Clinicopathological features of peripheral odontogenic fibromas in dogs and risk factors for their laboratory diagnosis.

OBJECTIVES: To explore clinicopathological features of peripheral odontogenic fibromas in dogs and risk factors for their diagnosis. MATERIALS AND METHODS: Data of cases with a histopathological diagnosis of peripheral odontogenic fibromas were obtained from a UK-based diagnostic laboratory and retrospectively reviewed. Prevalence amongst all biopsy submissions was assessed using binomial tests and Clopper-Pearson intervals. Age at diagnosis was assessed using t-test for independent samples. Lesion location, sex, and neuter status were assessed using χ2 and post hoc binomial tests. Breed odds ratios were calculated using univariable logistic regression modelling. RESULTS: The prevalence of peripheral odontogenic fibromas amongst all biopsy submissions was 2.8% (1001 of 35,328, 95% confidence interval [CI]: 2.7 to 3.0). The mean (sd) age was 8.1 (±2.7) years. The most affected quadrant was the rostral maxilla (40.1%). The ratio of maxillary to mandibular lesions was 1.3:1 (95% CI: 1.1 to 1.5), and for cases of multiple peripheral odontogenic fibromas the ratio of maxillary to mandibular lesions was 2.4:1 (95% CI: 1.1 to 5.6). Males had 1.2 times the odds of suffering of peripheral odontogenic fibromas compared to females (odds ratio [OR]: 1.2, 95% CI: 1.1 to 1.4). Neutering was associated with an increased risk of diagnosis (OR: 1.6, 95% CI: 1.3 to 1.9). Breeds with increased odds of peripheral odontogenic fibromas compared to crossbreed dogs included boxers (OR: 3.78, 95% CI: 2.80 to 5.09), border terriers (OR: 3.21, 95% CI: 2.10 to 4.91) and Basset Hounds (OR: 3.18, 95% CI: 1.58 to 6.44). Breeds with increased odds of multiple simultaneous peripheral odontogenic fibromas compared to crossbreed dogs included: Boxers (OR: 12.02, 95% CI: 7.13 to 20.24), border terriers (OR: 5.05, 95% CI: 2.32 to 11.43) and Staffordshire Bull terriers (OR: 2.42, 95% CI: 1.33 to 4.41). CLINICAL SIGNIFICANCE: Knowledge of clinicopathological features and at-risk breeds for peripheral odontogenic fibroma development can assist clinicians with making a diagnosis. The identification of risk factors provides targets for future research investigating peripheral odontogenic fibroma pathogenesis.

Ultra-long carrier lifetime in neutral graphene-hBN van der Waals heterostructures under mid-infrared illumination.

Graphene/hBN heterostructures are promising active materials for devices in the THz domain, such as emitters and photodetectors based on interband transitions. Their performance requires long carrier lifetimes. However, carrier recombination processes in graphene possess sub-picosecond characteristic times for large non-equilibrium carrier densities at high energy. An additional channel has been recently demonstrated in graphene/hBN heterostructures by emission of hBN hyperbolic phonon polaritons (HPhP) with picosecond decay time. Here, we report on carrier lifetimes in graphene/hBN Zener-Klein transistors of ~30 ps for photoexcited carriers at low density and energy, using mid-infrared photoconductivity measurements. We further demonstrate the switching of carrier lifetime from ~30 ps (attributed to interband Auger) down to a few picoseconds upon ignition of HPhP relaxation at finite bias and/or with infrared excitation power. Our study opens interesting perspectives to exploit graphene/hBN heterostructures for THz lasing and highly sensitive THz photodetection as well as for phonon polariton optics.

Gate-Dependent Electronic Raman Scattering in Graphene.

We report the direct observation of polarization resolved electronic Raman scattering in a gated monolayer graphene device. The evolution of the electronic Raman scattering spectra with gate voltage and its polarization dependence are in full agreement with theoretical expectations for nonresonant Raman processes involving interband electron-hole excitations across the Dirac cone. We further show that the spectral dependence of the electronic Raman scattering signal can be simply described by the dynamical polarizability of graphene in the long wavelength limit. The possibility to directly observe Dirac fermion excitations in graphene opens the way to promising Raman investigations of electronic properties of graphene and other 2D crystals.

Computer-assisted implant surgery and immediate loading in edentulous ridges with dental fresh extraction sockets. Two years results of a prospective case series study.

INTRODUCTION: The two-stage surgical approach for implant placement first documented in 1977 by Brånemark, represents today the most used protocol for placing implants. AIM: Aim of this prospective case series study was to compare the clinical and radiological performance of 12 edentulous jaws treated with of a modified prosthetic and surgical protocol for 3D software planning, guided surgery, immediate loading of implants inserted in edentulous jaws and extraction sockets and restored with Cad-Cam Zirconia and titanium full arch frameworks. PATIENTS AND METHODS: This work was designed as a prospective case series study. Twelve patients have been consecutively rehabilitated with an immediately loaded implant supported fixed full prosthesis. A total of 72 implants, Nobel Replace Tapered Groovy; Nobel Biocare AB, Goteborg, Sweden) 26 of which were inserted in fresh extraction sockets, were inserted. Outcome measures were implants survival, radiographic marginal bone-levels and bone remodeling, soft tissue parameters and complications. RESULTS: All patients reached 24 months follow-up, and no patients dropped out from the study. The cumulative survival rate was 100%; after 24 months mean marginal bone remodelling value was: 1.35 ± 0.25, mean PPD value was 2.75 ± 0.40 mm and mean BOP value was 3.8% ± 1.8%. Only minor prosthetic complications were recorded. CONCLUSIONS: These data seem to validate this surgical and prosthetic protocol with valid results when applied in selected cases.

Immunohistochemical expression of HOXA-13 in normal, hyperplastic and neoplastic canine prostatic tissue.

Homeobox genes are known to be examples of the intimate relationship between embryogenesis and tumourigenesis. Specifically, the HOXA13 gene plays a fundamental role in the development of the urogenital tract and external genitalia and in prostate organogenesis. There are no reports on the expression of HOXA13 in normal, hyperplastic or neoplastic canine prostate tissue or in other types of tumours. Six normal, 16 hyperplastic and 12 neoplastic canine prostates were examined microscopically and immunohistochemically with a polyclonal antibody specific for human HOXA13. An immunohistochemical score was generated. HOXA13 was expressed in the cytoplasm of epithelial cells in normal, hyperplastic and neoplastic prostates. The percentage of immunolabelled cells in all prostatic carcinomas (PCs) was greatly increased, with a score of 85.3 (±5.25) compared with normal (2 ± 0.71) and hyperplastic prostates (6.08 ± 2.21). The increase in HOXA13 expression in canine PCs suggests the involvement of this transcription factor in carcinogenesis and promotion of tumour growth.

Our experience in complications of orthognathic surgery: a retrospective study on 3236 patients.

BACKGROUND AND OBJECTIVES: From 1989 to 2009, at the Department of Cranio-Maxillo-Facial Surgery, Umberto I Polyclinic, "Sapienza" University of Rome, 3236 patients affected by maxillo-mandibular malformations were submitted to orthognathic surgery, by means of rigid internal fixation. Follow-up highlighted the surgical complications and the possible functional and/or esthetical disorders in the treatment of those pathologies. The data collected have been compared with the ones reported in the literature. MATERIALS AND METHODS: 3236 patients were evaluated clinically and radiographically. The X-rays have been performed before the study, after 24-48 hours, at 6 months and year after surgery. RESULTS: The most frequent surgical complication was the mandibular nerve sensitivity deficit (19%), irreversible only in 2% of the cases. Temporomandibular joint disorders (TMD), which are widely reported in the international literature, have been relevant in our study too. In particular, TMD occurred in those patients who were already affected by the disorder (from 28.3% to 18.1%); besides, in 11% of cases the symptom appeared after surgery and was treated by means of splint or physiotherapy. Infectious complications occurred in 2% of cases and fractures of the bone elements in 1.5% of cases. The other complications quoted internationally occurred in an irrelevant percentage in our study. CONCLUSIONS: We believe that orthognathic surgery complications are quite rare and the percentages reported both in our study and in the literature have to be considered as surgical mistakes related to the surgeon experience or as real complications of the orthognathic surgery. Furthermore, as the success of this kind of surgery depends upon many factors, surgical complications represent only one of the causes of the failure. Other causes could be mistakes in planning, unsuitable orthodontic treatment and, finally, an unsuitable assessment of the patients' esthetical and functional problems.

A retrospective analysis of the headache associated with temporomandibular joint disorder.

BACKGROUND: Headache is a common symptom, that can be extremely disabling, affecting 26 million of patients only in Italy. ICHD-II has reported two categories: "primary headaches" and "secondary headaches". Temporomandibular joint disorders can lead to a secondary headaches. AIM: We want to evaluate the prevalence and clinical features of headache among a series of patients having temporomandibular joint disorders and we illustrate the evolution of headache following medical treatament of temporomandibular joint (TMJ) disorders. MATERIALS AND METHODS: This is a retrospective study carried out on chart review of 426 consecutive patients with various degrees of temporomandibular disorders and treated with medical devices from 2007 to 2011. RESULTS: Headache was reported by 73 patients (17.14%). Headache was observed in 36 of 51 patients with lock and in 32 out of 130 patients with mandibular deflections (Table I). The remaining 5 patients with headache had articular noise. CONCLUSIONS: Headache is not a rare finding in a population with temporomandibular dysfunctions and is more often a tension-type rather than trigeminal headache.

Etiology and incidence of zygomatic fracture: a retrospective study related to a series of 642 patients.

BACKGROUND AND OBJECTIVES: The aim of this paper is to investigate epidemiological data (age, gender), sites, etiology and surgical approach of zygomatic fracture. MATERIALS AND METHODS: A 9 years retrospective clinical and epidemiologic study evaluated 642 patients treated for zygomatic fracture. There were 569 men and 77 women. The age range was 2 to 86 years with 205 (31.9%) in the 21 to 30 years age group. A number of parameters, including age, gender, cause of injury, site of injury, treatment modalities were evaluated. RESULTS: There were 552 (86%) zygoma fractures and 90 (14%) zygomatic arch fractures. The left zygoma was involved in 309 cases (56%); the right zygoma was involved in 243 cases (44%). Concerning the zygomatic arch, the left side was involved in 43 cases (48%) and the right side in 47 cases (52%). 7% of the patients were younger than 9 years old, about 70% between 10 and 39 years, and 18% between 40 and 59 years, while 4% were older than 60 years. Causes of zygoma fracture were traffic accidents in 151 (26%), assault in 117 (20%), accidental falls in 105 (19%), sports injuries in 56 (10%), home injuries in 45 (8%), work accidents in 34 (6%). Causes of zygomatic arch fractures 28 (29.1%) were assaults in 28 (29.1%), traffic accidents in 20 (21.5%), sports injuries in 14 (15.8%), accidental falls in 11 (14%), domestic accidents in 8 (8.8%) and work accidents in 4 (5%). The access to the fronto-zygomatic suture (74.6%) and the maxillary vestibular approaches (66.8%) were the commonest method of reduction of zygomatic fracture. About arch fractures, the Gillies temporal approach was the most used method of reduction (94.4%). CONCLUSIONS: The findings, compared with similar studies reported in the literature, support the view that the highest prevalence is in young male patients and, concerning cause, traffic accidents and assault are the most frequent.

Bisphosphonate-related osteonecrosis of the jaw (BRONJ): 5 year experience in the treatment of 131 cases with ozone therapy.

BACKGROUND: Bisphosphonate-Related Osteonecrosis of the Jaw (BRONJ) are the result of the assumption of such drugs. The most widely used molecules are pamidronate and zoledronic acid, which are pyrophosphate analogues and are usually given to patient with bone remodelling diseases. International literature reports showed an association between this therapy and avascular necrosis, thus leading to review the guidelines for their administer. AIM: The authors present their protocol based upon medical treatment, antibiotic and antimycotic, together with minimally invasive surgery and ozone therapy developed after a 5 year experience to assess the viability of this treatment. MATERIALS AND METHODS: In the last years researchers studied treatment protocols, both medical and surgical, for the management of BRONJ. Among these Ozone therapy is being adopted by several centers. From February 2004 and December 2010 a total number of 131 patients affected by BRONJ have been observed. Collected data include patients' age at the time of disorders, gender, presenting signs and symptoms, primary diagnosis, type and characteristics of the treatment performed, radiological findings and post-treatment results. CONCLUSIONS: At the present time there are no major guidelines in international literature for the treatment of BRONJ, the Authors then propose a therapeutic protocol based upon minimally invasive surgery, antibiotic and anti mycotic therapy with the adoption of ozone as regenerating factor for tissues. In 90% of the cases the results confirmed the procedure with successful outcomes.

Pleomorphic adenoma of the lacrimal gland: two clinical cases.

INTRODUCTION: Pleomorphic adenoma of the lacrimal gland is uncommon but it is the most common benign epithelial tumor of this gland. In the literature few cases have been reported in patients aged between 6 years and 80 years with a mean age of 39 years. A correct diagnosis and treatment is fundamental in order to avoid a relapse and sometimes their malignant transformation. An incisional biopsy is better to be avoided because it could injure the capsule, leading to dissemination of tumoral cells in the orbital tissues with a recurrence rate of 30% over 5 years. AIM: This papers want to support the use of mini-invasive surgery for the treatment of orbital lesions when it is possible. MATERIALS AND METHODS: We report two clinical cases of pleomorphic adenoma affecting the lacrimal gland treated with two different surgery approaches. The radiographic and photographic documentation of the patients was collected in the pre-and post-operatively. All patients underwent a CT scan and MRI. CONCLUSIONS: This lesions requires a well-grounded clinical and therapeutic protocol to avoid the risk of malignant transformation or disease recurrence, very dangerous at this site. CT scan and MRI scan are very important to recognize different types of lesions involving the lacrimal gland and fossa. A mini-invasive surgery reduces hospitalization, risk of complications, surgical times and bleedings and guarantees an excellent functional and esthetic result when performed by a skilled surgeon.

Le Fort III osteotomic variants.

INTRODUCTION: Midface hypoplasia is a skeletal defect involving all three space planes, hence needing a three-dimensional repositioning. This research study shows two cases of cranio-facial dysostosis, on which two Le Fort III variants were performed. CASE REPORT: In the first case we report the performing the two types of osteotomy simultaneously. Le Fort I, however, has been performed without any pterygomaxillary disjunctions, thus accomplishing a complete midface mobilization without any variation of the occlusal ratios. In the second case a modified Le Fort III osteotomy has been performed with median disjunction; reduction of the transverse interdacryal diameters and of the pyriform opening. DISCUSSION: Among all osteotomic variants we would like to mention the one introduced by Obwegeser in 1969 where, in patients with acceptable dental occlusal ratios, Le Fort III and Le Fort I have been performed in conjunction. This technique allows a different midface and dental occlusion repositioning. CONCLUSIONS: In adult patients with permanent dentition and normal occlusal ratios this technique may be chosen for a midface advancement without compromising the dento-skeletal relations, in order to achieve the best functional and aesthetical results.

Modulation of LTP at rat hippocampal CA3-CA1 synapses by direct current stimulation.

Transcranial direct current stimulation (tDCS) can produce a lasting polarity-specific modulation of cortical excitability in the brain, and it is increasingly used in experimental and clinical settings. Recent studies suggest that the after-effects of tDCS are related to molecular mechanisms of activity-dependent synaptic plasticity. Here we investigated the effect of DCS on the induction of one of the most studied N-methyl-d-aspartate receptor-dependent forms of long-term potentiation (LTP) of synaptic activity at CA3-CA1 synapses in the hippocampus. We show that DCS applied to rat brain slices determines a modulation of LTP that is increased by anodal and reduced by cathodal DCS. Immediate early genes, such as c-fos and zif268 (egr1/NGFI-A/krox24), are rapidly induced following neuronal activation, and a specific role of zif268 in the induction and maintenance of LTP has been demonstrated. We found that both anodal and cathodal DCS produce a marked subregion-specific increase in the expression of zif268 protein in the cornus ammonis (CA) region, whereas the same protocols of stimulation produce a less pronounced increase in c-fos protein expression in the CA and in dentate gyrus regions of the hippocampus. Brain-derived neurotrophic factor expression was also investigated, and it was found to be reduced in cathodal-stimulated slices. The present data demonstrate that it is possible to modulate LTP by using DCS and provide the rationale for the use of DCS in neurological diseases to promote the adaptive and suppress the maladaptive forms of brain plasticity.

A molecular dynamics study on the transport of a charged biomolecule in a polymeric adsorbent medium and its adsorption onto a charged ligand.

The transport of a charged adsorbate biomolecule in a porous polymeric adsorbent medium and its adsorption onto the covalently immobilized ligands have been modeled and investigated using molecular dynamics modeling and simulations as the third part of a novel fundamental methodology developed for studying ion-exchange chromatography based bioseparations. To overcome computational challenges, a novel simulation approach is devised where appropriate atomistic and coarse grain models are employed simultaneously and the transport of the adsorbate is characterized through a number of locations representative of the progress of the transport process. The adsorbate biomolecule for the system studied in this work changes shape, orientation, and lateral position in order to proceed toward the site where adsorption occurs and exhibits decreased mass transport coefficients as it approaches closer to the immobilized ligand. Furthermore, because the ligands are surrounded by counterions carrying the same type of charge as the adsorbate biomolecule, it takes the biomolecule repeated attempts to approach toward a ligand in order to displace the counterions in the proximity of the ligand and to finally become adsorbed. The formed adsorbate-ligand complex interacts with the counterions and polymeric molecules and is found to evolve slowly and continuously from one-site (monovalent) interaction to multisite (multivalent) interactions. Such a transition of the nature of adsorption reduces the overall adsorption capacity of the ligands in the adsorbent medium and results in a type of surface exclusion effect. Also, the adsorption of the biomolecule also presents certain volume exclusion effects by not only directly reducing the pore volume and the availability of the ligands in the adjacent regions, but also causing the polymeric molecules to change to more compact structures that could further shield certain ligands from being accessible to subsequent adsorbate molecules. These findings have significant practical implications to the design and construction of polymeric porous adsorbent media for effective bioseparations and to the synthesis and operation of processes employed in the separation of biomolecules. The modeling and analysis methods presented in this work could also be suitable for the study of biocatalysis where an enzyme is immobilized on the surface of the pores of a porous medium.

Dopamine D1-like receptor activation depolarizes medium spiny neurons of the mouse nucleus accumbens by inhibiting inwardly rectifying K+ currents through a cAMP-dependent protein kinase A-independent mechanism.

Dopamine/cAMP signaling has been reported to mediate behavioral responses related to drug addiction. It also modulates the plasticity and firing properties of medium spiny neurons (MSNs) in the nucleus accumbens (NAc), although the effects of cAMP signaling on the resting membrane potential (RMP) of MSNs has not been specifically defined. In this study, activation of dopamine D1-like receptors (D1Rs) by SKF-38393 elicited membrane depolarization and inward currents in MSNs from the NAc core of 14-17 day-old mice. Similar results were obtained following stimulation of adenylyl cyclase (AC) activity with forskolin or application of exogenous cAMP. Forskolin occluded SKF-38393's effects, thus indicating that D1R action is mediated by AC/cAMP signaling. Accordingly, AC blockade by SQ22536 significantly inhibited the responses to SKF-38393. Effects elicited by D1R stimulation or increased cAMP levels were unaffected by protein kinase A (PKA) or protein kinase C (PKC) blockade and were not mimicked by the Epac agonist, 8CPT-2Me-cAMP. Responses to forskolin were also not significantly modified by cyclic nucleotide-gated (CNG) channel blockade. Forskolin-induced membrane depolarization was associated with increased membrane input resistance. Voltage-clamp experiments revealed that forskolin and SKF-38393 effects were due to inhibition of resting K(+) currents exhibiting inward rectification at hyperpolarized potentials and a reversal potential (around -90 mV) that shifted with the extracellular K(+) concentration. Forskolin and D1R agonist effects were abolished by the inward rectifier K(+) (Kir)-channel blocker, BaCl(2). Collectively, these data suggest that stimulation of postsynaptic D1Rs in MSNs of the NAc core causes membrane depolarization by inhibiting Kir currents. This effect is mediated by AC/cAMP signaling but it is independent on PKA, PKC, Epac and CNG channel activation, suggesting that it may stem from cAMP's direct interaction with Kir channels. D1R/cAMP-mediated excitatory effects may influence the generation of output signals from MSNs by facilitating their transition from the quiescent down-state to the functionally active up-state.

Adsorption of a single protein interacting with multiple ligands: inner radial humps in the concentration profiles induced by non-uniform ligand density distributions.

The dynamic behavior of the concentration profiles of a single protein in the pore solution and the adsorbed phase is studied in different adsorbent media when the spatial density distribution of the immobilized ligands is either uniform or non-uniform and at the same time the single protein is forming one-site and two-site adsorbate-ligand complexes with the immobilized monovalent ligands. The competition for the formation of one-site and two-site interaction complexes leads to the formation of inner radial humps in the concentration profiles of the two-site adsorbate-ligand complex in adsorbent particles having either uniform or non-uniform spatial ligand density distributions. The results show that inner radial humps in the concentration profiles of the adsorbed protein (total concentration of adsorbed protein by one-site and two-site interactions) occur only in adsorbent media whose spatial ligand density distributions are non-uniform and have maxima or minima occurring in radial positions located between the center and the outer surface of the particles. The non-uniform spatial ligand density distributions satisfying this property provide the cause for the occurrence of inner radial humps in the concentration profiles of a single adsorbed protein, while the multi-site adsorption interactions affect the magnitude and the rate of propagation of the inner radial humps in the concentration profiles of the single adsorbed protein. It is also demonstrated that adsorbent media having certain non-uniform functional forms of spatial distribution in the density of immobilized ligands could provide more efficient adsorption of a protein than an adsorbent medium whose spatial distribution of the density of immobilized ligands is uniform. Furthermore, the results in this study suggest the type of information that could be obtained from finite bath experiments and could be used to (i) determine whether multi-site adsorbate-ligand complexes are formed during the adsorption of a single adsorbate and (ii) select between alternative adsorbent media the adsorbent particles that could provide the highest overall adsorption rate for a given adsorbate of interest. The results clearly indicate that it is very important to study the dynamic behavior of an adsorption system having a non-uniform spatial ligand density distribution and where the values of the pH and ionic strength are such that the electrophoretic effects are active.

Characteristics of cryptic/ectopic and contralateral scrotal testes in dogs between 1 and 2 years of age.

Testicular malposition represents a common developmental genital defect in dogs and can affect one or both testes. In both humans and dogs, unilateral cryptorchism is more frequently detected and thought to be the expression of a genetic abnormality affecting both the undescended and scrotal testis. In the dog, there is evidence of degenerative processes affecting the maldescended testis. However, the histologic and functional changes that occur in the scrotal testis of unilateral cryptorchid or ectopic individuals remain a source of debate. Because the bilateral surgical removal of the testes leads to some undesirable side effects, the aim of this study was to evaluate the necessity for performing bilateral orchiectomy in young unilateral cryptorchid dogs. A morphologic study of both cryptic/ectopic and scrotal testes in young dogs affected by unilateral testicular maldescent was therefore conducted. The study was conducted on 10 dogs aged 1 to 2 yr and affected by unilateral testicular maldescent. We found that, in young dogs, even if no neoplastic lesions were observed, morphologic abnormalities are detectable between 1 and 2 yr of age in the maldescended testes with severity dependent on testicular position. In contrast, in the scrotal testes, the histologic and immunohistochemical exam failed to find signs of incorrect development or morphologic abnormalities. The results seem to suggest that, though the early removal of the undescended testis is recommended, continuous monitoring of the scrotal testis for the life of the dog is preferable to removing it considering the undesirable side effects related to castration.

The design by molecular dynamics modeling and simulations of porous polymer adsorbent media immobilized on the throughpore surfaces of polymeric monoliths.

Ion-exchange porous adsorbent media having intermediate and low surface densities of dextran polymer grafted on the surface of the throughpores of polymeric monoliths are constructed and characterized by a molecular dynamics modeling and simulation approach that has also been shown to be effective in the construction and characterization of porous ion-exchange adsorbent media whose number of immobilized dextran polymer chains per unit surface area is high. The activation step that prepares the surface of the pores of the dextran polymer layer for the immobilization of the charged ligands insignificantly affected the pore structure of the dextran polymer layer, while this was found to not be the case for previously studied systems that involved high dextran polymer surface densities. Compared to the high dextran polymer density system studied previously, the intermediate dextran polymer density system can generate significantly larger pores but still possesses relatively high interconnection and mutual steric support between dextran chains to exhibit similar structural characteristics and responses to charged ligand immobilization, including dextran layer thickness, stability, monomer distribution, ligand-induced compact chain structures, dextran layer shrinkage, distributions of ligands and counterions, and local nonelectroneutrality. The low dextran polymer density system having relatively isolated dextran chains and insufficient mutual steric support can result in even larger pores than those obtained in the intermediate dextran polymer density system, but a significantly thinner porous dextran polymer layer and different dextran monomer distributions are obtained in the low dextran polymer density system. More importantly, the gradient of the local nonelectroneutrality after the immobilization of the charged ligands is significantly smaller in magnitude in the low dextran polymer density system than that obtained in the system having intermediate dextran polymer density, and, despite a lack of porous layer depth to accommodate adsorbate biomolecules in large amounts, it could still be useful for the effective transport and adsorption of very large biomolecules. Compared with the polymeric monoliths without a porous dextran polymer layer grafted on the surface of their throughpores, the intermediate and low dextran polymer density systems explored and studied in this work provide pore structures with desirable characteristics for the effective transport of adsorbate biomolecules and substantially larger effective surface areas and throughput capacities for the adsorption of the adsorbate biomolecules.

Structural changes induced in proteins by therapeutic ultrasounds.

The structural effect induced by therapeutic ultrasound on proteins in aqueous solution has been investigated with FTIR spectroscopy, UV-VIS spectroscopy, circular dichroism and light scattering. Six proteins (cytochrome, lysozyme, myoglobin, bovine serum albumin, trypsinogen, and alpha-chymotrypsinogen A) with different molecular weight and secondary structure have been studied. The experiment has been performed using an ultrasound source at resonant frequency of 1 MHz and sonication times of 10, 20, 30, 40, 50, and 60 min. A different behaviour of proteins under sonication depends on the dominant secondary structure type (alpha-helix or beta-sheets) and on the grade of the ordered structure. The results suggest that the free radicals, produced by water sonolysis, have an important role in the changes of structural order.

Porous polymer adsorbent media constructed by molecular dynamics modeling and simulations: the immobilization of charged ligands and their effect on pore structure and local nonelectroneutrality.

A molecular dynamics modeling and simulation approach is presented and employed to construct porous dextran polymer ion-exchange adsorbent media. Both the activation step of the surface of the pores of the dextran polymer layer grafted on an agarose surface and the immobilization of charged ligands on the activated surface of the porous dextran polymer layer are considered. For the systems studied in this work, the activation step modifies slightly the pore structure of the base, nonactivated porous dextran polymer, while the immobilization of the ligands on the activated pore surface of the dextran layer changes significantly the pore structure of the activated dextran layer. The density distributions of the counterions and immobilized charged ligands along the direction of net transport in the adsorbent media constructed in this study are found to be nonuniform. The variables that affect the shape and magnitude of the density distributions of the counterions and immobilized charged ligands as well as the total number of charged ligands that can be immobilized on the activated porous dextran layer are identified and presented in this work. Furthermore, the data clearly show that there is local nonelectroneutrality in the porous dextran polymer ion-exchange adsorbent media, and this result has very important practical implications for the operation and performance of separation systems involving ion-exchange adsorbent media (e.g., ion-exchange chromatography systems). Also, the results of this work suggest approaches for (1) controlling the immobilization process of charged ligands and (2) constructing and studying the behavior of chromatographic polymeric monoliths and packed bed columns having a gradient of density of functionalities along the axis of the chromatographic polymeric monolith or packed bed column.