Silver Diammine Fluoride Usage in General Dentistry Offices in Louisiana

Purpose: To evaluate the current knowledge and usage of silver diammine fluoride (SDF) by general dentists in Louisiana and to identify primary barriers to the imple- mentation of SDF. Methods: A 16-item survey was emailed to 1719 Louisiana Dental Association members to identify factors influencing general dentists' usage of SDF. Results: Eighty-two surveys were completed with a response rate of 4.8 percent, with 69 identified as general dentists. Over half of the respondents were male (53.6%) and their practice experience ranged from less than one year to 48 years. The majority were solo owners (43.5%) while 7.3 percent had jobs in the corporate setting. Most agreed/strongly agreed that their knowledge of SDF was from either dental journals or online resources, while fewer stated they were taught about SDF (25%) or used SDF (8%) in dental school. The majority knew the advantages and off-label usage of SDF. However, only 40 percent recognized that SDF was officially approved for tooth hypersensitivity only. The most reported perceived barrier to SDF implementation was not learning about SDF in dental school (36%). Conclusion: There is a lack of understanding of SDF usage among Louisiana general dentists. The main reason for not incorporating SDF into their practice is the lack of training in their dental education.

Detecting Induced p±ip Pairing at the Al-InAs Interface with a Quantum Microwave Circuit

Superconductor-semiconductor hybrid devices are at the heart of several proposed approaches to quantum information processing, but their basic properties remain to be understood. We embed a two-dimensional Al-InAs hybrid system in a resonant microwave circuit, probing the breakdown of superconductivity due to an applied magnetic field. We find a fingerprint from the two-component nature of the hybrid system, and quantitatively compare with a theory that includes the contribution of intraband p±ip pairing in the InAs, as well as the emergence of Bogoliubov-Fermi surfaces due to magnetic field. Separately resolving the Al and InAs contributions allows us to determine the carrier density and mobility in the InAs.

Point-of-care Hepatitis C virus testing and linkage to treatment in an Australian inner-city emergency department

BACKGROUND

In Australia, Hepatitis C Virus (HCV) treatment is declining, despite broad access to direct-acting antiviral medication. People who inject drugs are proportionally over-represented in emergency department presentations. Emergency department assessment of people who have injected drugs for HCV presents an opportunity to engage this marginalised population with treatment. We describe the outcomes of risk-based screening and point-of-care anti-HCV testing for emergency department patients, and linkage to outpatient antiviral treatment.

METHODS

During the three-month study period, consecutive adult patients who presented to the emergency department during the study times were screened for risk factors and offered the OraQuick oral HCV antibody test. Those with reactive results were offered venepuncture in the emergency department for confirmatory testing and direct-acting antiviral treatment in clinic. The main outcome measures were the number and proportion of viremic participants that were linked to the hepatitis clinic, commenced treatment and achieved a sustained viral response. Secondary outcome measures were the proportion (%) of presentations screened that were oral antibody reactive, and the prevalence and type of HCV risk factors.

RESULTS

During the study period, 2408 of the 3931 (61%) presentations to the emergency department were eligible for screening. Of these 2408 patients, 1122 (47%) participated, 307 (13%) declined participation and 977 (41%) could not be approached during their time in the emergency department. Among the 1122 participants, 378 (34%) reported at least one risk factor. Subsequently, 368 (97%) of the 378 participants underwent OraQuick anti-HCV test, and 50 (14%) had a reactive result. A risk factor of ever having injected drugs was present in 44 (88%) of participants who were sero-positive. Of the 45 that had blood tested, 30 (67%) were HCV ribonucleic acid (RNA) positive. Three participants died. Of the 27 remaining participants, 10 (37%) commenced treatment and 7 of these 10 (70%) obtained a cure. There was a high rate of homelessness (24%) among anti-HCV positive participants.

CONCLUSION

Among emergency department participants with a risk factor for HCV, positive serology was common using a rapid point-of-care test. A history of injecting drug use was identified as the risk factor with highest yield for positive HCV serology, and is suitable as a single screening question. However, linkage to care post ED presentation was low in this marginalised population. There is a need for new pathways to improve the care cascade for marginalised individuals living with HCV infection.

The influence of sagittal spinal deformity on anteversion of the acetabular component in total hip arthroplasty

The interaction between the lumbosacral spine and the pelvis is dynamically related to positional change, and may be complicated by co-existing pathology. This review summarises the current literature examining the effect of sagittal spinal deformity on pelvic and acetabular orientation during total hip arthroplasty (THA) and provides recommendations to aid in placement of the acetabular component for patients with co-existing spinal pathology or long spinal fusions. Pre-operatively, patients can be divided into four categories based on the flexibility and sagittal balance of the spine. Using this information as a guide, placement of the acetabular component can be optimal based on the type and significance of co-existing spinal deformity.

Androgen regulation of the cell-cell adhesion molecule-1 (Ceacam1) gene

Previous studies have established that the cell-cell adhesion molecule-1 (CEACAM1, previously known as C-CAM1) functions as a tumor suppressor in prostate cancer and is involved in the regulation of prostate growth and differentiation. However, the molecular mechanism that modulates CEACAM1 expression in the prostate is not well defined. Since the growth of prostate epithelial cells is androgen-regulated, we investigated the effects of androgen and the androgen receptor (AR) on CEACAM1 expression. Transient transfection experiments showed that the AR can enhance the Ceacam1 promoter activity in a ligand-dependent manner and that the regulatory element resides within a relatively short (-249 to -194 bp) segment of the 5'-flanking region of the Ceacam1 gene. This androgen regulation is likely through direct AR-promoter binding because a mutant AR defective in DNA binding failed to upregulate reporter gene expression. Furthermore, electrophoretic mobility shift assays demonstrated that the AR specifically binds to this sequence, and mutation analysis of the potential ARE sequences revealed a region within the sequence that was required for the AR to activate the Ceacam1 gene. Therefore, the regulation of Ceacam1 gene expression by androgen may be one of the mechanisms by which androgen regulates prostatic function.

Differences in tissue-specific and embryonic expression of mouse Ceacam1 and Ceacam2 genes

The intercellular adhesion molecule CEACAM1, also known as C-CAM1 (where CAM is cell-adhesion molecule), can function as a tumour suppressor in several carcinomas, including those of the prostate, breast, bladder and colon. This suggests that CEACAM1 may play an important role in the regulation of normal cell growth and differentiation. However, there is no direct evidence to support this putative function of CEACAM1. To elucidate its physiological function by targeted gene deletion, we isolated the Ceacam genes from a mouse 129 Sv/Ev library. Although there is only one Ceacam1 gene in humans and one in rats, two homologous genes (Ceacam1 and Ceacam2) have been identified in the mouse. Our sequence analysis revealed that the genes encoded nine exons and spanned approx. 16-17 kb (Ceacam1) and 25 kb (Ceacam2). The genes were highly similar (79.6%). The major differences in the protein-coding regions were located in exons 2, 5 and 6 (76.9%, 87.0% and 78.5% similarity respectively). In addition, introns 2, 5 and 7 were also significantly different, being 29.7%, 59.8% and 64.5% similar respectively. While most of these differences were due to nucleotide substitutions, two insertions of 418 and 5849 bp occurred in intron 2 of Ceacam2, and another two insertions of 1384 and 197 bp occurred in introns 5 and 7 respectively. To determine whether functional redundancy exists between Ceacam1 and Ceacam2, we examined their expression in 16 mouse tissues by using semi-quantitative reverse transcription-PCR. As in human and rat, in the mouse Ceacam1 mRNA was highly abundant in the liver, small intestine, prostate and spleen. In contrast, Ceacam2 mRNA was only detected in kidney, testis and, to a lesser extent, spleen. Reverse transcription-PCR using testis RNA indicated that Ceacam2 in the testis is an alternatively spliced form containing only exons 1, 2, 5, 6, 8 and 9. In the mouse embryo, Ceacam1 mRNA was detected at day 8.5, disappeared between days 9.5 and 12.5, and re-appeared at day 19. On the other hand, no Ceacam2 mRNA was detected throughout embryonic development. The different tissue expression patterns and regulation during embryonic development suggest that the CEACAM1 and CEACAM2 proteins, although highly similar, may have different functions both during mouse development and in adulthood.

Purification and characterization of human cell--cell adhesion molecule 1 (C-CAM1) expressed in insect cells

The cell--cell adhesion molecule 1 (C-CAM1) plays an important role as a tumor suppressor for prostate cancer. Decreased expression of C-CAM1 was detected in prostate, breast, and colon carcinoma. Reexpression of C-CAM1 in prostate and breast cancer cell lines was able to suppress tumorigenicity in vivo. These observations suggest that C-CAM1 may be used as a marker for cancer detection or diagnosis. To generate monoclonal antibodies specific to C-CAM1, we have overexpressed full-length human C-CAM1 in Sf9 cells using a baculovirus expression system. The protein was purified 104-fold using nickel affinity chromatography. About 0.4 mg purified C-CAM1 was obtained from 200 mg of infected cells. When the purified protein was digested with peptidyl-N-glycosidase, the apparent mobility of the protein on SDS--PAGE changed from 90 to 58 kDa, which is close to the molecular weight predicted from the cloned cDNA sequence. This observation suggests that C-CAM1 was glycosylated on asparagine residues when expressed in Sf9 cells. Western blotting and internal protein sequencing analysis confirmed that the purified protein is human C-CAM1. Biochemical and functional assays indicate that this protein expressed in Sf9 cells displays characteristics similar to those of native protein, including adhesion function and glycosylation modification. Using this protocol, sufficient quantity of this protein can be produced with purity suitable for monoclonal antibody generation and biochemical study.

The cytoplasmic domain of C-CAM1 tumor suppressor is necessary and sufficient for suppressing the tumorigenicity of prostate cancer cells

We have previously shown that C-CAM1 cell adhesion molecule can suppress the growth of prostate cancer cells in vivo. In this study, we determined the minimal domain of C-CAM1 that is required for its tumor-suppressive activity. DU145 prostate cancer cells were infected with recombinant adenoviruses containing various C-CAM1 mutant genes, and the effects of the mutant C-CAM1 proteins on the growth of DU145 cells were assessed in a nude-mice xenograft model. Deletion of C-CAM1's cytoplasmic domain, which is not required for its adhesion activity, abolished the growth-suppressive activity, whereas deletion of the adhesion domain did not. This observation suggests that C-CAM1's extracellular domain may be not essential for its tumor suppressive activity. Indeed, we found that expression of the C-CAM1 cytoplasmic domain alone led to growth suppression of DU145 cells. These results suggest that the cytoplasmic domain of C-CAM1 is necessary and sufficient for its growth-suppressive function.

pH dependent binding of high and low affinity myelin basic protein peptides to purified HLA-DR2

Major histocompatibility complex (MHC) class II molecules are cell surface glycoproteins and are known to display processed antigens on the surface of antigen presenting cells (APC). Within the APC, the loading of processed antigenic peptides to MHC class II molecules is known to take place in the endosomal compartment at acidic pH environment. The present study describes the in vitro effect of pH on binding of four biotinylated myelin basic protein (MBP) peptides to affinity purified HLA-DR2 containing a mixture of DRB1*1501 and DRB5*0101 beta chain. The binding affinity of the selected peptides are in the order of MBP(83-102)Y83 > MBP(124-143) > MBP(143-168) > MBP(1-14). Most of these peptides in association with HLA-DR2 are considered as immunodominant epitopes for human multiple sclerosis autoimmune disorder. One epitope, MBP(1-14), had almost no affinity to purified HLA-DR2 and was used as a control peptide in all binding assays. The quantitation of the bound peptide at various pH was carried out by antibody capture of complexes followed by avidin-alkaline phosphatase detection system. Among four peptides tested, only the highest affinity MBP(83-102)Y83 peptide showed maximum binding to purified HLA-DR2 at acidic pH. Two other epitopes, MBP(124-143) and MBP(143-168), showed maximum binding at basic and neutral pH values, respectively. The binding of only high affinity peptides, MBP(83-102)Y83 and MBP(124-143), was significantly affected by changing the pH of the binding buffer. Such alteration in pH of the binding buffer resulted in 100% occupancy of DR2 with both high affinity MBP peptides. In contrast, no significant increase in binding of the low affinity MBP(143-168) peptide was observed at altered pH values. The specificity of the increased binding of high affinity peptides to HLA-DR2 at optimum pH was demonstrated by competitive binding assays using non-biotinylated peptides. Finally, the stability of various MBP peptide bound complexes was tested at 4 degrees, 25 degrees and 37 degrees C which correlates well with their affinity to HLA-DR2. These results suggest that pH plays an important role in in vitro binding of antigenic peptides and such manipulation of binding conditions can be utilized in generating 100% loaded MHC class II with high affinity antigenic peptides. Since high affinity peptides are generally considered as major immunodominant epitopes, the in vitro pH dependent binding can be utilized in screening immunodominant epitopes of various autoantigens and generating complexes of defined composition.

Antigenic peptide binding to MHC class II molecules at increased peptide concentrations

Affinity-purified major histocompatibility complex (MHC) class II molecules are known to bind antigenic peptides in vitro. The percentage of MHC class II molecules occupied with such peptides is usually very low and varies significantly depending upon the sequence and size of a given antigenic peptide. The present study describes a method by which complete saturation of affinity-purified MHC class II with antigenic peptide can be achieved by simply incubating purified MHC class II molecules at neutral pH in the presence of several 100-fold molar excess of antigenic peptide. Complexes of human HLA-DR2 and a peptide analog from human myelin basic protein MBP (83-102)Y83 were selected for this study. The on-rate kinetic results showed saturation of MHC class II occupancy at 300-500-fold molar excess peptide concentrations. The specificity of the MBP (83-102)Y83 peptide binding to HLA-DR2 at higher peptide concentration was demonstrated by incubating an equivalent amount of another epitope from myelin basic protein [MBP (1-14) peptide] as well as by competitive binding assays. The quantitation of bound peptide was carried out using biotinylated-MBP (83-102)Y83 peptide which showed 100-125% occupancy of HLA-DR2 with a recovery of 100%. The presence of a single peptide entity in purified complexes was confirmed by reverse-phase narrowbore HPLC analysis of the acid extracted supernatant and by mass spectrometry analysis. Two-dimensional gel electrophoresis (IEF/SDS) of purified HLA-DR2 and DR2.MBP (83-102)Y83 complexes showed the absence of various endogenous polypeptides in 100% loaded complexes. These results demonstrate that higher peptide concentrations can be useful in generating MHC class II-peptide complexes of defined composition. Such complexes of MHC class II occupied with a single peptide may have significant clinical relevance for antigen-specific therapy of various autoimmune diseases and may provide better understanding of MHC-peptide-TCR interactions.

The stabilization of a human IgM monoclonal antibody with poly(vinylpyrrolidone)

An IgM anti-group B Streptococcus monoclonal antibody (4B9) was found to undergo irreversible heat-induced aggregation at 50 degrees C. A variety of excipients was tested for their ability to inhibit antibody aggregation. The amount of 4B9 aggregation, which was determined by analysis on a size-exclusion HPLC, was significantly reduced in the presence of low concentrations [between 0.1 and 1.0% (w/v)] of poly(vinylpyrrolidone) (PVP) molecules ranging in molecular weight from 10 to 40 kDa. When the PVP concentration was greater than 1.0%, antibody aggregation was enhanced, and with the highest molecular weight PVP, antibody precipitation occurred. HPLC was used to show that more PVP was associated with the 4B9 at 50 degrees C than at 25 degrees C. Differential scanning calorimetry revealed that PVP concentrations greater than 2.0% decreased the antibody thermal transition temperature. Enzyme-linked immunosorbent assays were used to assess the effects of PVP on the antigen binding capacity of 4B9 and on 4B9 quantitation. At 4 degrees C, PVP solutions of up to 5.0% had no effect on either 4B9 quantitation or antigen binding. At 50 degrees C, however, less 4B9 was detected in the 5.0% PVP solution. The heat stabilization of the 4B9 antibody by low concentrations of PVP can be explained by a weak binding of PVP to the native protein. The PVP may sterically interfere with protein-protein interactions, thus reducing aggregation. Higher concentrations of PVP lead to protein aggregation and precipitation, probably by a volume-exclusion mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Weaning of premature infants from the incubator to an open crib

Thirty pairs of healthy, growing preterm infants were included in this randomized prospective study comparing thermal weaning at 1700 g with that at 1800 g. Based on an intention-to-treat analysis, infants weaned at 1700 g were discharged 1.1 days sooner than those weaned at 1800 g. However, this result was not statistically significant (p = 0.13). On the other hand, differences are apparent between treatments in some strata based on birth weight (p = 0.0056). Evidence also existed that time from entry (at 1500 g) to discharge depended on birth weight stratum (p = 0.010). No infant in either group lost weight after successful weaning, and mean 24-hour weight gains were similar for both groups. Two infants were weaned at 1800 g requiring return to the incubator due to hypothermia, and four infants weaned at 1700 g likewise requiring return to the incubator. The number weaned at 1700 g who had birth weight of 1000 g or less and who developed hypothermia appeared substantial (three of six such infants). Thus, it appears that thermal weaning at 1700 g may be safe and effective only for prematures with birth weight above 1000 g. Additional study appears needed.

Uptake pathways for amino acids in mouse intestine

This paper characterizes amino acid (AA) uptake pathways in an everted-sleeve preparation of mouse jejunum. AA uptake is linear with time for 2-4 min, depending on the particular AA and its uptake rate. Escape of tracer to the serosal surface is still negligible at these times. Errors due to metabolism of labeled AAs to volatile products can be minimized by using 14C- rather than 3H-labeled AAs and by not drying tissues before counting. The dependence of AA uptake on concentration shows saturable kinetics, with apparent Km values in the range 1-4 mM. By 25 or 50 mM an uptake plateau is reached for leucine, lysine, methionine, and methylaminoisobutyric acid but not for aspartic acid, histidine, or proline. Proline kinetics are the result of a saturable Na+-dependent component, a linear diffusional component, and possibly a small saturable Na+-independent component. The Na+-dependent component of uptake for six AAs averages 83% of the total at 0.01 mM and 54% at 25 or 50 mM. Leucine and D-glucose exhibit modest (32%) cross-inhibition of Na+-dependent uptake. For the same six AAs we determined the percent inhibition of both the Na+-dependent and the Na+-independent components by the other AAs. These results suggest the presence of at least five or six AA uptake pathways in mouse jejunum: distinct Na+-dependent pathways for acidic, basic, and neutral AAs and for imino acids; a shared Na+-independent pathway for basic and neutral AAs; and possibly a Na+-independent pathway for acidic AAs. Comparisons of AA uptake pathways in mouse, rabbit, and rat intestine reveal many similarities but also some differences.

Digestive physiology is a determinant of foraging bout frequency in hummingbirds

Hummingbirds are among the smallest endothermic vertebrates. Because they forage by energetically costly hovering, and because weight-specific basal metabolic rates increase with decreasing body size, their basal and active metabolic rates are among the highest recorded. Hummingbirds fuel these metabolic requirements mainly with highly concentrated sugar in nectar, which they extract rapidly and efficiently by an unknown mechanism. It is especially puzzling that, despite their high energy requirements, hummingbirds spend only approximately 20% of their waking hours feeding, but 75% perched and apparently doing nothing. Here we report the first measurement of nutrient absorption by hummingbird intestine and present a new method for measuring crop-emptying times. We find that hummingbird intestine has the highest active glucose transport rate and lowest passive glucose permeability reported for any vertebrate. Crop-emptying time may limit feeding-bout frequency and could largely account for the time spent perched.

Human heterozygosity: a new estimate

Several hundred polypeptides from four human diploid fibroblast cell lines were compared by high-resolution two-dimensional polyacrylamide gel electrophoresis and double-label autoradiography under conditions where allelic products that differ by a single charged amino acid would be distinguished. The average heterozygosity represented by this set of gene products appears to be less than 1% for changes involving charged amino acids.