Increased RANK ligand in bone marrow of orchiectomized rats and prevention of their bone loss by the RANK ligand inhibitor osteoprotegerin

Orchiectomized (ORX) rats were used to examine the extent to which their increased bone resorption and decreased bone density might relate to increases in RANKL, an essential cytokine for bone resorption.Serum testosterone declined by > 95% in ORX rats 1 and 2 weeks after surgery (p < 0.05 versus sham controls), with no observed changes in serum RANKL. In contrast, RANKL in bone marrow plasma and bone marrow cell extracts was significantly increased (by  100%) 1 and 2 weeks after ORX. Regression analyses of ORX and sham controls revealed a significant inverse correlation between testosterone and RANKL levels measured in marrow cell extracts (R = − 0.58), while marrow plasma RANKL correlated positively with marrow plasma TRACP-5b, an osteoclast marker (R = 0.63). The effects of RANKL inhibition were then studied by treating ORX rats for 6 weeks with OPG-Fc (10 mg/kg, twice/week SC) or with PBS, beginning immediately after surgery. Sham controls were treated with PBS. Vehicle-treated ORX rats showed significant deficits in BMD of the femur/tibia and lower trabecular bone volume in the distal femur (p < 0.05 versus sham). OPG-Fc treatment of ORX rats increased femur/tibia BMD and trabecular bone volume to levels that significantly exceeded values for ORX or sham controls. OPG-Fc reduced trabecular osteoclast surfaces in ORX rats by 99%, and OPG-Fc also prevented ORX-related increases in endocortical eroded surface and ORX-related reductions in periosteal bone formation rate. Micro-CT of lumbar vertebrae from OPG-Fc-treated ORX rats demonstrated significantly greater cortical and trabecular bone volume and density versus ORX-vehicle controls. In summary, ORX rats exhibited increased RANKL protein in bone marrow plasma and in bone marrow cells, with no changes in serum RANKL. Data from regression analyses were consistent with a potential role for testosterone in suppressing RANKL production in bone marrow, and also suggested that soluble RANKL in bone marrow might promote bone resorption. RANKL inhibition prevented ORX-related deficits in trabecular BMD, trabecular architecture, and periosteal bone formation while increasing cortical and trabecular bone volume and density. These results support the investigation of RANKL inhibition as a strategy for preventing bone loss associated with androgen ablation or deficiency.     

Modified grading system for upper eyelid trachomatous trichiasis

Aim This study was conducted to determine the level of inter-observer agreement in the modified grading scheme for trichiasis of the upper eyelid. Methods A grading system that covers the entire spectrum of trachomatous trichiasis, extending from the simple to the severe forms, was initially developed by the first and second authors and field-tested. The grading scheme recognizes three levels of severity, based on deviation of the lid margin (TT1, TT2 and TT3); and four anatomical locations indicating where the eyelashes touch the globe in TT1 (nasal, central, temporal, or combined). The grading of trichiasis patients was then conducted on the basis of the modified grading scheme. Results The inter-observer agreement between the grades of simple trichiasis (TT1) and entropion (TT2) using Cronbach's alpha was 0.84, and the agreement within each sub-grade was 0.86. The weighted Kappa value was 0.68 (95% CI 0.57–0.79) for the main grades and 0.49 (95% CI 0.23–0.79) for the sub-grades. Conclusions The inter-observer agreement was very reliable and could easily be attained by all levels of ophthalmic professionals. As the grading follows the natural progression of trichiasis from the simple to the severe forms in relation to the anatomical site involved, it helps to determine the degree of correction and how far to extend the surgical incision.     

Spontaneous fat necrosis of the falciform ligament: Tale of the unexpected

Abdominal pain has a myriad of causes. Advances in technology have improved accuracy in diagnosis and management. Despite this, there are still cases that defy all diagnostic tests, showing themselves only at operation to the amazement of the surgeon. We report one such case, perhaps the second of its kind, as a literature search has shown.     

Infrequent delivery of a long-acting PTH-Fc fusion protein has potent anabolic effects on cortical and cancellous bone.

Skeletal anabolism with PTH is achieved through daily injections that result in brief exposure to the peptide. We hypothesized that similar anabolic effects could be achieved with less frequent but more sustained exposures to PTH. A PTH-Fc fusion protein with a longer half-life than PTH(1-34) increased cortical and cancellous BMD and bone strength with once- or twice-weekly injections. INTRODUCTION: The anabolic effects of PTH are currently achieved with, and thought to require, daily injections that result in brief exposure to the peptide. We hypothesized that less frequent but more sustained exposures to PTH could also be anabolic for bone, provided that serum levels of PTH were not constant. MATERIALS AND METHODS: PTH(1-34) was fused to the Fc fragment of human IgG1 to increase the half-life of PTH. Skeletal anabolism was examined in mice and rats treated once or twice per week with this PTH-Fc fusion protein. RESULTS: PTH-Fc and PTH(1-34) had similar effects on PTH/PTHrP receptor activation, internalization, and signaling in vitro. However, PTH-Fc had a 33-fold longer mean residence time in the circulation of rats compared with that of PTH(1-34). Subcutaneous injection of PTH-Fc once or twice per week resulted in significant increases in bone volume, density, and strength in osteopenic ovariectomized mice and rats. These anabolic effects occurred in association with hypercalcemia and were significantly greater than those achievable with high concentrations of daily PTH(1-34). PTH-Fc also significantly improved cortical bone volume and density under conditions where daily PTH(1-34) did not. Antiresorptive co-therapy with estrogen further enhanced the ability of PTH-Fc to increase bone mass and strength in ovariectomized rats. CONCLUSIONS: These results challenge the notion that brief daily exposure to PTH is essential for its anabolic effects on cortical and cancellous bone. PTH-derived molecules with a sustained circulating half-life may represent a powerful and previously undefined anabolic regimen for cortical and cancellous bone.     

Cardiac surgical experience in northern Nigeria

A pilot study was undertaken to determine the feasibility of establishing a heart surgery programme in northern Nigeria. During three medical missions by a visiting US team, in partnership with local physicians, 18 patients with heart diseases underwent surgery at two referral hospitals in the region. Sixteen (88.9%) patients underwent the planned operative procedure with an observed 30-day mortality of 12.5% (2/16) and 0% morbidity. Late complications were anticoagulant related in mechanical heart valve patients and included a first-trimester abortion one year postoperatively, and a death at two years from haemorrhage during pregnancy. This has prompted us to now consider bioprosthetics as the valve of choice in women of childbearing age in this patient population. This preliminary result has further stimulated the interest of all stakeholders on the urgency to establish open-heart surgery as part of the armamentarium to combat the ravages of heart diseases in northern Nigeria.     

Candidatus Rickettsia hoogstraalii in Ethiopian Argas persicus ticks

Ethiopian soft ticks Argas persicus, hard ticks including both Amblyomma variegatum and Rhipicephalus (Boophilus) spp., and fleas were collected from livestock, traditional human dwellings, and cracks and crevices of trees. They were assessed in pools for the presence of Rickettsia using PCR-based methods. The extracted tick DNA was subjected to molecular screening for Rickettsia, which revealed 50.5% of the pooled samples to be positive for Rickettsia spp. These were then subjected to multi-gene analysis using both outer surface proteins and housekeeping genes with proven discriminatory potential. Sequencing of the citrate synthase and outer membrane genes clearly led to the identification of three distinct rickettsial species, Candidatus Rickettsia hoogstraalii in Argas persicus ticks; R. africae in hard tick pools, and R. felis in fleas. Furthermore, we demonstrated the presence of the plasmid-borne small heat-shock protein gene hsp2 in DNA from A. persicus ticks suggesting that Candidatus R. hoogstraalii carried by these ticks possess a plasmid. Unlike chromosomal gene sequences, the hsp2 gene failed to cluster with Candidatus R. hoogstraalii, instead falling into an isolated separate clade, suggesting a different origin for the plasmid.     

RANKL is a marker and mediator of local and systemic bone loss in two rat models of inflammatory arthritis.

RANKL is an essential mediator of bone erosions, but the role of RANKL in systemic bone loss had not been studied in arthritis. RANKL protein was increased in rat joint extracts and serum at the earliest stages of arthritis. Osteoprotegerin (OPG) treatment reversed local and systemic bone loss, suggesting that RANKL is both a marker and mediator of bone loss in arthritis. INTRODUCTION: RANKL is well established as an essential mediator of bone erosions in inflammatory arthritis, but the role of RANKL in systemic bone loss in arthritis had not been studied. We hypothesized that serum RANKL could serve as both a mediator and as a novel biomarker for local and systemic bone loss in arthritis. We challenged this hypothesis in two established rat models of inflammatory arthritis. We sought to determine whether serum RANKL was elevated early in disease progression and whether RANKL suppression could prevent both local and systemic bone loss in these models. MATERIALS AND METHODS: Detailed time-course studies were conducted in animals with collagen-induced (CIA) or adjuvant-induced (AIA) arthritis to evaluate the onset and progression of inflammation (paw swelling), bone erosions, osteoclast numbers, and RANKL protein levels in arthritic joints and in serum. Additional CIA and AIA rats (n=8/group) received placebo (PBS) or recombinant OPG (3 mg/kg three times weekly) for 10 days beginning 4 days after disease onset (first macroscopic evidence of hind paw erythema and edema) to assess the role of RANKL in local and systemic bone loss. RESULTS: RANKL protein was significantly elevated in the joints and serum of CIA and AIA rats within 1-2 days of disease onset. Increased RANKL levels were associated with local (hind paw) and systemic (vertebral) osteopenia in both models. The RANKL inhibitor OPG prevented local and systemic osteopenia in both models of established disease. CONCLUSIONS: RANKL protein is significantly increased both locally and systemically during the earliest stages of inflammatory arthritis in rats, suggesting that serum RANKL might have prognostic value for bone erosions and systemic osteopenia in this condition. RANKL inhibition through OPG prevented local and systemic bone loss in these arthritis models, suggesting that RANKL inhibition is a promising new approach for treating bone loss in arthritis.     

Corneal antibody levels to ribitol teichoic acid in rabbits immunized with staphylococcal antigens using various routes

Although Staphylococcus aureus is an important cause of infectious diseases of the eye and hypersensitivity lesions of the cornea, little is known about ocular immunity to this pathogen. Using an enzyme-linked immunosorbent assay, we measured antibody titers to ribitol teichoic acid, the major antigenic determinant of S. aureus, in corneas as well as serum and tears after immunizing rabbits using the following routes: intradermal injection of cell wall mixed with complete Freund's adjuvant, subconjunctival injection of cell wall mixed with complete Freund's adjuvant, topical application of cell wall to the eye or topical application of viable S. aureus to the eye. IgG titers to ribitol teichoic acid were found consistently in corneas after intradermal and subconjunctival immunization with cell wall and topical immunization with viable S. aureus. After intradermal immunization with cell wall, IgG titers in cornea were higher than tears but lower than serum, which was presumably the source of the IgG antibodies for the cornea. After subconjunctival immunization with cell wall or topical immunization with viable S. aureus, IgG titers in corneas were higher than tears and generally higher than serum, suggesting that the ocular tissues were a local source of IgG. On the other hand, IgA titers to ribitol teichoic acid were found in tears but not in serum and were found only occasionally in corneas, suggesting that IgG responses to staphylococcal antigens may be more important than IgA responses in the cornea. The results of this study suggest that corneal antibodies to ribitol teichoic acid may be influenced by exposure to staphylococcal antigens not only in the external eye but also at sites remote from the eye.     

Sustained antiresorptive effects after a single treatment with human recombinant osteoprotegerin (OPG): a pharmacodynamic and pharmacokinetic analysis in rats.

Osteoprotegerin (OPG) is a naturally occurring negative regulator of osteoclast differentiation, activation, and survival. We created a recombinant form of human OPG (rhOPG), with a sustained serum half-life, to achieve prolonged antiresorptive activity. This study describes the rapid and sustained antiresorptive effects that are achieved with a single treatment with rhOPG. Male Sprague-Dawley rats (10 weeks old) were given a single bolus intravenous injection of vehicle (PBS) or rhOPG (5 mg/kg). PBS- and rhOPG-treated rats (n = 6/group) were killed at 0, 0.5, 1, 2, 5, 10, 20, and 30 days post-treatment. rhOPG-treated rats were compared with their age-matched controls. The main pharmacologic effect of rhOPG was a rapid (24 h) reduction in osteoclast surface in the tibia, which reached a nadir on days 5 and 10 (95% reduction vs. vehicle controls). Osteoclast surface remained significantly reduced 30 days after the single treatment with rhOPG. Tibial cancellous bone volume was significantly increased within 5 days of rhOPG treatment (23%) and reached a peak increase of 58% on day 30. Femoral bone mineral density was significantly increased in rhOPG-treated rats on days 10 and 20. Pharmacokinetic analysis revealed that serum concentrations of rhOPG remained at measurable levels throughout the 30-day study. These data show that a single intravenous injection of rhOPG in young growing rats causes significant gains in bone volume and density, which are associated with rapid and sustained suppression of osteoclastic bone resorption.