Pseudotumor of the mandible as first presentation of hemophilia in a 2-year-old male: a case report and review of jaw pseudotumors of hemophilia

Pseudotumor of hemophilia (PTH) is a rare complication seen in approximately 1-2% of cases of hemophilia. Although much more common in long bones, the pelvis, and small bones of the hands and feet than in the jaws, occasionally hemorrhage in the jaws occurs with this result. We present a case in a two-year-old male with a one-month swelling of the right mandible without significant medical history or diagnosis of hemophilia who was subsequently diagnosed as having Factor IX deficiency, or hemophilia B. A review of the literature revealed only 15 reported cases of PTH of the jaws and salient features of PTH in the jaws are discussed. The differential diagnosis of masses occurring in the jaws of children is limited and PTH should be considered when a mass presents with rapid growth and the histopathologic features are not diagnostic for a neoplastic process, even in the absence of a prior diagnosis of hemophilia as PTH may be the initial manifestation of this disease.

The role of β-blockers in the management of hypertension: an Asian perspective

Following publication of the National Institute of Clinical Excellence (NICE) Guidelines in 2006, the use of β-blockers as first-line therapy in hypertension has been somewhat controversial. However, a recent reappraisal of the European Society of Hypertension guidelines highlights that these agents exhibit similar BP lowering efficacy to other classes of agents, prompting a re-examination of the utility of these agents in various patient populations. The authors felt that it is important to address this controversy and provide an Asian perspective on the place of β-blockers in current clinical practice and the benefits of β-blockade in selected patient populations. In addition to their use as a potential first-line therapy in uncomplicated hypertension, β-blockers have a particular role in patients with hypertension and comorbidities such as heart failure or coronary artery disease, including those who had a myocardial infarction. One advantage which β-blockers offer is the additional protective effects in patients with prior cardiovascular events. Some of the disadvantages attributed to β-blockers appear more related to the older drugs in this class and further appraisal of the efficacy and safety profile of newer β-blockers will lend support to the current guideline recommendations in Asian countries and encourage increased appropriate use of β-blockade in current clinical practice within Asia.

Effect of mobile phone intervention for diabetes on glycaemic control: a meta-analysis

AIMS

  To assess the effect of mobile phone intervention on glycaemic control in diabetes self-management.

METHODS

We searched three electronic databases (PubMed, EMBASE and Cochrane Library) using the following terms: diabetes or diabetes mellitus and mobile phone or cellular phone, or text message. We also manually searched reference lists of relevant papers to identify additional studies. Clinical studies that used mobile phone intervention and reported changes in glycosylated haemoglobin (HbA(1c) ) values in patients with diabetes were reviewed. The study design, intervention methods, sample size and clinical outcomes were extracted from each trial. The results of the HbA(1c) change in the trials were pooled using meta-analysis methods.

RESULTS

  A total of 22 trials were selected for the review. Meta-analysis among 1657 participants showed that mobile phone interventions for diabetes self-management reduced HbA(1c) values by a mean of 0.5% [6 mmol/mol; 95% confidence interval, 0.3-0.7% (4-8 mmol/mol)] over a median of 6 months follow-up duration. In subgroup analysis, 11 studies among Type 2 diabetes patients reported significantly greater reduction in HbA(1c) than studies among Type 1 diabetes patients [0.8 (9 mmol/mol) vs. 0.3% (3 mmol/mol); P=0.02]. The effect of mobile phone intervention did not significantly differ by other participant characteristics or intervention strategies.

CONCLUSIONS

  Results pooled from the included trials provided strong evidence that mobile phone intervention led to statistically significant improvement in glycaemic control and self-management in diabetes care, especially for Type 2 diabetes patients.

Search for effects beyond the born approximation in polarization transfer observables in e(over→)p elastic scattering

Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton electric to magnetic form factor ratio, G(E)/G(M), obtained separately from cross section and polarization transfer measurements. One possible explanation for this difference is a two-photon-exchange contribution. In an effort to search for effects beyond the one-photon-exchange or Born approximation, we report measurements of polarization transfer observables in the elastic H(e[over →],e(')p[over →]) reaction for three different beam energies at a Q(2)=2.5  GeV(2), spanning a wide range of the kinematic parameter ε. The ratio R, which equals μ(p)G(E)/G(M) in the Born approximation, is found to be independent of ε at the 1.5% level. The ε dependence of the longitudinal polarization transfer component P(ℓ) shows an enhancement of (2.3±0.6)% relative to the Born approximation at large ε.

Detection of rpoB, katG and inhA gene mutations in Mycobacterium tuberculosis clinical isolates from Chongqing as determined by microarray

The emergence of multidrug-resistance Mycobacterium tuberculosis is an increasing threat to tuberculosis control programmes. Susceptibility testing of Mycobacterium tuberculosis complex isolates by traditional methods requires a minimum of 14 days. This can be reduced significantly if molecular analysis is used. DNA sequencing is a good method for detecting mutation, but cannot be used routinely because of its relatively high cost. A sensitive and specific microarray has been designed to detect mutations in the rifampin resistance determining region of rpoB and loci in katG and inhA associated with isoniazid (INH) resistance. A panel of Mycobacterium tuberculosis isolates containing 13 different rpoB genotypes, two mutation genotypes within codon 315 of katG and one mutation genotypes at inhA was used to validate the microarray. The results obtained indicate that 100% of rifampicin-resistant M. tuberculosis strains isolated in Chongqing had rpoB mutations, with 531-Ser and 526-His being the most common positions substituted. Of the total 50 INH resistant isolates, 82% had a katG315 mutation and 18% had an inhA mutation. All the mutations detected by the microarray method were also confirmed by conventional DNA sequencing. It is demonstrated that the microarray is an efficient, specialized technique and can be used as a rapid method for detecting rifampin and isoniazid resistance.

High resolution characterization of modifications in fused silica after exposure to low fluence 355 nm laser at different repetition frequencies

We report on the characterization of modifications in fused silica after exposure to low fluence (2 J/cm2) 355 nm laser at repetition frequencies of 1 Hz, 5 Hz and 10 Hz. Synchrotron based XRF spectroscopy is employed to study concentration variation of metal inclusions in the surface layer. Positron annihilation lifetime spectroscopy is used to probe atomic size defects variation in bulk silica. FT-IR is used to characterize changes of bond length and angle of Si-O-Si covalent bond of irradiated silica. Compared to the basic frequency, the big loss of cerium and iron concentration, the size enlargement of vacancy cluster and the decrease of Si-O-Si covalent bond length after 10 Hz laser irradiation are illustrated by our data. These tiny modifications provide important data to investigate laser damage mechanism.

First Report of Leaf Spot of Houttuynia cordata Caused by Alternaria alternata in China

Houttuynia cordata is a perennial herbaceous plant (family Saururaceae) that is native to southern China, Japan, Korea, and Southeast Asia where it grows well in moist to wet soils. It is commonly used as a Chinese herbal medicine and as a vegetable. In North America and Europe it is also used as an ornamental. From September 2007 to November 2009, symptoms of leaf spot were found on H. cordata leaves in Dangyang County, Hubei, China, with the crop area affected estimated to be over 600 ha per year. Rhizome yield was reduced by 20% on average, with up to 70% yield losses in some fields during the autumn growing season. Lesions were initially small, brown, and oval or circular that developed into dark spots and sometimes formed target spots with white centers. These spots enlarged and overlapped, extending until the leaves withered entirely usually within 2 months. A fungus was consistently recovered from symptomatic leaf samples collected in October 2008 or 2009 with an average 90% isolation rate from ~60 leaf pieces that were surface sterilized with 0.1% mercuric chloride solution. Three isolates, HCDY-2, HCDY-3, and HCDY-4, were used to further evaluate characteristics of the pathogen. On potato dextrose agar, all cultures initially developed white colonies and the centers turned gray or brown after 4 days of incubation. Conidiophores were single or fasciculate, straight or knee curved, gray-brown with regular septa, and 42 to 61 × 4 to 5 μm. Conidia were obclavate or ovate, brown, and 26 to 38 × 12 to 20 μm with three to five transverse and one to three longitudinal or oblique septa. The tops of some conidia developed into secondary conidiophores, which were cylindrical, beige, and 5 to 17 × 3 to 5 μm. The pathogen was identified as Alternaria alternata based on descriptions in Simmons (3). Genomic DNA of HCDY-2 was extracted, and the rDNA-internal transcribed spacer sequence showed 99.6% identity to A. alternata (GenBank No. AY513941). Pathogenicity tests were performed with the three isolates by spraying conidial suspensions (1 × 10⁶ conidia/ml) containing 0.1% Tween 20 onto upper and lower surfaces of leaves of 40-day-old 15-cm high plants. There were 20 leaves from five replicate plants for each isolate. Control plants were treated with sterilized water containing 0.1% Tween 20 only. All plants were incubated with a 16-h photoperiod at 25°C and 90% relative humidity in an artificial climate chamber. Five days after inoculation, typical brown spots were observed on all inoculated leaves but no symptoms were seen on water-treated control plants. Koch's postulates were fulfilled by reisolation of A. alternata from diseased leaves. The pathogenicity tests were carried out twice. A survey of the literature revealed only a few fungal diseases associated with H. cordata (1,2,4), including Phyllosticta houttuyniae, Pseudocercospora houttuyniae, Rhizoctonia solani, and Sclerotium rolfsii. Although A. alternata is a cosmopolitan plant pathogen, it has not been reported on any species in the four genera in Saururaceae (Anemopsis, Gymnotheca, Houttuynia, and Saururus) (3). To our knowledge, this is the first report of A. alternata infecting H. cordata worldwide. References: (1) Y. L. Guo and W. X. Zhao. Acta Mycol. Sin. 8:118, 1989. (2) K. Sawada. Spec. Publ. Taiwan Univ. 8:138, 1959. (3) E. G. Simmons. Alternaria: An Identification Manual. The American Phytopathological Society, St. Paul, MN, 2007. (4) Y. Wu et al. J. Changjiang Vegetables (In Chinese) 2:19, 2007.

Electrohydrodynamic deposition of nanotitanium doped hydroxyapatite coating for medical and dental applications

Nano-sized titanium containing hydroxyaptite has been prepared, the particle size of nanoTiHA was shown to be 12-20 nm in width and 30-40 nm in length, smaller than that of nanoHA. X-ray diffraction analysis revealed the phase purity of nanoTiHA produced. Antimicrobical assays demonstrated that nanoTiHA has excellent growth inhibitory properties, and is able to inhibit the growth of all bacterial strains tested, both Gram-negative and Gram-positive species, including multi-antibiotic resistant EMRSA 15 and EMRSA 16 'superbugs'. Biocidal activity against all four Staphylococcus spp was also shown at the concentration tested. Nanostuctured TiHA coating was successfully deposited onto Ti surfaces using EHDA spraying under optimized processing conditions with the thickness of the coating being further controlled by the spraying time. All of the nanoTiHA coated Ti surfaces were able to support human osteoblast (HOB) cell attachment and growth. The coating thickness did not significantly influence the proliferation of HOB cells on nanoTiHA coatings, while the ability of nanoTiHA coating to support HOB cell differentiation was demonstrated from the alkaline phosphatase activity. Our study showed that nanoTiHA has excellent anti-bacterial properties and the thin nanoTiHA coating was also able to support the attachment, growth and differentiation of HOB cells. Therefore, nanoTiHA coating could pave the way for the development of the next generation of dental and orthopedic implants by offering anti-infection potential in addition to osteoconductivity.

Percentage of positive biopsy cores to predict distant metastasis of prostate cancer after definitive radiation therapy

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Background: To assess the prognostic value of percentage of positive biopsy cores (PPC) and perineural invasion (PNI) in predicting clinical outcome following radiotherapy (RT) for prostate cancer.

Methods: One thousand and fifty-six patients with clinical stage T1-T3 N0 M0 prostate cancer, who had ≥ 4 biopsy cores sampled and complete biopsy core data available, were treated with either adaptive image-guided RT (median 75.6 Gy, n=387), low-dose EBRT (median 66.6 Gy, n=393), or EBRT and high-dose rate brachytherapy boost (n=276) at William Beaumont Hospital (1993-2004). Neoadjuvant and/or adjuvant androgen deprivation (AD) were given to 253 patients (24%). Multivariate cox regression analysis included PPC, gleason score, PSA, T stage, PNI, RT dose, androgen deprivation, and age. Biochemical failure (BF) was scored according to the Phoenix definition. Clinical failure (CF) was defined as any locoregional recurrence (LRR) or distant metastasis (DM). Median follow-up was 7.6 years.

Results: Median cores sampled was 7, median PPC was 33%, and 18% had PNI. On univariate Cox regression, both PPC and PNI were predicators of biochemical failure and clinical failure (all P<0.05). On multivariate Cox regression, PPC, either as continuous or categorical variable, remained an independent predicator of BF, CF, DM, cause-specific survival, and overall survival (all P<0.05). PPC of >50% was associated with significantly higher DM (HR 4.01, 95% CI 1.86-8.61), and its independent predicative value remained significant whether AD was given or not (all P<0.05). Combining ≤50% vs ≥50% PPC with NCCN risk group stratification demonstrated added prognostic value of DM for intermediate-risk (HR 5.44, 95% CI 1.78-16.6) and high-risk groups (HR 4.39, 95% CI 1.70-2.84), with or without AD (all P<0.05). On multivariate Cox regression, PNI was an independent predicator of LRR only (HR 2.51, 95% CI 1.18-5.33).

Conclusions: PPC is an independent and powerful predicator of DM for intermediate- and high-risk prostate cancer, regardless the use of AD. It should be considered for risk stratification and when designing for future trials testing adjuvant treatment after definitive RT for prostate cancer.

No significant financial relationships to disclose.

The farther from town the lower the blood pressure: report from rural Yunnan province

BACKGROUND

Hypertension (HTN) is a major cause of death in Chinese farmers. Remoteness from population centers may independently affect HTN prevalence and severity.

METHODS

We used random cluster sampling to select 27 villages in Yunnan province, China. Within each village, we randomly selected 50-80 men and women between the ages of 50 and 70 years. A total of 1,177 participants underwent interviews and blood pressure (BP) measurement. We evaluated the relationship between BP and distance of the participants' village from the town and county centers with and without adjustment for covariates.

RESULTS

There was a significant (P < 0.001) inverse relationship between BP and distance from populations centers. For every 10 km from the town center, the mean systolic BP (SBP) in the village decreased by 1.2 mm Hg and the mean diastolic by 0.5 mm Hg. After adjustment for age, gender, ethnicity, body mass index, smoking, and drinking, we found that SBP decreased by 1.8 mm Hg (P = 0.03) and diastolic BP by 1.0 mm Hg (P = 0.02) for every 10 km distance from the town center.

CONCLUSIONS

HTN prevalence and severity are significantly linked to distance from population centers in rural Chinese farmers. The farther a farmer's village is from larger population centers, the greater is the probability that his/her BP will be normal. This relationship is independent of age, gender, ethnicity, body mass index, smoking, and alcohol use. Strategies in addressing HTN in rural regions should take account of this geographic dependence on distance from population centers.

Investigation of Texture and Stress in Undoped Polysilicon Films

Undoped LPCVD polysilicon films deposited on thermal oxide and prepared under various process conditions have been investigated for their texture and stress characteristics. Pole figures measured by X-ray diffraction in reflection geometry were used to determine the orientation. distribution function which provides a quantitative description of the texture. Stresses were determined using wafer curvature measurements. Both texture and stress show substantial variation with deposition condition. Textures typically exhibit axial symmetry and appear to be correlated with the sign and magnitude of the stress. Under certain deposition conditions, the stress varies considerably along the tube, with the stress in the wafers at the upstream end being tensile and at the downstream end being compressive.

Inorganic Quantum Dot - Organic Dendrimer Nanocomposite Materials

Semiconductor quantum dots are of great current interest for their optical properties. We have developed a method for preparing CdS quantum dots in commercially available PAMAM Starburst dendrimers. The resulting CdS-dendrimer nanocomposites are exceptionally stable and emit brightly in the blue. The size of the dendrimer (its “generation”) has a surprisingly small effect on the optical properties of the resulting nanocomposites. The dot-dendrimer nanocomposites can be captured in a silica sol-gel matrix to yield a stable, bright blue-emitting glass.

Long-term results of full-dose gemcitabine with radiation therapy compared to 5-fluorouracil with radiation therapy for locally advanced pancreatic cancer

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Background: To retrospectively compare the efficacy and toxicity of full-dose gemcitabine-based chemoradiotherapy (GemRT) vs. 5-fluorouracil (5-FU)-based chemoradiotherapy (5FURT) for locally advanced pancreas cancer (LAPC).

Methods: From January 1998 to December 2008, 93 patients with LAPC were treated either with 5FURT (n=38) or GemRT (n=55). 5FURT consisted of standard-field radiotherapy given concurrently with infusional 5-FU or capecitabine. GemRT consisted of involved-field radiotherapy given concurrently with full-dose gemcitabine (1000 mg/m2 weekly) with or without erlotinib. The follow-up time was calculated from the time of diagnosis to the date of death or last contact.

Results: Eighty-eight of 93 patients have died, and only one was lost to follow-up after developing DM. The median OS was 11.2 months (range 1.5-96). Patient characteristics (including Zubrod score, age, tumor stage, nodal stage, tumor location, and grade) were not significantly different between treatment groups. The OS was significantly better for GemRT compared to 5FURT (median 12.5 months vs. 10.2 months; 51% vs. 34% at 1 year; 12% vs. 0% at 3 years; 7% vs. 0% at 5 years; respectively; p=0.04), although the two groups had same DM (34% at 1 year). GemRT cohort was more likely to receive gemcitabine before or after chemoradiotherapy than 5FURT cohort (85% vs. 37%, p<0.001). Of the subset who received gemcitabine either before or after chemoradiotherapy, OS was still significantly better for GemRT without concurrent erlotinib compared to 5FURT (median 15.1 months vs. 10.7 months; 70% vs. 36% at 1 year; 21% vs. 0% at 3 years; 11% vs. 0% at 5 years; respectively; p=0.005), as was the rate of DM (23% vs. 45%; respectively; p=0.04). The subsequent hospitalization, percent of survival time spend in the hospital, acute and late grade 3-5 gastrointestinal toxicities were not significantly different between the GemRT and 5FURT groups.

Conclusions: Full-dose GemRT was associated with improved OS compared to standard 5FURT. This approach yielded a moderate number of long-term survivors and was not associated with increased hospitalization or severe gastrointestinal toxicity.

No significant financial relationships to disclose.

Adjuvant FOLFIRI with or without cetuximab in patients with resected stage III colon cancer: NCCTG Intergroup phase III trial N0147

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Background: Irinotecan (CPT-11) has demonstrated antitumor activity against metastatic colorectal cancer used alone or with 5-fluorouracil (5FU)/leucovorin (LV). Two arms with CPT-11, 5FU, and LV (FOLFIRI) +/- cetuximab (Cmab) were originally included in N0147. However, after CALGB 89803 (J Clin Oncol. 25:3456, 2007), PETACC-3 (J Clin Oncol. 27:3117, 2009), and Accord02 (Ann Oncol. 20:674, 2009) showed no benefit to the three-drug combination in adjuvant therapy, the CPT-11 arms of N0147 were discontinued. We report the outcomes for patients given FOLFIRI +/- Cmab.

Methods: Following a signed informed consent patients with resected stage III colon cancer were randomized to one of 6 arms including 12 biweekly cycles of CPT-11 180 mg/m2 d1 with LV 400 mg/m2, 5FU 400 mg/m2 bolus IV, then 46-hr IV 5FU 2,400 mg/m2 on d1-2 without (Arm B, FOLFIRI) or with Cmab (Arm E) 400 mg/m2 d1 cycle 1 then Cmab at 250 mg/m2 d1 and 8. Primary endpoint was 3-year disease-free survival (DFS). Secondary endpoints included overall survival (OS) and toxicity.

Results: 156 patients (Arm B-111, Arm E-45) were enrolled; median follow-up on 81 patients in Arm B was 60.3 months and 58.2 months in Arm E for 41 patients. wtKRAS (vs mt) status was associated with improved DFS (HR=0.6 [95% CI 0.4-1.1], p = 0.09) and OS (HR 0.7 [95% CI 0.4-1.5], p = 0.38). The addition of Cmab improved DFS and OS in the overall group and within wtKRAS pts. Grade greater than III non-hematologic adverse effects were significantly increased in the Cmab arm (46% vs. 64%, p = 0.05).

Conclusions: In this randomized phase III trial adjuvant FOLFIRI resulted in a 3-year DFS lower than that expected for FOLFOX. Trends for improved DFS and OS with the addition of Cmab were observed in patients with resected stage III colon cancer patients, regardless of KRAS status. Supported by NIH Grant CA25224, Bristol-Myers Squibb, ImClone, Sanofi-Aventis, and Pfizer.

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Potential role of chemoradiotherapy for metastatic pancreatic cancer

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Background: Patients with metastatic pancreatic cancer have a poor outcome and the radiotherapy is typically only given to patients requiring palliation. We analyzed our institutional pancreas database to compare the outcome between chemotherapy alone vs. chemoradiotherapy.

Methods: From January 2000 to December 2008, 199 metastatic pancreatic cancer patients were retrospectively analyzed. 13 (6.5%) patients received chemoradiotherapy and 186 (93.5%) patients received chemotherapy alone. Chemotherapy regimens consisted of 5-fluorouracil, gemcitabine, erlotinib, or cisplatin. The follow-up time was calculated from the time of diagnosis to the date of death or the last contact. Kaplan-Meier analysis was used to calculate the overall survival (OS).

Results: Median OS was 5.3 months for all patients. Median OS was 4.9 months (0.4–27.0) for patients treated with chemotherapy alone and 7.8 months (0.6–44.1) for those treated with chemoradiotherapy (p = 0.013). Univariate survival analysis of categorical variables for patients treated with chemoradiotherapy revealed that age, race, gender, location of metastatic site, T stage (T3 v. T4) or nodal stage were not significant. However, ECOG performance status (1 v. 2/3) and the dose of radiation (<35 v. >35 Gy) received were associated with improved survival (p = 0.013, p=0.049). Median OS was 12.9 months for ECOG 1 vs. 5.6 months for ECOG 2/3. Median OS was 11.1 months for patients treated with radiotherapy dose > 35 Gy vs. 5.9 months for those who received less than 35 Gy. 3/13 (23%) patients who received chemoradiotherapy lived nearly two years or more.

Conclusions: Metastatic pancreatic cancer patients with good performance score may benefit from chemoradiotherapy. Long-term survival was observed in this selected group.

No significant financial relationships to disclose.

The I/D polymorphism of angiotensin-converting enzyme gene and asthma risk: a meta-analysis

BACKGROUND

  The insertion/deletion (I/D) polymorphism of angiotensin-converting enzyme (ACE) gene has been implicated in susceptibility to asthma, but a large number of studies have reported inconclusive results. The aim of this study is to investigate the association between the I/D polymorphism of ACE gene and asthma risk by meta-analysis.

METHODS

  We searched Medline (Ovid), Pubmed, CNKI, Wanfang, and Weipu database, covering all papers until March 12, 2010. Statistical analysis was performed by using the software revman 4.2 (The Cochrane Collaboration, http://www.cochrane.org) and stata 10.0 (StataCorp, College Station, TX, USA, http://www.stata.com).

RESULTS

  A total of 1946 cases and 2152 controls in 18 case-control studies were included in this meta-analysis. The results indicated that the DD homozygote carriers had a 59% increased risk of asthma, when compared with the homozygotes II and heterozygote DI [odds ratio (OR)=1.59, 95% confidence interval (CI): 1.16-2.18]. In the subgroup analysis by ethnicity, significant elevated risks were associated with DD homozygote carriers in Asians (OR=2.02 and 95% CI: 1.29-3.16 for DD vs DI+II) but not in Caucasians (OR=1.14 and 95% CI: 0.76-1.72 for DD vs DI+II). In the subgroup analysis by age, significant elevated risks were associated with DD homozygote carriers in children (OR=2.44 and 95% CI: 1.36-4.38 for DD vs II+DI) but not in adults (OR=1.54 and 95% CI: 0.94-2.51 for DD vs II+DI).

CONCLUSIONS

  This meta-analysis suggested that the I/D polymorphism of ACE gene would be a risk factor of asthma. To further evaluate gene-to-gene and gene-to-environment interactions between polymorphisms of ACE gene and asthma risk, more studies with large groups of patients are required.

A Novel Surface Topographical Concept for Bone Implant

Template-assisted electrohydrodynamic atomization (TAEA) spraying deposition, a recently developed and an electric-driven jet-based technique has been used to prepare bioactive surface topography on titanium (Ti). Nanometer-scaled SiHA (nanoSiHA), which closely resembles the bone mineral, has been synthesized and deposited on Ti surfaces with a range of patterns, such as pillars and tracks. A human osteoblast (HOB) cell model has been used to evaluate the in vitro cellular responses to nanoSiHA deposition. alamarBlue™ assay showed that nanoSiHA patterns are able to encourage the attachment and growth of HOB cells in comparison to those of nanoSiHA coating. The preferential growth of HOB cells was found along and across the track, HOB cells were also found to stretch between two tracks. Image analysis of HOB cell responses to the size of nanoSiHA pattern showed that the length of HOB cells was proportional to the gaps between the tracks until reaching the maximum length of 110 μm. The results indicate that the distance between the structures is paramount over the width. Our study will pave the way to control and guide cellular responses for new generation of bone implants.

The pathway to intelligent implants: osteoblast response to nano silicon-doped hydroxyapatite patterning

Bioactive hydroxyapatite (HA) with addition of silicon (Si) in the crystal structure (silicon-doped hydroxyapatite (SiHA)) has become a highly attractive alternative to conventional HA in bone replacement owing to the significant improvement in the in vivo bioactivity and osteoconductivity. Nanometre-scaled SiHA (nanoSiHA), which closely resembles the size of bone mineral, has been synthesized in this study. Thus, the silicon addition provides an extra chemical cue to stimulate and enhance bone formation for new generation coatings, and the next stage in metallic implantation design is to further improve cellular adhesion and proliferation by control of cell alignment. Topography has been found to provide a powerful set of signals for cells and form contact guidance. Using the recently developed novel technique of template-assisted electrohydrodynamic atomization (TAEA), patterns of pillars and tracks of various dimensions of nanoSiHA were achieved. Modifying the parameters of TAEA, the resolution of pattern structures was controlled, enabling the topography of a substrate to be modified accordingly. Spray time, flow rate and distance between the needle and substrate were varied to improve the pattern formation of pillars and tracks. The 15 min deposition time provided the most consistent patterned topography with a distance of 50 mm and flow rate of 4 µl min(-1). A titanium substrate was patterned with pillars and tracks of varying widths, line lengths and distances under the optimized TAEA processing condition. A fast bone-like apatite formation rate was found on nanoSiHA after immersion in simulated body fluid, thus demonstrating its high in vitro bioactivity. Primary human osteoblast (HOB) cells responded to SiHA patterns by stretching of the filopodia between track and pillar, attaching to the apex of the pillar pattern and stretching between two. HOB cells responded to the track pattern by elongating along and between the track, and the length of HOB cells was proportional to the gaps between track patterns, but this relationship was not observed on the pillar patterns. The study has therefore provided an insight for future design of next generation implant surfaces to control and guide cellular responses, while TAEA patterning provides a controllable technique to provide topography to medical implants.