Local properties of a functionally graded interphase between cementum and dentin

The study of natural interfaces may provide information necessary to engineer functionally graded biomaterials for bioengineering applications. In this study, the mechanical, structural, and chemical composition variations associated with a region between cementum and dentin were studied with the use of nanoindentation, microindentation, optical microscopy, and Raman microspectroscopy techniques. Three-millimeter-thick transverse sections (N = 5) were obtained from the apical one-third of the roots of sterilized human molars. The samples were ultrasectioned at room temperature with the use of a diamond knife and an ultramicrotome. Longitudinal ground sections of 100 microm thickness were prepared and stained with von Kossa stain to determine the mineralized regions within the molar roots. Raman microspectroscopy was used to determine the relative inorganic content, mainly apatite (PO4(3-)nu1 mode at 960 cm(-1)) and organic content, mainly collagen (C--H stretch at 2940 cm(-1)) between cementum and dentin bulk tissues. The microindentation and nanoindentation results indicated a gradual transition in hardness from cementum to dentin over a width ranging from 100 to 200 microm. However, the variation in hardness data for cementum and dentin by nanoindentation was larger (0.62 +/- 0.21, 0.77 +/- 0.14 GPa) than from microindentation (0.49 +/- 0.03, 0.69 +/- 0.07 GPa). Within the 100 to 200 microm region there was a 10 to 50 microm fibrillar hydrophilic cementum-dentin junction (CDJ) with mechanical properties significantly lower than either the cementum or the dentin side of CDJ. Light microscopy revealed a 100 to 200 microm translucent region between cementum and dentin. Raman microspectroscopy results showed a variation in organic and inorganic composition 80 to 140 microm wide. It was concluded that a morphologically and biomechanically different CDJ lies within a wider cementum-dentin interphase. Hence, cementum, dentin, and the interphase can be classified as a functionally graded dental tissue within the root of a tooth.     

Characteristics and Motivation of Solid Organ Transplant Recipients Attending the Canadian Transplant Games

BackgroundThe Canadian Transplant games (“Games”) were created to increase awareness of organ donation and highlight the importance of staying active and healthy post-transplant. It is unclear what motivates solid organ transplant (SOT) recipients to participate and whether the games serve as an incentive for SOT recipients to increase their physical activity (PA) levels.Objectives1. To describe the characteristics of participants from past games and their motivation for attending and 2. to determine whether there was an interest in participating in goal-based, pre-games exercise training programs.MethodsA web-based questionnaire was sent to adult SOT recipients who were members of the Canadian Transplant Association. The survey included questions about why participants attended, their PA levels, and their interest in a pre-games training program.ResultsOf the 157 participants, more were male than female; the 35-54-year-old age group was the most common; and 62% of respondents received a liver or kidney transplant. The most common reasons for participating in the games were to showcase health post-transplant, promote awareness of organ donation, sports competition, and social reasons. Sixty-five percent of respondents reported that they would be interested in an exercise program to be more physically prepared for the competition.ConclusionPre-games training programs could be developed to motivate participation and help participants achieve higher training intensities and foster social interaction. Directing resources to individuals who do not attend the games and to those who are not physically active should be considered.     

Biodegradation study of crop residues as affected by exogenous inorganic nitrogen and fungal inoculants

The comparative decomposition of chickpea residue, and chopped and unchopped wheat straw was investigated in pits for 120 days. Microbial biomass, humus, C/N ratio, pH, Electrical conductivity (EC), dehydrogenase, alkaline phosphatase, cellulase, xylanase, total phenol and soluble protein were determined to assess their response to the addition of inorganic nitrogen and mixed fungal inoculum of Aspergillus nidulans, Phanerochaete chrysosporium and Trichoderma viride. The evaluation of physico-chemical parameters (organic matter, organic carbon, N, C/N, pH, EC, microbial biomass) revealed that by supplementing unchopped wheat straw with 1% urea and mixed fungal inoculum, a lowest C/N ratio of 10.7, lowest biomass of 9.54 and highest humus content of 13% can be achieved within 3 months. Germination of Lepidium sativum (cress seeds) showed a germination index >60%, in this treatment. The enzyme assay for dehydrogenase indicated highest microbial activity in uninoculated treatments compared to fungal inoculated counterparts, in the second month sampling (active phase of composting). However, cellulase and xylanase activity showed an upward trend during curing phase of composting. Chickpea residue compost, though resulted in a C/N ratio of 17.3, but its germination index was less than 60%. The rapid quality tests conducted for H2S, NH3, NO3 and starch confirmed the stability and maturity of finished compost prepared from wheat straw through microbial inoculants.     

Postdatism -- a perinatal problem?

It has been traditionally accepted that maternal and fetal complications are at their lowest levels 37-42 weeks into gestation. 20% of pregnancies completed after 42 weeks gestation are thought to be affected by the postmaturity syndrome of uteroplacental insufficiency resulting in oligohydramnios, meconium passage, loss of fetal subcutaneous tissue, fetal asphyxia, and fetal death. Some workers, however, have also found that pregnancies completed between 40 and 42 weeks carry significant risk. The authors explored this question in a case-control study of 464 women seen at the Mahatma Gandhi Institute of Medical Sciences in Maharashtra, India. The cases of postdatism occurred in the absence of any other medical or obstetric problem. The operative delivery rate increased significantly among these patients compared to deliveries between 39 and 40 weeks. There was neither significant asphyxia nor perinatal loss in term completed normal patients. Asphyxia and perinatal mortality did, however, occur with postdatism. The authors note the likely role of oligohydramnios combined with placental dysfunction.     

Admission,recruitment, and retention

As the country strives to produce larger numbers of generalist physicians, considerable controversy has arisen over whether or not generalist applicants can be identified, recruited, and influenced to keep a generalist-oriented commitment throughout medical training. The authors present new and existing data to show that: 1) preadmission (BA/MD or post-baccalaureate) programs can help to identify generalist-oriented students; 2) characteristics determinedat admission to medical school are predictive of future generalist career choice; 3) current inpatient-oriented training programs strongly push students away from a primary care career; 4) women are more likely than men to choose generalist careers, primarily because of those careers’ interpersonal orientation; and 5) residency training programs are able to select applicants likely to become generalists. Therefore, to produce more generalists, attempts should be made to encourage generalist-oriented students to enter medical schools and to revise curricula to focus on outpatient settings in which students can establish effective and satisfying relationships with patients. These strategies are most likely to be successful if enacted within the context of governmental and medical school-based changes that allow for more reimbursement and respect for the generalist disciplines.     

Comparative Carcinogenicity of 5,5-Diphenylhydantoin with or without Perinatal Exposure in Rats and Mice

Volume 21, Number 2 (1993), in the article "Comparative Carcinogenicityof 5,5-Diphenyihydantoin with or without Perinatal Exposurein Rats and Mice," by R. S. Chhabra, J. R. Bucher, J. K. Haseman,M. R. Elwell, P. J. Kurtz, and B. D. Canton, pages 174–186:Since the publication of the above article, the authors havefound that the feed and estimated DPH consumption data reportedin Tables 2 and 6 were incorrect. The following Tables 2 and6 contain revised feed and DPH consumption data:     

Deletions in the ligand for CD40 in X-linked immunoglobulin deficiency with normal or elevated IgM (HIGMX-1)

Patients with X-linked Ig deficiency with normal or elevatedIgM (HIGMX-1) fail to switch from IgM/IgD to other Ig isotypes.Interaction between the B cell antigen CD40 and the CD40 ligandexpressed on activated T cells is critical for T cell drivenisotype switching. We have reported that T lymphocytes fromthree unrelated male patients with HIGMX-1 failed to expressCD40 ligand on their surface, but the mRNA for CD40 ligand wasof an apparently normal size and level. Analysis of CD40 ligandcDNA from two of the patients revealed deletions that alterthe reading frame. Patient 1 displayed two mutations: a C Atransversion at nucleotide 590 and the deletion of an adjacentC nucleotide. The second patient had a 58 bp deletion from nucleotides289–346. Furthermore, neither patient expressed a proteinproduct detectable by the CD40L mAb, 5c8.