Repair of a pathological radial fracture secondary to radioulnar ischemic necrosis in a dog.

CASE DESCRIPTION: A 3-year-old 2.5-kg (5.5-lb) sexually intact male Pomeranian was presented with a 1-day history of non-weight-bearing lameness of the right forelimb. CLINICAL FINDINGS: Signs of pain were localized to the proximal portion of the right antebrachium. Radiography revealed a minimally displaced fracture of the proximal portion of the radius that had propagated from a well-demarcated, ovoid, osteolytic lesion within the cortex of the caudolateral aspect of the radius. Computed tomographic findings supported the radiographic findings and did not reveal lesions in other evaluated body sites. TREATMENT AND OUTCOME: At surgery, the lateral aspect of the radial cortex appeared expanded, and tenacious fibrous tissue filled the gap between the fracture fragments. Fibrous tissue was resected and submitted for histologic examination, and the fracture was reduced and stabilized with a bone plate and a positional screw. Histologic examination revealed the presence of viable bone, fibrous tissue, and areas of coagulative necrosis. Imaging and histologic findings were consistent with radioulnar ischemic necrosis (RUIN). The patient ambulated normally at reexamination 12 days after surgery. At reexamination 15 weeks after surgery, the patient continued to ambulate normally, and radiography and CT indicated healing of the fracture and resolution of the RUIN lesion. CLINICAL RELEVANCE: RUIN should be considered as a differential diagnosis for a dog with forelimb lameness and radiographic focal osteolysis between the proximal and middle thirds of the diaphysis of the radius or ulna. Prognosis for dogs with RUIN may be good with surgical intervention.

Optimal sequencing of ibrutinib, idelalisib, and venetoclax in chronic lymphocytic leukemia: results from a multicenter study of 683 patients.

Background: Ibrutinib, idelalisib, and venetoclax are approved for treating CLL patients in the United States. However, there is no guidance as to their optimal sequence. Patients and methods: We conducted a multicenter, retrospective analysis of CLL patients treated with kinase inhibitors (KIs) or venetoclax. We examined demographics, discontinuation reasons, overall response rates (ORR), survival, and post-KI salvage strategies. Primary endpoint was progression-free survival (PFS). Results: A total of 683 patients were identified. Baseline characteristics were similar in the ibrutinib and idelalisib groups. ORR to ibrutinib and idelalisib as first KI was 69% and 81%, respectively. With a median follow-up of 17 months (range 1-60), median PFS and OS for the entire cohort were 35 months and not reached. Patients treated with ibrutinib (versus idelalisib) as first KI had a significantly better PFS in all settings; front-line [hazard ratios (HR) 2.8, CI 1.3-6.3, P = 0.01], relapsed-refractory (HR 2.8, CI 1.9-4.1, P < 0.001), del17p (HR 2.0, CI 1.2-3.4, P = 0.008), and complex karyotype (HR 2.5, CI 1.2-5.2, P = 0.02). At the time of initial KI failure, use of an alternate KI or venetoclax had a superior PFS when compared with chemoimmunotherapy. Furthermore, patients who discontinued ibrutinib due to progression or toxicity had marginally improved outcomes if they received venetoclax (ORR 79%) versus idelalisib (ORR 46%) (PFS HR .6, CI.3-1.0, P = 0.06). Conclusions: In the largest real-world experience of novel agents in CLL, ibrutinib appears superior to idelalisib as first KI. Furthermore, in the setting of KI failure, alternate KI or venetoclax therapy appear superior to chemoimmunotherapy combinations. The use of venetoclax upon ibrutinib failure might be superior to idelalisib. These data support the need for trials testing sequencing strategies to optimize treatment algorithms.

Brm inhibits the proliferative response of keratinocytes and corneal epithelial cells to ultraviolet radiation-induced damage.

Ultraviolet radiation (UV) from sunlight is the primary cause of skin and ocular neoplasia. Brahma (BRM) is part of the SWI/SNF chromatin remodeling complex. It provides energy for rearrangement of chromatin structure. Previously we have found that human skin tumours have a hotspot mutation in BRM and that protein levels are substantially reduced. Brm-/- mice have enhanced susceptibility to photocarcinogenesis. In these experiments, Brm-/- mice, with both or a single Trp53 allele were exposed to UV for 2 or 25 weeks. In wild type mice the central cornea and stroma became atrophic with increasing time of exposure while the peripheral regions became hyperplastic, presumably as a reparative process. Brm-/-, Trp53+/-, and particularly the Brm-/- Trp53+/- mice had an exaggerated hyperplastic regeneration response in the corneal epithelium and stroma so that the central epithelial atrophy or stromal loss was reduced. UV induced hyperplasia of the epidermis and corneal epithelium, with an increase in the number of dividing cells as determined by Ki-67 expression. This response was considerably greater in both the Brm-/- Trp53+/+ and Brm-/- Trp53+/- mice indicating that Brm protects from UV-induced enhancement of cell division, even with loss of one Trp53 allele. Cell division was disorganized in Brm-/- mice. Rather than being restricted to the basement membrane region, dividing cells were also present in the suprabasal regions of both tissues. Brm appears to be a tumour suppressor gene that protects from skin and ocular photocarcinogenesis. These studies indicate that Brm protects from UV-induced hyperplastic growth in both cutaneous and corneal keratinocytes, which may contribute to the ability of Brm to protect from photocarcinogenesis.

Polyostotic hyperostosis in a domestic shorthair cat.

CLINICAL PRESENTATION: An 11-year-old male neutered domestic shorthair cat was presented for investigation of weight loss and inappetence. On physical examination there was palpable enlargement and thickening of many bones, and this finding was confirmed radiographically. PROPOSED DIAGNOSIS: Based on clinical, radiological and histopathological findings, a polyostotic bone disease, best described as generalised idiopathic hyperostosis, was diagnosed. This condition has not been reported in cats previously. Canine and human diseases with similarities to this presentation are discussed.

Histological evaluation of repair of the rotator cuff in a primate model.

The establishment of a suitable animal model of repair of the rotator cuff is difficult since the presence of a true rotator cuff anatomically appears to be restricted almost exclusively to advanced primates. Our observational study describes the healing process after repair of the cuff in a primate model. Lesions were prepared and repaired in eight 'middle-aged' baboons. Two each were killed at four, eight, 12 and 15 weeks post-operatively. The bone-tendon repair zones were assessed macroscopically and histologically. Healing of the baboon supraspinatus involved a sequence of stages resulting in the reestablishment of the bone-tendon junction. It was not uniform and occurred more rapidly at the sites of suture fixation than between them. Four weeks after repair the bone-tendon healing was immature. Whereas macroscopically the repair appeared to be healed at eight weeks, the Sharpey fibres holding the repair together did not appear in any considerable number before 12 weeks. By 15 weeks, the bone-tendon junction was almost, but not quite mature. Our results support the use of a post-operative rehabilitation programme in man which protects the surgical repair for at least 12 to 15 weeks in order to allow maturation of tendon-to-bone healing.

Use of an elastic stain to show venous invasion in colorectal carcinoma: a simple technique for detection of an important prognostic factor.

BACKGROUND: Venous invasion (VI) is an important prognostic factor in colorectal cancer; it is positively associated with visceral metastases and may affect the decision to treat with adjuvant therapy. AIMS: To evaluate whether an elastic tissue (Movat) stain facilitates identification of VI, the number of Movat-stained blocks needed to detect VI, and whether VI identified with a Movat stain is prognostically equivalent to VI identified on H&E-stained slides. METHODS: H&E-stained sections from colorectal carcinomas from the year 2000 (n = 92) were examined for VI and compared to Movat-stained slides. Clinical charts were reviewed to compare rates of metastases in VI-positive versus VI-negative patients. RESULTS: With the Movat stain, VI was identified in 44% of cases previously categorised as negative (p<0.001) on review of H&E slides alone. One Movat-stained section was often sufficient to identify VI, with a statistically significant benefit to performing multiple stains if necessary. In H&E sections, two clues helped identify VI: the "unaccompanied artery" sign, where large arteries were seen without an accompanying vein; and the "protruding tongue" sign, where smooth tongues of tumour extended into pericolic/rectal fat. Metastases were present in 61% of cases positive for VI compared to 35% in VI-negative cases (p = 0.03). 45% of cases positive for intramural VI only developed metastases (p = 0.39), while 65% of cases positive for extramural VI only developed metastases (p = 0.03). CONCLUSIONS: Pathologists should look for morphological clues of VI in H&E stained sections; when VI is not apparent, an elastic tissue stain on all tumour blocks significantly improves identification of VI. Morphological clues include the "unaccompanied artery" and "protruding tongue" signs.

S100A8/S100A9 and their association with cartilage and bone.

S100A8 and S100A9 are calcium-binding proteins expressed in myeloid cells and are markers of numerous inflammatory diseases in humans. S100A9 has been associated with dystrophic calcification in human atherosclerosis. Here we demonstrate S100A8 and S100A9 expression in murine and human bone and cartilage cells. Only S100A8 was seen in preosteogenic cells whereas osteoblasts had variable, but generally weak expression of both proteins. In keeping with their reported high-mRNA expression, S100A8 and S100A9 were prominent in osteoclasts. S100A8 was expressed in alkaline phosphatase-positive hypertrophic chondrocytes, but not in proliferating chondrocytes within the growth plate where the cartilaginous matrix was calcifying. S100A9 was only evident in the invading vascular osteogenic tissue penetrating the degenerating chondrocytic zone adjacent to the primary spongiosa, where S100A8 was also expressed. Whilst, S100A8 has been shown to be associated with osteoblast differentiation, both S100A8 and S100A9 may contribute to calcification of the cartilage matrix and its replacement with trabecular bone, and to regulation of redox in bone resorption.

Effect of silicon doping on bone formation within alumina porous domains.

The effect of doping a porous bioinert bioceramic with silicon (Si) on tissue ingrowth, differentiation, and osteogenesis was studied using a rat intramedullary model. Alumina tubes (1.3-mm outer diameter, 0.6-mm inner diameter, 15-mm length) doped with Si at nominal concentrations of 0.5 and 5.0 mol % were implanted into femoral medullary canals of female rats for 16 weeks. Tissue formation within the tubes was determined by histology and histomorphometry. Addition of 0.5 mol % Si to alumina stimulated cellular activity at the bone-ceramic interface and impaired osteogenic maturation within the tubes. In contrast, osteogenesis was enhanced in the 5.0 mol % Si-doped alumina tubes. It is considered that effect of Si is related to surface chemistry rather than microstructure. This work demonstrates that doping a bioinert ceramic with small amounts of Si can significantly alter tissue ingrowth, differentiation, and osteogenesis within a porous implant.

Bone formation within alumina tubes: effect of calcium, manganese, and chromium dopants.

Alumina tubes (1.3mm outer diameter, 0.6mm inner diameter, 15 mm length) doped with Ca, Mn, or Cr at nominal concentrations of 0.5 and 5.0 mol% were implanted into femoral medullary canals of female rats for 16 weeks. Tissue formation within tubes was determined by histology and histomorphometry. Addition of Ca to alumina promoted hypertrophic bone formation at the advancing tissue fronts and tube entrances, and appeared to retard angiogenesis by limiting ongoing cellular migration into the tube. It is speculated that the presence of a secondary phase of calcium hexaluminate, probably having a solubility greater than that of alumina, possibly increased the level of extracellular Ca and, consequently, stimulated osteoclastic activity at the bone-ceramic interface. Addition of Mn significantly enhanced osteogenesis within the tubes. However, it is not possible to determine whether phase composition or microstructure of the ceramic was responsible for this because both were significantly altered by Mn addition. Addition of Cr to the alumina apparently stimulated bone remodelling as indicated by increased cellular activity and bone resorption at the tissue-implant interface. Cr was incorporated into the alumina as a solid solution and the tissue response was speculated to be an effect of surface chemistry rather than microstructure. The work demonstrates that doping a bioinert ceramic with small amounts of specific elements can significantly alter tissue ingrowth, differentiation, and osteogenesis within a porous implant.

Effect of rapidly resorbable calcium phosphates and a calcium phosphate bone cement on the expression of bone-related genes and proteins in vitro.

The use of biodegradable bone substitutes is advantageous for alveolar ridge augmentation because it avoids second-site surgery for autograft harvesting. This study examines the effect of novel, rapidly resorbable calcium phosphates and a calcium phosphate bone cement on the expression of bone-related genes and proteins by human bone-derived cells (HBDCs) and compares this behavior to that of tricalciumphosphate (TCP). Test materials were alpha-TCP, two materials with a crystalline phase Ca(2)KNa(PO(4))(2) and with a small amorphous portion containing either magnesium potassium phosphate (material denominated GB14) or silica phosphate (material denominated GB9), and a calcium phosphate bone cement (material denominated Biocement D). HBDCs were grown on the substrata for 3, 7, 14, and 21 days, counted, and probed for various mRNAs and proteins (type I collagen, osteocalcin, osteopontin, osteonectin, alkaline phosphatase, and bone sialoprotein). All substrates supported continuous cellular growth for 21 days. In the presence of GB14 and Biocement D specimens cell proliferation was reduced and cell differentiation increased. At day 21, the greatest number of cells was found on GB9 expressing significantly higher levels of bone-related proteins than cells grown on all other surfaces. Because all novel materials facilitated the expression of the osteoblastic phenotype at least as much as TCP and the polystyrene control, these biomaterials can be regarded as excellent candidate bone substitute materials. GB9 induced the highest proliferation and cellular differentiation after 21 days of incubation, suggesting that this material may possess a higher potency for enhancing osteogenesis than TCP.

Proliferation and bone-related gene expression of osteoblasts grown on hydroxyapatite ceramics sintered at different temperature.

Human osteoblast-like cells SaOS-2 (ATCC HTB85) were seeded onto three kinds of hydroxyapatite (HA) ceramics sintered at different temperature (1200 degrees C, 1000 degrees C and 800 degrees C). Scanning electron microscopy (SEM) was conducted to detect the surface microstructure. Cells were cultured on these substrates for 6 and 12 days and cell proliferation rate and mRNA expression for osteocalcin, osteonectin, type I collagen and alkaline phosphatase and protein production for osteocalcin, bone sialoprotein and osteonectin were detected with quantitative in situ hybridization and immunocytochemistry techniques. SEM revealed that crystal particle size was affected by sintering temperature. Result showed that cell proliferation rate on HA ceramics sintered at 1200 degrees C was the highest. Osteonectin and type I collagen mRNA expression was not altered by sintering temperature. After 12 days in culture, bone sialoprotein, osteocalcin and osteonectin proteins levels were significantly (p<0.05) higher when SaOS-2 cells were cultured on HA sintered at 1200 degrees C, compared to the other two surfaces, suggesting that HA sintered at high temperature may be a better candidate for in vivo implantation. This result provides valuable information concerning the clinic application of HA ceramics sintered at different temperature.

Phenotypic expression of bone-related genes in osteoblasts grown on calcium phosphate ceramics with different phase compositions.

Calcium phosphate ceramics with different hydroxyapatite (HA) and tricalcium phosphate (TCP) ratios have different chemical properties. Does the difference in phase composition affect osteoblast behavior? In this study, osteoblasts were cultured on 4 kinds of calcium phosphate ceramics, i.e. pure (HA), HT1 (HA/TCP, 70/30), HT2 (HA/TCP, 35/65), and pure TCP. Cell proliferation of SaOS-2 cells together with bone-related genes' mRNA expression and protein production in osteoblasts cultured on different calcium phosphate ceramics were detected at different time points. Data suggested that cell proliferation rate on TCP ceramics was lower than that on the other substrates tested. Generally, mRNA expressions for osteonectin and osteocalcin were similar among the four kinds of ceramics in most circumstances, whereas at six days, alkaline phosphatase mRNA expression was higher on HA and HT1 surfaces than on the other two materials. Collagen I mRNA expression was also affected by the phase composition of substrates. Osteocalcin and bone sialoprotein production in SaOS-2 cells was very similar no matter which ceramic surface the cells were grown upon. This study revealed that calcium phosphate ceramics substrate could support osteoblast growth and bone-related gene expression and its gene expression pattern explained the basis of the biocompatibility and bioactivity for calcium phosphate ceramics.

Use of an intramedullary in vivo model to study bone formation and maintenance in ceramic porous domains.

Tissue ingrowth, differentiation, and osteogenesis in a porous bioinert bioceramic were studied using an intramedullary model. Pure alumina tubes (1.3 mm outer diameter, 0.6 mm inner diameter, 15 mm length) were implanted in the femoral medullary canal of young female rats for 4, 6, 8, 12, and 16 weeks. Tissues present within each tube were characterized by histology and quantified by histomorphometry. A tissue front consisting of undifferentiated mesenchymal cells, fibrovascular tissue, osteoid, woven bone, and marrow penetrated the tube from both ends. Behind the front, woven bone remodeled to produce a thin layer of lamellar bone that lined the tube walls the entire distance to the tube ends and enclosed a marrow-filled lumen. The front was considered to represent the differentiation cascade from mesenchymal cells to fibrovascular tissue to osteoid to woven bone and marrow to lamellar bone and marrow. The fronts advanced into the tube with time such that, by 16 weeks, they were close to meeting or had met. In several instances, the tube was completely lined with a thin layer of mature lamellar bone continuous between the two ends and enclosing marrow. This configuration was considered to be the final equilibrium of tissues within the tube.

Collagen-hydroxyapatite composite prepared by biomimetic process.

A novel bone graft substitute comprising a porous, collagenous scaffold was biomimetically coated with hydroxyapatite using a simulated body fluid solution chemistry method. The scaffold had a porosity of approximately 85%, with pore sizes between 30 microm and 100 microm. Glutaraldehyde vapor was used to stabilize the collagenous scaffold, giving a significantly increased thermal stability over an unstabilized scaffold, as shown by differential scanning calorimetry. A thin layer (<10 microm) of crystalline hydroxyapatite was deposited onto the stabilized collagenous scaffold by soaking the collagenous construct in simulated body fluid in the presence of calcium silicate glass. The presence of crystalline hydroxyapatite was confirmed by X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. In vitro cytotoxicity testing of the composite construct using L-929 fibroblasts (ISO 10993-5) and rabbit periosteal cells revealed a cytocompatible material that supported cellular attachment and proliferation.

The functional expression of human bone-derived cells grown on rapidly resorbable calcium phosphate ceramics.

The use of biodegradable bone substitutes is advantageous for alveolar ridge augmentation, since it avoids second-site surgery for autograft harvesting. This study examines the effect of novel, rapidly resorbable calcium phosphates on the expression of bone-related genes and proteins by human bone-derived cells (HBDC) and compares this behavior to that of tricalciumphosphate (TCP). Test materials were alpha-TCP, and four materials which were created from beta-Rhenanite and its derivatives: R1-beta-Rhenanite (CaNaPO(4)); R1/M2 composed of CaNaPO(4) and MgNaPO(4); R1+SiO(2) composed of CaNaPO(4) and 9% SiO(2) (wt%); and R17-Ca(2)KNa(PO(4))(2). HBDC were grown on the substrata for 3, 5, 7, 14 and 21 days, counted and probed for various mRNAs and proteins (Type I collagen, osteocalcin, osteopontin, osteonectin, alkaline phosphatase and bone sialoprotein). All substrata supported continuous cellular growth for 21 days. At day 21, surfaces of R1+SiO(2) and R17 had the highest number of HBDC. At 14 and 21 days, cells on R1 and on R1+SiO(2) displayed significantly enhanced expression of all osteogenic proteins. Since all novel calcium phosphates supported cellular proliferation together with expression of bone-related proteins at least as much as TCP, these ceramics can be regarded as potential bone substitutes. R1 and R1+SiO(2) had the most effect on osteoblastic differentiation, thus suggesting that these materials may possess a higher potency to enhance osteogenesis than TCP.

Reversible metaphyseal dysplasia, a novel bone phenotype, in two unrelated children with autoimmunepolyendocrinopathy-candidiasis-ectodermal dystrophy: clinical and molecular studies.

We report the association of an undescribed, reversible metaphyseal dysplasia (RMD) with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) in two patients, one homozygous and one heterozygous for a 13-bp deletion in exon 8 of the autoimmune regulator (AIRE) gene. One patient also had a novel deletion in exon 6, resulting in a frameshift mutation and introduction of a STOP codon in exon 10. Their APECED phenotypes differed, but both patients developed progressive skeletal deformities and growth failure from early childhood. Radiological examination suggested a generalized abnormality of endochondral ossification, with irregular, flared, radioopaque regions in the metaphyses, subjacent to the growth plates. Histopathology in patient 1 showed islands of calcified cartilage within bone, consistent with impaired coupling of cartilage resorption with vascular invasion and ossification. Despite discordance for puberty, both patients experienced radiological resolution of their bone disease in their mid-teens, with improvement in histopathology in patient 1. RMD may constitute a rare phenotypic variation of APECED, possibly resulting from autoimmunity directed against skeletal proteins. We also demonstrated AIRE expression in chondrocytes derived from human fetal growth plates, primary culture of human chondrocytes, and two chondrosarcoma cell lines, suggesting a potential role for abnormal AIRE expression in the development of RMD.

Effect of supplemental nutrient source on heifer growth and reproductive performance, and on utilization of corn silage-based diets by beef steers.

Two experiments were conducted to determine effects of oilseeds or soybean hulls on growth and reproductive performance of heifers and utilization of corn silage diets by growing beef cattle. In Exp. 1, 96 beef heifers (249 kg of BW) were used in a randomized complete block design. Treatments were as follows: 1) corn and soybean meal (CON) at 56% of the DMI; 2) whole linted cottonseed at 15% of the DMI (COT); 3) whole raw soybeans at 15% of the DMI (SB); or 4) pelleted soyhulls at 30% of the DMI (SH). Diets were formulated to be isonitrogenous (13.8% CP) and fed to achieve target weights equal to 65% of expected mature BW at the time of AI. Estrus was synchronized and heifers were inseminated by AI in response to detected estrus. Because the energy value for SH was underestimated, cumulative ADG for SH (1.03 kg/d) was greater (P < or = 0.03) than for CON (0.89 kg/d), COT (0.87 kg/d), or SB (0.86 kg/d). Treatment did not affect (P > 0.10) the proportion of pubertal heifers at the beginning of the breeding season: CON (60%), COT (53%), SB (69%), SH (71%), or first-service conception rates: CON (37%); COT (38%); SB (57%); SH (42%). In Exp. 2, crossbred steers (387 kg) were used in a 6 x 6 Latin square design to evaluate the effects of supplemental nutrient source on utilization of corn silage diets. Treatments included diets used in Exp. 1, plus a negative control (soybean meal at 10% of the DMI; SIL) and whole raw soybeans at 25% of the DMI (SB25). Diets were formulated to be isonitrogenous (13.8% CP) except SB25 (17% CP), and were fed twice daily at 1.8 x NEm. Oilseed inclusion decreased (P < 0.10) acetate:propionate ratios and (P < 0.10) apparent ruminal OM and ruminal and total tract NDF digestibilities. The CON and SH diets had the greatest (P < 0.10) total-tract OM digestibilities. Microbial efficiencies were greatest (P < 0.10), and long chain fatty acid flow to the duodenum increased (P < 0.10) with oilseeds. Biohydrogenation averaged 90.4% and increased slightly (P < 0.10) when oilseeds were added to the diet. Adding oilseeds or soybean hulls to corn silage-based diets did not affect reproductive performance of heifers. Although oilseed additions increased total fatty acid flow to the duodenum, a high degree of biohydrogenation occurred, greatly increasing C18:0, with only marginal increases in unsaturated fatty acid flow. Depending on diet and feeding conditions, inclusion of whole oilseeds may not be an effective means of increasing linoleic acid supply for ruminant animals.

Characterization of season and sampling method effects on measurement of forage quality in fescue-based pastures.

Information on seasonal changes and effects of sampling methods on the measurement of forage quality is limited for fescue-based pastures. Eight continuously grazed, 0.76-ha, fescue-based pastures were used to compare forage type, method of collection, and seasonal effects on forage quality in a repeated-measures, split-plot design. Four pastures were interseeded with red clover in March 2000. Masticate (M; from four ruminally cannulated steers) and hand--clipped (C) samples were collected every 28 d from April to October 2000. Interseeding red clover did not affect (P > 0.10) OM, CP, NDF, and ADF concentrations or CP degradability. Sampling method and season interacted (P < 0.03) for OM, CP, NDF, and ADF concentrations. Concentrations of OM averaged 5 percentage units more (P < 0.01) in C than in M in all months and were more variable with M than with C. Samples clipped between April and September averaged 5.5 percentage units greater NDF (P < 0.01), 3.0 percentage units greater ADF (P < 0.01), and 4.5 percentage units less CP (P < 0.01) than masticate samples obtained during the same time period. Fiber and CP concentrations did not differ (P > 0.10) between C and M samples obtained in October. Differences in CP degradability estimates (using Streptomyces griseus protease) between the two sample types were greater in late-season samples than in samples obtained from April to June. When S. griseus protein degradability estimates were compared with in situ estimates for masticate samples, no differences (P > 0.10) were detected early in the season (April to June). However, the S. griseus procedure overestimated in situ values (P < 0.01) by an average of 3 percentage units in samples obtained between July and October. Differences in composition of C and M samples were substantial until late season, when opportunities for selective grazing were minimal. Small differences between S. griseus and in situ estimates of CP degradability indicate that the S. griseus procedure can yield useful CP degradability estimates for fescue-based pasture samples. Although it might be possible to apply correction values to clipped samples to estimate CP and fiber concentrations of diets selected by grazing cattle, inconsistent relationships preclude this approach for estimates of CP degradability.

Macrophages at the skeletal tissue-device interface of loosened prosthetic devices express bone-related genes and their products.

Aseptic loosening of prosthetic arthroplasty is the most common reason for implant failure in adult orthopaedic reconstruction. At the interface of aseptic loosened prostheses, there is an abundance of particle-activated macrophages and other inflammatory cells. The role of these particle-laden macrophages in the osteogenic arm of the remodeling skeleton in this pathological condition is poorly understood. Molecular signaling by mesenchymal cells and mononuclear inflammatory cells residing in the interfacial tissues between bone and cement or prosthetic material of aseptically loosened joint prostheses was studied using in situ hybridization and immunohistochemical techniques. We found that a range of collagenous and noncollagenous matrix proteins, including osteopontin, osteocalcin, bone sialoprotein, and type I collagen, were produced in the periprosthetic tissue by foamy macrophages, as well as nearby osteogenic cells. The former accumulated in profusion in the three zones of interfacial tissues: pseudomembranous, fibrous, and osseous. Spindle mesenchymal cells in the fibrous zone failed to express any of the osteogenic mRNAs or proteins sought. The expression of bone-related genes and proteins by foamy macrophages at the interface of an aseptic loosened prosthesis may contribute to the disturbance of bone remodeling at this site.