Synthesis, mechanical and biological characterization of ionic doped carbonated hydroxyapatite/β-tricalcium phosphate mixtures

The influence of ionic substituents in calcium phosphates intended for bone and tooth replacement biomedical applications is an important research topic, owing to the essential roles played by trace elements in biological processes. The present study investigates the mechanical and biological evaluation of ionic doped hydroxyapatite/β-tricalcium phosphate mixtures which have been prepared by a simple aqueous precipitation method. Heat treating the resultant calcium phosphates in a carbonated atmosphere led to the formation of ionic doped carbonated hydroxyapatite/β-tricalcium phosphate mixtures containing the essential ions of biological apatite. The structural analysis determined by Rietveld refinement confirmed the presence of hydroxyapatite as the main phase, together with a considerable amount of β-tricalcium phosphate. Such phase assemblage is essentially due to the influence of substituted ions during synthesis. The results from mechanical tests proved that carbonate substitutions are detrimental for the mechanical properties of apatite-based ceramics. In vitro proliferation assays of osteoblastic-like cells (MC3T3-E1 cell line) to powders revealed that carbonate incorporation can either delay or accelerate MC3T3 proliferation, although reaching the same proliferation levels as control cells after 2 weeks in culture. Further, the powders enable pre-osteoblastic differentiation in a similar manner to control cells, as indirectly measured by ALP activity and Type-I collagen medium secretion.

Influence of methylenetetrahydrofolate reductase polymorphisms in oral cancer patients

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme in folate metabolism. Two common polymorphisms associated with MTHFR gene - C677T and A1298C - influence the thermolabile nature and activity of the enzyme. This study aimed to investigate the role of MTHFR polymorphisms on oral cancer susceptibility and its potential impact on the prognostic outcome.

METHODS

Oral cancer cases and controls were genotyped using PCR-RFLP technique for MTHFR C677T and A1298C polymorphisms. Disease susceptibility analysed using regression analysis. The association between clinical outcomes and the polymorphisms were analysed using univariate and multivariate model.

RESULTS

The 677CT+TT genotype showed a significant three-fold reduction in oral cancer risk (RR-0.35, p-0.009). 1298CC genotype showed decreased cancer risk when compared to AA+AC genotype (RR-0.55, p-0.062). When prognostic significance of MTHFR polymorphism was evaluated, 677CT+TT patients showed improved survival than the CC individuals (RR = 0.56, P = 0.378). The 1298 CC and AC+CC showed an increased risk for treatment failure and poor survival when compared with the wild AA genotype (HR = 4.27, P = 0.001).

CONCLUSION

Here we observed MTHFR C677T to influence oral cancer susceptibility, while A1298C polymorphism associated with patient prognosis. Our data support MTHFR polymorphism to be an independent prognostic marker in oral carcinoma.

Spectroscopic characterization of nanohydroxyapatite synthesized by molten salt method

Hydroxyapatite (HAP) nanopowders were synthesized by molten salt method at 260 degrees C. The as-prepared powders were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM) and thermo gravimetric analysis (TGA). With the aid of the obtained results the effect of calcining time on the crystallinity, size and morphology of HAP nanopowders is presented. The HAP nanopowders synthesized by molten salt method consist of pure phase of HAP without any impurities and showed the rod-like morphology without detectable decomposition up to 1100 degrees C.

Expression of p53 in leukoplakia and squamous cell carcinoma of the oral mucosa: correlation with expression of Ki67

Aim-To study p53 expression in relation to proliferative status in normal and nondysplastic, dysplastic and malignant lesions of the oral mucosa.Method-The standard avidin-biotin complex (ABC) immunohistochemical staining method was used to study the expression of p53 and Ki67 on frozen sections of oral leukoplakias and carcinomas.Results-Of the leukoplakia and carcinoma samples, 70% expressed p53 in over 5% of cells. In normal mucosa less than 5% of cells expressed p53. The proliferation index, as assessed by expression of Ki67, was highest in the malignant lesions (43%) and lowest in normal mucosa (11%). Statistical analysis revealed that expression of both p53 and Ki67 was correlated significantly with the histopathological stage of the tumour. However, expression of p53 was not correlated with that of Ki67. In leukoplakia lesions with proliferative features p53 immunostaining was less intense than in non-proliferative lesions; this difference was statistically significant.Conclusions-These results emphasise the potential of Ki67 and p53 as biomarkers of carcinogenesis in oral cancer and may also serve as intermediate points for cancer prevention programmes, such as the oral chemopreventive trials. Factors other than p53 may have a more important role in the deregulation of proliferation in pre-malignant oral lesions.

Amino acid-functionalized dendrimers with heterobifunctional chemoselective peripheral groups for drug delivery applications

Dendrimers have emerged as multifunctional carriers for targeted drug delivery, gene delivery and imaging. Improving the functional versatility at the surface for carrying multiple conjugation reactions is becoming vital. Typically, generation four polyamidoamine (G4-PAMAM) dendrimers bear approximately 64 symmetrical end groups, often requiring different spacers to conjugate various functional groups (drugs and targeting moities), increasing the synthetic steps. In the present study, a simple one-step synthesis to convert each symmetrical end group of G4-PAMAM dendrimers into two reactive, distinct orthogonal and chemoselective groups is described. A near-complete end-capping of the dendrimers (87-93%) with amino acids results in heterobifunctional G4-PAMAM dendrimers bearing a very high (> or = 110) diverse peripheral end groups (OH+NHBoc, OH+COOMe, SH+NHBoc, and COOH+NHBoc). Postfunctionalization ability of these dendrimers was evaluated. The heterobifunctional groups at the dendrimer periphery could be chemoselectively conjugated to multiple moities such as drugs (indomethacin and dexamethasone) and drugs and imaging agents (dexamethasone and FITC). These conjugations could be achieved in immediate succession without functional group conversions, eliminating the additional elaborate synthetic steps traditionally required to append specific linkers. Furthermore, one of the two functional handles at periphery was used to develop in situ forming hydrogels, whereas the other handle could be used for conjugating the drugs (e.g., dexamethasone). The heterobifunctional dendrimers with either "NH(2) or SH (thiopyridyl protected form)" terminations showed in situ hydrogel formation by cross-linking with N-hydroxysuccinimide or thiol-terminated multiarm polyethylene glycol (20 kDa). The choice of amino acids as versatile linkers would enable biocompatible dendrimer scaffolds for use in drug delivery. Zeta-potential measurements showed drastic lowering of the charge on G4-PAMAM-NH(2) dendrimers by end-capping with amino acids, whereas in the case of neutral G4-PAMAM-OH dendrimers, the charge did not increase or decrease substantially. The in vitro cytotoxicity and hemolysis assay showed that the heterobifunctional dendrimers were noncytotoxic in the 100 ng/mL to 1 mg/mL concentration range. With this study, we demonstrate the development of biocompatible dendrimers bearing multiple orthogonal surface groups, enabling the attachment of drugs, imaging agents, and gel formation using minimal synthetic steps.

CD26 expression in donor stem cell harvest and its correlation with engraftment in human haematopoietic stem cell transplantation: potential predictor of early engraftment

BACKGROUND

The efficiency of haematopoietic stem and progenitor cells (HSPCs) is important when donor cell numbers are limiting. Stable white blood cell (WBC) and platelet engraftment is crucial for the outcome of haematopoietic stem cell transplantation (HSCT).

DESIGN

This article evaluates CD26/dipeptidyl peptidase-IV expression on mobilised peripheral blood stem cell (PBSC) harvest of donors and its correlation with engraftment in HSCT. We have analysed CD26 expression on cells in various gates, that is, lymphocytes, monocytes, neutrophils and all populations using flow cytometry tool.

RESULTS

Ours is the first study on human mobilised PBSC harvest from cancer patients or allogeneic related donors (n = 28) to demonstrate that increased CD26 expression leads to early engraftment in transplanted cancer patients. Correlation of CD26 expression with WBC engraftment was statistically significant (lymphocyte gate: P < 0.00001; monocyte gate: P < 0.00001; neutrophil gate: P < 0.00001; all populations: P < 0.00001). CD34 expression is a known predictor of engraftment. Nevertheless, there was no correlation between CD34 and CD26 expression in these cases.

CONCLUSIONS

This study has given important leads indicating that CD26 expression may be an independent predictor of engraftment. Further study with large number of patients as well as study on circulatory CD26 may add valuable information towards improving current knowledge on CD26.

Synthesis and structural characterization of strontium- and magnesium-co-substituted beta-tricalcium phosphate

The synthesis of five different Sr(2+)- and Mg(2+)-co-substituted beta-tricalcium phosphate (beta-TCP) has been obtained by heating the calcium-deficient apatites above 800 degrees C. With the investigated concentrations of Sr(2+) and Mg(2+) from the present study, no additional phases other than beta-TCP have been detected. The synthesized powders have been characterized by X-ray diffraction, Fourier transform infrared spectrometry, elemental analysis and Rietveld refinement studies. The co-substitution of Sr(2+) and Mg(2+) in the beta-TCP has resulted in the formation of crystalline beta-TCP at hexagonal setting (space group R3c). The reduction of lattice a- and c-axis parameters with the combined substitution of Sr(2+) and Mg(2+) in the beta-TCP has been found evident from the present results. Sr(2+) has been found occupying the Ca(1,2,3,4) sites and Mg(2+) was found at the sixfold coordinated Ca(5) site of beta-TCP structure.

Synthesis of delaminated LDH: A facile two step approach

One-step synthesis of carbonate-free nitrate containing LDHs was achieved using hexamine hydrolysis at low temperature and the products were delaminated successfully in water; materials showed total delamination in formamide while restacking behavior depended critically on the medium.

Extraction studies of uranium(VI), plutonium(IV) and americium(III) from nitric acid using the bi-functional carbamoyl methyl sulfoxide ligands

The extraction behavior of new bi-functional ligands containing sulfoxide and amide groups viz. N,N'-dibutyl carbamoyl methyl phenyl sulfoxide (L1) and N,N'-dibutyl carbamoyl methyl benzyl sulfoxide (L2) towards the U(VI), Pu(IV) and Am(III) ions from nitric acid was studied. Both of these extractants showed appreciable extractions for U(VI) and Pu(IV) from 1 to 9.5 M nitric acid concentrations. Am(III) did not show an appreciable extraction under the conditions studied. The species extracted from a nitric acid medium correspond to the compositions of [UO2(NO3)(2).2L] and [Pu(NO3)4.2L] for L1 and a mixture of [UO2(NO3)(2).2L], [UO2(NO3)2.L] and [Pu(NO3)(4).2L] for the L2. The conditional extraction constant (Kex) values for the Pu(IV) with L1 and L2 were estimated for the first time, and found to be 6.21 x 10(2) and 5.64 x 10(2) mol(-4) dm, respectively.

Anti-inflammatory and anti-oxidant activity of anionic dendrimer-N-acetyl cysteine conjugates in activated microglial cells

Dendrimers are emerging as potential intracellular drug delivery vehicles. Understanding and improving the cellular efficacy of dendrimer-drug conjugates, can lead to significant in vivo benefits. This study explores efficacy of anionic polyamidoamine (PAMAM-COOH) dendrimer-N-acetyl cysteine (NAC) conjugates for applications in neuroinflammation. The anti-oxidative and anti-inflammatory effects of PAMAM-(COOH)(46)-(NAC)(18) conjugate is evaluated on microglial cells in vitro. Cell entry and localization of PAMAM-(COOH)(62)-(FITC)(2) conjugate in BV-2 microglial cells were assessed using flow cytometry and confocal microscopy. ELISA assays were used to evaluate markers of oxidative stress (ROS, NO) and inflammation (TNF-alpha) after stimulation of microglial cells with lipopolysaccharides (LPS), following treatment with increasing doses of free N-acetyl-L-cysteine (NAC) or PAMAM-(COOH)(46)-(NAC)(18) conjugate containing an equivalent molar concentration of NAC. Flow cytometry and confocal microscopy demonstrated the PAMAM-(COOH)(62)-(FITC)(2) conjugate entered BV-2 cells rapidly with significant increase in fluorescence within 15 min and localized mostly in the cytoplasm. PAMAM-(COOH)(46)-(NAC)(18) conjugate was non-toxic, and significantly reduced ROS, NO and TNF-alpha release by activated microglial cells after 24 h and 72 h stimulation of LPS following 3h pre-treatment when compared to the same concentration of free NAC (P<0.05 or P<0.01). Anionic PAMAM dendrimer-NAC conjugate was synthesized with a glutathione sensitive linker for intracellular release. The non-toxic conjugate is a more effective anti-oxidant and anti-inflammatory agent when compared to free NAC in vitro. The conjugate showed significant efficacy even at the lowest dose (0.5mM NAC), where the activity was comparable or better than that of free drug at 8mM (16x higher dosage). The improved efficacy of the conjugate, when combined with the intrinsic neuroinflammation-targeting ability of the PAMAM dendrimers, may provide new opportunities for in vivo applications.

Results of autologous transplants for lymphomas from a tertiary cancer center in India

7106

Background: Autologous stem cell transplanation is the standard of care for patients of relapsed and refractory non-Hodgkin's lymphoma (NHL) and Hodgkin's lymphoma (HL). We report the results of transplants in lymphomas from our center and role of possible prognostic factors. Methods: All 50 consecutive patients who underwent transplant for HL (70%) and NHL (30%) from August 1994- August 2008 were included in this retrospective study. Fifty eight percent of patients received BEAM (carmustine, etoposide, ara-c and melphalan), 30% LACE (lomustine, ara-c, cyclophosphamide and etoposide), 8% ICE (ifosfamide,carboplatin and etoposide) and 4% high dose melphalan (200mg/m2) conditioning regimens. Seventy eight percent of patients received peripheral blood stem cells (PBSC), 8% bone marrow (BM) and 14% both PBSC and BM. Prognostic factors evaluated for progression free survival (PFS) were serum albumin level and body mass index (BMI) at the time of transplant, stage at diagnosis and source of stem cells, while for over all survival (OS), status of disease at transplant was also included. Results: The median time to transplant was 2.25 years from the time of diagnosis. The median age at transplant was 25 years. Seventy four percent of patients were male. At the time of transplant, thirty two percent were in complete remission (CR), 50% in partial remission (PR) and 18% had refractory disease (RD). The median serum albumin and BMI at the time of transplant were 4 g/dl and 22.5 kg/m2 respectively. The best disease response rate was 86% (CR+PR) in patients evaluable for response. Thirteen patients relapsed at a median interval of 11 months post transplant. The cumulative probability of OS and progression free survival PFS at 5 years were 40% and 34% respectively for the whole group. Multivariate analysis using cox regression identified serum albumin greater than 4 g/dl and those receiving PBSC grafts as independently associated with improved OS and PFS. Conclusions: These data provide the first published report of outcomes of autologous transplants in lymphomas from India. Our data suggests that serum albumin level at the time of transplant and stem cell source are important prognostic factors for PFS and OS.

No significant financial relationships to disclose.

Rater

e20678

Background: Management of neutropenic fever is based on risk stratification of the episode which helps in optimizing treatment. MASCC is the most commonly used for risk stratification Patients with a score of > 21 were regarded as low risk; patients with a score of <21 were regarded as high risk. We tried to validate the MASCC index for our ethnic population. Methods: Patients were recruited throughout a 12 month period. Inclusion criteria were diagnosis of hematolymphoid malignancy, neutropenic febrile episode secondary to chemotherapy or during induction therapy of acute leukemia and more than 18 years of age All patients were risk stratified, hospitalized and treated with broad-spectrum, empiric, intravenous antibiotic therapy until recovery or outcome of the event. The incidence of medical complications in both groups and death related to the neutropenic infection was recorded. The data was entered on SPSS software and MASCC criteria was analyzed for sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). Results: A total of 81 febrile neutropenic episodes were included; 34 classified as low risk and 47 as high risk according to MASCC risk index score. The sensitivity, specificity, PPV, NPV and accuracy of MASCC risk index score were 45.5%, 40%, 11%, 82%, 40.7%. We subsequently analyzed the subset of Acute Myeloid Leukemia (AML) patients as they were the majority comprising of 62/81 episodes. The subset of AML patients risk stratified according to MASCC risk index showed sensitivity, specificity, PPV, NPV and accuracy of 71%, 25.5%, 11%, 87.5%, 31% respectively. Conclusions: In our patient group, the value of MASCC score is limited with poor sensitivity, specificity and PPV. This trend is also seen in the subset analysis of AML patients. The value of the MASCC index with the score of 21 as the cut-off between low risk and high risk seems limited in our patients and requires confirmation with larger set of patients.

No significant financial relationships to disclose.

Relational pathways between socioeconomic position and cardiovascular risk in a multiethnic urban sample: complexities and their implications for improving health in economically disadvantaged populations

BACKGROUND

The study was designed to provide evidence of a cascade effect linking socioeconomic position to anthropometric indicators of cardiovascular disease (CVD) risk through effects on psychosocial stress, psychological distress and health-related behaviours, and consider implications for disease prevention and health promotion.

METHODS

A cross-sectional stratified two-stage probability sample of occupied housing units in three areas of Detroit, Michigan, was used in the study. 919 adults aged > or =25 years completed the survey (mean age 46.3; 53% annual household income <$20 000; 57% non-Hispanic black, 22% Latino, 19% non-Hispanic white). Variables included self-report (eg, psychosocial stress, depressive symptoms, health behaviours) and anthropometric measurements (eg, waist circumference, height, weight). The main outcome variables were depressive symptoms, smoking status, physical activity, body mass index and waist circumference.

RESULTS

Income was inversely associated with depressive symptoms, likelihood of current smoking, physical inactivity and waist circumference. These relationships were partly or fully mediated by psychosocial stress. A suppressor effect of current smoking on the relationship between depressive symptoms and waist circumference was found. Independent effects of psychosocial stress and psychological distress on current smoking and waist circumference were found, above and beyond the mediated pathways.

CONCLUSIONS

The results suggest that relatively modest improvements in the income of economically disadvantaged people can set in motion a cascade of effects, simultaneously reducing exposure to stressful life conditions, improving mental well-being, increasing health-promoting behaviours and reducing anthropometric risks associated with CVD. Such interventions offer important opportunities to improve population health and reduce health disparities.

Maxillary Expansion in Cleft Lip and Palate using Quad Helix and Rapid Palatal Expansion Screw

BACKGROUND

Management of patients with cleft lip and palate (CLP) includes orthodontic treatment prior to bone grafting. Palatal expansion is done using slow or rapid palatal expansions (RPE). Controversy still exists regarding choice of expansion appliances used. This study was conducted to find out whether the Quad helix appliance represents a reasonable alternative to using conventional rapid maxillary expansion appliance among cleft lip and palate patients.

METHODS

Twenty cleft lip and palate patients had orthodontic study models taken prior to expansion and at the end of expansion. There pre and post treatment study models were analyzed for changes in intermolar width, molar tipping and molar rotation.

RESULT

The difference in molar tipping, increase in intercanine and molar width between slow palatal expansion (SPE) and rapid palatal expansion (RPE) group was not statistically significant. A difference between the two groups was found in the ability to rotate molars.

CONCLUSION

The clinical findings suggest that maxillary expansion using the Quad helix appliance represents a reasonable alternative to using conventional rapid maxillary expansion appliances among cleft patients.

Function prediction of hypothetical proteins without sequence similarity to proteins of known function

Function prediction by sequence-similarity based methods identifies only approximately 50% of the proteins deduced from newly sequenced genomes. We have developed an approach to annotate the 'leftover proteins' i.e., those which cannot be assigned function using sequence similarity. Our method (MOPS) is pan-taxonomic, predicting fine-grained molecular function (rather than a broad functional category) with high performance. In addition, we developed a validation scheme that assesses predictions using domain-specific knowledge.