Natural anticoagulants and fibrinolytic activity following interferon therapy in chronic viral hepatitis.

Chronic liver disease is accompanied by derangement of hepatocyte function including the synthesis of haemostastic factors. It is, however, not known whether the improvement in liver functions as a result of interferon (IFN)-alpha therapy would be reflected in the plasma levels of these factors. To evaluate the effect of IFN-alpha therapy on the plasma levels of natural anticoagulants and on the fibrinolytic parameters, in patients with chronic viral hepatitis. Twenty one patients with chronic viral hepatitis (B and C) were treated with IFN-alpha, and were studied before commencement of therapy (first sample) 3 (second sample) and 6 months (third sample) later. The coagulation screening tests: activated partial thromboplastin time, prothrombin time, thrombin time, reptilase time and plasma fibrinogen and the natural anticoagulants: antithrombin, Protein C and free and total protein S as well as fibrinolytic parameters (tissue type plasminogen activator, plasminogen activator inhibitor type-1 and plasminogen) were measured. An increase in the levels of total protein S at 3 and 6 months after the commencement of IFN therapy was noted but the increase was statistically significant in the latter period. Reptilase time was prolonged in the first (pretreatment) and in the second samples and then began to decrease in the third sample but remained higher than the pretreatment level. Fibrinogen level increased in the second and third samples. No remarkable changes were noted in other haemostatic parameters. Total protein S level is a good marker of response to IFN therapy. IFN therapy does not affect other natural anticoagulants or fibrinolytic parameters. More detailed studies need to be done to confirm these findings.     

Chronically administered Agave americana var. marginata extract ameliorates diabetes mellitus,associated behavioral comorbidities and biochemical parameters in alloxan-induced diabetic rats

IntroductionDiabetes mellitus causes hyperglycemia and associated complications to the brain. In current study, the traditionally reported remedial claims of Agave americana var. marginata has been scientifically investigated in diabetic rats.MethodologyThe methanolic extract of leaves of Agave americana var. marginata (Aa.Cr) was characterized for total phenols, flavonoids, and antioxidant potential through in-vitro testing. The rats chronically pre-treated with Aa.Cr (400 and 600 mg/kg) for 45 days were challenged with alloxan-induced hyperglycemia. The dose-dependent effects of Aa.Cr on blood glucose levels and body weights were compared with diabetic rats using glibenclamide (0.6 mg/kg) as a standard. The animals were tested for diabetes-associated neurological comorbidities through behavioral and biochemical evaluation.ResultsThe phenols and flavonoids enriched Aa.Cr caused a significant dose-dependent hypoglycemic effect. Aa.Cr showed protection from comorbid anxiety, depression and cognitive impairment as compared to diabetic rats. The alanine aminotransferase, total cholesterol, triglycerides and low-density lipoprotein were prominently reduced, and high-density lipoprotein was increased in rats treated with Aa.Cr. Moreover, the oxidative stress in isolated brains was reduced by Aa.Cr.ConclusionThese findings suggest that Aa.Cr is enriched with antioxidant and anti-inflammatory phytoconstituents valuable for diabetes and related neurological complications.     

The effect of autoclaving on the physical and biological properties of dicalcium phosphate dihydrate bioceramics: brushite vs. monetite

Dicalcium phosphate dihydrate (brushite) is an osteoconductive biomaterial with great potential as a bioresorbable cement for bone regeneration. Preset brushite cement can be dehydrated into dicalcium phosphate anhydrous (monetite) bioceramics by autoclaving. This heat treatment results in changes in the physical characteristics of the material, improving in vivo bioresorption. This property is a great advantage in bone regeneration; however, it is not known how autoclaving brushite preset cement might improve its capacity to regenerate bone. This study was designed to compare brushite bioceramics with monetite bioceramics in terms of physical characteristics in vitro, and in vivo performance upon bone implantation. In this study we observed that monetite bioceramics prepared by autoclaving preset brushite cements had higher porosity, interconnected porosity and specific surface area than their brushite precursors. In vitro cell culture experiments revealed that bone marrow cells expressed higher levels of osteogenic genes Runx2, Opn, and Alp when the cells were cultured on monetite ceramics rather than on brushite ones. In vivo experiments revealed that monetite bioceramics resorbed faster than brushite ones and were more infiltrated with newly formed bone. In summary, autoclaving preset brushite cements results in a material with improved properties for bone regeneration procedures.     

Doxycycline sustained release from brushite cements for the treatment of periodontal diseases

Doxycycline (DOXY) is a wide spectrum antibiotic used in the treatment of dental, periodontal, and bone infections. Brushite cements are calcium phosphate biomaterials especially interesting for bone regeneration processes. In this work, we describe the preparation of a brushite cement containing DOXY and the drug release from the cement. DOXY solutions were mixed with the cement powder and after a 50% burst release in the first 12 h, a slow and controlled release was achieved over 3.5 days. The release of DOXY hyclate was controlled by both, diffusion and Ca(2+) interaction. Formation of DOXY-Ca(2+) chelates was detected in the cement structure using solid state fluorescence. The brushite cement loaded with DOXY hyclate had antibacterial activity against periodontal pathogens: Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Bacteroides frosthytus. This new biomaterial may be helpful for the treatment of periodontal diseases.     

Correlation between handwriting, drawing skills and dental skills of junior dental students

Learning fine motor skills is a pre-requisite for succeeding in dental practice and it is sometimes challenging for dental students. Most of the methods used in the selection process depend on evaluation of intellectual ability or structured interview while manual competence is not. However, no test on aptitude or manual dexterity is used as criteria. Objective: The purpose of the present study intended to evaluate the fine motor skills of beginning dental students which could in turn be used as a method of selection of students for the dental degree admission process. Materials and methods: A study was conducted among 71 second year dental students at College of Dentistry, King Saud University in Riyadh. A test composed of three parts, writing an answer for a question in four lines, drawing a picture of a smile and doing a class 1 amalgam preparation on a plastic molar tooth. The students were evaluated based on their handwriting, basic drawing skills and their skills in performing the tooth preparation by experts in each fields following certain criteria. Results: The results showed a significant correlation between writing and drawing skills and dental skills of the student with p < 0.001. Conclusions: The results of the current study support the use of the writing or drawing test as one of the test used for the applicants for dental school admission. However, the value given to such test in the selection of students needs further investigations and consensus.     

Dicalcium phosphate cements: brushite and monetite

Dicalcium phosphate cements were developed two decades ago and ever since there has been a substantial growth in research into improving their properties in order to satisfy the requirements needed for several clinical applications. The present paper presents an overview of the rapidly expanding research field of the two main dicalcium phosphate bioceramics: brushite and monetite. This review begins with a summary of all the different formulae developed to prepare dicalcium phosphate cements, and their setting reaction, in order to set the scene for the key cement physical and chemical properties, such as compressive and tensile strength, cohesion, injectability and shelf-life. We address the issue of brushite conversion into either monetite or apatite. Moreover, we discuss the in vivo behavior of the cements, including their ability to promote bone formation, biodegradation and potential clinical applications in drug delivery, orthopedics, craniofacial surgery, cancer therapy and biosensors.     

Regulation of enamel hardness by its crystallographic dimensions

Enamel is a composite biomaterial comprising a minor organic matrix (~2%) and a hierarchically organized inorganic ultrastructure (~96-98%). Surprisingly, to date there is no available information in the literature regarding the possible role of the enamel ultrastructure on the nanoscale level in tooth macroscopic properties. Understanding this relationship is of special interest for restorative purposes in dentistry. Accordingly, this study was designed to investigate how enamel nanocrystals regulate its hardness. We performed microindentation analysis on 100 extracted human teeth. The tooth enamel hardness was quantified and correlated with changes in enamel chemical composition and crystallographic dimensions obtained from Fourier transform infrared spectroscopy and X-ray diffraction, respectively. Enamel hardness was not related to the variability in organic content, but was associated with the size of apatite crystals along the c-axis. This association followed the Hall-Petch model for polycrystalline materials, indicating that the optimal size of apatite nanocrystals (larger than the critical size) provides enamel with the greatest hardness, which enables teeth to survive the heavy wear over a human lifetime.