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Biomedical subjects

J Lawrence

Publications and source records attributed to J Lawrence.

At least 19 recordsLinked to original sources
PubMed2006

Wettability modification and the subsequent manipulation of protein adsorption on a Ti6Al4V alloy by means of CO2 laser surface treatment.

Improvements in the wettability of the Ti6Al4V alloy following CO(2) laser treatment were identified as being due mainly to the increase in surface roughness, surface oxygen content and surface energy of the material. Untreated and mechanically roughened samples had higher amounts of adsorbed albumin and lower amounts of adsorbed fibronectin than CO(2) laser treated samples. Moreover, as the wettability of the Ti6Al4V alloy increased the adsorbed amounts of fibronectin increased, while the adsorbed amounts of albumin decreased--indicating the controllability of the CO(2) laser process. From this finding it is possible to assert that the wettability of the Ti6Al4V alloy was the prime influence on the observed changes in in vitro protein adsorption. Further, the noted considerable change in the polar component of surface energy, [Formula: see text], on the protein adsorption implied that the protein adsorption on the Ti6Al4V alloy was probably due to the polar and chemical interactions. This work has demonstrated that CO(2) laser radiation could be a suitable means to modify the wettability of the Ti6Al4V alloy and thereby manipulate protein adsorption and consequently render the material more bone cell responsive.

Adhesiveness↗
PubMed2006

Structured treatment interruptions (STI) in chronic unsuppressed HIV infection in adults.

BACKGROUND: Structured treatment interruptions (STI) of antiretroviral therapy (ART) have been investigated as part of novel treatment strategies, with different aims and objectives depending on the populations involved. These populations include: 1) patients who initiate ART during acute HIV infection; 2) patients with chronic HIV infection, on ART, with successfully suppressed viremia; and 3) patients with chronic HIV infection and treatment failure, with persistent viremia due to multi-drug resistant HIV (Hirschel 2001; Deeks 2002; Miller 2003). In an earlier Cochrane review (Pai 2005), we had summarized the evidence about the effects of STI in chronic suppressed HIV infection. In this review, we summarize the evidence on STI in patients with chronic unsuppressed HIV infection due to drug-resistant HIV. Unsuppressed HIV infection describes those patients who cannot suppress viremia, due to the presence of multi-drug-resistant virus. It is also referred to as treatment failure. Drug resistance is identified by the presence of resistant mutations at baseline.STI as a treatment strategy in HIV-infected patients with chronic unsuppressed viremia involves interrupting ART in controlled clinical settings, for a pre-specified duration of time. These interruptions have various aims, including the following: 1) to allow wild virus to re-emerge and replace the resistant mutant virus, with the hope of improving the efficacy of a subsequent ART regimen; 2) to halt development of drug resistance and to preserve subsequent treatment options; 3) to alleviate treatment fatigue and reduce drug-related adverse effects; and 4) to improve quality of life (Miller 2003; Montaner 2001; Vella 2000;). OBJECTIVES: The objective of our systematic review was to synthesize the evidence on the effect of structured treatment interruptions in adult patients with chronic unsuppressed HIV infection. SEARCH STRATEGY: We included all available intervention studies (randomized controlled trials and non-randomized trials) conducted in HIV-infected patients worldwide. We searched nine databases, covering the period from January 1996 to February 2006. We also scanned bibliographies of relevant studies and contacted experts in the field to identify unpublished research, abstracts and ongoing trials. In the first screen, a total of 3186 potentially eligible citations from nine databases and sources were identified, of which 2047 duplicate citations were excluded. The remaining 1139 citations were examined in detail, and we further excluded 951 citations that were modeling studies, animal studies, case reports, and opinion pieces. As shown in Figure 01, 188 citations were identified in the second screen as relevant for full-text screening. Of these, 60 basic science studies, editorials and abstracts were excluded and 128 full-text articles were retrieved. In the third screen, all full-text articles were examined for eligibility in our review. These were subclassified into three categories: 1) chronic suppressed HIV infection; 2) chronic unsuppressed HIV infection; and 3) acute HIV infection. Studies were further excluded if their abstracts did not contain enough information for inclusion in our reviews. A total of 62 studies were finally classified into chronic suppressed, acute, and chronic unsuppressed categories. Of these, 17 trials met the eligibility criteria for this review. SELECTION CRITERIA: Inclusion criteriaAll available randomized or non-randomized controlled trials investigating planned treatment interruptions among patients with chronic unsuppressed HIV infection. Early pilot non-randomized prospective studies on treatment interruptions of fixed and variable durations were also included. Relevant abstracts on randomized controlled trials were also included if they contained sufficient information. Exclusion criteriaEditorials, reviews, modeling studies, and basic science studies were excluded. Studies on STI among patients with chronic suppressed HIV infection were summarized in a separate review. Studies on STI in primary HIV infection were beyond the scope of this review. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted data, evaluated study eligibility and quality. Disagreements were resolved in consultation with a third reviewer.A total of seventeen studies on STI were included in our review. However, due to significant heterogeneity across studies (i.e. in study design, populations, baseline characteristics, and reported outcomes; and in reporting of measures of effect, hazard ratios, and risk ratios), we considered it inappropriate to perform a meta-analysis. MAIN RESULTS: In early pilot non-randomized trials, a pattern was evident across studies. During treatment interruption, a decline in CD4 cell counts, increase in viral load, and a shift in the level of genotypic drug resistance towards more of a wild-type HIV virus was reported. This suggests that STI may be used to increase drug susceptibility to an optimized salvage regimen upon treatment re-initiation. These studies generated useful data and hypotheses that were later tested in randomized controlled trials. Randomized controlled trials rated high on quality. Of the eight randomized controlled trials reviewed, seven had been completed while one was ongoing and remains blinded. Of the seven completed randomized controlled trials, six have reported consistent virologic and immunologic patterns, and found no significant benefit in virologic response to subsequent ART in the STI arm, compared to the control arm. In addition, the largest completed randomized trial reported greater numbers of clinical disease progression events and evidence of prolonged negative impact on CD4 cell counts in the STI arm (Beatty 2005; Benson 2004; Deeks 2001; Lawrence 2003; Walmsley 2005; Ruiz 2003). The single RCT with divergent findings from the others (GigHAART), reporting a significant virologic and immunologic benefit due to STI, was different in prescribing a shorter STI duration and a salvage ART regimen of 8-9 drugs. There were also differences in the patient population characteristics with this study, targeting those with very advanced HIV disease (Katlama 2004). Although we await the unblinded results of the eighth RCT (OPTIMA), the evidence so far does not support STI in the setting of chronic unsuppressed HIV infection with antiretroviral treatment failure (Brown 2004; Holodniy 2004; Kyriakides 2002; Singer 2006). AUTHORS' CONCLUSIONS: The current available evidence primarily supports a lack of benefit of STI before switching therapy in patients with unsuppressed HIV viremia despite ART. There is evidence of harm in attempting STI in patients with relatively advanced HIV disease, due to the associated CD4 cell decline and the increased risk of clinical disease progression. At this time, there is no evidence to recommend the use of STI in this clinical category of patients with treatment failure.

Adult↗
PubMed2006

Fine mapping of a susceptibility locus for bipolar and genetically related unipolar affective disorders, to a region containing the C21ORF29 and TRPM2 genes on chromosome 21q22.3.

Linkage analyses of bipolar families have confirmed that there is a susceptibility locus near the telomere on chromosome 21q. To fine map this locus we carried out tests of allelic association using 30 genetic markers near the telomere at 21q22.3 in 600 bipolar research subjects and 450 ancestrally matched supernormal control subjects. We found significant allelic association with the microsatellite markers D21S171 (P=0.016) and two closely linked single-nucleotide polymorphisms, rs1556314 (P=0.008) and rs1785467 (P=0.025). A test of association with a three locus haplotype across the susceptibility region was significant with a permutation test of P=0.011. A two SNP haplotype was also significantly associated with bipolar disorder (P=0.01). Only two brain expressed genes, TRPM2 and C21ORF29 (TSPEAR), are present in the associated region. TRPM2 encodes a calcium channel receptor and TSPEAR encodes a peptide with repeats associated with epilepsy in the mouse. DNA from subjects who had inherited the associated marker alleles was sequenced. A base pair change (rs1556314) in exon 11 of TRPM2, which caused a change from an aspartic acid to a glutamic acid at peptide position 543 was found. This SNP showed the strongest association with bipolar disorder (P=0.008). Deletion of exon 11 of TRPM2 is known to cause dysregulation of cellular calcium homeostasis in response to oxidative stress. A second nonconservative change from arginine to cysteine at position 755 in TRPM2 (ss48297761) was also detected. A third nonconservative change from histidine to glutamic acid was found in exon 8 of TSPEAR. These changes need further investigation to establish any aetiological role in bipolar disorder.

Amino Acid Substitution↗
PubMed2006

Albumin and fibronectin protein adsorption on CO2-laser-modified biograde stainless steel.

The surface properties of a biomaterial play an essential role in protein adsorption, which in turn determines the cellular response to the adsorbed surface. In order to obtain a surface that would yield favourable protein adsorption for successful cellular response, the surface properties of a biograde stainless steel were modified by CO2 laser treatment. An investigation of the CO2-laser-modified surface properties and the effects thereof on the adsorption of human serum albumin (no-cell adhesive) and human plasma fibronectin (cell adhesive) was conducted. It was found that the thickness of the adsorbed fibronectin layer increased with increasing CO2 laser power density, while the thickness of the adsorbed albumin layer decreased with increasing CO2 laser power density. The surface roughness and wettability characteristics contributed to the observed changes in protein adsorption. The wettability characteristics of the biograde stainless steel were found to be the predominant mechanism governing the observed change in protein adsorption. Since the wettability characteristics of the biograde stainless steel can be modified in an efficient and controllable way with the CO2 laser, it is believed that this work presents a demonstrable alternative to the techniques currently available for enhancing the biocompatibility of biograde stainless steels.

Adsorption↗
PubMed2005

Structured treatment interruptions (STI) in chronic suppressed HIV infection in adults.

BACKGROUND: Although antiretroviral treatment (ART) has led to a decline in morbidity and mortality of HIV-infected patients in developed countries, it has also presented challenges. These challenges include increases in pill burden; adherence to treatment; development of resistance and treatment failure; development of drug toxicities; and increase in cost of HIV treatment and care. These issues stimulated interest in investigating the short-term and long-term consequences of discontinuing ART, thus providing support for research in structured treatment interruptions (STI). Structured treatment interruptions of antiretroviral treatment involve taking supervised breaks from ART. STI are defined as one or more planned, timing pre-specified, cyclical interruptions in ART. STI are attempted in monitored clinical settings in eligible participants. STI have generated hopes of reducing drug toxicities, decreasing costs and total time on treatment in HIV-positive patients. The first STI was attempted in the case of a patient in Germany, who later permanently discontinued treatment. This successful anecdotal case report led to several trials on STI worldwide. OBJECTIVES: The objective of this systematic review was to assess the effects of structured treatment interruptions (STI) of antiretroviral therapy (ART) in the management of chronic suppressed HIV infection, using all available high-quality studies. SEARCH STRATEGY: Nine databases covering the time period from January 1996 to March 2005 were searched. Bibliographies were scanned and experts contacted in the field to identify unpublished research and ongoing trials. Two reviewers independently extracted data, and evaluated study eligibility and quality. Disagreements were resolved in consultation with a third reviewer. Data from 33 studies were included in the review. SELECTION CRITERIA: STI is a planned, timing pre-specified experimental intervention. In our review, we decided to include all available intervention trials in HIV-infected patients, with or without control groups. We reviewed evidence from 18 randomized and non-randomized controlled trials, and 15 single arm trials. Single arm trials were included because these pilot studies made significant contribution to the early development and refutation of hypotheses in STI. DATA COLLECTION AND ANALYSIS: Trials included in this review varied in study participants, methodology and reported inconsistent measures of effect. Due to this heterogeneity, we did not attempt to meta-analyse them. Results were tabulated and a qualitative systematic review was done MAIN RESULTS: For the purpose of this review, STI strategies were classified either as a timed-cycle STI strategy or a CD4-guided STI strategy. In timed-cycle STI strategy, a predetermined period of fixed duration (e.g. one week, one month) off ART was attempted followed by resumption of ART, while closely monitoring changes in CD4 levels and viral load levels. Predetermined criteria for interruption and resumption were laid out in this strategy. Timed-cycle STI fell out of favor due to reports of development of resistance in many studies. Moreover, there were no significant immunological and virological benefits, and no reduction in toxicities, reported in these studies. In CD4-guided STI strategy, ART was interrupted for variable durations guided by CD4 levels. Participants with high nadir CD4 levels qualified for this approach. A reduction in costs of ART, a reduction in mutation, and a better tolerability of this CD4-guided STI strategy was reported. However, concerns about long-term safety of this strategy on immunological, virological, and clinical outcomes were also raised. AUTHORS' CONCLUSIONS: Timed-cycle STI have not been proven to be safe in the short term. Although CD4-guided STI strategy has reported favorable outcomes in the short term, the long-term safety, efficacy and tolerability of this strategy has not been fully investigated. Based on the studies we reviewed, the evidence to support the use of timed-cycle STI and CD4-guided STI cycles as a standard of care in the management of chronic suppressed HIV infection is inconclusive.

Adult↗
PubMed2005

Enhanced human osteoblast cell adhesion and proliferation on 316 LS stainless steel by means of CO2 laser surface treatment.

An effective and novel technique for improving the biocompatibility of a biograde 316 LS stainless steel through the application of CO(2) laser treatment to modify the surface properties of the material is described herein. Different surface properties, such as surface roughness, surface oxygen content, and surface energy for CO(2) laser-treated 316 LS stainless steel, untreated, and mechanically roughened samples were analyzed, and their effects on the wettability characteristics of the material were studied. It was found that modification of the wettability characteristics of the 316 LS stainless steel following CO(2) laser treatment was achieved. This improvement was identified as being mainly due to the change in the polar component of the surface energy. One-day cell adhesion tests showed that cells not only adhered and spread better, but also grew faster on the CO(2) laser-treated sample than on either the untreated or mechanically roughened sample. Further, compared with the untreated sample, MTT cell proliferation analysis revealed that the mechanically roughed surface resulted in a slight enhancement, and CO(2) laser treatment brought about a significant increase in cell proliferation. An increase in the wettability of the 316 LS stainless steel was observed to positively correlate with the cell proliferation.

Biocompatible Materials↗
PubMed2005

Osteoblast cell adhesion on a laser modified zirconia based bioceramic.

Due to their attractive mechanical properties, bioinert zirconia bioceramics are frequently used in the high load-bearing sites such as orthopaedic and dental implants, but they are chemically inert and do not naturally form a direct bond with bone and thus do not provide osseointegration. A CO2 laser was used to modify the surface properties with the aim to achieve osseointegration between bioinert zirconia and bone. The surface characterisation revealed that the surface roughness decreased and solidified microstructure occurred after laser treatment. Higher wettability characteristics generated by the CO2 laser treatment was primarily due to the enhancement of the surface energy, particularly the polar component, determined by microstructural changes. An in vitro test using human fetal osteoblast cells (hFOB) revealed that osteoblast cells adhere better on the laser treated sample than the untreated sample. The change in the wettability characteristics could be the main mechanism governing the osteoblast cell adhesion on the YPSZ.

Biocompatible Materials↗
PubMed2005

Adaptive hypersensitivity to estrogen: mechanisms and clinical relevance to aromatase inhibitor therapy in breast cancer treatment.

Breast tumors in women can adapt to endocrine deprivation therapy by developing hypersensitivity to estradiol. For this reason, aromatase inhibitors can be effective in women relapsing after treatment with tamoxifen or following oophorectomy. To understand the mechanisms responsible, we examined estrogenic stimulation of cell proliferation in a model system and provided in vitro and in vivo evidence that long-term estradiol deprivation (LTED) causes "adaptive hypersensitivity". The primary mechanisms responsible involve up-regulation of ER alpha as well as the MAP kinase, PI-3 kinase, and mTOR growth factor pathways. ER alpha is 4-10-fold up-regulated and co-opts a classical growth factor pathway using Shc, Grb2, and Sos. This induces rapid non-genomic effects which are enhanced in LTED cells. Estradiol binds to cell membrane associated ER alpha, physically associates with the adaptor protein Shc, and induces its phosphorylation. In turn, Shc binds Grb2 and Sos which result in the rapid activation of MAP kinase. These non-genomic effects of estradiol produce biologic effects as evidenced by Elk activation and by morphologic changes in cell membranes. Additional effects include activation of PI-3 kinase and mTOR pathways through estradiol induced binding of ER alpha to the IGF-1 and EGF receptors. Further proof of the non-genomic effects of estradiol involved use of "designer" cells which selectively express ER alpha in nucleus, cytosol, and cell membrane. We have used a new downstream inhibitor of these pathways, farnesyl-thio-salicylic acid (FTS), to block proliferation in hypersensitive cells as a model for a potentially effective strategy for treatment of patients.

Animals↗
PubMed2005

Long-term estradiol deprivation in breast cancer cells up-regulates growth factor signaling and enhances estrogen sensitivity.

Deprivation of estrogen causes breast tumors in women to adapt and develop enhanced sensitivity to this steroid. Accordingly, women relapsing after treatment with oophorectomy, which substantially lowers estradiol for a prolonged period, respond secondarily to aromatase inhibitors with tumor regression. We have utilized in vitro and in vivo model systems to examine the biologic processes whereby long-term estradiol deprivation (LTED) causes cells to adapt and develop hypersensitivity to estradiol. Several mechanisms are associated with this response, including up-regulation of estrogen receptor-alpha (ERalpha) and the MAP kinase, phosphoinositol 3 kinase (PI3-K) and mammalian target of rapamycin (mTOR) growth factor pathways. ERalpha is four- to tenfold up-regulated and co-opts a classical growth factor pathway using Shc, Grb-2 and Sos. This induces rapid non-genomic effects which are enhanced in LTED cells. The molecules involved in the non-genomic signaling process have been identified. Estradiol binds to cell membrane-associated ERalpha, which physically associates with the adaptor protein Shc, and induces its phosphorylation. In turn, Shc binds Grb-2 and Sos, which result in the rapid activation of MAP kinase. These non-genomic effects of estradiol produce biologic effects as evidenced by Elk-1 activation and by morphologic changes in cell membranes. Additional effects include activation of the PI3-K and mTOR pathways through estradiol-induced binding of ERalpha to the IGF-I and epidermal growth factor receptors. A major question is how ERalpha locates in the plasma membrane since it does not contain an inherent membrane localization signal. We have provided evidence that the IGF-I receptor serves as an anchor for ERalpha in the plasma membrane. Estradiol causes phosphorylation of the adaptor protein, Shc and the IGF-I receptor itself. Shc, after binding to ERalpha, serves as the 'bus' which carries ERalpha to Shc-binding sites on the activated IGF-I receptors. Use of small inhibitor (si) RNA methodology to knockdown Shc allows the conclusion that Shc is needed for ERalpha to localize in the plasma membrane. In order to abrogate growth factor-induced hypersensitivity, we have utilized a drug, farnesylthiosalicylic acid, which blocks the binding of GTP-Ras to its membrane acceptor protein, galectin 1, and reduces the activation of MAP kinase. We have also shown that this drug is a potent inhibitor of mTOR as an additional mechanism of inhibition of cell proliferation. The concept of 'adaptive hypersensitivity' and the mechanisms responsible for this phenomenon have important clinical implications. The efficacy of aromatase inhibitors in patients relapsing on tamoxifen could be explained by this mechanism and inhibitors of growth factor pathways should reverse the hypersensitivity phenomenon and result in prolongation of the efficacy of hormonal therapy for breast cancer.

Adaptor Proteins, Signal Transducing↗
PubMed2004

On the role of CO2 laser treatment in the human serum albumin and human plasma fibronectin adsorption on zirconia (MGO-PSZ) bioceramic surface.

The nature of the surface strongly influences the composition and recognizability of the adsorbed protein layer, which in turn affects the subsequent cellular interactions. Thus, to understand the biological response to a material, especially in vitro, one must fully understand the nature of the adsorbed protein film that forms on the material. This study investigates the fundamental interactions between the human serum albumin (no-cell adhesive) and human plasma fibronectin and bioinert ceramic following CO(2) laser treatment. The analysis of the albumin and fibronectin adsorption was conducted on the untreated and CO(2) laser-modified magnesia partially stabilized zirconia (MgO-PSZ) bioceramic using an ellipsometry. It was found that the adsorptions of albumin and fibronectin were influenced by the surface properties. The albumin adsorption was affected by the surface roughness and wettability characteristics of the MgO-PSZ and decreased with these properties, while the fibronectin adsorption was increased with wettability characteristics and predominantly governed by this property. Moreover, the considerable change in the polar component of surface energy, gamma(sv) (p), and its effect on protein adsorption implied that the albumin and fibronectin adsorption on the MgO-PSZ surfaces was probably due to the polar and chemical interactions. The value of this work is to provide a novel technique and useful information for manipulating protein adsorption and thereof cellular interactions.

Biocompatible Materials↗
PubMed2004

Randomized controlled trial of yoga and exercise in multiple sclerosis.

OBJECTIVE: To determine the effect of yoga and of aerobic exercise on cognitive function, fatigue, mood, and quality of life in multiple sclerosis (MS). METHODS: Subjects with clinically definite MS and Expanded Disability Status Score less than or equal to 6.0 were randomly assigned to one of three groups lasting 6 months: weekly Iyengar yoga class along with home practice, weekly exercise class using a stationary bicycle along with home exercise, or a waiting-list control group. Outcome assessments performed at baseline and at the end of the 6-month period included a battery of cognitive measures focused on attention, physiologic measures of alertness, Profile of Mood States, State-Trait Anxiety Inventory, Multi-Dimensional Fatigue Inventory (MFI), and Short Form (SF)-36 health-related quality of life. RESULTS: Sixty-nine subjects were recruited and randomized. Twelve subjects did not finish the 6-month intervention. There were no adverse events related to the intervention. There were no effects from either of the active interventions on either of the primary outcome measures of attention or alertness. Both active interventions produced improvement in secondary measures of fatigue compared to the control group: Energy and Fatigue (Vitality) on the SF-36 and general fatigue on the MFI. There were no clear changes in mood related to yoga or exercise. CONCLUSION: Subjects with MS participating in either a 6-month yoga class or exercise class showed significant improvement in measures of fatigue compared to a waiting-list control group. There was no relative improvement of cognitive function in either of the intervention groups.

Adult↗
PubMed2004

The adsorption of human serum albumin (HSA) on CO2 laser modified magnesia partially stabilised zirconia (MgO-PSZ).

Magnesia partially stabilised zirconia (MgO-PSZ), a bioinert ceramic, exhibits high mechanical strength, excellent corrosion resistance and good biocompatibility, but it does not naturally form a direct bond with bone resulting in a lack of osteointegration. The surface properties and structure of a biomaterial play an essential role in protein adsorption. As such, changes in the surface properties and structure of biomaterials may in turn alter their bioactivity. So, the fundamental reactions at the interface of biomaterials and tissue should influence their integration and bone-bonding properties. To this end, CO2 laser radiation was used to modify the surface roughness, crystal size, phase and surface energy of the MgO-PSZ. The basic mechanisms active in improving the surface energy were analysed and found to be the phase change and augmented surface area. The adsorption of human serum albumin (HSA), which is a non-cell adhesive protein, was compared on the untreated and CO2 laser modified MgO-PSZ. It was observed that the thickness of the adsorbed HSA decreased as the polar surface energy of the MgO-PSZ increased, indicating that HSA adsorbed more effectively on the hydrophobic MgO-PSZ surface than the hydrophilic surface. The current study provided important information regarding protein-biomaterial interactions and possible mechanisms behind the cell interaction and in vivo behaviour.

Adsorption↗
PubMed2004

The formation of a hydroxyl bond and the effects thereof on bone-like apatite formation on a magnesia partially stabilized zirconia (MgO-PSZ) bioceramic following CO2 laser irradiation.

For the purpose of improving the bioactivity of a magnesia partially stabilized zirconia (MgO-PSZ) and to explore a new technique for inducing OH group and apatite formation, a CO(2) laser has been used to modified the surface properties. The bioactivity of the CO(2) laser modified MgO-PSZ has been investigated in stimulated human fluids (SBF) with ion concentrations almost equal to those in human blood plasma. Some hydroxyl groups were found on the MgO-PSZ following CO(2) laser treatment with selected power densities. The surface melting on the MgO-PSZ induced by CO(2) laser processing provides the Zr(4+) ion and OH(-) ion, in turn, the incorporation of the Zr(4+) ion and the OH(-) ion creates the Zr-OH group on the surface. After 14 days of SBF soaking, the apatites formed on the MgO-PSZ with relatively high amount of hydroxyl groups generated by the CO(2) laser treatment, while no apatite was observed on the untreated with few hydroxyl groups. It exhibits that the Zr-OH groups on the MgO-PSZ surface is the functional groups to facilitate the apatite formation. The increased surface roughness provides more active sites, meantime, increased surface energy benefits to the adsorption and reaction on the surface.

Adsorption↗
PubMed2004

Effects of CO2 laser irradiation on the surface properties of magnesia-partially stabilised zirconia (MgO-PSZ) bioceramic and the subsequent improvements in human osteoblast cell adhesion.

In order to acquire the surface properties favouring osseo-integration at the implant and bone interface, human foetal osteoblast cells (hFOB) were used in an in vitro test to examine changes in cell adhesion on a magnesia-partially stabilised zirconia (MgO-PSZ) bioceramic after CO(2) laser treatment. The surface roughness, microstructure, crystal size and surface energy of untreated and CO(2) laser-treated MgO-PSZ were fully characterised. The in vitro cell evaluation revealed a more favourable cell response on the CO(2) laser-treated MgO-PSZ than on the untreated sample. After 24-h cell incubation, no cell was observed on the MgO-PSZ, whereas a few cells attached on the CO(2) laser-treated MgO-PSZandshowedwellspreadandgood attachment. Moreover, the cell coverage density indicating cell proliferation generally increases with CO(2) laser power densities applied in the experiments. The enhancement of the surface energy of the MgO-PSZ, especially its polar component caused by the CO(2) laser treatment, was found to play a significant role in the initial cell attaching, thus enhancing the cell growth. Moreover, the change in topography induced by the CO(2) laser treatment was identified as one of the factors influencing the hFOB cell response.

Bone Substitutes↗
PubMed2003

Batches of intravenous immunoglobulin associated with adverse reactions in recipients contain atypically high anti-Rh D activity.

BACKGROUND AND OBJECTIVES: The presence of anti-Rh D in intravenous immunoglobulin (IVIG) products has been claimed to be associated with adverse reactions in recipients. There is currently no regulatory specification to control the level of anti-D in IVIG products and it is unclear what this should be. Two reports of haemolysis occurring in recipients of IVIG manufactured from US plasma provided a rare opportunity to investigate whether high anti-D levels could have induced the haemolysis. MATERIALS AND METHODS: We developed a direct microtitre plate haemagglutination method suitable for screening IVIG products and starting plasma pools for haemagglutinating activity. RESULTS: Of 101 batches of IVIG tested, six were found to contain specific anti-D. Four of these batches had anti-D titres ranging from 64 to 256 (including the two batches each associated with a report of haemolysis) and could be linked, in each case, to a starting plasma pool also positive for anti-D. CONCLUSIONS: Our results show that IVIG products can contain appreciable anti-D levels. To avoid potential problems in recipients, we propose an anti-D titre of 8 as the maximum permissible limit of anti-D in IVIG products for batch acceptance and release. The availability of a reference preparation is essential for control of this proposed requirement.

Blood Cells↗