Application of Backscattered Electron Imaging and Lectin-Gold Cytochemistry to Visualize the Distribution of Glycoconjugates in a Basal Lamina

Basement membranes generally appear in transmission electron microscopy as thin, cross-sectioned profiles. Face-views are difficult to obtain particularly when their contours are curved or undulated. Such preparations are suited for the study of the distribution of basement membrane constituents through thickness but are limited for examining their spatial distribution. Scanning electron microscopy offers the potential of visualizing surface views. We have applied this approach to examining the three-dimensional distribution of glycoconjugates in a basement membrane. Large, face-views of the basal lamina related to maturation ameloblasts in the region where enamel of the rat incisor is EDTA soluble were exposed. Glycoconjugates were then revealed by incubating the segments in lectin-gold complexes and binding sites were visualized by backscattered electron imaging. This basal lamina was found to contain fucose, mannose and to be extremely rich in N-acetyl-D-galactosamine. The abundance of glycoconjugates containing the latter sugar residue may impart on this basal lamina selective properties which could regulate the movement of material into, and out of, the enamel layer

Bone healing response in cyclically loaded implants : comparing zero, one, and two loading sessions per day

When bone implants are loaded, they are inevitably subjected to displacement relative to bone. Such micromotion generates stress/strain states at the interface that can cause beneficial or detrimental sequels. The objective of this study is to better understand the mechanobiology of bone healing at the tissue-implant interface during repeated loading. Machined screw shaped Ti implants were placed in rat tibiae in a hole slightly bigger than the implant diameter. Implants were held stable by a specially-designed bone plate that permits controlled loading. Three loading regimens were applied, (a) zero loading, (b) one daily loading session of 60 cycles with an axial force of 1.5 N/cycle for 7 days, and (c) two such daily sessions with the same axial force also for 7 days. Finite element analysis was used to characterize the mechanobiological conditions produced by the loading sessions. After 7 days, the implants with surrounding interfacial tissue were harvested and processed for histological, histomorphometric and DNA microarray analyses. Histomorphometric analyses revealed that the group subjected to repeated loading sessions exhibited a significant decrease in bone-implant contact and increase in bone-implant distance, as compared to unloaded implants and those subjected to only one loading session. Gene expression profiles differed during osseointegration between all groups mainly with respect to inflammatory and unidentified gene categories. The results indicate that increasing the daily cyclic loading of implants induces deleterious changes in the bone healing response, most likely due to the accumulation of tissue damage and associated inflammatory reaction at the bone-implant interface

Ameloblastin is a cell adhesion molecule required for maintaining the differentiation state of ameloblasts

Tooth morphogenesis results from reciprocal interactions between oral epithelium and ectomesenchyme culminating in the formation of mineralized tissues, enamel, and dentin. During this process, epithelial cells differentiate into enamel-secreting ameloblasts. Ameloblastin, an enamel matrix protein, is expressed by differentiating ameloblasts. Here, we report the creation of ameloblastin-null mice, which developed severe enamel hypoplasia. In mutant tooth, the dental epithelium differentiated into enamel-secreting ameloblasts, but the cells were detached from the matrix and subsequently lost cell polarity, resumed proliferation, and formed multicell layers. Expression of Msx2, p27, and p75 were deregulated in mutant ameloblasts, the phenotypes of which were reversed to undifferentiated epithelium. We found that recombinant ameloblastin adhered specifically to ameloblasts and inhibited cell proliferation. The mutant mice developed an odontogenic tumor of dental epithelium origin. Thus, ameloblastin is a cell adhesion molecule essential for amelogenesis, and it plays a role in maintaining the differentiation state of secretory stage ameloblasts by binding to ameloblasts and inhibiting proliferation

Tooth movement into the maxillary sinus

Objectives: To evaluate the effect of overloading on the palatal movement of the maxillary molar. Materials and methods: The maxillary first molar of male C57Bl/6 mice was moved palatally with 10-g or 30-g load for 14 days, and amount of tooth movement was longitudinally measured on micro-computed tomography images (each group, N=5). Bone remodeling around the molar root under the 30-g load was evaluated at days 3, 5, 7, and 14 after the starting of tooth movement using histomorphometry and immunodetection of bone-restricted Ifitm (interferon inducible transmembrane)-like protein, a novel marker of active bone formation (each group, N=5). Result: In the 10-g load group, the amount of tooth movement increased dramatically between day 5 to day 7, and gradually increased thereafter. In 30-g load group, tooth movement at day 5 and day 7 was significantly lower than those in the 10-g load group; however, total tooth movement for 14 days was similar in both groups. Orthodontic load of 30-g stimulated bone formation on the sinus wall, but bone resorption on the periodontal ligament side was delayed because of the hyalinization, which means strong force application was not accelerate tooth movement. Moreover, some root resorption was induced under the excessive force application. Conclusion: Root penetration into sinus and bone height reduction does not occur because new bone formation on the maxillary sinus is induced prior to bone resorption on the periodontal side, even though excessive orthodontic force is applied. However, excessive force is subject to induce root resorption

Nursing staff absenteeism rates as a personnel management indicator

Absenteeism in nursing is a difficult problem for health organizations; hence it is an indicator that must be monitored. The objective of this study was to analyze the absenteeism rate of nursing professionals in a public hospital. Absenteeism data were collected monthly, from January to July 2008, and calculated by means of an electronic program. The mean absenteeism index for nurses varied from 5.6% to 9.7% for technicians/nursing aides. Sick leaves were the most prevalent reason for absences. The data revealed the major cause of absenteeism and pointed at the need to change policies for hiring nursing professionals, in addition to reviewing the working processes in order to improve the workers' health conditions.O absenteísmo dos profissionais de enfermagem é um problema complexo para as organizações de saúde, constituindo-se um indicador que necessita ser monitorado. Este estudo objetivou analisar a taxa de absenteísmo dos profissionais de enfermagem em um hospital público de ensino. As ausências por absenteísmo foram coletadas a partir das escalas mensais, no período de janeiro a julho de 2008, e calculadas por meio de planilha eletrônica. Constatou-se um índice médio de absenteísmo de 5,6% para os enfermeiros e de 9,7% para técnicos/auxiliares de enfermagem. As ausências que mais contribuíram para esses índices referiram-se aos afastamentos por doença. Os dados obtidos evidenciaram o principal motivo de absenteísmo e sinalizam a necessidade de mudanças nas políticas de contratação dos profissionais de enfermagem, além da revisão dos processos de trabalho, visando favorecer melhores condições de saúde a esses profissionais.El ausentismo de profesionales de enfermería es un problema complejo para las organizaciones de salud, constituyéndose en un indicador que necesita monitoreo. Este estudio objetivó analizar la tasa de ausentismo de profesionales de enfermería en hospital público de enseñanza. El ausentismo fue analizado a partir de escalas mensuales, en período de enero a julio de 2008, y calculadas mediante planilla electrónica. Se constató un índice medio de ausentismo para enfermeros del 5,6% y del 9,7% para técnicos/auxiliares de enfermería. Las ausencias que más engrosaron tales índices se relacionaron con licencias de salud. Los datos obtenidos evidenciaron el principal motivo de ausentismo y señalan la necesidad de cambios en las políticas de contratación de profesionales de enfermería, además de la revisión de los procesos de trabajo, apuntando a favorecer mejores condiciones de salud para tales profesionales

Eschar-associated Spotted Fever Rickettsiosis, Bahia, Brazil

In Brazil, Brazilian spotted fever was once considered the only tick-borne rickettsial disease. We report eschar-associated rickettsial disease that occurred after a tick bite. The etiologic agent is most related to Rickettsia parkeri, R. africae, and R. sibirica and probably widely distributed from São Paulo to Bahia in the Atlantic Forest

Regulation of pH During Amelogenesis

During amelogenesis, extracellular matrix proteins interact with growing hydroxyapatite crystals to create one of the most architecturally complex biological tissues. The process of enamel formation is a unique biomineralizing system characterized first by an increase in crystallite length during the secretory phase of amelogenesis, followed by a vast increase in crystallite width and thickness in the later maturation phase when organic complexes are enzymatically removed. Crystal growth is modulated by changes in the pH of the enamel microenvironment that is critical for proper enamel biomineralization. Whereas the genetic bases for most abnormal enamel phenotypes (amelogenesis imperfecta) are generally associated with mutations to enamel matrix specific genes, mutations to genes involved in pH regulation may result in severely affected enamel structure, highlighting the importance of pH regulation for normal enamel development. This review summarizes the intra- and extracellular mechanisms employed by the enamel-forming cells, ameloblasts, to maintain pH homeostasis and, also, discusses the enamel phenotypes associated with disruptions to genes involved in pH regulation

International society of sports nutrition position stand: caffeine and exercise performance

Following critical evaluation of the available literature to date, The International Society of Sports Nutrition (ISSN) position regarding caffeine intake is as follows: 1. Supplementation with caffeine has been shown to acutely enhance various aspects of exercise performance in many but not all studies. Small to moderate benefits of caffeine use include, but are not limited to: muscular endurance, movement velocity and muscular strength, sprinting, jumping, and throwing performance, as well as a wide range of aerobic and anaerobic sport-specific actions. 2. Aerobic endurance appears to be the form of exercise with the most consistent moderate-to-large benefits from caffeine use, although the magnitude of its effects differs between individuals. 3. Caffeine has consistently been shown to improve exercise performance when consumed in doses of 3–6 mg/ kg body mass. Minimal effective doses of caffeine currently remain unclear but they may be as low as 2 mg/kg body mass. Very high doses of caffeine (e.g. 9 mg/kg) are associated with a high incidence of side-effects and do not seem to be required to elicit an ergogenic effect. 4. The most commonly used timing of caffeine supplementation is 60 min pre-exercise. Optimal timing of caffeine ingestion likely depends on the source of caffeine. For example, as compared to caffeine capsules, caffeine chewing gums may require a shorter waiting time from consumption to the start of the exercise session. 5. Caffeine appears to improve physical performance in both trained and untrained individuals. 6. Inter-individual differences in sport and exercise performance as well as adverse effects on sleep or feelings of anxiety following caffeine ingestion may be attributed to genetic variation associated with caffeine metabolism, and physical and psychological response. Other factors such as habitual caffeine intake also may play a role in between-individual response variation. 7. Caffeine has been shown to be ergogenic for cognitive function, including attention and vigilance, in most individuals. 8. Caffeine may improve cognitive and physical performance in some individuals under conditions of sleep deprivation. 9. The use of caffeine in conjunction with endurance exercise in the heat and at altitude is well supported when dosages range from 3 to 6 mg/kg and 4–6 mg/kg, respectively. 10. Alternative sources of caffeine such as caffeinated chewing gum, mouth rinses, energy gels and chews have been shown to improve performance, primarily in aerobic exercise. 11. Energy drinks and pre-workout supplements containing caffeine have been demonstrated to enhance both anaerobic and aerobic performance