Efficacy of bioactive nanoparticles on tissue-endotoxin induced suppression of stem cell viability, migration and differentiation.

AIM: To characterize a lipopolysaccharide (LPS)-treated dentine tissue model (LPS dentine) to analyse the efficacy of polycationic chitosan nanoparticles (CSnp) and/or dexamethasone conjugate chitosan nanoparticles (Dex-CSnp) on the viability/differentiation potential of stem cells from apical papilla (SCAP) when exposed to LPS dentine. A further aim was to understand the effect of macrophage-dependent inflammation on SCAP migration in the presence of LPS dentine. METHODOLOGY: A total of 88 dentine slabs were used. TOF-SIMS analysis was performed amongst the LPS-treated and untreated dentine groups (n = 2/group). The study was conducted using four dentine groups: no treatment (control); LPS treatment only; LPS treatment followed by CSnp conditioning; and LPS treatment followed by Dex-CSnp conditioning groups. SCAP adherence, viability, differentiation and biomineralization potential on dentine from different groups were studied using fluorescent and scanning electron microscopy. Inflammation by macrophages in response to LPS dentine was quantified, and effect on SCAP migration was analysed. Statistical analysis was performed using Student's t-test with a significance level of P < 0.05. RESULT: TOF-SIMS analysis confirmed LPS contamination. LPS dentine affected SCAP viability but not adherence to dentine (P < 0.001). Conditioning of LPS dentine with either nanoparticles improved SCAP viability (P < 0.01) and rescued other LPS related adverse effects on SCAPs, such as F-actin disruption, decrease in differentiation/biomineralization potential. IL-6 produced by macrophages in response to LPS-treated dentine impeded SCAP migration (P < 0.001), diminished on CSnp and Dex-CSnp conditioning groups (P < 0.01). CONCLUSION: This study developed an LPS-dentine model and highlighted the ability of CSnp and Dex-CSnp to promote stem cell viability, migration, differentiation potential and reduce inflammation, providing an environment conducive for tissue regeneration/repair.

Down's syndrome and cardiac tamponade with pulmonary tuberculosis in adults.

We describe a combination case of Down's syndrome and Cardiac Tamponade with Pulmonary Tuberculosis in an adult patient.

An update on non-peptide angiotensin receptor antagonists and related RAAS modulators.

The renin-angiotensin-aldosterone-system (RAAS) is an important regulator of blood pressure and fluid-electrolyte homeostasis. RAAS has been implicated in pathogenesis of hypertension, congestive heart failure, and chronic renal failure. Aliskiren is the first non-peptide orally active renin inhibitor approved by FDA. Angiotensin Converting Enzyme (ACE) Inhibitors are associated with frequent side effects such as cough and angio-oedema. Recently, the role of ACE2 and neutral endopeptidase (NEP) in the formation of an important active metabolite/mediator of RAAS, ang 1-7, has initiated attempts towards development of ACE2 inhibitors and combined ACE/NEP inhibitors. Furukawa and colleagues developed a series of low molecular weight nonpeptide imidazole analogues that possess weak but selective, competitive AT1 receptor blocking property. Till date, many compounds have exhibited promising AT1 blocking activity which cause a more complete RAAS blockade than ACE inhibitors. Many have reached the market for alternative treatment of hypertension, heart failure and diabetic nephropathy in ACE inhibitor intolerant patients and still more are waiting in the queue. But, the hallmark of this area of drug research is marked by a progress in understanding molecular interaction of these blockers at the AT1 receptor and unraveling the enigmatic influence of AT2 receptors on growth/anti-growth, differentiation and the regeneration of neuronal tissue. Different modeling strategies are underway to develop tailor made molecules with the best of properties like Dual Action (Angiotensin And Endothelin) Receptor Antagonists (DARA), ACE/NEP inhibitors, triple inhibitors, AT2 agonists, AT1/TxA2 antagonists, balanced AT1/AT2 antagonists, and nonpeptide renin inhibitors. This abstract gives an overview of these various angiotensin receptor antagonists.

Memory recuperative potential of rifampicin in aluminum chloride-induced dementia: role of pregnane X receptors.

The present study has been designed to investigate the potential of rifampicin [Pregnane X receptors (PXR) agonist] in experimental dementia. Aluminum chloride (AlCl3) [100mg/kg, p.o. for 42days] was administered to Wistar rats (n=6) to induce dementia. Morris water maze (MWM) test was used to assess learning and memory and rota rod test was used to assess locomotor activity of the animals. A battery of biochemical tests and histopathological evaluation using hematoxylin and eosin (H&E) and Congo Red stains were performed at the end of the study. AlCl3-treated rats demonstrated impaired cognition and locomotor activity on MWM apparatus and rota rod test, respectively. These animals exhibited a significant rise in acetylcholinesterase (AChE) activity (138±3.6), thiobarbituric acid reactive species (TBARS) level (15±1.6), nitrite (56±2.4) level and myeloperoxidase (MPO) activity (4.1±0.9) along with decline in reduced glutathione (GSH) level (22±1.3) in comparison to the control group (p<0.05). Further the H&E and Congo Red-stained cerebral cortex sections of AlCl3-treated rats indicated severe neutrophilic infiltration and amyloid deposition. Rifampicin-treated AlCl3-rats exhibited significant attenuation in memory deficits, biochemical parameters like AChE activity (33±1.4), TBARS level (4.1±1.0), nitrite level (64±2.6), MPO activity (3.6±1.0) and GSH level (53±2.4) along with improved histopathological alterations and locomotor activity when compared with AlCl3-treated rats (p<0.05). Combined administration of ketoconazole (a PXR antagonist) and rifampicin to AlCl3-treated animals reversed the rifampicin-induced protective effects. Therefore the results obtained from the study indicate a defensive role of rifampicin in memory dysfunction which may probably be due to its anti-cholinesterase, anti-oxidative, anti-inflammatory and amyloid lowering effects. Moreover the study speculates the potential of PXR in the pathophysiology of dementia which is subject to further evaluation.

Examination by X-ray photoelectron spectroscopy of the adsorption of chlorhexidine on hydroxyapatite.

X-ray photoelectron spectroscopy (XPS) was used for determination of the effects of chlorhexidine (CHX) solutions (0.2% and 1% solutions of the digluconate salt) on the elemental composition of hydroxyapatite surfaces. So that the nature of the adsorbed species after they were washed with water could be identified, comparisons were made with reference spectra for CHX obtained from a CHX digluconate film and CHX dichloride powder. The XPS results clearly indicated the retention of CHX moieties, which could be ascertained from the spectra by the presence of N and Cl, features unique to CHX. The spectral envelopes were virtually identical to those obtained from the reference spectra. High-resolution C 1s spectra also gave support for the retention of CHX; however, the spectra differed from those of the CHX digluconate film in that no feature attributable to the C-OH of the gluconate anion was present, consistent with the view that the CHX cation remains behind to form an electrostatic bond with the phosphate groups of the hydroxyapatite. The N:Cl ratio for the washed samples was found to be higher than that for the reference samples and may be indicative of partial decomposition of the CHX. Decomposition was also seen to be induced by x-ray exposure. While the high-resolution spectra presented here do not directly address the controversy on the mechanism for the anti-plaque efficacy of CHX, they do provide the necessary basis for the application of XPS to future in vitro studies on the retention of CHX to dental surfaces.

Anaplastic thyroid carcinoma presenting as bilateral pleural effusion.

Anaplastic thyroid cancer presenting as bilateral malignant pleural effusion is rarely reported. We present a case who presented solely with respiratory symptoms and subsequently found to be having bilateral malignant pleural effusion secondary to anaplastic thyroid cancer.

X-ray photoelectron spectroscopy (XPS) surface analysis of HEMA-MMA microcapsules.

High resolution carbon, C 1s, X-ray photoelectron spectroscopy (XPS) of the surface of hydroxyethyl methacrylate-methyl methacrylate (HEMA-MMA; 75 mol% HEMA) capsules maintained in PBS for 1 week showed that the surface was not pure HEMA-MMA. In these spectra, more carbon was bonded in the C-O form than in the C-C form indicating the presence of the Pluronic surfactant, L101, adsorbed from the precipitation bath to the surface during microcapsule preparation. Capsules maintained in medium containing fetal bovine serum for 1 week showed a nitrogen signal consistent with the presence of adsorbed serum proteins. There was a decrease in the amount of nitrogen on the surface after phosphate buffered saline (PBS) washing, however this did not decrease to zero. These preadsorbed proteins, present on the surface of capsules incubated in serum-containing medium before their implantation, may affect the tissue response to these capsules. Calcium was not detected on freshly-made capsules or capsules maintained in PBS for 1 week but was detected on capsules maintained in medium containing serum. Calcium deposits, if formed in vitro, could act as nucleation sites for calcification of the polymer in vivo.

Behavior of primary bone cells on characterized polystyrene surfaces.

Primary bone cells, isolated from the periosteally stripped calvariae of neonate rats, were cultured on 60Co gamma-irradiation-sterilized bacteriologic-grade polystyrene that had been either surface treated with concentrated sulfuric acid or received further gamma-irradiation treatments facilitated cell colonization of the polystyrene compared to those surfaces not treated in the laboratory. x-Ray photoelectron spectroscopy (XPS) showed that the two treatments introduced different chemical groups onto the polymer surface and that cell adhesion was related to gamma-irradiation in a dose-dependent manner. These results show that simple biologic assays, such as cell colonization, are not able to distinguish between differences in surface chemistry demonstrated by such a routinely employed surface analysis technique. Thus, there is a need to develop more sensitive biologic assays that provide functional information of a precision that can be correlated with subtle changes in substratum surface chemistry. Further, we argue that because cells isolated by tissue digestion using proteolytic enzymes respond more readily to changes in the surface chemistry of the substratum they colonize, compared to explanted cells; biologic assays designed for biomaterials testing must take into account changes effected in cell adhesion behavior by isolation procedures.

Nitric acid passivation of Ti6Al4V reduces thickness of surface oxide layer and increases trace element release.

Passivation of Ti6Al4V and cpTi implants using methods based on the ASTM-F86 nitric acid protocol are used with the intention of reducing their surface reactivity, and consequently the corrosion potential, in the highly corrosive biologic milieu. The ASTM-F86 passivation protocol was originally developed for surgical implants made of stainless steel and chrome cobalt alloy. Using X-ray photoelectron spectroscopy (XPS) to examine the effect of nitric acid passivation on the surface oxide layer of mill-annealed Ti6Al4V and cpTi, we have found that such treatment actually reduced the oxide thickness on the alloy while having no significant effect on the pure metal. These results correlated with observations obtained using graphite furnace atomic absorption spectrophotometry (GFAAS) to detect trace element release from solid, mill-annealed, Ti6Al4V and cpTi into serum-containing culture medium. We detected significantly greater levels of Ti, Al, and V in the presence of passivated compared to nonpassivated Ti6Al4V. In contrast, nitric acid passivation did not influence Ti release from mill-annealed cpTi. These results, derived from two mill-annealed Ti-based metals, would indicate that re-examination of ASTM-F86-based passivation protocols with respect to Ti6Al4V should be considered in view of the widespread use of this alloy for biomedical devices.

Evaluating sol-gel ceramic thin films for metal implant applications: III. In vitro aging of sol-gel-derived zirconia films on Ti-6Al-4V.

Sol-gel-derived zirconia films were deposited onto polished Ti-6Al-4V substrates by dip-coating from an alkoxide precursor solution. No change in morphology of the zirconia film was observed after aging at 37 degrees C for 4-12 weeks in pH 4.0 buffer solution or Hanks' balanced salt solution (HBSS), although a precipitate predominantly composed of calcium phosphate was formed on those films aged in HBSS. X-ray diffraction identified the phase of the zirconia film as either cubic or tetragonal, and revealed no degradation to the monoclinic phase after aging. By a substrate straining test, the fracture strain of the coating was revealed to be 1.5%, above the yield strain of the titanium alloy substrate. At this strain level, through-thickness cracks formed in the coating where slip bands emerged from the substrate. Qualitatively, the adhesion of the film was sufficient to prevent gross delamination of the film at high strain levels, although small regions of delamination were caused by compressive buckling of the film. This behavior indicates generally good adhesion. No change in this behavior was observed after aging.

Retrospective validation of a surveillance system for unexplained illness and death: New Haven County, Connecticut.

OBJECTIVES: This study investigated retrospective validation of a prospective surveillance system for unexplained illness and death due to possibly infectious causes. METHODS: A computerized search of hospital discharge data identified patients with potential unexplained illness and death due to possibly infectious causes. Medical records for such patients were reviewed for satisfaction of study criteria. Cases identified retrospectively were combined with prospectively identified cases to form a reference population against which sensitivity could be measured. RESULTS: Retrospective validation was 41% sensitive, whereas prospective surveillance was 73% sensitive. The annual incidence of unexplained illness and death due to possibly infectious causes during 1995 and 1996 in the study county was conservatively estimated to range from 2.7 to 6.2 per 100,000 residents aged 1 to 49 years. CONCLUSIONS: Active prospective surveillance for unexplained illness and death due to possibly infectious causes is more sensitive than retrospective surveillance conducted through a published list of indicator codes. However, retrospective surveillance can be a feasible and much less labor-intensive alternative to active prospective surveillance when the latter is not possible or desired.