Nuclear Charge Radius of ^{26m}Al and Its Implication for V_{ud} in the Quark Mixing Matrix

Collinear laser spectroscopy was performed on the isomer of the aluminium isotope ^{26m}Al. The measured isotope shift to ^{27}Al in the 3s^{2}3p ^{2}P_{3/2}^{○}→3s^{2}4s ^{2}S_{1/2} atomic transition enabled the first experimental determination of the nuclear charge radius of ^{26m}Al, resulting in R_{c}=3.130(15)  fm. This differs by 4.5 standard deviations from the extrapolated value used to calculate the isospin-symmetry breaking corrections in the superallowed β decay of ^{26m}Al. Its corrected Ft value, important for the estimation of V_{ud} in the Cabibbo-Kobayashi-Maskawa matrix, is thus shifted by 1 standard deviation to 3071.4(1.0) s.

^{159}Dy Electron-Capture: A New Candidate for Neutrino Mass Determination

The ground state to ground state electron-capture Q value of ^{159}Dy (3/2^{-}) has been measured directly using the double Penning trap mass spectrometer JYFLTRAP. A value of 364.73(19) keV was obtained from a measurement of the cyclotron frequency ratio of the decay parent ^{159}Dy and the decay daughter ^{159}Tb ions using the novel phase-imaging ion-cyclotron resonance technique. The Q values for allowed Gamow-Teller transition to 5/2^{-} and the third-forbidden unique transition to 11/2^{+} state with excitation energies of 363.5449(14) keV and 362.050(40) keV in ^{159}Tb were determined to be 1.18(19) keV and 2.68(19) keV, respectively. The high-precision Q value of transition 3/2^{-}→5/2^{-} from this work, revealing itself as the lowest electron-capture Q value, is used to unambiguously characterize all the possible lines that are present in its electron-capture spectrum. We performed atomic many-body calculations for both transitions to determine electron-capture probabilities from various atomic orbitals and found an order of magnitude enhancement in the event rates near the end point of energy spectrum in the transition to the 5/2^{-} nuclear excited state, which can become very interesting once the experimental challenges of identifying decays into excited states are overcome. The transition to the 11/2^{+} state is strongly suppressed and found unsuitable for measuring the neutrino mass. These results show that the electron-capture in the ^{159}Dy atom, going to the 5/2^{-} state of the ^{159}Tb nucleus, is a new candidate that may open the way to determine the electron-neutrino mass in the sub-eV region by studying electron-capture. Further experimental feasibility studies, including coincidence measurements with realistic detectors, will be of great interest.

Discovery of an Exceptionally Strong β-Decay Transition of ^{20}F and Implications for the Fate of Intermediate-Mass Stars

A significant fraction of stars between 7 and 11 solar masses are thought to become supernovae, but the explosion mechanism is unclear. The answer depends critically on the rate of electron capture on ^{20}Ne in the degenerate oxygen-neon stellar core. However, because of the unknown strength of the transition between the ground states of ^{20}Ne and ^{20}F, it has not previously been possible to fully constrain the rate. By measuring the transition, we establish that its strength is exceptionally large and that it enhances the capture rate by several orders of magnitude. This has a decisive impact on the evolution of the core, increasing the likelihood that the star is (partially) disrupted by a thermonuclear explosion rather than collapsing to form a neutron star. Importantly, our measurement resolves the last remaining nuclear physics uncertainty in the final evolution of degenerate oxygen-neon stellar cores, allowing future studies to address the critical role of convection, which at present is poorly understood.

From feces to data: A metabarcoding method for analyzing consumed and available prey in a bird-insect food web

Diets play a key role in understanding trophic interactions. Knowing the actual structure of food webs contributes greatly to our understanding of biodiversity and ecosystem functioning. The research of prey preferences of different predators requires knowledge not only of the prey consumed, but also of what is available. In this study, we applied DNA metabarcoding to analyze the diet of 4 bird species (willow tits Poecile montanus, Siberian tits Poecile cinctus, great tits Parus major and blue tits Cyanistes caeruleus) by using the feces of nestlings. The availability of their assumed prey (Lepidoptera) was determined from feces of larvae (frass) collected from the main foraging habitat, birch (Betula spp.) canopy. We identified 53 prey species from the nestling feces, of which 11 (21%) were also detected from the frass samples (eight lepidopterans). Approximately 80% of identified prey species in the nestling feces represented lepidopterans, which is in line with the earlier studies on the parids' diet. A subsequent laboratory experiment showed a threshold for fecal sample size and the barcoding success, suggesting that the smallest frass samples do not contain enough larval DNA to be detected by high-throughput sequencing. To summarize, we apply metabarcoding for the first time in a combined approach to identify available prey (through frass) and consumed prey (via nestling feces), expanding the scope and precision for future dietary studies on insectivorous birds.

Immunohistochemical localization of Toll-like receptors 1-10 in periodontitis

BACKGROUND/AIM

In periodontitis, bacteria and pathogen-associated molecular patterns are sensed by Toll-like receptors (TLRs), which initiate intracellular signaling cascades that may lead to host inflammation. In this study, the expression and distribution of TLRs (TLR-1 to TLR-10) were immunohistochemically detected in gingival epithelium and connective tissue.

METHODS

Immunohistochemistry was used for the localization of TLRs in gingival tissue samples from 10 patients with chronic periodontitis and 10 healthy controls; these samples were obtained during routine periodontal flap operations and during extraction operations performed for retained wisdom teeth, respectively. For the evaluation, epithelial layers were stratified to basal, spinous, and superficial layers, and the percentages of TLR-positive cells were determined.

RESULTS

Both healthy and periodontitis gingival tissues expressed all TLRs except TLR-10. In patients with periodontitis, epithelial cells showed increased TLR expression towards the basal layer. Healthy controls showed more variable cellular TLR expression and distribution between the layers of epithelium. In the connective tissue, consistently higher TLR expression was found within the periodontitis group compared to the healthy group.

CONCLUSIONS

For the first time, the cellular expression and distribution of TLR-1 to TLR-10 have been studied in periodontitis, indicating that TLR-1 to TLR-9 are differentially expressed both in connective tissue and epithelial layers. Except for TLR-7 and TLR-8, all the other TLRs showed statistically significant differences between patients with periodontitis and healthy controls, suggesting their involvement in the pathogenesis of periodontitis.

Blood vessels of human islets of Langerhans are surrounded by a double basement membrane

AIMS/HYPOTHESIS

Based on mouse study findings, pancreatic islet cells are supposed to lack basement membrane (BM) and interact directly with vascular endothelial BM. Until now, the BM composition of human islets has remained elusive.

METHODS

Immunohistochemistry with specific monoclonal and polyclonal antibodies as well as electron microscopy were used to study BM organisation and composition in human adult islets. Isolated islet cells and function-blocking monoclonal antibodies and recombinant soluble Lutheran peptide were further used to study islet cell adhesion to laminin (Lm)-511. Short-term cultures of islets were used to study Lutheran and integrin distribution.

RESULTS

Immunohistochemistry revealed a unique organisation for human Lm-511/521 as a peri-islet BM, which co-invaginated into islets with vessels, forming an outer endocrine BM of the intra-islet vascular channels, and was distinct from the vascular BM that additionally contained Lm-411/421. These findings were verified by electron microscopy. Lutheran glycoprotein, a receptor for the Lm alpha5 chain, was found prominently on endocrine cells, as identified by immunohistochemistry and RT-PCR, whereas alpha(3) and beta(1) integrins were more diffusely distributed. High Lutheran content was also found on endocrine cell membranes in short-term culture of human islets. The adhesion of dispersed beta cells to Lm-511 was inhibited equally effectively by antibodies to integrin and alpha(3) and beta(1) subunits, and by soluble Lutheran peptide.

CONCLUSIONS/INTERPRETATION

The present results disclose a hitherto unrecognised BM organisation and adhesion mechanisms in human pancreatic islets as distinct from mouse islets.

Involvement of a disintegrin and a metalloproteinase 8 (ADAM8) in osteoclastogenesis and pathological bone destruction

Objectives:

The eventual role of a disintegrin and a metalloproteinase 8 (ADAM8) in osteoclastogenesis was studied in erosive rheumatoid arthritis (RA) and in vitro.

Methods:

ADAM8 protein and mRNA expression was measured in RA pannus and synovitis and compared to osteoarthritic (OA) synovial membrane. Human monocytes were isolated and stimulated with proinflammatory cytokines and their ADAM8 expression and surface ADAM8 were measured. Human peripheral blood monocytes and RAW 264.7 mouse monocyte/macrophage cells were stimulated to osteclast like-cells, and their expression of ADAM8 and osteoclastic markers (calcitonin receptor, integrin β 3, cathepsin K, TRAP) were analysed. Transfection and small interfering RNA (siRNA) were used to assess the role of ADAM8 in formation of polykaryons.

Results:

Increased numbers of ADAM8 positive cells were shown particularly in the pannus-cartilage/bone junction close or adjoining to TRAP positive multinucleate cells under formation (60 (2)% in pannus, 47 (2)% in synovitis vs 10 (1)% in OA, p<0.001). Human pannus contained high ADAM8 mRNA copy numbers (23 (7) in pannus, 14 (4) in synovitis vs 1.7 (0.3) in OA, p<0.001). Functional studies in vitro disclosed ADAM8 mRNA and protein, which was first converted to a proteolytically active and then to fusion-active form. Gene transfection and siRNA experiments enhanced and inhibited, respectively, expression of osteoclast markers and maturation of multinuclear cells.

Conclusions:

ADAM8 may be involved in bone destruction in RA because it is upregulated in RA pannus adjacent to developing erosions and enhances maturation of osteoclast-like cells.

MMPs, IL-1, and TNF are regulated by IL-17 in periodontitis

Periodontitis is characterized by periodontal tissue destruction. Since interleukin-17 (IL-17) has been reported to up-regulate IL-1beta and tumor necrosis factor-alpha (TNF-alpha), it was hypothesized that it is increased in periodontitis and up-regulates these cytokines and tissue-destructive matrix metalloproteinases (MMP) in local migrant and resident cells. Immunocytochemistry disclosed elevated IL-1beta, TNF-alpha, and IL-17 levels in periodontitis. These cytokines induced proMMP-1 and especially MMP-3 in gingival fibroblasts, whereas MMP-8 and MMP-9 were not induced. IL-17 was less potent as a direct MMP inducer than IL-1beta and TNF-alpha, but it induced IL-1beta and TNF-alpha production from macrophages, and IL-6 and IL-8 from gingival fibroblasts. In accordance with these findings, immunocytochemistry disclosed that MMP-1 and MMP-3 were increased in periodontitis. Gingival fibroblasts may play an important role in tissue destruction in periodontitis via cytokine-inducible MMP-1 and MMP-3 production, in which IL-17 plays a role as a key regulatory cytokine.

RANKL and cathepsin K in diffuse sclerosing osteomyelitis of the mandible

BACKGROUND

Diffuse sclerosing osteomyelitis (DSO) of the mandible is characterized by mixed bone resorption and formation.

METHODS

Immunohistopathology of DSO in the clinically acute and subacute phases was compared with healthy bone.

RESULTS

Receptor activator of nuclear factor kappaB ligand (RANKL) was found in DSO lesions. When it was used in vitro to stimulate monocytes, cathepsin K expression was observed in mononuclear prefusion precursors and in multinuclear giant cells. Similarly, exacerbations of DSO were characterized by RANKL and induction of cathepsin K in mononuclear precursor cells, which subsequently seem to differentiate into osteoclasts or foreign body giant cells. The proportion of bone to soft tissue increased with the duration of disease.

CONCLUSIONS

RANKL-driven osteoclastogenesis and acidic cysteine endoproteinase cathepsin K seem to play important roles in DSO as osteoclast-mediated bone resorption may represent the primary disease process later followed by new bone formation.

Characterization of human primary osteoblast response on bioactive glass (BaG 13–93)- coated poly-L,DL-lactide (SR-PLA70) surfacein vitro

Bioabsorbable polylactide-based polymers are commonly used for bone reconstruction. Although these polymers have proven successful in many applications, they do not have the capacity to induce osteoconduction. Therefore, several strategies have been developed to manufacture osteoconductive polylactide-based composites. In this study, we have investigated in vitro response of human primary osteoblasts for self-reinforced poly-L,DL-lactide 70/30 (SR-PLA70) plates coated with spheres of bioactive glass 13-93 (SR-PLA70 + BaG). Osteoblasts were cultured on SR-PLA70 and SR-PLA70 + BaG plates for 2, 7, or 14 days. By day 7, both materials induced a reduction in total cell population. However, by day 14 the proliferative response of osteoblasts on SR-PLA70 + BaG surface was such that the cell population had regained similar levels as that of day 2 controls. Alkaline phosphatase activity was higher on SR-PLA70 at day 7 but declined to control levels by day 14. There were no significant time-dependent variations in alkaline phosphatase activity on SR-PLA70 + BaG. After in vitro hydrolysis for 7 days, the elemental analysis of SR-PLA70 + BaG surface showed the presence of mineral precipitates that were confirmed as crystalline hydroxyapatite. This was accompanied by osteoblast spreading, protrusions of microvilli adhered to BaG 19-39 surface, cuboidal phenotype and cell surface associated formation of hydroxyapatite microspheres. In conclusion, the SR-PLA70 + BaG composite is capable of inducing a proliferative response of human primary osteoblasts, and appears to support the development of mature osteoblast phenotype. Therefore, the SR-PLA70 + BaG composites appear as promising osteoconductive scaffold candidates for reconstruction and regeneration of bone matrix.

Chondrocyte-mediated collagenolysis correlates with cartilage destruction grades in osteoarthritis

OBJECTIVE

Osteoarthritis (OA) is associated with destruction of type II collagen-rich hyaline articular cartilage. We hypothesized that classical interstitial collagenases cleave collagen type II, leading to the increased expression of the 3/4 native type II collagen fragment (COL2-3/4C) and the corresponding denatured type II collagen fragment (COL2-3/4M), which could correlate with different cartilage destruction grades. In addition, we assessed whether these fragments could be measured in joint fluid and serve as diagnostic markers.

METHODS

Cartilage specimens were obtained from the femoral heads of hip joints from total hip replacement operations. Articular gliding surfaces of the cartilage were categorized into normal (G0), fibrillated (G1), superficiallyfissured (G2) and deeplyfissured (fissures that reach to the subchondral bone) (G3). A histological scoring of the cartilage was also used. COL2-3/4C and COL2-3/4M were detected by immunohistochemical staining. Dot blotting was used to detect these fragments in joint fluid.

RESULTS

COL2-3/4C and COL2-3/4M were found in the perichondrocyte matrix around lacunae. Such COL2-3/4C (p < 0.05) and COL2-3/4M (p < 0.05) immunoreactivity was significantly increased in G3 and G2 compared to GO and G1. A positive correlation (n = 35, Spearman rank correlation) was observed between the histological score and the percentage of COL2-3/4C positive lacunae (r = 0.43, p = 0.01) and COL2- 3/4M positive lacunae (r = 0.53, p = 0.001). All 7/7 joint fluid samples contained COL2-3/4C in dot blots whereas only 4/7 contained COL2-3/4M.

CONCLUSION

Collagenase-cleaved collagen--both native and denatured--increases as the severity of OA increases, assessed using a macroscopic clinical and microscopic histological grading system. Collagen degradation was always most apparent around chondrocytes. Furthermore, the native COL2-3/4C fragment has potential as a joint fluid marker for OA.

The protein kinase C system in focal adenitis of the lacrimal gland in the non-obese diabetic mouse model for Sjögren's syndrome

PURPOSE

Non-obese diabetic (NOD) mice develop an autoimmune exocrinopathy characterized by hyposecretion of saliva and acinar cell atrophy. As the protein kinase C (PKC) system is involved in the signal transduction pathways associated with primary secretion and acinar cell differentiation and growth, the PKC profile was analysed in NOD mice.

METHODS

Lacrimal glands from BALB/c, NOD, NOD scid and transgenic NOD x interferon-gamma (IFN-gamma) mice were analysed for their PKC profiles using antibodies against several conventional (alpha, beta, gamma), novel (delta, epsilon, theta) and atypical (iota, lambda) PKC isoforms using the Streptavidin/HRP (horseradish peroxidase) method.

RESULTS

Acinar cells in BALB/c control mice expressed two conventional (alpha, beta) and two atypical (iota, lambda) PKC isoforms. In NOD and transgenic NOD x IFN-gamma mice the same isoforms were more strongly expressed. NOD scid mice lacked all other PKC isoforms except PKC lambda.

CONCLUSIONS

Co-expression of several PKC isoforms in single cell type may be necessary for transcriptional activation and agonist-induced secretory responses. Hyposecretion in NOD mice was paradoxically associated with up-regulation of the PKC system. This may be associated with a deranged signal transduction per se rather than with the immune-inflammation, as the transgenic NOD x IFN-gamma mice showed similar PKC profiles. The NOD model does not reproduce lack/consumption of PKC II and PKC as in Sjögren's syndrome. This may be because the receptor autoantibodies in mice are directed against the adrenergic, not muscarinic, receptors. Lack and/or low level PKC expression in NOD scid mouse may explain the excessive acinar cell apoptosis in this model.

Vascular damage and lack of angiogenesis in systemic sclerosis skin

The aim of this study was to analyse microvascular damage and compensatory angiogenesis in skin from patients with systemic sclerosis (SSc) compared with systemic lupus erythematosus (SLE), Raynaud's phenomenon (RP) and healthy controls. Immunohistochemistry was used for skin biopsies (9 SSc, 10 SLE, 9 RP and 12 healthy controls) using von Willebrand factor and beta3 integrin subunit specific antibodies, TechMate immunostaining robot and biotin-streptavidin protocol. In the early stages of SSc, vWF was found in the perivascular space and interstitial matrix in papillary but not in the reticular dermis, in particular around small oedematous blood vessels infiltrated by mononuclear cells. The extravascular release of vWF in SSc specimens was associated with weak or even a total lack of immunoreactivity within the associated endothelial cells. Late stages of SSc were characterised by loss of the dermal papillae, subepidermal fibrosis, hypovascularity and strong endothelial vWF expression without extravascular leakage. In all SSc patients studied only a few vascular profiles were weakly immunostained for beta3 integrin subunit. This work demonstrates that vWF is not only released into the systemic circulation, but is also leaked to the perivascular space/matrix. This local release and deposition of vWF is probably a sensitive and early marker of microvascular involvement in SSc pathogenesis. Local vWF release may play a role in platelet adhesion, aggregation, thrombogenesis and dermal connective tissue remodelling. In spite of some attempts towards compensatory angiogenesis in SSc, as evidenced by beta3 integrin subunit expression, it was evident that the angiogenic response was not able to prevent the development of hypovascularity during the advanced stages of the disease.

Regulation of macrophage activation

IFN-gamma rapidly primes the macrophage via JAK1/2-STAT1 pathway so that it can subsequently undergo a slower classical type 1 activation upon exposure to T helper (Th)1 cytokines such as IFNgamma or other activators, including tumor necrosis factor and lipopolysaccharide, e.g. in intracellular killing of phagocytosed Mycobacterium tuberculosis. If instead it is driven by Th2 cytokines interleukin (IL)-4 and IL-13, it undergoes alternate type 2 activation, which enhances endocytotic antigen uptake and presentation, mast cell and eosinophil involvement and type 2 granuloma formation, e.g. in response to parasitic and extracellular pathogens. Particle-induced macrophage activation was shown to differ from classical and alternate activation, showing in DNA microarray experiments (complete linkage/ Euclidean distance metric analysis) upregulation of nonsecreted structural/signaling molecules and lack of secreted proinflammatory cyto- and chemokines. The switch-off (deactivation) of already activated macrophages is an active, controlled process in which IL-10 and corticosteroids play important roles and to which 15dPGJ2, PGA1/2 and vasoactive intestinal peptide often contribute.

Protein kinase C expression in salivary gland acinar epithelial cells in non-obese diabetic mice, an experimental model for Sjögren's syndrome

We planned to investigate the expression of protein kinase C (PKC) isoforms in acinar epithelial cells of salivary glands in the non-obese diabetic (NOD) mouse to find out if they develop changes of the PKC system like those seen in the human counterpart, i.e. in Sjögren's syndrome. Parotid, submandibular, and sublingual glands from NOD and control BALB/c mice were stained with a panel of monoclonal antibodies directed against conventional (alpha, beta, and gamma), novel (delta, epsilon, and theta), and atypical (lambda and iota) PKC isoforms using the streptavidin/HRP method. Similarly to human labial salivary glands, acinar epithelial cells of the healthy control BALB/c mice contained two of the conventional PKC isoforms, alpha and beta. Acinar and ductal epithelial cells also contained the atypical PKC isoforms lambda and iota. PKC isoforms gamma, delta, epsilon, and theta were not found. NOD mice which displayed focal sialadenitis contained the same conventional and atypical PKC isoforms. The acinar cells in NOD mice, in contrast to the Sjögren's syndrome patients, did not lack PKC alpha or beta. On the contrary, PKC alpha and beta staining was stronger than in the control BALB/c mice. The present results demonstrate that both conventional and atypical PKC isoforms participate in the salivary epithelial cell biology and that there are mouse strain-associated and/or disease state-associated changes in their expression. The lack of PKC alpha and beta isoforms found in Sjögren's syndrome was not reproduced in NOD mice, which discloses one more difference between the human disease and its NOD mouse model.

Suppression of pro-inflammatory cytokine release by selective inhibition of inducible nitric oxide synthase in mucosal explants from patients with ulcerative colitis

BACKGROUND

In ulcerative colitis (UC), inflammatory damage is associated with increased production of pro-inflammatory cytokines and nitric oxide through the inducible nitric oxide synthase (iNOS) pathway. In an animal model of acute experimental colitis we have previously shown amelioration of inflammation with the highly selective iNOS inhibitor 1400W. The aim of the present study was to investigate the effects of selective iNOS inhibition on the production of pro-inflammatory cytokines by the colon mucosa in UC.

METHODS

Inflamed and uninflamed mucosa from patients with severe UC were incubated with a highly selective iNOS inhibitor N-[3-(aminomethyl)benzyl]acetamidine (1400W), with a relatively selective cNOS inhibitor N(G)-nitro-L-arginine-methyl-esther (L-NAME), or with an NO-donor, S-nitroso-acetylpenicillamine (SNAP). Cytokine concentrations in the incubation medium were quantitated with ELISA.

RESULTS

Compared to uninflamed mucosa there was an increase in iNOS protein and nitrotyrosine levels in inflamed mucosal samples. Immunolocalization of iNOS and nitrotyrosine showed their expression in inflammatory cells in the lamina propria. Expression of iNOS was also found in the epithelial brush border. Selective inhibition of iNOS suppressed the release of tumour necrosis factor alpha (TNF-alpha, by 66%) and interleukin-6 (IL-6, by 27%). The NO-donor, SNAP, augmented the secretion of TNF-alpha, IL-6 and IL-1-beta (by 62%, 52% and 175%, respectively) and decreased the release of IL-1 receptor antagonist (IL-1Ra, by 34%) by the inflamed mucosa. Moreover, in uninflamed samples, 1400W suppressed the production of TNF-alpha (by 69%) and incubation with SNAP decreased IL-6 concentrations by 48%. The cNOS over iNOS selective inhibitor L-NAME had no significant effects on the accumulation of cytokines.

CONCLUSION

Selective inhibition of iNOS suppresses mucosal TNF-alpha and IL-6 release in active UC, whereas NO seems to exacerbate the inflammatory response. These results suggest that selective iNOS inhibition may have therapeutic promise in the treatment of UC.

Effect of nitric oxide donor nitroglycerin on bone mineral density in a rat model of estrogen deficiency-induced osteopenia

Nitric oxide (NO) may modulate estrogen's anabolic effects on bone homeostasis by restraining osteoclast-mediated bone resorption and stimulation of osteoblast activity. Accordingly, NO donated by organic nitrates, including nitroglycerin, is thought to protect against bone loss associated with estrogen deficiency. In this study, we have explored this phenomenon. Thirty-two 12-week-old female Wistar rats were divided into four groups prior to bilateral ovariectomy or a sham operation. The ovariectomised rats received (1). vehicle control (OVX control), (2). 17-beta-estradiol (OVX+E2), or (3). transdermal nitroglycerin (OVX+NG) for 4 weeks. Femoral and tibial bone mineral density (BMD), serum alkaline phosphatase and urine deoxypyridinoline and NO metabolites were analysed at the end of the study period together with failure torque and torsional rigidity of the tibiae and cellular localisation of the NO-synthase (NOS) isoforms. In OVX+E2 group, proximal and distal femoral and proximal tibial BMD exceeded that of the Sham controls. Nitroglycerin prevented BMD loss at these three sites at levels comparable to that of the Sham controls. Deoxypyridinoline excretion did not change except in the OVX-E2 group that showed an expected reduction when compared to the Sham and OVX controls. There were no treatment-related differences in total alkaline phosphatase or urinary NO metabolites. Tibial failure torque was comparable between the groups but both OVX+E2 and OVX+NG groups showed decreased torsional rigidity compared with the OVX controls. Endothelial and inducible NOS were found in osteoblast-like cells associated with calcifying cartilage spicules in the distal femoral metaphysis. These data confirm previous findings and show that nitroglycerin counteracts the estrogen deficiency-induced osteopenia in the ovariectomised rat model. Organic nitrates may thus be beneficial in conditions where bone turnover is compromised such as in osteoporosis.

Dual effects of caspase-1, interleukin-1 beta, tumour necrosis factor-alpha and nerve growth factor receptor in inflammatory myopathies

OBJECTIVE

To analyse the expression of factors potentially involved in skeletal muscle degeneration and regeneration in dermatomyositis (DM), systemic sclerosis (SSc), polymyositis (PM), systemic lupus erythematosus (SLE) and non-inflammatory myopathies.

METHODS

Immunohistochemical staining of skeletal muscle biopsies (10 DM, 10 SSc, 10 PM, 10 SLE, 10 non-inflammatory myopathies) for tumour necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), activated caspase-1, pan-macrophage marker CD68, inducible nitric oxide synthase (NOS2) and nerve growth factor receptor (NGFR). TechMate staining robot and biotin-streptavidin protocol were used.

RESULTS

Expression of TNF-alpha, IL-1 beta, caspase-1 and NOS2 was found in the cytoplasm and sarcolemma of dystrophic skeletal muscle fibres. TNF-alpha and IL-1 beta immunoreactive profiles were faint and few and close to satellite nuclei-containing regenerating muscle fibres both in inflammatory and non-inflammatory myopathies. NGFR expression was found in comparable areas. In non-inflammatory inherited myopathies more nuclei were caspase-1 immunoreactive whereas caspase-1 expression was rarely seen in inflammatory myopathies, implying regeneration of the affected muscle fibres.

CONCLUSION

Prominent expression of the proinflammatory factors TNF-alpha, IL-1 beta and NOS2 and caspase-1 is associated with muscle fibre damage, albeit when expressed to a low degree these factors may, like NGFR, contribute to muscle regeneration and healing.

The influence of chemical sympathectomy on pain responsivity and alpha 2-adrenergic antinociception in neuropathic animals

We studied the effect of chemical sympathectomy by 6-hydroxydopamine (6-OHDA) on pain behavior and alpha(2)-adrenergic antinociception in rats with a spinal nerve ligation-induced neuropathy. For assessment of alpha(2)-adrenergic antinociception, the rats were treated systemically with two alpha(2)-adrenoceptor agonists, one of which only poorly (MPV-2426) and the other very well (dexmedetomidine) penetrates the blood-brain barrier. Moreover, the effect of MPV-2426 on spontaneous activity of dorsal root nerve fibers proximal to the nerve injury was determined. Systemic treatment with 6-OHDA produced a marked decrease in immunocytochemical labeling of sympathetic nerve fibers in the skin but it produced no marked change in basal pain sensitivity to mechanical stimulation either in neuropathic or sham-operated animals. Systemic administration of MPV-2426 and dexmedetomidine produced a dose-dependent tactile antiallodynic effect in neuropathic animals. Intraplantar injection of MPV-2426 had an identical antiallodynic effect independent of whether it was injected into the neuropathic or contralateral hindpaw. In a test of mechanical nociception and hyperalgesia, dexmedetomidine markedly attenuated pain responses in all experimental groups, whereas MPV-2426 had a weak but significant pain attenuating effect only in neuropathic animals. In the tail flick test, both alpha(2)-adrenoceptor agonists had a significant antinociceptive effect. The pain attenuating effect of MPV-2426 was enhanced by pretreatment with 6-OHDA, except in a test of tactile allodynia. MPV-2426-induced modulation of spontaneous activity was not a general property of dorsal root fibers proximal to the injury. The results indicate that a chemical destruction of sympathetic postganglionic nerve fibers innervating the skin does not markedly influence cutaneous pain sensitivity nor is it critical for the alpha(2)-adrenoceptor agonist-induced attenuation of pain behavior in neuropathic or non-neuropathic animals. Chemical sympathectomy, independent of neuropathy, enhanced the pain attenuating effect by MPV-2426, probably due to a peripheral action, whereas in non-sympathectomized control and neuropathic animals peripheral mechanisms have only a minor, if any, role in the alpha(2)-adrenoceptor agonist-induced antinociception.

Increased but imbalanced expression of VEGF and its receptors has no positive effect on angiogenesis in systemic sclerosis skin

OBJECTIVE

To investigate the expression of vascular endothelial growth factor (VEGF) and its vascular and lymphatic receptors in skin in systemic sclerosis (SSc) compared to systemic lupus erythematosus (SLE), Raynaud's phenomenon (RP) and normal healthy control skin.

METHODS

Staining was performed using rabbit anti-human antibodies in DAKO TechMate Horizon staining robot programmed for the biotin-streptavidin protocol.

RESULTS

VEGF was sporadically and weakly expressed in normal skin, but in spite of vascular damage in diseased skin, VEGF expression was only slightly upregulated. In contrast, its vascular receptors VEGFR-1 (Flt-1) and VEGFR-2 (Flk-1), were clearly upregulated. Finally, the lymphatic VEGFR-3 (Flt-4) receptor was also upregulated in diseased skin and ectopically expressed also in blood vessels. Negative staining and positive sample controls confirmed the specificity of the staining.

CONCLUSION

The imbalanced expression of VEGF and its vascular receptors suggest that the compensatory efforts to angiogenesis fail in SSc, in part due to insufficient local production of VEGF, which was low compared to VEGFR expression. This is compatible with the recent observations on the lack of alpha V beta 3+ newly formed blood vessels in SSc skin. Since microvascular angiogenic stimuli normally induce first VEGF and then VEGFR, these findings also suggest that the angiogenic cascade is turned on, but there is a defect in the finalization of its effects. Normalization of angiogenic cascade in SSc could provide a future therapeutic target.

Neuropeptides in experimental and degenerative arthritis

Classical symptoms of both inflammatory and degenerative arthritides may contribute to neurogenic responses like wheal, flare, edema, and pain. Rheumatoid arthritis (RA) is an autoimmune disease with an immunogenetic background. Neurogenic inflammation has been considered to play an essential role in RA, in part because of the symmetrical involvement (cross-spinal reflexes) and the predominant involvement of the most heavily innervated small joints of the hands and the feet (highly represented in the hominiculus). In contrast, osteoarthritis (OA) is considered to arise as a result of degeneration of the hyaline articular cartilage, which secondarily results in local inflammation and pain. However, it is possible that the age-related and predominant (compared to nociceptive nerves) degeneration of the proprioceptive, kinesthetic and vasoregulatory nerves can represent the primary pathogenic events. This leads to progressive damage of tissue with extremely poor capacity for self-regeneration. Inflammation, be it primary/autoimmune or secondary/degenerative, leads to peripheral sensitization and stimulation, which may further lead to central sensitization, neurogenic amplification of the inflammatory responses and activation of the neuro-endocrine axis. Neuropeptides serve as messengers, which modulate and mediate the actions in these cascades. Accordingly, many neuropeptides have been used successfully as experimental treatments, most recently VIP, which effectively controlled collagen-induced arthritis in mice. Therefore, it can safely be concluded that better treatment/control of disease activity and pain can be achieved by blocking the cascade leading to initiation and/or amplification of inflammatory process combined with effects on central nociceptive and neuroendocrine responses.

Dendritic cells in rheumatoid synovial membrane after total removal of the hyaline articular cartilage

OBJECTIVE

To investigate the effect of total removal of the hyaline articular cartilage on dendritic cells in synovial membrane in rheumatoid arthritis (RA) or ankylosing spondylitis (AS).

PATIENTS AND METHODS

Immunohistochemical staining for two dendritic cell markers, CD35 and RFD1, was carried out on synovial membrane specimens from arthritis patients undergoing primary (n=10) or revision (n=8) total hip replacement (THR). The results are expressed as the number (mean+/-standard deviation) of positive cells per 1000 total cells.

RESULTS

CD35-(112+/-9) and RFD1-(27+/-5) positive cells were found in all primary RA synovial membrane, while only two out of eight synovial membrane samples from revision THR contained CD35-positive follicular dendritic cells (nine and 12 cells), and no revision samples contained any RFD1-positive interdigitating dendritic cells.

CONCLUSION

Removal of the hyaline articular cartilage reduces the infiltration and functional differentiation of dendritic cells in synovial membrane. Our findings suggest that the antigen driving chronic arthritis/synovitis is contained in the hyaline articular cartilage.

Endothelial nitric oxide synthase gene-deficient mice demonstrate marked retardation in postnatal bone formation, reduced bone volume, and defects in osteoblast maturation and activity

Nitric oxide (NO) has been implicated in the local regulation of bone metabolism. However, the contribution made by specific NO synthase (NOS) enzymes is unclear. Here we show that endothelial NOS gene knockout mice (eNOS-/-) have marked abnormalities in bone formation. Histomorphometric analysis of eNOS-/- femurs showed bone volume and bone formation rate was reduced by up to 45% (P: < 0.01) and 52% (P: < 0.01), respectively. These abnormalities were prevalent in young (6 to 9 weeks old) adults but by 12 to 18 weeks bone phenotype was restored toward wild-type. Dual energy X-ray absorptiometry analysis confirmed the age-related bone abnormalities revealing significant reductions in femoral (P: < 0.05) and spinal bone mineral densities (P: < 0.01) at 8 weeks that were normalized at 12 weeks. Reduction in bone formation and volume was not related to increased osteoclast numbers or activity but rather to dysfunctional osteoblasts. Osteoblast numbers and mineralizing activity were reduced in eNOS-/- mice. In vitro, osteoblasts from calvarial explants showed retarded proliferation and differentiation (alkaline phosphatase activity and mineral deposition) that could be restored by exogenous administration of a NO donor. These cells were also unresponsive to 17ss-estradiol and had an attenuated chemotactic response to transforming growth factor-beta. In conclusion, eNOS is involved in the postnatal regulation of bone mass and lack of eNOS gene results in reduced bone formation and volume and this is related to impaired osteoblast function.

Disorder-specific changes in innervation in oral lichen planus and lichenoid reactions

The peripheral nervous system was analysed in the oral mucosa of eight patients with oral lichen planus (OLP), five with a lichenoid reaction (LR) and three with mild chronic inflammation (MCI), by morphometric analysis of nerve fibres containing immunoreactive PGP 9.5, substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP), or C-flanking peptide of neuropeptide Y (CPON). Overall nerve fibre density was higher in OLP (P=0.039) and LR (P=0.026) compared with healthy oral mucosa and was compatible with sprouting and collateral formation. In contrast to the innervation visualized with structural nerve fibre-marker PGP 9.5, the densities of neuropeptide-immunoreactive nerves were low in inflamed tissue. This is consistent with depletion via local release. Retraction and local loss of innervation were found in areas coinciding with the most severe inflammation and basal membrane (BM) damage. Interestingly, LR showed a twenty-eight-fold loss of post-ganglionic CPON-ir sympathetic nerve fibres (P=0.044). In LR, CPON-ir innervation was markedly lower than in OLP. Finally, the pattern of innervation in relation to inflammatory cell infiltrates and tissue structures differed between OLP and LR. In conclusion, the peripheral nervous system is implicated in the immunopathogenesis of lichen planus and lichenoid reactions, with a disorder-specific difference in this involvement.

Time-dependent sensory nerve ingrowth into a bone conduction chamber

We studied time-dependent ingrowth of sensory nerve fibers into a bone defect in a rat bone conduction chamber model. In 10 male Sprague Dawley rats, a titanium chamber was implanted bilaterally in the proximal tibiae, representing an experimental bone defect. To mimic a clinical situation, the chambers were filled with a fresh blood clot After 1, 2, 4, 6 and 8 weeks, 2 rats were fixed in vivo at each time before removal of specimens, and histological and immunohistochemical analyses. We used antisera against protein gene product 9.5, neural growth-associated protein 43/B-50, calcitonin gene-related peptide, and substance P, to locate regenerating sensory nerve fibers in the chamber. During bone defect healing, hematoxylin/eosin sections showed that new bone grew in through the ingrowth openings in the chamber, gradually filling it and replacing the blood clot. At 1 and 2 weeks after implantation, no nerve fibers could be detected. At 4, 6 and 8 weeks, however, small numbers of nerve fibers were seen in 8 of 11 specimens. The nerve fibers were located mainly in the dense fibrous tissue in close proximity to the new bone, and in some cases within the new forming bone. In this chamber model, the periosteum is not in contact with the bone ingrowth openings, and all ingrowing nerve fibers thus originated from the cortical bone, endosteum or bone marrow. We speculated that these late ingrowing sensory nerve fibers may actively participate in bone repair.

Growth and adhesion of osteoblast-like cells derived from neonatal rat calvaria on calcium phosphate ceramics

The effects of biocompatible ceramics on the growth and adhesion of osteoblast-rich rat calvarial cell cultures were investigated. Osteoblast-like cells and mouse fibroblast-like L-929 cells were cultured on composite sinters of hydroxyapatite (HAP) and beta-tricalcium phosphate (TCP) culture carriers, whose Ca/P molar ratios were adjusted to values of 1.50, 1.55, 1.60, 1.64 and 1.67. The growth rates of both cell types were accelerated on the TCP-HAP ceramics as compared to those on polystyrene plastic (LUX) or bioinert zirconia ceramics. The population of osteoblast-like cells reached a density of 2.28 x 10(5) cells/cm2 on 100% HAP (Ca/P ratio 1.67) at 9 d of culture, while the corresponding cell density was 1.66 x 10(5) cells/cm2 on LUX and 1.26 x 10(5) cells/cm2 on zirconia. Adhesion of the osteoblast-like cells on TCP-HAP ceramics was similarly increased as compared with that on LUX or zirconia ceramics. The adhesion of L-929 cells on TCP-HAP ceramics was found to be weaker than that on cultures on LUX or zirconia ceramics. The time-dependent variations in the alkaline phosphatase activity of the osteoblast-like cells showed that the osteoblastic phenotype was potentiated by culturing the cells in calcium-rich media. The surface analyses of the Ca/P ratio and the microstructure by XRD and FTIR suggest that the Ca-rich surface was newly formed by recombination on the surface layer in the culture medium containing fetal bovine serum. These results suggest that the surface of TCP-HAP ceramics, especially that of 100% HAP ceramics, are effective for accelerating growth and differentiation of osteoblast-like cells. This is most probably due to the chemical and physical instability and composition of 100% HAP, which promote the formation of a Ca-rich layer at the cell-material interface and provision of Ca ions to the osteoblast-like cells.

Fibroblast biology. Signals targeting the synovial fibroblast in arthritis

Fibroblast-like cells in the synovial lining (type B lining cells), stroma and pannus tissue are targeted by many signals, such as the following: ligands binding to cell surface receptors; lipid soluble, small molecular weight mediators (eg nitric oxide [NO], prostaglandins, carbon monoxide); extracellular matrix (ECM)-cell interactions; and direct cell-cell contacts, including gap junctional intercellular communication. Joints are subjected to cyclic mechanical loading and shear forces. Adherence and mechanical forces affect fibroblasts via the ECM (including the hyaluronan fluid phase matrix) and the pericellular matrix (eg extracellular matrix metalloproteinase inducer [EMMPRIN]) matrices, thus modulating fibroblast migration, adherence, proliferation, programmed cell death (including anoikis), synthesis or degradation of ECM, and production of various cytokines and other mediators [1]. Aggressive, transformed or transfected mesenchymal cells containing proto-oncogenes can act in the absence of lymphocytes, but whether these cells represent regressed fibroblasts, chondrocytes or bone marrow stem cells is unclear.

Increased nitric oxide synthase-3 expression in kidneys of deoxycorticosterone acetate-salt hypertensive rats

In addition to its hemodynamic effects, nitric oxide (NO) may play a role in the renal tubular handling of sodium. Experiments were conducted to determine possible changes in renal nitric oxide synthase-3 (NOS3) expression in rats treated with deoxycorticosterone acetate (DOCA) and high salt. All rats were uninephrectomized, and either a placebo or DOCA pellet was implanted subcutaneously. Placebo-treated rats were then given tap water to drink ad libitum, and DOCA-treated rats received a 0.9% NaCl solution to drink. Once a week, rats were placed in metabolic cages so that a 24-h urine sample could be collected. After 3 wk, the animals were sacrificed and the kidneys removed and prepared for subsequent immunohistochemical or Western blot analysis. Urinary excretion of nitrate and nitrite (NOx) was measured to provide an indication of the intrarenal production of NO. DOCA-salt hypertensive rats exhibited increased urinary NOx excretion (2.43 +/- 0.48 micromol NOx/mg creatinine) compared with the placebo control animals (1.17 +/- 0.06 micromol NOx/mg creatinine). Western blot analysis revealed that NOS3 protein levels in both the cortex and medulla were greater in DOCA-salt rats compared with placebo-treated animals. Immunohistochemical analysis of kidneys revealed that NOS3 expression in placebo rats was localized in vascular endothelial cells with slight, but detectable, immunoreactivity in medullary collecting ducts. In DOCA-salt rats, a very large increase in the intensity of immunostaining was detected in tubular epithelia of the proximal tubule, thick ascending limb of Henle's loop, and cortical and medullary collecting duct; immunoreactivity in endothelial cells appeared unchanged. These data suggest that increased tubular expression of NOS3 is responsible, at least in part, for the increased renal production of NO in DOCA-salt hypertension, and are consistent with a role for NO in the renal tubular response to salt loading.

Nitric oxide mediated vasoreactivity during fracture repair

An experimental model of fracture healing has been used to investigate whether nitric oxide mediated vascular reactivity, determined using laser Doppler flowmetry, is present in bone after a fracture. Times corresponding to Days 0, 1, 3, 7, 14, and 28 after fracture were used to study the injured and contralateral limbs in response to bolus intravenous administration of nitric oxide inhibitor, N-nitro-L-arginine methyl ester, and nitric oxide stimulator, acetylcholine. N-nitro-L-arginine methyl ester administration (1 mumol/kg, 10 mumol/kg, and 100 mumol/kg) caused a dose dependent increase in systemic blood pressure in each of the assessment groups; however, there was no statistical difference between the groups. Doppler flow readings at the fracture site showed measurable changes in local vascular reactivity after drug administration. At Day 1 after fracture, the magnitude of unit change in vascular reactivity in response to N-nitro-L-arginine methyl ester (1 mumol/kg, 10 mumol/kg, and 100 mumol/kg) was significantly higher in the fractured limb compared with the contralateral limb and also when compared with other points of assessment. These results show that nitric oxide mediated vasoreactivity is present about a fracture site and is maximal in the early healing phase, before returning to basal levels as healing progresses. This is compatible with an initial restoration of blood flow at a fracture site by nitric oxide dependent vasodilation of preexisting blood vessels, followed by ingrowth of less nitric oxide dependent angiogenic vessels during the later phase of repair.

Mechanical strain stimulates nitric oxide production by rapid activation of endothelial nitric oxide synthase in osteocytes

Previous studies have indicated that physiological levels of dynamic mechanical strain produce rapid increases in nitric oxide (NO) release from rat ulna explants and primary cultures of osteoblast-like cells and embryonic chick osteocytes derived from long bones. To establish the mechanism by which loading-induced NO production may be regulated, we have examined: nitric oxide synthase (NOS) isoform mRNA and protein expression, the effect of mechanical loading in vivo on NOS mRNA expression, and the effect of mechanical strain on NO production by bone cells in culture. Using Northern blot analyses, in situ hybridization, and immunocytochemistry we have established that the predominant NOS isoform expressed in rat long bone periosteal osteoblasts and in a distinct population of cortical bone osteocytes is the endothelial form of NOS (eNOS), with little or no expression of the inducible NOS or neuronal NOS isoforms. In contrast, in non-load-bearing calvariae there are no detectable levels of eNOS in osteocytes and little in osteoblasts. Consistent with these observations, ulnar explants release NO rapidly in response to loading in vitro, presumably through the activation of eNOS, whereas calvarial explants do not. The relative contribution of different bone cells to these rapid increases in strain-induced NO release was established by assessment of medium nitrite (stable NO metabolite) concentration, which showed that purified populations of osteocytes produce significantly greater quantities of NO per cell in response to mechanical strain than osteoblast-like cells derived from the same bones. Using Northern blot hybridization, we have also shown that neither a single nor five consecutive daily periods of in vivo mechanical loading produced any significant effect on different NOS isoform mRNA expression in rat ulnae. In conclusion, our results indicate that eNOS is the prevailing isoform expressed by cells of the osteoblast/osteocyte lineage and that strain produces increases in the activity of eNOS without apparently altering the levels of eNOS mRNA.

Nitric oxide in fracture repair

Our aim was to investigate whether nitric oxide synthase (NOS) isoforms, responsible for the generation of NO, are expressed during the healing of fractures. To localise the sites of expression compared with those in normal bone we made standardised, stabilised, unilateral tibial fractures in male Wistar rats. Immunostaining was used to determine the precise tissue localisation of the different NOS isoforms. Western blotting was used to assess expression of NOS isoform protein and L-citrulline assays for studies on NOS activity. Control tissue was obtained from both the contralateral uninjured limb and limbs of normal rats.

Immunohistochemistry showed increased expression of endothelial NOS (eNOS) to be strongest in the cortical blood vessels and in osteocytes in the early phase of fracture repair. Western blot and image analysis confirmed this initial increase. Significantly elevated calcium-dependent NOS activity was observed at day 1 after fracture.

Inducible NOS (iNOS) was localised principally in endosteal osteoblasts and was also seen in chondroblasts especially in the second week of fracture healing. Western blotting showed a reduction in iNOS during the early healing period. Significantly reduced calcium-independent NOS activity was also seen. No neuronal NOS was seen in either fracture or normal tissue.

Increased eNOS in bone blood vessels is likely to mediate the increased blood flow recognised during fracture healing. eNOS expression in osteocytes may occur in response to changes in either mechanical or local fluid shear stress. The finding that eNOS is increased and iNOS reduced in early healing of fractures may be important in their successful repair.

Nitric oxide in fracture repair. Differential localisation, expression and activity of nitric oxide synthases

Our aim was to investigate whether nitric oxide synthase (NOS) isoforms, responsible for the generation of NO, are expressed during the healing of fractures. To localise the sites of expression compared with those in normal bone we made standardised, stabilised, unilateral tibial fractures in male Wistar rats. Immunostaining was used to determine the precise tissue localisation of the different NOS isoforms. Western blotting was used to assess expression of NOS isoform protein and L-citrulline assays for studies on NOS activity. Control tissue was obtained from both the contralateral uninjured limb and limbs of normal rats. Immunohistochemistry showed increased expression of endothelial NOS (eNOS) to be strongest in the cortical blood vessels and in osteocytes in the early phase of fracture repair. Western blot and image analysis confirmed this initial increase. Significantly elevated calcium-dependent NOS activity was observed at day 1 after fracture. Inducible NOS (iNOS) was localised principally in endosteal osteoblasts and was also seen in chondroblasts especially in the second week of fracture healing. Western blotting showed a reduction in iNOS during the early healing period. Significantly reduced calcium-independent NOS activity was also seen. No neuronal NOS was seen in either fracture or normal tissue. Increased eNOS in bone blood vessels is likely to mediate the increased blood flow recognised during fracture healing. eNOS expression in osteocytes may occur in response to changes in either mechanical or local fluid shear stress. The finding that eNOS is increased and iNOS reduced in early healing of fractures may be important in their successful repair.

Cathepsin G in degenerating and healthy discal tissue

OBJECTIVES

To assess the eventual presence, tissue localization, molecular forms, amount and activity of cathepsin G in the annulus fibrosus.

METHODS

Normal non-autolytic disc tissue was collected from cadavers within six hours after death. Degenerate disc samples were collected from low back pain patients undergoing anterior interbody fusion due to severe, discographically verified and painful disc degeneration, and from the posterior parts of intervertebral discs from 10 patients undergoing microscopic discoidectomy because of intervertebral herniation. Avidin-biotinperxidase complex staining of cathepsin G was quantitated by morphometry. Cellular localization was analyzed using double immunofluorescence staining of cathepsin G and CD68, proline 4-hydroxylase or von Willebrand factor. Neutral salt extracts were analyzed by using synthetic cathepsin G substrate in spectrophotometry, dot-immunoblotting and Western blotting.

RESULTS

Histological and morphometric image analysis showed increased cellularity, increased numbers of cathepsin G positive cells and neovascularization in degenerated discs compared to control discs. Neutral salt extract of disc tissue, degenerated or normal, in contrast to control material from synovial capsular tissue, did not contain measurable cathepsin G activity, although immunoreactive enzyme was detected in dot-immunoblotting. Western blotting demonstrated that the discal cathepsin G had an apparent molecular weight of 27 kDa.

CONCLUSION

Due to its properties and localization in normal and pathologically altered tissue, cathepsin G probably plays both a direct and an indirect role in extracellular matrix degradation in the annulus fibrosus. Extracted cationic cathepsin G was immunoreactive, but was functionally inhibited by serpins or, more likely, by polyanionic proteoglycans and saccharins derived from the connective tissue matrix of the annulus fibrosus.

Nitric oxide in the local host reaction to total hip replacement

Nitric oxide is emerging as one of the most studied molecules in many aspects of human physiology and pathophysiology. Because of the inflammatory nature of aseptic loosening of total hip replacement, it is likely that nitric oxide plays a major role in this condition as well. Nitric oxide is known to interact with cyclooxygenase enzymes that produce prostanoids. Nitric oxide can stimulate synthesis and activity of the inducible, proinflammatory isoform of the enzyme, namely, cyclooxygenase 2. Interactions between the cytokine inducible nitric oxide synthase and cyclooxygenase 2 pathways serve to regulate bone cell viability such that cyclooxygenase 2 activity can protect against nitric oxide mediated programmed cell death. In the pseudomembrane these two pathways are coactivated in CD68 positive macrophages, fibroblasts, lining cells, and in vascular smooth muscles. Particle generation from wear of the prosthesis has a significant role as an inducer of nitric oxide synthase and cyclooxygenase 2; macrophages laden with small size particles and positive for inducible nitric oxide synthase and cyclooxygenase 2 are a frequent finding. Nitric oxide readily reacts with superoxide to form peroxynitrite, which is a strong oxidant species. In pseudosynovial interface membrane, detection of nitrotyrosine provides evidence for the formation and activity of peroxynitrite. These findings show evidence that nitric oxide, superoxide, and peroxynitrite mediated cellular damage is part of the pathophysiology of aseptic loosening of joint implants. These new findings suggest that antiinflammatory compounds can be useful to treat early aseptic loosening of joint implants.

Fracture healing and callus innervation after peripheral nerve resection in rats

The effects of femoral and sciatic nerve resection on fracture healing and innervation of the fracture callus were studied using a stable fracture model. In 34 rats the right tibia was subjected to a standardized closed fracture and stabilized with a modular intramedullary nail. In half of the animals, resection of 1 cm of the femoral and sciatic nerves was performed (nerve resection group), whereas the other animals had sham operations (sham group). To avoid unequal load-bearing between the two groups, all fractured hindlimbs were immobilized in a plaster of Paris cast. The trial was terminated after 5 weeks of fracture healing. Callus size was scored radiographically, and bone mineralization was measured by 85-strontium incorporation. Seven rats from each group had immunohistochemical examination for neural regeneration and ingrowth. Antisera for protein gene product 9.5, neurofilaments, neural growth associated protein 43/B-50, calcitonin gene related peptide, and substance P were used. The mechanical properties of the healing fractures were recorded in a three-point cantilever bending test. After 5 weeks, the normally innervated, fractured tibias had regained approximately 50% strength compared with the unfractured side, in comparison with only 20% in the animals that had nerve resection. Although the fracture calluses were mechanically weaker, they were significantly larger in the nerve resection group, indicating defects in tissue composition or organization rendered by the nerve injury. The mineralization rate, as measured by 85-strontium incorporation, was the same in the two groups. However, the nerve resection did not provide complete denervation but changed the innervation pattern of the healing fracture, as the density of sensory nerve fibers immunostaining for substance P and neurofilaments was less in the group with femoral and sciatic nerve resection. The results suggest that intact innervation is essential for normal fracture healing because nerve injury induced a large, but mechanically insufficient, fracture callus.

Nitric oxide synthase in rat neuromuscular junctions and in nerve terminals of Torpedo electric organ: its role as regulator of acetylcholine release

The distribution of nitric oxide synthase on peripheral motor system was studied using a specific antibody against the neuronal isoform of nitric oxide synthase (nNOS). The immunoreactivity for nNOS was detected on the sarcolemmal surface of muscle cells, in intramuscular axons and in neuromuscular synapses. At the neuromuscular junctions, ultrastructural immunolabeling demonstrated that nNOS immunoreactivity was localized mainly into the presynaptic nerve terminals as well as adjacent postsynaptic muscle membrane. Similar immunostaining pattern was present in frog muscles and Torpedo electric organs. After chronic muscle denervation, nNOS immunoreactity at endplate level decreased during the first week but it was upregulated after 30 days of denervation. In denervated endplates, nNOS immunoreactivity was localized in the terminal Schwann cells covering the degenerated neuromuscular junctions whereas nNOS was not detected in Schwann cells under normal conditions. In Torpedo synaptosomes, acetylcholine (ACh) release elicited by potassium depolarization was inhibited by NO donors such as sodium nitroprusside. In contrast, application of inhibitors of NOS activity, aminoguanidine (AMG) and N(omega)-Nitro-L-arginine methyl esther (L-NAME) increased acetylcholine release. These results indicate that nNOS is present at the motor nerve terminals in a variety of vertebrates and that it may be involved in the physiological modulation of ACh release and in the regulation of muscle response to nerve injury.

Age and continuous lactose challenge modify lactase protein expression and enzyme activity in gut epithelium in the rat

The activity of lactase enzyme declines after weaning. This study was to investigate changes in the lactase expression in the whole gastrointestinal tract during the development and the possibility that this and activity can be induced by lactose. Expression of lactase protein in the gut of 1-12-weeks old rats was studied by immunocytochemistry. Possible induction was evaluated by immunohistochemical and biochemical techniques in 8-week-old rats after lactose challenge for seven days. Lactase immunoreactivity was detected only in the small intestine and it decreased 20% during the week after weaning. A steady level of 40% lower than in the sucklings was found in the adult rats. In the lactose-challenged rats the optical density of immunoreactivity increased by about 30% in those that consumed the highest concentration of lactose. In the proximal jejunum, elevation of the enzymatic activity was three-fold. In the rat lactase protein expression decreased rapidly after weaning and expression and activity were induced by lactose-rich diet, most notably in the proximal jejunum.

ASEPTIC LOOSENING OF TOTAL HIP REPLACEMENT

Aseptic loosening is a major cause of failure of total hip arthroplasty. The adverse tissue response to prosthetic wear particles, with activation of cytokine and prostanoid production, contributes to bone loss around the implants. We have investigated the possibility that inducible nitric oxide synthase (iNOS) and cyclo-oxygenase-2 (COX-2) are expressed in macrophages in the pseudomembrane at the bone-implant interface, thereby contributing to the periprosthetic bone resorption.

We also assessed whether peroxynitrite, a nitric oxide (NO)-derived oxidant associated with cellular injury, is generated in the membrane. Enzymatic activity of iNOS was measured using the arginine-citrulline assay technique and prostaglandin E2 (PGE2), as an indicator of COX-2 activity, was measured using an enzyme immunoassay.

Cellular immunoreactivity for iNOS, nitrotyrosine (a marker of peroxynitrite-induced cellular injury) and COX-2 was assessed by quantitative peroxidase immunocytochemistry while immunofluorescence methods were used for subsequent co-localisation studies with CD68+ macrophages.

The presence of calcium-independent iNOS activity and PGE2 production was confirmed in the homogenized interface membrane. Immunocytochemistry showed that periprosthetic CD68+ wear-debris-laden macrophages were the most prominent cell type immunoreactive for iNOS, nitrotyrosine and COX-2. Other periprosthetic inflammatory and resident cell types were also found to immunolocalise nitrotyrosine thereby suggesting peroxynitrite-induced protein nitrosylation and cellular damage not only in NO-producing CD68+ macrophages, but also in their neighbouring cells. These data indicate that both iNOS and COX-2 are expressed by CD68+ macrophages in the interface membrane and peroxynitrite-induced cellular damage is evident in such tissue. If high-output NO and peroxynitrite generation were to cause macrophage cell death, this would result in the release of phagocytosed wear debris into the extracellular matrix. A detrimental cycle of events would then be established with further phagocytosis by newly-recruited inflammatory cells and subsequent NO, peroxynitrite and prostanoid synthesis. Since both NO and have been implicated in the induction and PGE2 maintenance of chronic inflammation with resulting loss of bone, and peroxynitrite in the pathogenesis of disease states, they may be central to the pathogenesis of aseptic loosening.

Aseptic loosening of total hip replacement. Macrophage expression of inducible nitric oxide synthase and cyclo-oxygenase-2, together with peroxynitrite formation, as a possible mechanism for early prosthesis failure

Aseptic loosening is a major cause of failure of total hip arthroplasty. The adverse tissue response to prosthetic wear particles, with activation of cytokine and prostanoid production, contributes to bone loss around the implants. We have investigated the possibility that inducible nitric oxide synthase (iNOS) and cyclo-oxygenase-2 (COX-2) are expressed in macrophages in the pseudomembrane at the bone-implant interface, thereby contributing to the periprosthetic bone resorption. We also assessed whether peroxynitrite, a nitric oxide (NO)-derived oxidant associated with cellular injury, is generated in the membrane. Enzymatic activity of iNOS was measured using the arginine-citrulline assay technique and prostaglandin E2 (PGE2), as an indicator of COX-2 activity, was measured using an enzyme immunoassay. Cellular immunoreactivity for iNOS, nitrotyrosine (a marker of peroxynitrite-induced cellular injury) and COX-2 was assessed by quantitative peroxidase immunocytochemistry while immunofluorescence methods were used for subsequent co-localisation studies with CD68+ macrophages. The presence of calcium-independent iNOS activity and PGE2 production was confirmed in the homogenised interface membrane. Immunocytochemistry showed that periprosthetic CD68+ wear-debris-laden macrophages were the most prominent cell type immunoreactive for iNOS, nitrotyrosine and COX-2. Other periprosthetic inflammatory and resident cell types were also found to immunolocalise nitrotyrosine thereby suggesting peroxynitrite-induced protein nitrosylation and cellular damage not only in NO-producing CD68+ macrophages, but also in their neighbouring cells. These data indicate that both iNOS and COX-2 are expressed by CD68+ macrophages in the interface membrane and peroxynitrite-induced cellular damage is evident in such tissue. If high-output NO and peroxynitrite generation were to cause macrophage cell death, this would result in the release of phagocytosed wear debris into the extracellular matrix. A detrimental cycle of events would then be established with further phagocytosis by newly-recruited inflammatory cells and subsequent NO, peroxynitrite and prostanoid synthesis. Since both NO and PGE2 have been implicated in the induction and maintenance of chronic inflammation with resulting loss of bone, and peroxynitrite in the pathogenesis of disease states, they may be central to the pathogenesis of aseptic loosening.

Role of nitric oxide in Sjögren's syndrome

OBJECTIVE

To measure levels of salivary nitrite (NO2-) and to localize nitric oxide synthases (NOS) in the labial salivary glands (LSGs) of patients with Sjögren's syndrome (SS).

METHODS

NO2- was measured by the Griess reaction. LSGs were analyzed using NADPH-diaphorase histochemical and immunohistochemical studies to determine the constitutive NOS (neuronal [ncNOS] and endothelial [ecNOS]) and inducible NOS (iNOS) isoforms.

RESULTS

The NO2- concentration (mean +/- SEM 307 +/- 51 microM versus 97 +/- 16 microM; P < 0.05) and output (166 +/- 46 nmoles/minute versus 37 +/- 7 nmoles/minute) were increased in SS patients compared with healthy control subjects. NADPH-diaphorase was found in some nerve fibers and endothelial cells, and, in SS, was found in myoepithelial, acinar, and ductal epithelial cells, but in only a few inflammatory cells. In SS, ncNOS-immunoreactive nerve fibers were sparse and ecNOS was found in a minority of the CD31-positive vascular endothelial cells and acinar cells, whereas iNOS was localized in myoepithelial, acinar, and ductal epithelial cells, often together with tumor necrosis factor alpha.

CONCLUSION

Nitrite was found in normal human saliva. NO produced by ncNOS probably acts as a nonadrenergic, noncholinergic neurotransmitter, whereas that produced by ecNOS exerts a vasodilatory effect. SS patients had increased NO2- concentrations, with most of the superfluous salivary NO being produced not by the immigrant inflammatory cells, but rather, by the resident salivary gland cells. NO may contribute to inflammatory damage and acinar cell atrophy in SS.

The presence of secretoneurin in human synovium and synovial fluid

Secretoneurin is a neuropeptide formed from the proprotein secretogranin II. It is found in afferent nerve fibres and has chemotactic activity for monocytes, neutrophils and fibroblasts. We investigated the presence of secretoneurin in synovial fluid and synovium from patients with osteoarthritis and rheumatoid arthritis. The secretoneurin immunoreactive material found in synovial fluid was identified by high performance liquid chromatography as the free peptide secretoneurin. Its level in hip joints was 15.6, in knee joints of osteoarthritis patients 17.3 and in rheumatoid patients significantly lower (8.6 fmol/ml). Immunocytochemistry provided evidence for the presence of sub-intimal secretoneurin-immunoreactive nerve fibres in knee synovium in osteoarthritic patients. In rheumatoid synovium, only very few immunoreactive fibres were found these being mostly localised in deep stroma. The results show that secretoneurin is present in osteoarthritic joint and suggest that secretoneurin levels are down-regulated in rheumatoid joint. Therefore, secretoneurin may participate in acute or mild phases of inflammation but is unlikely to have a major role when more severe inflammation is present such as that seen in rheumatoid joint.

Aberrant vascularity and von Willebrand factor distribution in inflamed synovial membrane

OBJECTIVE

Von Willebrand factor (vWF) is an adhesive glycoprotein produced and secreted constitutively by endothelial cells. vWF is released upon endothelial stimulation and/or vascular injury, and mediates adhesion and aggregation of platelets. Our aim was to quantify synovial vasculature and to evaluate vWF distribution in situ in synovial membranes in various arthritides.

METHODS

Immunohistochemical staining of vWF in synovial membranes from patients with rheumatoid arthritis (RA) (N = 9), psoriatic (PsA) (N = 3), and reactive (ReA) (N = 4) arthritis, and from 6 noninflammatory controls: osteoarthritis (N = 1), chondromatosis (N = 1), meniscus lesion (N = 4). Morphometric assessments were performed with an image analyzer.

RESULTS

In RA, mean number of blood vessels/mm2 in the thickened synovium was relatively low (131 +/- 57 vs control 257 +/- 115, p = 0.0137, ReA 346 +/- 83, p = 0.0002, PsA 434 +/- 157, p = 0.0127). In particular, the superficial layer, corresponding to the thickness of normal synovial membrane (i.e., 56 +/- 5 microns), was sparsely vascularized (70 +/- 37 in the superficial vs 219 +/- 104 in the deeper layer, p = 0.0047). Synovial thickening was not seen in ReA and PsA. In accordance with its constitutive metabolism, vWF was found in the endothelial cells, inside the blood vessels, and in the subendothelium. In addition, RA was characterized by weak endothelial immunoreactivity and perivascular vWF. In ReA, perivascular vWF staining was visible in areas of inflammatory cell infiltrates.

CONCLUSION

Morphometric findings indicate decreased vascularization of the superficial synovial membrane in RA. Second, vWF may play a role in the inflammatory/reparative responses in synovium in RA and ReA, which were characterized by vascular stimulation/injury and abnormal vWF distribution.

Neutral endopeptidase (EC 3.4.24.11) in labial salivary glands in healthy controls and in patients with Sjögren's syndrome

OBJECTIVE

Neuropeptides from nerve fibres can cause neurogenic inflammation. The potency of these peptides in vitro has led to the hypothesis that enzyme degradative systems are operative in vivo to limit their action. To consider this question neutral endopeptidase (NEP) in labial salivary glands in patients with Sjögren's syndrome was studied.

METHODS

Synthesis of NEP mRNA in situ in labial salivary glands was studied using the reverse transcriptase polymerase chain reaction (RT-PCR). Immunohistochemical staining was used to localise the NEP enzyme protein and its neuropeptide substrates and fluorophotometry to measure the corresponding enzyme activities in saliva.

RESULTS

NEP was found in nerve fibres and in perivascular, periductal, and periacinar axon terminal varicosities. Double labelling of PGP 9.5 and NEP confirmed this neuronal localisation of NEP. Although some fibroblast-like cells and occasional intravascular neutrophils were NEP positive, NEP mRNA was not found in labial salivary glands. Patients with Sjögren's syndrome and healthy controls did not have nerves containing NEP or neuropeptides (vasoactive intestinal peptide, substance P, or calcitonin gene related peptide (CGRP)) in lymphocyte foci. Salivary NEP activity was not decreased in patients compared with controls.

CONCLUSION

NEP in labial salivary glands is almost totally of neuronal origin and plays a part in proteolytic modulation of neuropeptides in salivary glands and saliva. These regulatory interactions seem to be altered in focal lymphocyte accumulations in Sjögren's syndrome.

Sensory nerve ingrowth during bone graft incorporation in the rat

We studied nerve ingrowth into a cancellous bone graft in a bone conduction chamber model in the rat. Before implantation of the chamber bilaterally in the proximal tibiae of 8 Sprague-Dawley rats, a defatted cancellous bone graft from separate donor rats was fitted snugly into each chamber. After 6 weeks, the animals were perfused with Zamboni's fixative and the chambers were harvested. Immunohistochemical detection of nerve fibers was performed in cryostat sections, using antisera to protein gene product 9.5 (PGP 9.5), neural growth-associated protein GAP-43/B-50, calcitonin gene-related peptide (CGRP), substance P and C- flanking peptide of neuropeptide Y (CPON). Nerve fibers were found in 10 out of 16 samples in the newly formed bone, and also in the fibrous tissue which had penetrated deeper into the graft. The nerve fibers were mainly of sensory origin, as they showed immunoreactivity for CGRP and GAP-43/B-50. We speculate that the nerve fibers may act as transmitters of nociceptive impulses from the graft, and as transport pathways for neuropeptides that are actively involved in angiogenesis and in the recruitment and activity of osteogenic cell populations from the graft recipient.