Epoetin alfa in platinum-treated ovarian cancer patients: results of a multinational, multicentre, randomised trial

This multicentre, open-label, controlled clinical trial assessed the effects of epoetin alfa treatment on haematologic and quality of life (QOL) parameters in 182 anaemic (Hb⩽12 g dl⁻¹) ovarian cancer patients receiving platinum chemotherapy. Patients were randomised 2 : 1 to receive epoetin alfa 10 000–20 000 IU three times weekly plus best standard treatment (BST) or BST only. Main study end points were changes from baseline in haemoglobin (Hb) level, transfusion requirements, and QOL. For the epoetin alfa group, mean Hb increased by 1.8 g dl⁻¹ by weeks 4–6 and was significantly increased from baseline through study end (P<0.001). The mean change in Hb from baseline was significantly (P<0.001) greater for epoetin alfa than BST patients at all postbaseline evaluations. Significantly fewer epoetin alfa than BST patients required transfusion(s) after the first 4 weeks of treatment (7.9 vs 30.5%; P<0.001). Also, significant (P⩽0.04) differences favouring the epoetin alfa group over the BST group were found for all three median CLAS scores (Energy Level, Ability to Do Daily Activities, Overall QOL) and the median average CLAS score during chemotherapy. These findings support use of epoetin alfa to increase Hb levels, reduce transfusion use, and improve QOL in anaemic ovarian cancer patients receiving platinum chemotherapy.

Recombinant human vascular endothelial growth factor enhances bone healing in an experimental nonunion model

The re-establishment of vascularity is an early event in fracture healing; upregulation of angiogenesis may therefore promote the formation of bone. We have investigated the capacity of vascular endothelial growth factor (VEGF) to stimulate the formation of bone in an experimental atrophic nonunion model.

Three groups of eight rabbits underwent a standard nonunion operation. This was followed by interfragmentary deposition of 100 μg VEGF, carrier alone or autograft.

After seven weeks, torsional failure tests and callus size confirmed that VEGF-treated osteotomies had united whereas the carrier-treated osteotomies failed to unite. The biomechanical properties of the groups treated with VEGF and autograft were identical. There was no difference in bone blood flow.

We considered that VEGF stimulated the formation of competent bone in an environment deprived of its normal vascularisation and osteoprogenitor cell supply. It could be used to enhance the healing of fractures predisposed to nonunion.

Gemcitabine twice weekly as a radiosensitiser for the treatment of brain metastases in patients with carcinoma: a phase I study

Conventional treatment for brain metastases (BM) is whole-brain radiotherapy (WBRT). Efficacy is poor. It might be increased by a potent radiosensitiser such as gemcitabine which is believed to cross the disrupted blood–brain barrier. Primary objective of this study was to determine the maximum tolerated dose (MTD) of twice weekly gemcitabine given concurrently with WBRT. Patients with BM from carcinoma were included. The dose of WBRT was 30 Gys (10 daily fractions). Gemcitabine was given 2–4 h prior to WBRT on days 1 and 8 for the first cohort of patients and then on days 1, 4, 8 and 11. Starting dose was 25 mg m⁻², escalated by 12.5 mg m⁻² increments. At least three patients were included per level. Dose limiting toxicity (DLT) was defined as grade 4 haematological or grade ⩾3 nonhaematological toxicity. A total of 25 patients were included; 74% had a PS 1 (ECOG). In all, 23 had non-small-cell lung cancer, six colorectal, four breast, two renal cell and one oesophageal carcinoma. A total of 92% had concurrent extracranial disease. Six had single BM, 13 had two or three BM and six multiple. Up to 50 mg m⁻² (level 4) no DLT was observed. At 62.5 mg m⁻², one out of six patients developed DLT (thrombocytopenia-bleeding). The next dose level (75 mg m⁻²) was abandoned after grade 4 bone marrow toxicity (fatal neutropenic sepsis) was seen in one out of two patients. So that the dose of 50 mg m⁻² will be taken forward for further study.

Randomized phase II study of two gemcitabine schedules for patients with impaired performance status (Karnofsky performance status </= 70) and advanced non-small-cell lung cancer

PURPOSE

This randomized phase II study compared two treatment schedules of gemcitabine in patients with non-small-cell lung cancer (NSCLC) and impaired Karnofsky performance status (KP). Primary objectives were to record changes from baseline KP and to assess symptom palliation. Secondary objectives were overall survival, tumor response, and toxicity.

PATIENTS AND METHODS

Patients with stage IIIb and IV NSCLC and KP </= 70 were randomly assigned to receive gemcitabine 1,000 mg/m(2) on days 1, 8, and 15 of each 28-day cycle (3w4) or gemcitabine 1,500 mg/m(2) on days 1 and 8 of each 21-day cycle (2w3), both for up to six cycles. KP, toxicity, and SS14 lung cancer specific questions were recorded before each cycle of treatment. Response was evaluated 4 weeks after the last cycle.

RESULTS

One hundred seventy-four patients were enrolled. There was significant early attrition due to disease progression; only 61.5% of patients were alive at 2 months. There was a significant improvement in KP from baseline to pre-cycle 3 in both arms, with a trend in favor of the 3w4 regimen for duration and faster onset of improvement. Eight of the 17 quality-of-life (QOL) variables assessed showed an improvement of more than 10% between baseline and the start of the third cycle of treatment. Response rate, survival, and duration were similar in both arms.

CONCLUSION

There was no significant difference between the two schedules examined in terms of improvement in KP or QOL, but there seemed to be a trend in favor of the 3w4 schedule.

Phase II studies of BBR3464, a novel tri-nuclear platinum complex, in patients with gastric or gastro-oesophageal adenocarcinoma

BBR3464, a novel tri-nuclear platinum complex, forms long-range DNA adducts and is highly potent when compared with cisplatin in vitro. Preclinical studies demonstrated activity in cisplatin-resistant tumours and tumours with mutated p53 status. Phase I & II clinical studies gave preliminary indications of activity in melanoma, pancreatic, lung and ovarian cancers. The aim of this study was to determine the efficacy and confirm the toxicity of BBR3464 when given either as first- or second-line treatment for advanced disease in patients with gastric and gastro-oesphageal adenocarcinoma. Two multicentre, open label, Gehan design studies were conducted; one study used BBR3464 as first-line and the other as second-line treatment for metastatic or locally advanced disease. Nineteen first-line and 26 second-line patients were enrolled receiving a total of 74 and 53 infusions, respectively. Initially, seven patients in the second-line study received BBR3464 using the planned schedule of 1.1 mg/m2 every 4 weeks; however, 5 of these patients experienced dose-limiting grade 3 or 4 febrile neutropenia; subsequent patients in both studies were treated using the modified schedule of 0.9 mg/m2, every 21 days. In 1 of 17 evaluable, previously untreated patients, regression of multiple skin lesions was noted with stabilisation of lung metastases and maxillary sinus mass, lasting 155 days. In the first-line study, the median time to progression was 85 days [95% Confidence Interval (CI): 42, 127] (2.8 months) and in the second-line study, the median time to progression was 71 days [95% CI: 42, 109] and 38 days [95% CI: 32, 73] in the 1.1 and 0.9 mg/m2 dose level groups, respectively. Toxicity data were available for 45 patients. Neutropenia was the main toxicity seen (G3: 40%, G4: 40%). Febrile neutropenia was observed in six patients (15%) treated with 0.9 mg/m2 compared with five patients (71%) treated with 1.1 mg/m2 BBR3464. Other drug-related toxicities (G3/4) included: anaemia, thrombocytopenia, nausea, vomiting, diarrhoea, mucositis and fatigue. Diarrhoea and nausea/ vomiting were adequately controlled by the use of loperamide and antiemetics, respectively. Recruitment to the second-line study was closed early due to the poor response rate (1/17 evaluable, 6%; 95% CI: 1%, 27%) and short time to progression noted in the first-line study. Further studies with BBR3464 in this tumour type are not recommended.

Nurses' ethical perceptions about coercion

PURPOSE OF THE STUDY

The purpose of this study was to describe Finnish psychiatric nurses' ethical perceptions about coercive measures in acute psychiatric setting.

METHODS

The data were collected with a questionnaire developed for this study. The sample included 170 Finnish psychiatric nurses on acute wards in five psychiatric hospitals. The data were analysed using frequency and percentage distributions, mean and standard deviations. The internal consistency of the instrument was explored with Cronbach's alpha. The association between the background variables and the sum score of the items of the questionnaire was tested with Mann-Whitney U-test and Kruskal-Wallis test. The open-ended question was analysed with content analysis.

RESULTS

Some psychiatric nurses perceived coercive measures as ethically problematic. In particular, the implementation of forced medication (18%), four-point restraints (16%) and patient seclusion (11%) were perceived as ethically problematic. Female nurses and nurses who worked on closed wards perceived the measures to be more problematic than male nurses and nurses who did not work on closed wards.

CONCLUSION

In Finland, special attention has been paid to ethical questions related to the care of psychiatric patients and to the enhancement of patients' rights, yet the majority of the nurses participating in the survey did not perceive coercive measures as ethically problematic. More research on this issue as well as further education of the personnel and more extensive teaching of ethics in nursing schools are needed to support the ability of the psychiatric personnel to identify ethically problematic situations. In addition, it is important to consider new measures for generating genuine moral reflection among the personnel on the usage of coercive measures as well as on their effectiveness and legitimacy in the psychiatric care.

Expression of Cox-2 protein in radioresistant laryngeal cancer

BACKGROUND

Radiotherapy is the principal modality used to treat early stage laryngeal cancer. Unfortunately treatment failures occur in 10-25% of patients. Subsequent salvage surgery is technically more difficult, with increased complication and failure rates. The ability to predict or prevent radioresistance would improve the poor survival associated with this disease. Cox-2 is an inducible enzyme involved with prostaglandin synthesis. We investigated a potential role for Cox-2 in predicting radioresistance in laryngeal cancer.

PATIENTS AND METHODS

Using immunohistochemical techniques we examined the expression of Cox-2 protein in 122 pre-treatment laryngeal biopsies. All tumours were treated with single modality radiotherapy (curative intent). The group comprised of 61 radioresistant and 61 radiosensitive tumours matched for T stage, laryngeal subsite, gender and smoking history.

RESULTS

Cox-2 expression was detected in 41 of 61 (67%) biopsy samples from patients with radioresistant tumours and 25 of 61 (41%) radiosensitive tumours. Overexpression was significantly associated with radioresistant tumours (P = 0.004). Cox-2 has a 67% accuracy in predicting radiotherapy failure.

CONCLUSION

Cox-2 may have prognostic value in predicting response to radiotherapy. Cox-2 inhibitors such as NS-398 have been shown to enhance the effects of radiotherapy. We suggest that their use may be beneficial in patients who are destined to fail radiotherapy.

Semiquantitative mRNA measurements of osteoinductive growth factors in human iliac-crest bone: expression of LMP splice variants in human bone

Although osteotropic growth factors are known to play an important role in bone metabolism, knowledge about their expression in relation to age, sex and smoking remains limited. In this study we report mRNA levels of the recently discovered Lim mineralization protein splice variants (LMP-1, LMP-2, LMP-3) and the established osteotropic growth factors BMP-2, BMP-6, BMP-7, TGF-beta, IGF-I, IGF-II and b-FGF in human iliac crest bone. Standardized bone biopsy specimens were obtained from the iliac crest during graft harvesting in 62 patients (38 males, 24 females, mean age 44.7 years, range 13-78 years) undergoing spinal surgery. Samples were immediately stored in liquid nitrogen for PCR analysis. Semi-quantitative RT-PCR was performed for TGF-beta, IGF-I, IGF-II, BMP2, BMP-6, BMP7, bFGF, LMP-1, LMP-2 and LMP-3 using beta-actin as internal standard. Triplicate measurements were made of each growth factor and beta-actin. mRNA for all examined growth factors was detected in 69% of the specimens. The lowest degree of detection was present for b-FGF and BMP-2, both of which were found in 85% of the specimens. LMP-1 was detected in 98% of the specimens. LMP-2 in 94% and LMP-3 in 27%, respectively. LMP-1 was generally expressed in higher amounts than LMP-2 and LMP-3. Nondetectable levels of the growth factors were more frequent in the >60-year-old males compared with >60-year-old females ( P < 0.05) and <60-year-old males ( P < 0.01). LMP-1 expression was more variable among young individuals, but mean values were similar between age groups. TGF-beta, BMP-2 and BMP-7 values did not differ between age groups, but generally a higher variation was found among older patients. IGF-I values were significantly higher ( P < 0.05) in males over 60 years, whereas the highest level of bFGF mRNA was present in males younger than 20 years ( P < 0.05). In addition, regression analysis revealed correlation between BMP-2 and BMP-7 (R2 = 0.74, P < 0.0005), LMP-2 and BMP-2 (R2 = 0.27, P < 0.0005) and LMP-2 and bFGF (R2 = 0.40, P < 0.0005). In conclusion, we have demonstrated expression of LMP-1 and LMP-2 in human bone. LMP-1 was expressed in higher amounts and showed a higher degree of variation among young individuals. LMP-2 was correlated to a number of other growth factors, suggesting that LMPs may also play a role in human bone metabolism. Higher variation in the expression of TGF-beta, BMP-2 and BMP-7 was found in the older age groups, but whether or not this can be correlated to age-related changes in bone turnover requires further studies.

Phase II study of pemetrexed in breast cancer patients pretreated with anthracyclines

BACKGROUND

To assess antitumor activity and toxicity of pemetrexed in metastatic breast cancer (MBC) patients previously treated with anthracyclines.

PATIENTS AND METHODS

Seventy-seven MBC patients from 12 European institutions were entered into the study. Seventy-two patients were considered evaluable for response and toxicity. Forty-two patients were classified as anthracycline-failure (relapse >30 days after completion of a prior anthracycline regimen) and 30 as anthracycline-refractory (progression within 30 days after anthracycline therapy). Pemetrexed 600 mg/m(2) was administered intravenously every 3 weeks until progressive disease or unacceptable toxicity.

RESULTS

There were three complete and 12 partial responders [response rate 21% (95% confidence interval 12%)]. Response rates in the anthracycline-failure and anthracycline-refractory groups were 24% and 17%, respectively. A subset of 31 patients pretreated with anthracyclines and taxanes had a response rate of 26%. Median duration of response and median survival were 5.5 and 10.7 months, respectively (13 months in the failure group and 5.7 months for refractory). Grade 3/4 toxicities included neutropenia and thrombocytopenia in 56% and 19% of patients, respectively. Nine patients (12%) experienced neutropenic fever. Grade 3/4 non-hematological toxicities included skin rash (10%), nausea (12%), fatigue (10%) and stomatitis (5%).

CONCLUSION

Our trial demonstrates pemetrexed to be active in breast cancer, with manageable toxicity. Activity of pemetrexed did not appear to be adversely affected by prior taxane, 5-fluorouracil or endocrine treatments.

Chromosomal alterations in small cell lung cancer revealed by multicolour fluorescence in situ hybridization

Small cell lung cancer (SCLC) is a major cause of cancer related morbidity and mortality. Karyotypic studies have revealed numerous chromosomal aberrations in most SCLC however, classical G-banding analysis is unable to fully characterise complex marker chromosomes. Recent developments in molecular cytogenetics now allow accurate identification of the chromosomal components of complicated rearrangements. We have applied the technique of multicolour fluorescence in situ hybridization (M-FISH) in combination with comparative genomic hybridization (CGH) to the analysis of 5 SCLC cell lines and 1 primary tumour specimen to characterise the chromosomal abnormalities. CGH analysis identified many similarities between specimens, with frequent DNA copy number decreases on chromosomes 3p, 5q, 10, 16q, 17p and frequent gains on 3q, 1p, 1q and 14q. In contrast, M-FISH analysis revealed a large number of structural abnormalities, with each specimen demonstrating an individual pattern of chromosomal translocations. Forty different translocations were identified with the vast majority (39) being unbalanced. Chromosome 5 was the most frequently rearranged chromosome (9 translocations) followed by chromosomes 2, 10 and 16 (6 translocations each). Further investigation of these frequently involved chromosomes is warranted to establish whether consistent break points are involved in these translocations, causing dysregulation of specific genes that are crucial for tumour progression and secondly to identify the affected genes.

Impaction allografting for femoral revision hip arthroplasty. Mid-term results after minimum five year follow-up in 46 cases

Previously, only short-term follow-up results after femoral revision using impacted allograft and cemented stems the exchange technique have been published. We present the results of 46 femoral exchange revision procedures performed on 42 patients with five to nine years follow-up. At follow-up, five patients had died and two patients did not complete follow-up. Two patients were re-revised. One patient underwent re-revision due to early collapse of the impaction construct. In another patient, stem loosening due to acetabular revision occurred and a full re-revision of the impaction area was performed. One patient suffered late post-operative femoral fracture and three patients experienced hip dislocations. Ninety percent expressed satisfaction with the result. Harris Hip Score (HHS) improved from 36 to 82 (p < 0.001). Radiographically, one patient demonstrated stem subsidence of greater than 5mm. Eighty-six percent demonstrated signs of graft incorporation and only one patient demonstrated signs of loosening. Our results after a minimum of five years follow-up of patients surgically treated with the exchange femoral revision technique demonstrated good clinical and radiological results. With a re-revision rate of 4.3%, one case with subsidence exceeding 5 mm and one case with diaphyseal fracture, we did not observe the problems of subsidence and femoral fractures described in previous studies. (Hip International 2002; 4: 357-64).

The level of haemoglobin in anaemic cancer patients correlates positively with quality of life

The aim of this study was to assess the relationship between haemoglobin level and quality-of-life in anaemic cancer patients. Patients, diagnosed with one of four cancers, were recruited if their haemoglobin level was <12 g dl(-1) (female) or <13 g dl(-1) (male). The condition-specific Functional Assessment of Cancer Therapy-Anaemia and the generic SF-36 were used to assess quality-of-life. Thirty-six per cent of the 179 recruited patients had breast cancer, 28% ovarian cancer, 25% lung cancer, and 11% multiple myeloma. Their mean (s.d.) haemoglobin level was 10.66 (1.04) g dl(-1). Partial correlations controlling for the potentially confounding effects of age, gender, and time since diagnosis found significant positive relationships between haemoglobin and all domains of the Functional Assessment of Cancer Therapy-Anaemia, and with all but two of the SF-36 domains. On linear regression controlling for the same factors, each unit haemoglobin rise equalled an average 8.19 Functional Assessment of Cancer Therapy-Anaemia, and an average 6.88 Functional Assessment of Cancer Therapy-Fatigue, increase. Haemoglobin accounted for a similar amount of variability (8%) in SF-36 scores. In conclusion, quality-of-life has been found to be significantly positively related to haemoglobin level in anaemic cancer patients. This suggests that normalisation of haemoglobin in cancer patients is likely to increase their quality-of-life. The greater sensitivity of the condition-specific Functional Assessment of Cancer Therapy-Anaemia compared with the generic SF-36 suggests that the Functional Assessment of Cancer Therapy-Anaemia can be used alone to assess quality-of life in this patient group.

Karyotypic variation between independently cultured strains of the cell line MCF-7 identified by multicolour fluorescence in situ hybridization

The breast cancer cell line MCF-7 is a widely used model in breast cancer research however a number of conflicting reports have been published regarding its biological properties. We hypothesised that there will be significant in vitro mutation and genotypic evolution over time in this cell line. To assess the genetic divergence of MCF-7 at the chromosomal level, we analysed MCF-7 cell lines grown independently at three different laboratories using M-FISH and CGH. In addition, MCF-7 cells from our own laboratory were also analysed at two time points 18 months apart. Several common chromosomal translocations were identified in all variants of the cell lines. In addition, a significant number of unique abnormalities were identified, characterising each of the variants studied. Genotypic differences between cell lines grown independently in different laboratories would significantly alter the phenotypic characteristics of each cell line rendering biological properties inconsistent between laboratories.

Factors stimulating bone formation

The aim of this review is to describe major approaches for stimulating bone healing and to review other factors affecting bone healing. Spinal bone fusion after surgery is a demanding process requiring optimal conditions for clinical success. Bone formation and healing can be enhanced through various methods. Experimental studies have revealed an array of stimulative measures. These include biochemical stimulation by use of hormones and growth factors, physical stimulation through mechanical and electromagnetic measures, and bone grafting by use of bone tissue or bone substitutes. Newer biological techniques such as stem cell transplantation and gene therapy can also be used to stimulate bone healing. Apart from bone transplantation, clinical experience with the many stimulation modalities is limited. Possible areas for clinical use of these novel methods are discussed.

Fibroblast expression of C-C chemokines in response to orthopaedic biomaterial particle challenge in vitro

C-C chemokines are soluble mediators that occur in a periprosthetic granuloma and influence recruitment, localization and activation of inflammatory cells. This study tested effects of titanium and polymethylmethacrylate (PMMA) particles on expression of selected C-C chemokines in cultured human fibroblasts. The C-C chemokines analyzed included monocyte chemoattractant protein-1. 2 (MCP-1. 2), monocyte inflammatory protein-1 alpha (MIP-1 alpha), and regulated on activation, normal T-cell expressed and secreted protein (RANTES). Interleukin-1 beta (IL-1 beta) served as a known stimulator of chemokine release while interleukin-6 (IL-6) expression served as a marker for fibroblast activation. Protein and mRNA signal levels were determined by ELISA and RT-PCR, respectively. The results demonstrated that exposure of fibroblasts to titanium and PMMA particles resulted in increased release of MCP-1 in a dose- and time-dependent manner. After 24 h, titanium particles maximally upregulated MCP-1 release 7-fold while PMMA particles increased MCP-1 levels 2-fold, when compared to unchallenged fibroblasts. MCP-2, MIP-1 alpha and RANTES levels remained unchanged following exposure of fibroblasts to titanium or PMMA particles at any concentration or time point tested. However, IL-1 beta stimulated release of MCP-1, MCP-2, and RANTES, but not MIP-1 alpha from the fibroblasts. IL-1 beta, not particles, exhibited the most prominent effect on MCP-1 mRNA levels. Increased release of MCP-1 from fibroblasts exposed to titanium and PMMA particles coincided with increased release of IL-6. This study suggests that release of chemoattractant factors from fibroblasts localized in periprosthetic membranes enhances the chronic inflammatory process leading to bone resorption and implant loosening.

Interleukin-10 inhibits polymethylmethacrylate particle induced interleukin-6 and tumor necrosis factor-alpha release by human monocyte/macrophages in vitro

Periprosthetic membranes commonly observed at sites of total joint implant loosening exhibit abundant macrophages and particulate debris. Macrophages phagocytose orthopedic debris and release the pro-inflammatory mediators interleukin-1, interleukin-6, tumor necrosis factor-alpha, and prostaglandin E2. Populations of activated lymphocytes are often seen in periprosthetic membranes. These lymphocytes may modulate the monocyte/macrophage response to particulate debris and influence aseptic loosening. In addition, other immunologic agents, such as interleukin-10, are present in tissues harvested from the bone-implant interface of failed total joint arthroplasties. The present study examined the effects of interleukin-10 on polymethylmethacrylate (PMMA) particle challenged human monocyte/macrophages in vitro. Human monocyte/macrophages isolated from buffy coats of five healthy individuals were exposed to 1-10 microm PMMA particles. Interleukin-10 was added to the monocyte/macrophages with and without the addition of PMMA particles. Interleukin-10-induced alterations in monocyte/macrophage metabolism were determined measuring interleukin-6 and tumor necrosis factor-alpha release by the cells following exposure to PMMA particles. Exposure of the monocyte/macrophages to PMMA particles resulted in a dose-dependent release of interleukin-6 and tumor necrosis factor-alpha at 48 h. Interleukin-10 reduced the levels of interleukin-6 and tumor necrosis factor-alpha release by macrophages in response to PMMA particles in a dose-dependent manner. At 48 h, particle-induced interleukin-6 release was inhibited by 60 and 90% with 1.0 and 10.0 ng/ml treatments of interleukin-10, respectively. At 48 h, particle-induced tumor necrosis factor-alpha release was inhibited by 58 and 88% with 1.0 and 10.0 ng/ml treatments of interleukin-10, respectively. Interleukin-10 challenge alone did not significantly alter basal interleukin-6 or tumor necrosis factor-alpha release relative to control cultures. The data presented in this study demonstrate that the anti-inflammatory cytokine, interleukin-10, inhibits monocyte/macrophage release of the pro-inflammatory cytokines interleukin-6 and tumor necrosis factor-alpha in response to PMMA particle challenge in vitro.

Effect of osteogenic protein 1/collagen composite combined with impacted allograft around hydroxyapatite-coated titanium alloy implants is moderate

This study evaluated the effects of osteogenic protein 1/collagen composite (OP-1/col) mixed with impacted allograft around hydroxyapatite (HA)-coated titanium alloy implants in a canine model. The aim of the study was to test different doses of OP-1 growth factor in a collagen composite for stimulatory effect on allograft incorporation around an implant. Unloaded implants were inserted in each proximal humerus of 16 skeletally mature dogs. The cylindrical implants (4 x 9 mm) coated with HA were initially surrounded by a 3-mm gap into which allograft mixed with OP-1/col was impacted. Two different doses of OP-1 were investigated. In eight animals 325 mg OP-1 protein and 130 mg bovine collagen type I as carrier were mixed with the allograft chips. This composite is identical to the clinically used OP-1 device called Novus. In another eight animals a lower dose of 65 mg OP-1 protein and 130 mg bovine collagen type I was used. Control implants placed in the contralateral humerus were surrounded by allograft mixed with collagen carrier only. The dogs were euthanized at 6 weeks. Implant fixation was determined by push-out testing. Bone ingrowth and bone formation were evaluated by quantitative histomorphometry on serial sections of the bone-implant interface. Impacted allograft together with low-dose OP-1 enhanced bone volume in a zone adjacent to HA-coated titanium alloy implants. The high dose had no effect on bone formation. Mechanical fixation, bone ingrowth, and bone volume in the gap near the original trabecular bone were unaffected by both low and high OP-1/col composite. In this model and observation period, the low dose of OP-1/col composite mixed with impacted allograft has a moderate effect on bone healing around HA-coated implants and no effect on implant fixation.

Perceived structure from optic flow: consistent versus variable mapping of 3-D Euclidean structure

In an earlier study (Börjesson & Lind, 1996), the perception of Euclidean structure from polar projected two-frame apparent motion sequences was studied. The results showed that Euclidean structure is not perceived. However, at larger visual angles a certain consistency in the mapping between distal and perceived structure exists. The aim of the present study was to more precisely examine how this degree of consistency varies as a function of visual angle. In Experiments 1 and 2, slant judgments of simulated and real planes indicated that the degree of consistency is a positive function of visual angle. No definite sign of a Euclidean mapping could, however, be found even in the full view condition. Experiment 3 examined texture gradients and the response method used. The results showed that texture gradients did not influence the degree of consistency of the mapping between distal and judged depth and that the response method was both reliable and valid. However, texture gradients did influence the absolute values of the slant judgments. The role of Euclidean and affine mappings of distal structure is discussed and it is proposed that the perceptually important distinction is not between affine and Euclidean mapping, but rather between two types of affine mappings--consistent and variable.

Sealing effect of hydroxyapatite coating on peri-implant migration of particles. An experimental study in dogs

We have studied the beneficial effects of a hydroxyapatite (HA) coating on the prevention of the migration of wear debris along the implant-bone interface. We implanted a loaded HA-coated implant and a non-coated grit-blasted titanium alloy (Ti) implant in each distal femoral condyle of eight Labrador dogs. The test implant was surrounded by a gap communicating with the joint space and allowing access of joint fluid to the implant-bone interface. We injected polyethylene (PE) particles into the right knee three weeks after surgery and repeated this weekly for the following five weeks. The left knee received sham injections. The animals were killed eight weeks after surgery. Specimens from the implant-bone interface were examined under plain and polarised light. Only a few particles were found around HA-coated implants, but around Ti implants there was a large amount of particles. HA-coated implants had approximately 35% bone ingrowth, whereas Ti implants had virtually no bone ingrowth and were surrounded by a fibrous membrane. Our findings suggest that HA coating of implants is able to inhibit peri-implant migration of PE particles by creating a seal of tightly-bonded bone on the surface of the implant.