought to be regulated in part by soluble N-ethylmaleimide-sensitive factor-attachment protein receptors (SNAREs) through the formation of complexes between these proteins present on vesicle and target membranes. All known SNARE-mediated fusion events involve members of the syntaxin and vesicle-associated membrane protein families. The diversity of mammalian membrane compartments predicts the existence of a large number of different syntaxin and vesicle-associated membrane protein genes. To further investigate the spectrum of SNAREs and their roles in membrane trafficking we characterized three novel members of the syntaxin and SNAP-25 (synaptosome-associated protein of 25 kDa) subfamilies. The proteins are broadly expressed, suggesting a general role in vesicle trafficking, and localize to distinct membrane compartments. Syntaxin 8 co-localizes with markers of the endoplasmic reticulum. Syntaxin 17, a divergent member of the syntaxin family, partially overlaps with endoplasmic reticulum markers, and SNAP-29 is broadly localized on multiple membranes. SNAP-29 does not contain a predicted membrane anchor characteristic of other SNAREs. In vitro studies established that SNAP-29 is capable of binding to a broad range of syntaxins.

Fatty acid composition of lipids in sea buckthorn (Hippophaë rhamnoides L.) berries of different origins

The oil content and fatty acid composition of berries from two subspecies of sea buckthorn (Hippophaë rhamnoides L.) were investigated. The berries of subsp. rhamnoides contained a higher proportion of oil in seeds (11.3% vs 7.3%, p < 0.01), berries (3.5% vs 2.1%, p < 0.001), and seedless parts (2.8% vs 1.7%, p < 0.01) than the berries of subsp. sinensis. Linoleic (18:2n-6) and alpha-linolenic acids (18:3n-3) comprised about 70% of seed oil fatty acids. Palmitoleic acid (16:1n-7), practically absent in the seed oil, comprised 12.1--39.0% of oil in pulp/peel and 8.9--31.0% of that in the whole berries. More linoleic acid (40.9% vs 39.1%) and less alpha-linolenic acid (26.6% vs 30.6%) was found in the seed oil of subsp. sinensis than in the seed oil of subsp. rhamnoides (p < 0.05). The proportion of palmitoleic acid was higher in the oil of berries of subsp. rhamnoides than the berries of subsp. sinensis (26.0% vs 21.5%, 0.05 < p < 0.1), but was vice versa with alpha-linolenic acid (8.8% vs 11.2%, 0.05 < p < 0.1). The proportions of alpha-linolenic acid correlated inversely with oleic and linoleic acids in the seed oil. In the oil of whole berries, the proportion of palmitoleic acid correlated negatively with the proportions of linoleic and alpha-linolenic acids.

The virulence factor AvrXa7 of Xanthomonas oryzae pv. oryzae is a type III secretion pathway-dependent nuclear-localized double-stranded DNA-binding protein

AvrXa7 is a member of the avrBs3 avirulence gene family, which encodes proteins targeted to plant cells by a type III secretion apparatus. AvrXa7, the product of avrXa7, is also a virulence factor in strain PXO86 of Xanthomonas oryzae pv. oryzae. Avirulence and virulence specificities are associated with the central repeat domain, which, in avrXa7, consists of 25.5 direct repeat units. Mutations in three C-terminal nuclear localization signal motifs eliminated avirulence and virulence activities in rice and severely reduced nuclear localization in a yeast assay system. Both pathogenicity functions and nuclear localization were restored on the addition of the sequence for the nuclear localization signal motif from SV40 T-antigen. The loss of avirulence activity because of mutations in the acidic transcriptional activation domain was restored by addition of the activation domain from the herpes simplex viral protein VP16. The activation domain was also required for virulence activity. However, the VP16 domain could not substitute for the endogenous domain in virulence assays. In gel shift assays, AvrXa7 bound double-stranded DNA with a preference for dA/dT rich sequences. The results indicate that products of the avrBs3-related genes are virulence factors targeted to host cell nuclei and have the potential to interact with the host DNA and transcriptional machinery as part of their mode of action. The results also suggest that the host defensive recognition mechanisms are targeted to the virulence factor site of action.

Preservation of endogenous antioxidant activity and inhibition of lipid peroxidation as common mechanisms of antiatherosclerotic effects of vitamin E, lovastatin and amlodipine

OBJECTIVES

We sought to document the common mechanisms of the antiatherogenic effects of the cholesterol-lowering hydroxy-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor lovastatin, the dihydropyridine Ca2+ blocker amlodipine and the antioxidant vitamin E.

BACKGROUND

Vitamin E, HMG-CoA reductase inhibitors and Ca2+ blockers each inhibit atherosclerosis in hypercholesterolemic animals.

METHODS

New Zealand White rabbits were fed regular chow (Group A), chow with 1% cholesterol (Group B), 1% cholesterol diet plus lovastatin (Group C), 1% cholesterol diet plus vitamin E (Group D) or 1% cholesterol diet plus amlodipine (Group E) for 12 weeks. The extent of aortic atherosclerosis was measured by planimetry of the sudanophilic area. Malondialdehyde (MDA) and superoxide dismutase (SOD) in blood were measured as indexes of lipid peroxidation and antioxidant activity, respectively.

RESULTS

Group A rabbits showed no atherosclerosis, whereas Group B rabbits had 17.4 +/- 9.3% (mean +/- SD) of the aorta covered with atherosclerosis, and Groups C, D and E rabbits had significantly less atherosclerosis. Plasma SOD activity was lower in Group B than in Group A (6.9 +/- 1.1 vs. 12.8 +/- 1.5 U/ml, p < 0.01) and was preserved in the groups given lovastatin, vitamin E or amlodipine with a high cholesterol diet. The serum MDA level was higher in Group B rabbits than Group A rabbits (12.1 +/- 2.6 vs. 1.2 +/- 0.1 nmol/ml, p < 0.01) and increased minimally in rabbits given lovastatin, vitamin E or amlodipine with a high cholesterol diet. In in vitro experiments, both lovastatin and amlodipine preserved SOD activity and reduced the oxidizability of low density lipoproteins by rabbit leukocytes.

CONCLUSIONS

This study suggests that a reduction in lipid peroxidation and preservation of SOD may be common mechanisms of antiatherosclerotic effects of lovastatin, vitamin E and amlodipine.

Posterior corneal surface topographic changes after laser in situ keratomileusis are related to residual corneal bed thickness

OBJECTIVE

To determine whether ectasia after laser in situ keratomileusis (LASIK) is related to residual corneal bed thickness.

DESIGN

Retrospective noncomparative case series.

PARTICIPANTS

Thirty-two eyes of 16 patients with refractive errors of -4.00 to -18.00 diopters were examined.

INTERVENTION

LASIK was performed. The topography of the posterior corneal surface was examined with the Orbscan slit scanning corneal topography/pachymetry system.

MAIN OUTCOME MEASURES

The difference in the elevation of posterior corneal surface regarding the best-fit sphere was measured.

RESULTS

After surgery, mean bulge of 17.2 +/- 7.2 microns was found in eyes with residual corneal bed of 250 microns or greater, whereas 41.0 +/- 22.1 microns was seen in eyes with bed thickness less than 250 microns (t = 4.29; P = 0.000).

CONCLUSION

Posterior corneal bulge is correlated with the residual corneal bed thickness. The risk of ectasia may be increased if the residual corneal bed is thinner than 250 microns.

Transport measurements across a tunable potential barrier in graphene

The peculiar nature of electron scattering in graphene is among many exciting theoretical predictions for the physical properties of this material. To investigate electron scattering properties in a graphene plane, we have created a gate-tunable potential barrier within a single-layer graphene sheet. We report measurements of electrical transport across this structure as the tunable barrier potential is swept through a range of heights. When the barrier is sufficiently strong to form a bipolar junction (n-p-n or p-n-p) within the graphene sheet, the resistance across the barrier sharply increases. We compare these results to predictions for both diffusive and ballistic transport, as the barrier rises on a length scale comparable to the mean free path. Finally, we show how a magnetic field modifies transport across the barrier.

Carbon dioxide permeability of aquaporin-1 measured in erythrocytes and lung of aquaporin-1 null mice and in reconstituted proteoliposomes

Measurements of CO(2) permeability in oocytes and liposomes containing water channel aquaporin-1 (AQP1) have suggested that AQP1 is able to transport both water and CO(2). We studied the physiological consequences of CO(2) transport by AQP1 by comparing CO(2) permeabilities in erythrocytes and intact lung of wild-type and AQP1 null mice. Erythrocytes from wild-type mice strongly expressed AQP1 protein and had 7-fold greater osmotic water permeability than did erythrocytes from null mice. CO(2) permeability was measured from the rate of intracellular acidification in response to addition of CO(2)/HCO(3)(-) in a stopped-flow fluorometer using 2',7'-bis-(2-carboxyethyl)-5-(and -6)-carboxyfluorescein (BCECF) as a cytoplasmic pH indicator. In erythrocytes from wild-type mice, acidification was rapid (t((1)/(2)), 7.3 +/- 0.4 ms, S.E., n = 11 mice) and blocked by acetazolamide and increasing external pH (to decrease CO(2)/HCO(3)(-) ratio). Apparent CO(2) permeability (P(CO(2))) was not different in erythrocytes from wild-type (0.012 +/- 0.0008 cm/s) versus null (0.011 +/- 0.001 cm/s) mice. Lung CO(2) transport was measured in anesthetized, ventilated mice subjected to a decrease in inspired CO(2) content from 5% to 0%, producing an average decrease in arterial blood pCO(2) from 77 +/- 4 to 39 +/- 3 mm Hg (14 mice) with a t((1)/(2)) of 1.4 min. The pCO(2) values and kinetics of decreasing pCO(2) were not different in wild-type versus null mice. Because AQP1 deletion did not affect CO(2) transport in erythrocytes and lung, we re-examined CO(2) permeability in AQP1-reconstituted liposomes containing carbonic anhydrase (CA) and a fluorescent pH indicator. Whereas osmotic water permeability in AQP1-reconstituted liposomes was >100-fold greater than that in control liposomes, apparent P(CO(2)) (approximately 10(-3) cm/s) did not differ. Measurements using different CA concentrations and HgCl(2) indicated that liposome P(CO(2)) is unstirred layer-limited and that HgCl(2) slows acidification because of inhibition of CA rather than AQP1. These results provide direct evidence against physiologically significant AQP1-mediated CO(2) transport and establish an upper limit to the CO(2) permeability through single AQP1 water channels.

Migration of bovine aortic smooth muscle cells after wounding injury. The role of hyaluronan and RHAMM

The migration of smooth muscle cells is a critical event in the pathogenesis of vascular diseases. We have investigated the role of hyaluronan (HA) and the hyaluronan receptor RHAMM in the migration of adult bovine aortic smooth muscle cells (BASMC). Cultured BASMC migrated from the leading edge of a single scratch wound with increased velocity between 1 and 24 h. Polyclonal anti-RHAMM antisera that block HA binding with this receptor abolished smooth muscle cell migration following injury. HA stimulated the random locomotion of BASMC and its association with the cell monolayer increased following wounding injury. Immunoblot analysis of wounded monolayers demonstrated a novel RHAMM protein isoform that appeared within one hour after injury. At the time of increased cell motility after wounding, FACS analysis demonstrated an increase in the membrane localization in approximately 25% of the cell population. Confocal microscopy of injured monolayers confirmed that membrane expression of this receptor was limited to cells at the wound edge. Collectively, these data demonstrate that RHAMM is necessary for the migration of smooth muscle cells and that expression and distribution of this receptor is tightly regulated following wounding of BASMC monolayers.

Cloning of a novel water and urea-permeable aquaporin from mouse expressed strongly in colon, placenta, liver, and heart

An aquaporin-type water channel was isolated from mouse based on homology to known aquaporins. A 1447 bp cDNA was sequenced (designated AQP8) with a 783 bp open reading frame encoding a 261 amino acid hydrophobic protein which contained the conserved NPA motifs of MIP family members. Amino acid alignment showed greatest homology of AQP8 to plant water channel gamma TIP (38% identity) followed by mammalian water channels AQP4 (32%) and AQP2 (31%). Northern blot analysis indicated a 1.7 kb transcript expressed strongly in placenta > colon > liver approximately heart. RT-PCR with AQP8-specific primers and Southern blot analysis showed AQP8 transcript in the above tissues and in pancreas, lung, kidney, submandibular gland, diaphragm, testis, spleen, stomach and brain. Expression of AQP8 cRNA in Xenopus oocytes increased osmotic water permeability from (0.8 +/- 0.1) x 10(-3) cm/s to (22 +/- 3) x 10(-3) cm/s (10 degrees C) in a mercurial-sensitive manner. AQP8 was also permeable to urea but not to glycerol. Normalization for oocyte plasma membrane expression using cMyc-tagged AQP8 indicated a single channel water permeability of 8.2 x 10(-14) cm3/s. AQP8 is unique among the water channels in terms of its urea permeability and its strong expression in gastrointestinal organs, placenta and heart.

Fourfold reduction of water permeability in inner medullary collecting duct of aquaporin-4 knockout mice

Aquaporin (AQP)-3 and AQP4 water channels are expressed at the basolateral membrane of mammalian collecting duct epithelium. To determine the contribution of AQP4 to water permeability in the initial inner medullary collecting duct (IMCD), osmotic water permeability (Pf) was compared in isolated perfused IMCD segments from wild-type and AQP4 knockout mice. The AQP4 knockout mice were previously found to have normal gross appearance, survival, growth, and kidney morphology and a mild urinary concentrating defect (T. Ma, B. Yang, A. Gillespie, E. J. Carlson, C. J. Epstein, and A. S. Verkman, J. Clin. Invest. 100: 957-962, 1997). Transepithelial Pf was measured in microdissected IMCDs after 18-48 h of water deprivation and in the presence of 0.1 nM arginine vasopressin (to make basolateral Pf rate limiting). Pf values (37 degrees C; means +/- SE in cm/s x 10(-3)) were 56.0 +/- 8.5 for wild-type mice (n = 5) and 13.1 +/- 3.7 for knockout mice (n = 6) (P < 0.001). Northern blot analysis of kidney showed that transcript expression of AQP1, AQP2, AQP3, and AQP6 were not affected by AQP4 deletion. Immunoblot analysis indicated no differences in protein expression of AQP1, AQP2, or AQP3, and immunoperoxidase showed no differences in staining patterns. Coexpression of AQP3 and AQP4 in Xenopus laevis oocytes showed additive water permeabilities, suggesting that AQP4 deletion does not affect AQP3 function. These results indicate that AQP4 is responsible for the majority of basolateral membrane water movement in IMCD but that its deletion is associated with a very mild defect in urinary concentrating ability.

Reduced water permeability and altered ultrastructure in thin descending limb of Henle in aquaporin-1 null mice

It has been controversial whether high water permeability in the thin descending limb of Henle (TDLH) is required for formation of a concentrated urine by the kidney. Freeze-fracture electron microscopy (FFEM) of rat TDLH has shown an exceptionally high density of intramembrane particles (IMPs), which were proposed to consist of tetramers of aquaporin-1 (AQP1) water channels. In this study, transepithelial osmotic water permeability (Pf) was measured in isolated perfused segments (0.5-1 mm) of TDLH in wild-type (+/+), AQP1 heterozygous (+/-), and AQP1 null (-/-) mice. Pf was measured at 37 degrees C using a 100 mM bath-to-lumen osmotic gradient of raffinose, and fluorescein isothiocyanate (FITC)-dextran as the luminal volume marker. Pf was (in cm/s): 0.26 +/- 0.02 ([+/+]; SE, n = 9 tubules), 0.21 +/- 0.01 ([+/-]; n = 12), and 0.031 +/- 0.007 ([-/-]; n = 6) (P < 0.02, [+/+] vs. [+/-]; P < 0.0001, [+/+] vs. [-/-]). FFEM of kidney medulla showed remarkably fewer IMPs in TDLH from (-/-) vs. (+/+) and (+/-) mice. IMP densities were (in microm-2, SD, 5-12 micrographs): 5,880 +/- 238 (+/+); 5,780 +/- 450 (+/-); and 877 +/- 420 (-/-). IMP size distribution analysis revealed mean IMP diameters of 8.4 nm ([+/+] and [+/-]) and 5.2 nm ([-/-]). These results demonstrate that AQP1 is the principal water channel in TDLH and support the view that osmotic equilibration along TDLH by water transport plays a key role in the renal countercurrent concentrating mechanism. The similar Pf and AQP1 expression in TDLH of (+/+) and (+/-) mice was an unexpected finding that probably accounts for the unimpaired urinary concentrating ability in (+/-) mice.

MCP-1 enhances excitability of nociceptive neurons in chronically compressed dorsal root ganglia

Previous experimental results from our laboratory demonstrated that monocyte chemoattractant protein-1 (MCP-1) depolarizes or increases the excitability of nociceptive neurons in the intact dorsal root ganglion (DRG) after a chronic compression of the DRG (CCD), an injury that upregulates neuronal expression of both MCP-1 and mRNA for its receptor CCR2. We presently explore the ionic mechanisms underlying the excitatory effects of MCP-1. MCP-1 (100 nM) was applied, after CCD, to acutely dissociated small DRG neurons with nociceptive properties. Under current clamp, the proportion of neurons depolarized was similar to that previously observed for CCD-treated neurons in the intact ganglion, although the magnitude of depolarization was greater. MCP-1 induced a decrease in rheobase by 44 +/- 10% and some cells became spontaneously active at resting potential. Action potential width at a voltage equal to 10% of the peak height was increased from 4.94 +/- 0.23 to 5.90 +/- 0.47 ms. In voltage clamp, MCP-1 induced an inward current in 27 of 50 neurons held at -60 mV, which increased with concentration over the range of 3 to 300 nM (EC(50) = 45 nM). The MCP-1-induced current was not voltage dependent and had an estimated reversal potential of -27 mV. In addition, MCP-1 inhibited a voltage-dependent, noninactivating outward current, presumably a delayed rectifier type K(+) conductance. We conclude that MCP-1 enhances excitability in CCD neurons by, at least, two mechanisms: 1) activation of a nonvoltage-dependent depolarizing current with characteristics similar to a nonselective cation conductance and 2) inhibition of a voltage-dependent outward current.

Binary cooperative complementary nanoscale interfacial materials

Binary cooperative complementary nanoscale interfacial materials, i.e, materials with two complementary properties on the nanoscale, are introduced as a new concept for the design of functional materials. The concept is based on the generation of nanostructures with mutually compensating properties on the surface of a solid. Under certain coordinating conditions, unexpected properties may often appear at these kinds of interfaces, creating a huge potential for applications and theoretical research. Recent research indicates that the binary cooperative complementary concept is extremely useful for the design and creation of nanoscale functional materials.

The emerging role of circular RNAs in transcriptome regulation

Circular RNAs (circRNAs) are a recently discovered form of RNA that has been found to regulate mammalian transcription. CircRNAs are covalently closed, single-stranded transcripts produced from precursor mRNA. While initially circRNAs were considered to be splicing artefacts, next-generation RNA sequencing of non-polyadenylated transcriptomes has recently shown that the expression of circRNAs is widespread and over 20% of expressed genes in examined cells and tissues can produce these transcripts. Until now thousands of circRNAs have been discovered in organisms ranging from Drosophila melanogaster to Homo sapiens. Functional studies indicate that these transcripts regulate expression of protein-coding linear transcripts and thus comprise an important component of gene expression regulation. Here we provide a comprehensive overview on the biology of circRNAs, including the expression patterns and function. Moreover, we discuss current methodologies for the discovery and validation of circular transcripts. Finally, perspectives on the utilization of circRNA as molecular markers of complex diseases are presented.

Influence of air-abrasion on zirconia ceramic bonding using an adhesive composite resin

OBJECTIVES

Air-abrasion as bonding conditioning method for zirconia ceramic might compromise the mechanical strength of zirconia restorations. The purpose of this study was to evaluate the influence of surface conditioning parameters, i.e., air-abrasion with reduced pressure or no air-abrasion and priming with adhesive primers on the long-term resin bond strength to zirconia ceramic.

METHODS

Zirconia ceramic disks were polished with 600 grit abrasive paper. Plexiglas tubes filled with composite resin were bonded with RelyX Unicem luting composite resin to the conditioned zirconia disks. Three surface conditions (unconditioned, air-born particle abrasion at 0.05 or 0.25 MPa) and four priming conditions (no priming, priming with Metal/Zirconia Primer, priming with Alloy Primer, priming with Clearfil Ceramic Primer) were tested. Sixteen specimens of each combination were bonded. Subgroups of eight bonded samples were stored in water either for 3 days or 150 days with 37,500 thermocycling. Tensile bond strengths (TBSs) were determined with a universal testing machine at a crosshead speed of 2mm/min.

RESULTS

Without priming, RelyX Unicem showed durable bond strength to 0.25 MPa airborne-particle abraded ceramic. When combined with 10-methacryloyloxy-decyl dihydrogenphosphate containing primers, air-abrasion resulted in a durable TBS to zirconia ceramic even at a reduced abrasion pressure. However, combined with Metal/Zirconia Primer air-abrasion did not provide a durable TBS to zirconia ceramic.

SIGNIFICANCE

Using a self-adhesive luting resin composite (RelyX Unicem), air-abrasion at 0.25 MPa or the combination of low pressure air-abrasion and priming with MDP-containing primers seems to be useful to achieve durable long-term bonding to zirconia ceramic.

Effects of short-term high-fat overfeeding on genome-wide DNA methylation in the skeletal muscle of healthy young men

AIMS/HYPOTHESIS

Energy-dense diets that are high in fat are associated with a risk of metabolic diseases. The underlying molecular mechanisms could involve epigenetics, as recent data show altered DNA methylation of putative type 2 diabetes candidate genes in response to high-fat diets. We examined the effect of a short-term high-fat overfeeding (HFO) diet on genome-wide DNA methylation patterns in human skeletal muscle.

METHODS

Skeletal muscle biopsies were obtained from 21 healthy young men after ingestion of a short-term HFO diet and a control diet, in a randomised crossover setting. DNA methylation was measured in 27,578 CpG sites/14,475 genes using Illumina's Infinium Bead Array. Candidate gene expression was determined by quantitative real-time PCR.

RESULTS

HFO introduced widespread DNA methylation changes affecting 6,508 genes (45%), with a maximum methylation change of 13.0 percentage points. The HFO-induced methylation changes were only partly and non-significantly reversed after 6-8 weeks. Alterations in DNA methylation levels primarily affected genes involved in inflammation, the reproductive system and cancer. Few gene expression changes were observed and these had poor correlation to DNA methylation.

CONCLUSIONS/INTERPRETATION

The genome-wide DNA methylation changes induced by the short-term HFO diet could have implications for our understanding of transient epigenetic regulation in humans and its contribution to the development of metabolic diseases. The slow reversibility suggests a methylation build-up with HFO, which over time may influence gene expression levels.

Fears in American, Australian, Chinese, and Nigerian children and adolescents: a cross-cultural study

The fears of childhood and adolescence may differ from one cultural context to another. We explored this possibility in 1200 American, Australian, Chinese, and Nigerian children and adolescents between 7 and 17 years of age. Responses to a standard fear survey schedule revealed significant differences in the number, content, pattern, and level of fears. Nigerian children and adolescents endorsed fears at higher levels than American, Australian, or Chinese youth who did not differ from one another. However, differences in the pattern and content of fears for boys and girls of different ages were noted across the countries. Results were interpreted within a cultural context, which suggested that cultures which favor inhibition, compliance, and obedience serve to increase levels of fear. Alternative interpretations are offered and limitations of cross-cultural research are explored.

Is EBV persistence in vivo a model for B cell homeostasis?

We have measured the absolute numbers of EBV-infected B cells in the peripheral blood of healthy persistently infected individuals. Single measurements on a panel of 15 healthy individuals demonstrate that the frequency varies over a wide range from 1-50 per 10(6) B cells. Repeat measurements over 1-3.5 years on several individuals whose frequencies varied over a 10-fold range showed that the variation does not represent the fluctuation in the frequency that can occur within an individual; rather, the frequencies are specific to the individual. The frequency within an individual measured over time is stable and contributes less than 10% to the variance seen in the whole population. These measurements suggest that the level of EBV-infected B cells is tightly regulated and we propose that the same homeostatic mechanisms that regulate the levels of normal B cells also regulate B cells latently infected with EBV.

Fetal hemorrhage and platelet dysfunction in SLP-76-deficient mice

The adapter protein SLP-76 is expressed in T lymphocytes and hematopoietic cells of the myeloid lineage, and is known to be a substrate of the protein tyrosine kinases that are activated after ligation of the T-cell antigen receptor. Transient overexpression of SLP-76 in a T-cell line potentiates transcriptional activation after T-cell receptor ligation, while loss of SLP-76 expression abrogates several T-cell receptor-dependent signaling pathways. Mutant mice that lack SLP-76 manifest a severe block at an early stage of thymocyte development, implicating SLP-76 in signaling events that promote thymocyte maturation. While it is clear that SLP-76 plays a key role in development and activation of T lymphocytes, relatively little is understood regarding its role in transducing signals initiated after receptor ligation in other hematopoietic cell types. In this report, we describe fetal hemorrhage and perinatal mortality in SLP-76-deficient mice. Although megakaryocyte and platelet development proceeds normally in the absence of SLP-76, collagen-induced platelet aggregation and granule release is markedly impaired. Furthermore, treatment of SLP-76-deficient platelets with collagen fails to elicit tyrosine phosphorylation of phospholipase C-gamma2 (PLC-gamma2), suggesting that SLP-76 functions upstream of PLC-gamma2 activation. These data provide one potential mechanism for the fetal hemorrhage observed in SLP-76-deficient mice and reveal that SLP-76 expression is required for optimal receptor-mediated signal transduction in platelets as well as T lymphocytes.

Expression of aquaporin water channels in mouse spinal cord

Aquaporins (AQPs) are membrane proteins involved in water transport in many fluid-transporting tissues. Aquaporins AQP1, AQP4, and AQP9 have been identified in brain and hypothesized to participate in brain water homeostasis. Here we use reverse transcriptase-polymerase chain reaction (RT-PCR), Western blotting and immunohistochemistry to describe the expression and immunolocalization of AQPs in adult mouse spinal cord. AQP4 was expressed in glial cells, predominantly in gray matter, and in astrocytic end-feet surrounding capillaries in spinal cord white matter. AQP9 expression extensively co-localized with glial fibrillary acidic protein-immunoreactive astrocytes, located predominantly in the white matter. AQP5 was detected by RT-PCR but not by immunohistochemical analysis. Interestingly, AQP8 was detected primarily in ependymal cells lining the fluid-filled central canal. The aquaporin expression pattern in spinal cord suggests involvement in water homeostasis and diseases associated with abnormal water fluxes such as spinal cord injury and syringomyelia.

The prevalence and treatment gap in epilepsy in China: an ILAE/IBE/WHO study

The authors carried out a door-to-door survey to determine the prevalence of epilepsy among 55,000 people in China. The lifetime prevalence was 7.0/1000, and 41% of all persons had never received appropriate treatment. The prevalence of active epilepsy was 4.6/1000, and 63% of people with active epilepsy had not received antiepileptic treatment in the week before the survey. Figures for the prevalence and the treatment gap were significantly higher than previous estimates.