Success rate of immediately loaded implants in the posterior zone.

Dental implants are considered an ideal treatment for a missing single tooth. Immediate loading of implants can hasten the procedure, providing comfort to the patients. Recently, immediate loading of implants has gained much importance as it helps hasten the procedure and provides more comfort to patients. A previous systematic review published 5 years ago compared the success rates between immediate and conventional loading. There are several factors that influence the success rate of implants that were not discussed in detail in the previous review. Hence, the present systematic review is done to report differences in the outcomes from single implant restorations of missing teeth in the posterior region in patients who were subjected to immediate loading and conventional loading. A follow up for 1 year was done. Electronic databases of Medline, Scopus, and Web of Science were searched for publications in the English Language during May 2021. The search results yielded 306 articles, out of which 225 were excluded based on title and abstract screening. Screening of the remaining 81 full text articles yielded 14 original research articles that satisfied the predefined inclusion criteria. Meta analysis was not possible due to the heterogeneity of the data. The overall success rate of the immediate loading of a single implant is 94.31%. Implants in the maxillary region had a higher survival rate than those in the mandibular region. The age range between 18 and 80 years showed good prognosis and outcomes in older individuals. Good oral hygiene was emphasized for all patients to prevent any secondary conditions or delays in healing.

An innovative application of pre-medicated collagen sponges with regenerative biomaterials for management of an infected extraction socket: A case report.

Localized infection of the extraction socket can compromise bone quality and quantity within the socket and bone support for the adjacent dentition. These events can preclude immediate rehabilitative interventions, such as implant placement, and increase the technical sensitivity of guided bone regeneration procedures for successful tissue and bone gain. The use of local scaffolds containing effective antimicrobial agents may suppress local infection and facilitate the regenerative process related to the introduced bone graft particles and barrier collagen membrane. In this case report, pre-medicated collagen sponges containing chlorhexidine and metronidazole were used in conjunction with a bone graft and collagen membrane for guided tissue and bone regeneration, which was followed by delayed implant placement with 2 years of follow-up evaluations.

In vivo Study of a Newly Synthesized Chromen-4-one Derivative as an Antitumor Agent against HCC.

BACKGROUND: Chromenes are a wide group of natural compounds that can be synthesized chemically. The chromen-4-one nucleus acts as a skeleton for varieties of additional active groups that makes the chromene activity vary between antioxidant and anti-inflammatory agents. In the present study, a newly synthesized chromene compound exhibits different behaviors other than anti-inflammatory and antioxidant activities that it is the first time that a member of chromen-4-one compound can control the cancer progress. Inflammation is the first step in tumor development where the severity grade can potentiate tumor growth and progression. In many tumors, pro-inflammatory genes record high expression level such as tumor necrosis factor (TNF-α) and vascular endothelial growth factors (VEGF). These pro-inflammatory factors act as rate limiting steps in tumor initiation, and controlling its expression acts as an early therapeutic way to control the tumor proliferation. The chromone derivatives have biological activities such as anti-inflammatory and anti-tumor activity. METHODS: In the present study, hepatocellular cancer (HCC) induced by diethylnitrosamine (DEN) in rats and then treated with the new chromene derivative and the parameters TNF-α, VEGF, p53, Cyt C, MMP-9, Bcl2, and Bax were measured. RESULTS: The treatment strategy Ch compound is to downregulate pro-inflammatory gene expression of early genes as TNF-α as well as VEGF and subsequently control other factors such as p53, Cyt C, and MMP-9. Also, retrieve the balance between Bcl2 and Bax proteins in DEN-induced HCC in rats. CONCLUSION: The ability of the new Ch derivative to control the primary initiators of HCC such as TNF-α offers this derivative an anti-tumor activity and encourages further researches to follow and monitor its effect on the molecular level.

Factors Affecting Clinical Decision-Making and Treatment Planning Strategies for Tooth Retention or Extraction: An Exploratory Review.

Dentists are often confronted with challenges concerning the determination of the treatment type for questionable teeth (retention or extraction) in their routine dental practice. The objective of this review was to explore the available literature pertaining to the factors influencing clinical decision-making and treatment strategies of dentists regarding tooth retention or extraction. Explorative analysis of the literature was conducted based on its relevance to the subjected study area and scope. Primarily, the papers were extracted from sources such as ERIC, PubMed, Scopus, and Medline. The keywords used for searching articles include Clinical Decision-Making, Treatment Strategies, Tooth Extraction, and Tooth Retention. Papers published up to 2018 were extracted and evaluated. The analyzed studies highlighted that a successful treatment plan is based on the practitioner's knowledge, abilities, and skills as well as patients' preference, which is also a determinant of treatment success in restorative dentistry. Multidisciplinary dental treatment is generally adopted for decision making in dental clinics. Overall, the treatment plan should be based on the extensive learning and keen observation of the disease and the associated factors which enable long-term success of the treatment.

Two-piece mesostructure and vertically oriented locking screws design for implant-assisted prosthesis in the esthetic zone.

Restoration of the malaligned dental implants in the esthetic zone is a challenge for dental practitioner because of the difficulty in obtaining balance and harmony between position and color of the final prosthesis and the adjacent teeth. Mesostructure is a part of the prosthesis that located ontop of the dental implant and bearing the final prosthesis. It has a form of milled bar to bear an overdenture or as abutment used for the correction of malaligned dental implants. Such approach maintains screw-retained prosthesis option while allowing complete retrievability, improved accessibility, usage of thicker abutment screws, and acceptable esthetic outcomes. In this case report, a two-piece mesostructure was designed to correct the malposition of dental implants in the esthetic zone with 1-year follow-up system.

Effect of Layering Techniques on Polymerization Shrinkage Stress of High- and Low-viscosity Bulk-fill Resins.

CLINICAL RELEVANCE: The use of layering techniques is still advisable with many bulk-fill resins and should be the default unless a particular resin is known to not need it. SUMMARY: Objective: The purpose of this study was to investigate how layering techniques affect polymerization shrinkage stresses of high-and low-viscosity bulk-fill resins.Method: Six high-viscosity and six low-viscosity bulk-fill resins were evaluated. Aluminum blocks with a mesial-occlusal-distal (MOD) cavity were machined and randomly divided into groups for different filling techniques (bulk-fill vs horizontal layering vs oblique layering) and further subdivided according to type of resin (high- vs low-viscosity). The cuspal deflection resulting from the polymerization of bulk-fill resin bonded to a MOD cavity within an aluminum block was measured with a digimatic micrometer. Scanning electron microscopy analyses of tested resins were also conducted.Results: In the high-viscosity bulk-fill resins, cuspal deflection of the MOD cavity ranged from 11.2 to 18.2 µm with the bulk-filling technique, from 10.7 to 15.5 µm with the horizontal layering technique, and from 10.9 to 15.2 µm with the oblique layering technique. In the low-viscosity bulk-fill resins, cuspal deflection of the material ranged from 9.2 to 19.8 µm with the bulk-filling technique, from 8.2 to 15.7 µm with the horizontal layering technique, and from 8.4 to 16.4 µm with the oblique layering technique.Conclusion: Cuspal deflections for some high-and low-viscosity bulk-fill resins were significantly reduced by using layering techniques, but the resultant improvement of layering techniques was not applicable to all the bulk-fill resins used in this study.

Marjoram extract down-regulates the expression of Pasteurella multocida adhesion, colonization and toxin genes: A potential mechanism for its antimicrobial activity.

Due to the emergence of virulent and antibiotic-resistant microbes, natural antimicrobials from herbal origins have been given more attention as an alternative therapy. This study provides an in vitro research framework to investigate the antibacterial activities of 5 herbal (marjoram, garlic, onion, cinnamon and black seed) oil extracts against 16 multidrug-resistant (MDR) and virulent P. multocida serogroup A isolates recovered from dead and clinically diseased rabbits. Pathogenicity of the screened isolates was further proven experimentally and was verified by PCR analyses of 5 randomly selected virulence genes encoding attachment and colonization proteins (ptfA, pfhA, and omp87), sialidases (nanB) and dermonecrotoxin (toxA). A total of 12 P. multocida isolates were highly pathogenic with the possession of all examined virulence genes, while the other 4 isolates were of lower pathogenicity with expression of the target genes except toxA. In vitro anti-P. multocida activities of the 5 extracts and their synergism rates with 4 antibiotic drugs revealed that marjoram and cinnamon extracts had the highest antibacterial activities and the highest synergism rates against the screened isolates. Pasteurella multocida virulence gene expression profiles were assessed via real-time quantitative reverse transcription PCR (qRT-PCR) in response to marjoram extract. The quantitative analyses showed less than five-fold reduction in the targeted virulence genes expression in presence of marjoram extract compared with the control. The findings from this study document a novel molecular inhibitory activity of marjoram against P. multocida multiple virulence genes and provide a proof of concept for its implementation as an alternative candidate for the treatment of pasteurellosis in farm animals in future.

An expanded evaluation of protein function prediction methods shows an improvement in accuracy.

BACKGROUND: A major bottleneck in our understanding of the molecular underpinnings of life is the assignment of function to proteins. While molecular experiments provide the most reliable annotation of proteins, their relatively low throughput and restricted purview have led to an increasing role for computational function prediction. However, assessing methods for protein function prediction and tracking progress in the field remain challenging. RESULTS: We conducted the second critical assessment of functional annotation (CAFA), a timed challenge to assess computational methods that automatically assign protein function. We evaluated 126 methods from 56 research groups for their ability to predict biological functions using Gene Ontology and gene-disease associations using Human Phenotype Ontology on a set of 3681 proteins from 18 species. CAFA2 featured expanded analysis compared with CAFA1, with regards to data set size, variety, and assessment metrics. To review progress in the field, the analysis compared the best methods from CAFA1 to those of CAFA2. CONCLUSIONS: The top-performing methods in CAFA2 outperformed those from CAFA1. This increased accuracy can be attributed to a combination of the growing number of experimental annotations and improved methods for function prediction. The assessment also revealed that the definition of top-performing algorithms is ontology specific, that different performance metrics can be used to probe the nature of accurate predictions, and the relative diversity of predictions in the biological process and human phenotype ontologies. While there was methodological improvement between CAFA1 and CAFA2, the interpretation of results and usefulness of individual methods remain context-dependent.

The activity of detoxifying enzymes in the infective juveniles of Heterorhabditis bacteriophora strains: Purification and characterization of two acetylcholinesterases.

The infectivity and detoxifying enzyme activities including glutathione-S-transferase (GST), acetylcholinesterase (AChE) and carboxylesterase (CaE) are investigated in the infective juveniles (IJs) of six different strains of Heterorhabditis bacteriophora as a biocontrol agent against insect pests. The specific activities ranged from 10.8-29.8 and 50-220units/mg protein for GST and AChE, respectively; and from 24.7-129 and 22.6-77.3units/mg protein for CaE as estimated by P-nitrophenyl and α-naphthyl acetates, respectively. H. bacteriophora EM2 strain has the highest infectivity and the highest enzymatic activities as well. AChE is the predominant detoxifying enzyme that might imply its major role in the detoxification of insecticide(s). The isoenzyme pattern demonstrated two major slow-moving isoforms in all EPN strains examined. Purification of two AChE isoforms, AChEAII and AChEBI, from H. bacteriophora EM2 strain is performed by ammonium sulfate precipitation, gel filtration on Sephacryl S-200 and chromatography on DEAE-Sepharose. AChEAII and AChEBII have specific activities of 1207 and 1560unit/mg protein, native molecular weights of 180 and 68kDa, and are found in dimeric and monomeric forms, respectively. Both isoforms showed optimum activity at pH8.5 and 35°C. AChEBI exhibited higher thermal stability and higher activation energy than AChEAII. The enzymatic activities of purified AChEs are completely inhibited by Hg(+2) and Ni(+2) and greatly enhanced by Mn(+2). The substrate specificity, the relative efficiency of substrates hydrolysis, substrate inhibition and inhibition by BW284C51, but not by iso-OMPA, clearly indicated that they are true AChEs; their properties are compared with those recorded for insects as target hosts for H. bacteriophora EM2.

Alleviation of Dimethylnitrosamine-Induced Liver Injury and Fibrosis by Supplementation of Anabasis articulata Extract in Rats.

Anabasis articulata (Forssk) Moq. (Chenopodiaceae) is an herb, grows in Egypt, and used in folk medicine to treat diabetes, fever, and kidney infections. The protective and therapeutic effects of the ethanol extract of A. articulata aerial parts were evaluated against dimethylnitrosamine (DMN)-induced liver fibrosis, compared with the standard drug, silymarin. Hepatic hydroxyproline content, serum transforming growth factor-ß1 (TGF-ß1), interleukin 10 (IL-10) and fructosamine were measured as liver fibrosis markers. Hepatic malondialdehyde (MDA), nitric oxide (NO), catalase (CAT), glutathione reductase (GR) and glutathione content (GSH) were measured as oxidant/antioxidant markers. Parallel histopathological investigations were also performed. Protective and therapeutic administration of A. articulata (100 mg/kg daily for 4 weeks), markedly prevented DMN-induced loss in body and liver weights. The extract significantly inhibited the elevation of hepatic hydroxyproline, NO and MDA (P < 0.05), as well as serum fructosamine, and TGF-ß1 (P < 0.05) induced by DMN while it restored IL-10 to normal level in both protective and therapeutic groups. Furthermore, A. articulata prevented the depletion in CAT, GR, and GSH levels (P ≤ 0.05). In addition, oral administration of A. articulata extract and silymarin to both protective and therapeutic groups reduced the increase in liver function enzyme activities; alanine and aspartate amintransferases, gamma-glutamyl transferase in addition to alkaline phosphatase, and caused significant increase in serum albumin concentration as compared to DMN group. These data corresponded closely with those obtained for the drug silymarin. Histopathological studies confirmed the biochemical data and revealed remarkable improvement in liver architecture. Thus, it could be concluded that, A. articulata extract exhibited in vivo hepatoprotective and therapeutic effects against DMN-induced liver injury and may act as a useful agent in controlling the progression of hepatic fibrosis through reduction of oxidative stress and improving liver function.

Egyptian horned viper Cerastes cerastes venom hyaluronidase: purification, partial characterization and evidence for its action as a spreading factor.

Novel Hyaluronidase CcHaseII (33 kDa) of the most dangerous horned viper Cerastes cerastes (Cc) was purified and partial characterized in a set of biochemical assays. CcHaseII was purified by applying a protocol of two successive chromatographic steps; gel filtration on a Sephacryl S-200 and cation exchange chromatography on CM-Sepharose columns. It has specific activity 4000 units/mg protein against 154 units/mg protein for the whole venom with 26-purification fold. The enzymatic activity of the purified Hyaluronidase stimulated by Na(+) and inhibited by entire tested cations, metalloproteinase inhibitors and heparin. CcHaseII (5-10 µg) enhanced one hundred percent of hemorrhagic activity of the potent purified hemorrhagic SVMP of corresponding venom (CcHTI) and enhanced edema-inducing activity of Cc venom in a dose-dependent manner. Furthermore, the described purification procedure allows simple preparation of appreciable quantities of the CcHaseII for further studies. Eventually, exploration of snake venom antigenic parts is the most crucial factor for establishing good immunogens and specific diagnostic reagents.

Antioxidant activity of new aramide nanoparticles containing redox-active N-phthaloyl valine moieties in the hepatic cytochrome P450 system in male rats.

We report the synthesis of aramide nanoparticles containing a chiral N-phthaloyl valine moiety and their antioxidant activities on hepatic contents of cytochrome P450, amidopyrene N-demethylase, aniline-4-hyroxylase and induced the hepatic content of cytochrome b5 and nicotinamide adenine dinucleotide phosphate (NADPH) cytochrome C-reductase. Polymers were obtained as well-separated spherical nanoparticles while highly aggregated particles via H-bonding organization of the aramide-containing pyridine led to a thin layer formation. The effects of the nanoparticles and CCl4 on enzyme activities and thiobarbituric acid reactive substances (TBARS) levels of male rat liver were studied. Pretreatments of rats with the polyamides prior to the administration of CCl4 decreased the hepatic content of the tested enzymes. Doses reduced the toxic effects exerted by (•CCl3) upon the liver through inhibition of the cytochrome P450 system. Inhibition of such metabolizing enzymes could reduce the carcinogenic effects of chemical carcinogens.

The prognostic significance of inflammation and medullary histological type in invasive carcinoma of the breast.

UNLABELLED: The new gene expression molecular taxonomy of breast cancer places medullary carcinoma in the basal group. The basal group is considered to have a poor prognosis, but medullary carcinoma is considered to have a better prognosis than other grade 3 carcinomas. The prognostic significance of tumour associated inflammation, an important feature of medullary carcinomas, remains controversial. The aim of this study was to assess the prognostic importance of medullary histological type and inflammation in breast cancer. One thousand five hundred and ninety-seven patients who received no systemic adjuvant treatment and who had a median follow up of 9.5 years were studied. RESULTS: Prominent inflammation was associated with high histological grade and with better survival [relative risk (RR) 0.57, 95% confidence intervals (CI) 0.44-0.74] on multivariate analysis. Typical and atypical medullary carcinomas (n=132) did not have significantly different survival and were grouped together. Medullary carcinoma did not have significantly different prognosis than grade 3 ductal carcinoma with prominent inflammation, but both had a better prognosis than grade 3 ductal carcinoma without prominent inflammation (P<0.0001 and P=0.03). These differences were independent of other prognostic factors. These results question the current separation of typical and atypical medullary carcinoma. Prominent inflammation is associated with a better prognosis, and may explain the better prognosis in medullary carcinoma compared with grade 3 ductal carcinoma without prominent inflammation. The good prognosis of medullary carcinoma emphasises the heterogeneity of basal-like breast carcinomas. Further studies are needed to investigate the difference in survival between medullary carcinoma and other forms of basal carcinomas and the role of inflammation in any such differences in behaviour.

Predictive value of needle core biopsy diagnoses of lesions of uncertain malignant potential (B3) in abnormalities detected by mammographic screening.

AIMS: Breast needle core biopsy (NCB) is now a commonplace diagnostic procedure in breast cancer screening, providing accurate diagnoses of both benign and malignant lesions. However, NCB may result in the borderline diagnoses of lesion of uncertain malignant potential (B3) or suspicious of malignancy (B4). The aim was to study a large series of B3 cases from population-based screening subjects in order to evaluate positive predictive values (PPVs) for malignancy. METHODS AND RESULTS: The results of 523 NCBs of women screened over a 7-year period (1999-2006) in the East Midlands region, UK, with a B3 diagnosis who underwent surgical excision, were reviewed and compared with the final excision histology. Five percent of NCBs were reported as B3. The most frequent histological subtypes were atypical intraductal epithelial proliferation (AIDEP) and radial scar/complex sclerosing lesion (RS/CSL). Final excision histology was benign in 417 (80%) and malignant in 106 (20%) subjects (60 ductal carcinoma in situ and 46 invasive carcinoma). Lesion-specific PPVs were as follows: AIDEP 32%; lobular neoplasia (LN) 30%; RS/CSL with AIDEP or LN 24%; RS/CSL without atypia 9%; papillary lesion with AIDEP or LN 36%; and papillary lesion without atypia 4%. Five of the 32 fibroepithelial lesions with cellular stroma were phyllodes tumours (four benign and one borderline). None of the five mucinous lesions on NCB was malignant. CONCLUSIONS: Our results show that approximately one-fifth of NCB of screen-detected breast lesions classified as B3 are malignant on excision, and the likelihood of malignancy varies substantially between different histological subtypes.

Expression profiling technology: its contribution to our understanding of breast cancer.

Breast cancer is a complex genetic disease characterized by the accumulation of multiple molecular alterations. Routine clinical management of breast cancer relies on clinical and pathological factors, however. These seem insufficient to reflect the whole clinical heterogeneity of tumours and are less than perfectly adapted to each patient. Recent advances in human genome research and high-throughput molecular technologies have made it possible to tackle the molecular complexity of breast cancer and have contributed to the realization that the biological heterogeneity of breast cancer has implications for treatment. Gene expression profiling of breast cancer has been performed using several approaches. This review will describe the details of gene expression profiling of breast cancer, the different approaches and the impact on clinical management.

Breast carcinoma with basal differentiation: a proposal for pathology definition based on basal cytokeratin expression.

AIM: To assess the expression and coexpression of a range of different biomarkers that have been used to define breast carcinomas with a basal phenotype (BP) and their relationship with prognosis in an attempt to refine the definition of BP and to evaluate the reliability of using a single biomarker to identify these tumours. METHODS AND RESULTS: The expression pattern of basal cytokeratins (CK5/6 and CK14), oestrogen, progesterone and androgen receptors, epidermal growth factor receptor, HER2, BRCA1, P-cadherin and myoepithelial markers (smooth muscle actin and p63) were studied in a well-characterized series of invasive breast carcinoma (1872 cases) with long-term follow-up using immunohistochemistry and tissue microarray. Although the additional markers were associated with basal CK expression, they did not serve to improve recognition of cases with differing outcome when compared with basal CKs alone and, if used to define cases, reduced considerably the proportion of cases allocated to this poor prognostic type of breast cancer. CONCLUSION: BP can be defined based on the expression of basal CKs regardless of the expression of other markers.

Serodiagnosis of human intestinal schistosomiasis.

We developed an enzyme linked-immunosorbent assay (ELISA) for serodiagnosis of Schistosoma mansoni infection using a purified immunogenic fraction from schistosome adult worm, obtained by SDS-polyacrylamid gel electrophoresis. Sera from patients with active schistosomiasis (egg passers; n=10); inactive schistosomiasis previously treated with praziquantel (not passing eggs; n=10); fascioliasis, hydatosis (n=5); and healthy controls (n=10) were examined. Western blot analysis revealed that the Sm 31/32 KDa fraction of Schistosoma mansoni is recognized by sera from of both active and inactive schistosomiasis. ELISA IgG reactivity (optical density, OD) to Sm 31/32 KDa fraction by ELISA was significantly higher in sera of schistosomiasis patients (active and inactive), (p<0.001) compared to normal controls, while no significant difference was detected between active (OD=0.79 +/- 0.23) & inactive (OD=0.87 +/- 0.37) patients. No reactivity was detected using facioliasis or hydatosis sera. The overall level of specificity and sensitivity attained was 90% and 93%, respectively. It is concluded that the developed Sm 31/32 KDa ELISA may be of value in serodiagnosis of active and inactive intestinal Schistosoma mansoni infection in humans.

Redox cycling of adrenaline and adrenochrome catalysed by mitochondrial Complex I.

Complex I in bovine heart submitochondrial particles catalyses the NADH-supported generation of superoxide anion; adrenaline is oxidised by superoxide to adrenochrome that, on its hand, is reduced by Complex I, thus establishing a redox cycle that amplifies the superoxide production. The routes in Complex I for superoxide formation and for adrenochrome reduction appear to be different, since they have a different sensitivity to Complex I inhibitors. The results are discussed in terms of current assays for superoxide detection and of pathologies linked to catecholamine oxidation.

'Smart' delivery systems for biomolecular therapeutics.

OBJECTIVE: There is a strong need for drug delivery systems that can deliver biological signals from biomaterials and tissue engineering scaffolds, and a particular need for new delivery systems that can efficiently deliver biomolecules to intracellular targets. Viruses and pathogens have evolved potent molecular machinery that sense the lowered pH gradient of the endosomal compartment and become activated to destabilize the endosomal membrane, thereby enhancing protein or DNA transport to the cytoplasmic compartment. A key feature of many of these biological delivery systems is that they are reversible, so that the delivery systems are not directly toxic. These delivery systems have the ability to change their structural and functional properties and thus display remarkable 'smart' material properties. The objective of this presentation is to review the initial development of smart polymeric carriers that mimic these biological delivery systems and combine similar pH-sensitive, membrane-destabilizing activity for the delivery of therapeutic biomolecules. DESIGN: We have developed new 'smart' polymeric carriers to more effectively deliver and broaden the available types of biomolecular therapeutics. The polymers are hydrophilic and stealth-like at physiological pH, but become membrane-destabilizing after uptake into the endosomal compartment where they enhance the release of therapeutic cargo into the cytoplasm. They can be designed to provide a range of pH profiles and membrane-destabilizing activities, allowing their molecular properties to be matched to specific drugs and loading ranges. A versatile set of linker chemistries is available to provide degradable conjugation sites for proteins, nucleic acids, and/or targeting moieties. RESULTS: The physical properties of several pH-responsive polymers were examined. The activity and pH profile can be manipulated by controlling the length of hydrophobic alkyl segments. The delivery of poly(propyl acrylic acid) (PPAA)-containing lipoplexes significantly enhanced wound healing through the interconnected effects of altered extracellular matrix organization and greater vascularization. PPAA has also been shown to enhance cytoplasmic delivery of a model protein therapeutic. Polymeric carriers displaying pH-sensitive, membrane-destabilizing activity were also examined. The pH profile is controlled by the choice of the alkylacrylic acid monomer and by the ratio of the carboxylate-containing alkylacrylic acid monomer to alkylacrylate monomer. The membrane destabilizing activity is controlled by the lengths of the alkyl segment on the alkylacrylic acid monomer and the alkylacrylate monomer, as well as by their ratio in the final polymer chains. CONCLUSION: The molecular mechanisms that proteins use to sense and destabilize provide interesting paradigms for the development of new polymeric delivery systems that mimic biological strategies for promoting the intracellular delivery of biomolecular drugs. The key feature of these polymers is their ability to directly enhance the intracellular delivery of proteins and DNA, by destabilizing biological membranes in response to vesicular compartment pH changes. The ability to deliver a wide variety of protein and nucleic acid drugs to intracellular compartments from tissue engineering and regenerative scaffolds could greatly enhance control of important processes such as inflammation, angiogenesis, and biomineralization.

Effect of forty-eight-hour glucose infusion into rats on islet ion fluxes, ATP/ADP ratio and redox ratios of pyridine nucleotides.

Glucose infusion into rats has been shown to sensitize/desensitize insulin secretion in response to glucose. In pancreatic islets from glucose-infused rats (GIR) (48 h, 50%, 2 ml/h) basal insulin release (2.8 mmol/l glucose) was more than fourfold compared with islets from saline-infused controls and the concentration-response curve for glucose was shifted to the left with a maximum at 11.1 mmol/l. The concentration-response curve for 45Ca2+ uptake was also shifted to the left in islets from GIR with a maximum at 11.1 mmol/l glucose. Starting from a high basal level at 2.8 mmol/l glucose KCl produced no insulin release or 45Ca2+ uptake in islets from GIR. Islets from GIR exhibited a higher ATP/ADP ratio in the presence of 2.8 mmol/l glucose and marked inhibition of 86Rb+ efflux occurred even at 3 mmol/l glucose. Moreover, in islets from GIR the redox ratios of pyridine nucleotides were increased. On the other hand insulin content was reduced to about 20%. The data suggest that a 48-h glucose infusion sensitizes glucose-induced insulin release in vitro in concentrations below 11.1 mmol/l. This may, at least in part, be due to enhanced glucose metabolism providing increased availability of critical metabolic factors including ATP which, in turn, decrease the threshold for depolarization and therefore calcium uptake. Calcium uptake may then be further augmented by elevation of the redox state of pyridine nucleotides.