[Pre- and post-treatment changes of gingvitis-associated peptidomic profiles in the saliva and gingival crevicular fluid by mass spectrometry]

Objective: To explore peptidomic changes of peptides in saliva and gingival crevicular fluid (GCF) before and after treatment of gingivitis. Methods: From January 2017 to September 2017, seventeen participants at the age of 24-62 (6 males and 11 females) at Department of Preventive Dentistry, Peking University School and Hospital of Stomatology with gingivitis were recruited in the present study. Their clinical parameters were measured and recorded. Saliva and GCF samples were collected from each of the participants at the baseline and 7 days after ultrasonic supragingival scaling, respectively. Matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS) was employed to detect the changes of peptidomic profiles, while ano-liquid chromatography-electrospray ionization-tandem mass spectrometry (nano-LC/ESI-MS/MS) was performed to identify the possible proteins from which the peptides might derive. Results: Initially, four peptide peaks [mass-to-charge ratio (m/z) values: 1 030.6, 1 043.4, 1 053.4 and 1 064.6] were screened out exhibiting a decreasing trend after treatment (P<0.05). Besides, five peptide peaks from gingival crevicular fluid (P<0.05) exhibited differential expression, among which 1 055.5 and 1 168.3 demonstrating a decrease after treatment, while 3 363.7, 3 480.9 and 3 489.5 increased overtime. Certain positive correlations were detected between some peptides and clinical parameters. Principle component analysis using the above mentioned peptide peaks showed a distinct distribution before and after treatment and peptides from GCF showed a slightly better capacity to discriminate patients before and after treatment. The peptides with m/z values of 1 055.5 in GCF and 1 064.6 in saliva were identified to be segments of serum albumin and complement C3, respectively. Conclusions: Several differentially expressed peptides were detected in saliva and GCF by MALDI-TOF MS, exhibiting the potentiality to act as biomarkers in gingivitis patients.

Small rat islets are superior to large islets in in vitro function and in transplantation outcomes

Barriers to the use of islet transplantation as a practical treatment for diabetes include the limited number of available donor pancreata. This project was designed to determine whether the size of the islet could influence the success rate of islet transplantations in rats. Islets from adult rats were divided into two groups containing small (diameter <125 microm) or large (diameter >150 microm) islets. An average pancreas yielded three times more small islets than large. Smaller islets were approximately 20% more viable, with large islets containing a scattered pattern of necrotic and apoptotic cells or central core cell death. Small islets in culture consumed twice as much oxygen as large islets when normalized for the same islet equivalents. In static incubation, small islets released three times more insulin under basal conditions than did large islets. During exposure to high glucose conditions, the small islets released four times more insulin than the same islet equivalencies of large islets, and five times more insulin was released by the small islets in response to glucose and depolarization with K+. Most importantly, the small islets were far superior to large islets when transplanted into diabetic animals. When marginal islet equivalencies were used for renal subcapsular transplantation, large islets failed to produce euglycemia in any recipient rats, whereas small islets were successful 80% of the time. The results indicate that small islets are superior to large islets in in vitro testing and for transplantation into the kidney capsule of diabetic rats.

Simple partial status epilepticus in Chinese adults

Simple partial status epilepticus (SPSE) is uncommon compared with generalized tonic-clonic status epilepticus. We evaluated the clinical profile and predictors of poor outcome in a group of Chinese patients with this condition. We identified 32 patients above the age of 14 years with SPSE from a large urban hospital over an eleven-year period. Factors for poor outcome, defined as death or morbidity, were analyzed. The most common underlying causes were due to cerebrovascular disease (46.9%), CNS infection (15.6%), metabolic derangement (12.5%) and tumor (12.5%). At 30 days from the onset of seizures, 13(40.5%) patients had recovered fully and seven (21.9%) had died. Poor outcome was associated with the presence of an acute symptomatic injury.

Bacterial meningitis in Hong Kong: 10-years’ experience

OBJECTIVE

We studied the etiology, clinical features and outcome of patients with bacterial meningitis from an urban Chinese city over a 10-years period.

METHODS

We reviewed the files of all persons aged 15-years old or above diagnosed with community-acquired bacterial meningitis from a regional hospital. The clinical findings, relevant laboratory and imaging results as well as outcome were recorded in cases with microbiological evidence of meningitis. Neurosurgical and pediatric patients were excluded.

RESULTS

Sixty-five patients between the ages of 15 and 86 years of age (mean 52 years) were identified of whom 18 (28%) died. The four most common causes were Mycobacteria tuberculosis (46%), Streptococcus pneumoniae (11%), Streptococcus suis (9%) and Klebsiella pneumoniae (8%). Neisseria meningitidis and Haemophilus influenzae were rare pathogens. The annual incidence of community-acquired bacterial meningitis was 1.27/100,000 adults. Delay in treatment was associated with a poorer prognosis (p<0.001, OR=38.84, CI=7.33-205.80).

CONCLUSION

The causative organisms found in this region of China differ from that reported from Europe and the US; tuberculous meningitis is the most common cause of bacterial meningitis.

Screening for amblyopia in preverbal children with photoscreening photographs: IV. Interobserver variability in photograph grading: origin and method of reduction

BACKGROUND

Earlier detection of childhood vision disorders is a prominent goal of vision screening. The Medical Technology and Innovation (MTI) PhotoScreener addresses this objective. Use of this camera does not require verbal feedback and may be administered early in a child's development. Decreasing the variability in photograph grading results will boost the utility of any photoscreening system. This report aims to understand and to decrease intra- and inter-observer variability in grading photoscreening photographs.

METHODS

We dissected the photograph grading process and quantified the intra- and inter-observer agreement using intraclass plot correlation coefficients. We evaluated the outcome of a two grader verification system vs. adjudicated measurements with Receiver Operator Characteristic (ROC) curves.

PARTICIPANTS

Data on 955 children under 5 years of age, normal except for refractive error, each with complete photoscreening and eye examination data, culled from two previous studies.

MAIN OUTCOME MEASURES

Intra- and inter-observer agreement in measuring bright crescent dimensions and pupillary diameters. Sensitivity and specificity of detection of hyperopia.

RESULTS

Measurements of bright crescents are associated with greater variability than are measurements of pupillary diameters. Recognition and omission of light "rim" measurements from photograph grading will result in superior inter-observer agreement. Photograph independent errors increase variability and may be corrected by remeasurement. A verification system in which the most discrepant 5% of measurements are redone results in ROC curves similar to adjudicated dimension.

CONCLUSIONS

We conclude: 1) two novices grading photographs can do as well as one expert in most cases; 2) the proposed grading methodology has undergone statistical validation and can be used in other areas of ophthalmology and medicine; and 3) inter-observer variability, one of the limitations of photoscreening photograph grading, can be reduced. For 95% of the photographs, two novices achieve similar true positive and true negative values with or without adjudication.

Identification of the antivasopermeability effect of pigment epithelium-derived factor and its active site

Vascular permeability plays a key role in a wide array of life-threatening and sight-threatening diseases. Vascular endothelial growth factor can increase vascular permeability. Using a model system for nonproliferative diabetic retinopathy, we found that pigment epithelium-derived factor (PEDF) effectively abated vascular endothelial growth factor-induced vascular permeability. A 44-amino acid region of PEDF was sufficient to confer the antivasopermeability activity. Additionally, we identified four amino acids (glutamate-101, isoleucine-103, leucine-112, and serine-115) critical for this activity. PEDF, or a derivative, could potentially abate or restore vision loss from diabetic macular edema. Furthermore, PEDF may represent a superior therapeutic approach to sepsis-associated hypotension, nephrotic syndrome, and other sight-threatening and life-threatening diseases resulting from excessive vascular permeability.

Clinical diagnoses that overlap with choroideremia

PURPOSE

To understand which clinical presentations suggest a diagnosis of choroideremia (CHM).

METHODS

Retrospective chart review. Included were patients for whom a clinical diagnosis of CHM was suggested, but either protein analysis or direct sequencing of the CHM gene could not confirm the diagnosis. Clinical presentation, family history and fundus photographs were reviewed.

RESULTS

We analyzed protein and DNA samples from members of more than 100 families in which at least 1 member had a clinical diagnosis of CHM. For 26 of these families, the clinical diagnosis of CHM could not be confirmed by laboratory analysis. Relevant clinical information was requested from the referring ophthalmologists so that alternative diagnoses could be considered. Sufficient information was provided for 13 of the 26 families. Four patients were reclassified as having retinitis pigmentosa (RP) from the clinical phenotype; only two clearly had X-linked inheritance. One patient had a syndrome including macular dystrophy, hearing loss, developmental delay and cerebral palsy. One patient was reclassified as having congenital stationary night blindness on the basis of an electronegative electroretinogram and a normal fundus. One patient had hearing loss suggesting Usher syndrome. One patient had signs consistent with cone-rod dystrophy (CRD). Five patients could not be reclassified on the basis of the clinical presentation.

CONCLUSION

RP, Usher syndrome and CRD are clinical phenotypes that may overlap with CHM. Clinical features that suggest CHM include severe chorioretinal atrophy with preservation of the macula, X-linked inheritance and retinal changes in a related female.

Effects of dental resins on TNF-alpha-induced ICAM-1 expression in endothelial cells

Many reports have demonstrated inflammation after the placement of dental restorations. To explain this side-effect, we studied a biomarker in the inflammatory response. The intercellular adhesion molecule-1 (ICAM-1) is a key mediator for recruitment of leukocytes to the site of inflammation. Therefore, we investigated whether methacrylates (a BISGMA-based dental resin, BISGMA, and MAA) and Cyracure UVR 6105, an epoxy monomer, could alter ICAM-1 expression in unstimulated and TNF-alpha-stimulated endothelial cells. Six-well plates with monolayers of human umbilical vein cells, ECV 304 (ATCC CRL 1998), were exposed to TNF-alpha (1 ng/mL) in the presence and absence of subtoxic and TC50 doses of chemicals for 24 hrs at 37 degrees C/5% CO2. Several doses of TNF-alpha (0.5-2 ng/mL) were coincubated with 100 microL of undiluted aqueous dental resin extracts. Cells were harvested and stained with mAB FITC-conjugated anti-human ICAM-1 (CD54). ICAM-1 expression was measured by flow cytometry. Cells expressed basal levels of ICAM-1, which was up-regulated by TNF-alpha but was not changed by all samples studied. Except for UVR 6105, the methacrylates significantly decreased ICAM-1 expression in TNF-alpha-stimulated cells. These findings suggest that methacrylates may decrease the recruitment of leukocytes to sites of inflammation.

Timely surgery in intermittent and constant exotropia for superior sensory outcome

PURPOSE

To determine whether time of strabismus surgery for patients with acquired intermittent exotropia and constant exotropia influences postoperative sensory outcome.

METHODS

In a retrospective, cross-sectional study, 76 patients with acquired intermittent or constant exotropia and motor realignment were evaluated for postoperative sensory status. Age at surgery, duration of exotropia, and presence of intermittent or constant exotropia were correlated with postoperative sensory status. The 23 male and 53 female patients had an average age of 9.3 years at the time of surgery and a mean follow-up of 5.9 years.

RESULTS

Patients had a significantly greater chance of having postoperative stereoacuity better than 60 seconds of arc (bifixation) if they were surgically aligned before 7 years of age (P <.01) or before 5 years of strabismus duration (P <.05), or with intermittent as compared with constant exotropia (P <.001). Patients with postoperative bifixation had earlier surgical intervention (P <.025) and shorter duration of exotropia (P <.025) than those with postoperative monofixation.

CONCLUSIONS

Patients with intermittent or constant exotropia may achieve superior sensory outcome with motor realignment before age 7, before 5 years of strabismus duration, or while the deviation is intermittent.

Screening for amblyopia in preverbal children with photoscreening photographs. III. improved grading criteria for hyperopia

OBJECTIVE

To examine the ability of the Medical Technology and Innovations (MTI), Inc., Photoscreener (Cedar Falls, IA) to detect hyperopia and to improve the photograph grading criteria to screen for amblyopiogenic levels of hyperopia.

DESIGN

Cross-sectional study and reanalysis. PARTICIPANTS AND TESTING: In previous work, 392 participants received a complete ophthalmologic examination and were photographed using the MTI Photoscreener. For this study, all 209 participants with normal examination findings (65 children) or hyperopia without anisometropia (144 children) were selected. The data were reanalyzed using modified photograph grading and ophthalmologic examination failure criteria. Potential reasons for why many children with hyperopia passed photoscreening were explored.

MAIN OUTCOME MEASURES

We determined whether a study participant would pass or fail screening with a given photograph grading and ophthalmologic examination failure criteria.

RESULTS

Most children with hyperopia of +2.00 to +3.50 diopters (D) passed screening with the MTI instrument, in most cases because their photographs lacked bright crescents. When bright crescents in at least two of the four possible meridians were the grading guideline for screening failure and the pediatric ophthalmologists' consensus hyperopia failure criteria (> +3.50 D) were adopted, the sensitivity for hyperopia detection was 100% and the specificity was 88%. Identical results were obtained using the American Academy of Ophthalmology Preferred Practice Pattern hyperopia failure criteria (>/= +4.50 D).

CONCLUSIONS

The MTI photograph grading guidelines can be simplified, and the ophthalmologic examination failure criteria for hyperopia can be improved. The presence of a bright crescent in the lower or the left pupillary margin indicate hyperopia in an amblyopiogenic range (> +3.50 D).

Screening for amblyopia in preverbal children with photoscreening photographs: II. Sensitivity and specificity of the MTI photoscreener

OBJECTIVE

To determine the sensitivity and specificity of vision screening using the Medical Technology and Innovations (MTI), Inc., PhotoScreener.

DESIGN

Cross-sectional study. PARTICIPANTS AND TESTING: Three hundred ninety-two children less than 4 years of age received a complete ophthalmologic examination and were photographed using the MTI PhotoScreener. One hundred three children had normal examinations, and the remaining 284 children had conditions of interest for pediatric screening: ptosis, media opacity, refractive error, or strabismus. Five children were excluded.

MAIN OUTCOME MEASURES

The grading of the photographs by the manufacturer's representative was compared with the results of the ophthalmologic examinations. Sensitivity and specificity of vision screening were determined.

RESULTS

The analysis of all informative photographs resulted in a sensitivity of 65% and a specificity of 87%. The sensitivity of detection for children with some forms of strabismus was high, up to 95% for esotropia of 10Delta or more. Sensitivities for the detection of ptosis, media opacity, and refractive error were poor in patients where strabismus was not also present.

CONCLUSIONS

The MTI PhotoScreener may play a role in preverbal vision screening; identification of two of three children with amblyopiogenic factors before age 4 would be an exciting advance in public health. However, improvement in the ability to identify children with media opacity and refractive error is necessary. Improvements may be possible with modifications of the examination failure and photograph grading criteria.

In vitro toxicity of spiroorthocarbonate monomers designed for non-shrinking dental restoratives

In development of photopolymerized expanding monomers with epoxy resin systems, there is a need for reactive expanding monomers that exert a good biocompatibility profile. The objective of this study was to evaluate the in vitro toxicology of new spiroorthocarbonates designed to be expanding monomers. The expanding monomers investigated were: trans/trans-2,3,8,9-di(tetramethylene)-1,5,7,11-tetraoxaspiro[5,5] undecane (DTM-TOSU), 5,5-diethyl-19-oxadispiro-[1,3-dioxane-2,2'-1,3-dioxane-5',4'-bicy clo[4.1.0]heptane] (DECHE-TOSU); 3,9-diethyl-3,9-dipropionyloxy methyl-1,5,7,11-tetraoxaspiro[5.5]undecane (DEDPM-TOSU); and 3,9-diethyl-3,9-diacetoxy methyl-1,5,7,11-tetraoxaspiro[5.5]undecane (DAMDE-TOSU). The in vitro toxicology of these monomers measured their cytotoxicity and mutagenicity potential. Succinic dehydrogenase (SDH) activity in the MTT assay was used to assess the toxic dose that kills 50% of cells (TC50) for all the monomers. Their mutagenic potential was measured in the Ames Salmonella assay with and without metabolic activation. Two solvents, DMSO and acetone, were used to validate effects. Appropriate controls included the solvents alone. All the expanding monomers in this study were less cytotoxic than BISGMA (p < 0.01), a commercial component of dental restoratives. The relative cytotoxicity of the expanding monomers in DMSO was defined in the following order: DTM-TOSU (more toxic) > DECHE-TOSU > DEDPM-TOSU > DAMDE-TOSU. Each was significantly different from the other (p < 0.05). Overall, the TC50 values of all expanding monomers were significantly greater in DMSO than in acetone (p < 0.05). However, for BISGMA this trend was opposite. For mutagenicity results, the expanding monomers were non-mutagenic and there was no solvent effect on this outcome. The non-mutagenicity and low cytotoxicity profile of these expanding monomers suggests their potential for development of biocompatible non-shrinking composites.

Orthostatic intolerance and chronic fatigue syndrome associated with Ehlers-Danlos syndrome

OBJECTIVE

To report chronic fatigue syndrome (CFS) associated with both Ehlers-Danlos syndrome (EDS) and orthostatic intolerance.

STUDY DESIGN

Case series of adolescents referred to a tertiary clinic for the evaluation of CFS. All subjects had 2-dimensional echocardiography, tests of orthostatic tolerance, and examinations by both a geneticist and an ophthalmologist.

RESULTS

Twelve patients (11 female), median age 15.5 years, met diagnostic criteria for CFS and EDS, and all had either postural tachycardia or neurally mediated hypotension in response to orthostatic stress. Six had classical-type EDS and 6 had hypermobile-type EDS.

CONCLUSIONS

Among patients with CFS and orthostatic intolerance, a subset also has EDS. We propose that the occurrence of these syndromes together can be attributed to the abnormal connective tissue in dependent blood vessels of those with EDS, which permits veins to distend excessively in response to ordinary hydrostatic pressures. This in turn leads to increased venous pooling and its hemodynamic and symptomatic consequences. These observations suggest that a careful search for hypermobility and connective tissue abnormalities should be part of the evaluation of patients with CFS and orthostatic intolerance syndromes.

In vitro cytotoxicity of solid epoxy-based dental resins and their components

OBJECTIVE

The objective of this study was to evaluate the effect of adding a spiroorthocarbonate (SOC) or a polyol on the cytotoxicity of epoxy-based dental resins.

METHODS

Resins contained one of the epoxies: diglycidyl ether Bisphenol A (GY-6004); 3,4-epoxycyclohexanemethyl-3,4-epoxycyclohexane carboxylate (UVR-6105); vinyl cyclohexane dioxide (ERL-4206) or the three-epoxy mixture (Epoxy-M). The SOC was t/t-2,3,8,9-di(tetramethylene)-1,5,7,11-tetraoxaspiro[5.5]undecane (SOC). The polyols were polytetrahydrofuran (p-THF-250) and polycaprolactone triol (TONE-301). The photoinitiator (4-octylphenyl)phenyliodonium hexafluoroantimonate and camphorquinone were used for light curing the resins. Four types of resins (epoxy, SOC/epoxy, polyol/epoxy and SOC/polyol/epoxy) were evaluated for cytotoxicity as solids in the agar diffusion assay and as aqueous extracts in the MTT assay using L929 cells.

RESULTS

In agar diffusion analysis, ERL-4206 and UVR-6105 resins were severely cytotoxic (+3), but the addition of SOC changed them to non-cytotoxic (-). Addition of 1-3% SOC changed Epoxy-M from mild (+) to non-cytotoxic. Adding SOC changed GY-6004 from moderate (+2) to mild (-) cytotoxicity. Generally, addition of SOC did not change cytotoxicity when added to polyol/epoxy combinations. Either polyol produced resins with reduced cytotoxicity when added to UVR-6105, but the opposite occurred when added to Epoxy-M resins. In MTT analysis, percent cell survival from 100 microliters resin extracts were statistically compared (ANOVA, p < 0.05). Epoxy-M and GY-6004 resin extracts were significantly less cytotoxic than UVR-6105 and ERL-4206 resin extracts were. Overall, the SOC component reduced the cytotoxicity of all SOC/epoxy combinations, except SOC/ERL-4206, which was significantly more cytotoxic than ERL-4206 resin extract. This may be the result of cell fixative effects observed for SOC/ERL-4206 in agar diffusion analysis. Addition of SOC produced significantly less cytotoxic SOC/polyol/Epoxy-M resins when compared to its non-SOC counterpart. The contrary result was obtained with SOC/polyol/UVR-6105 resin combinations. Consistent with agar diffusion results, adding polyol significantly decreased cytotoxicity of UVR-6105 resins. The cytotoxicity of these resins may be related to the 50% cytotoxicity (TC50) of their components as leachates. The TC50 values of the individual components were compared to BISGMA. Polyols, epoxy monomers, SOC monomer and camphorquinone were significantly (p < 0.05) less cytotoxic than BISGMA.

SIGNIFICANCE

Addition of SOCs and polyols in the formulation of epoxy-based resins may contribute to development of biocompatible dental composites.

Screening for amblyopia in preverbal children with photoscreening photographs. National Children's Eye Care Foundation Vision Screening Study Group

OBJECTIVE

This study aimed to determine the ability of healthcare professionals and lay volunteers to grade photoscreening photographs.

DESIGN

The study design was a cross-sectional study.

PARTICIPANTS AND INTERVENTION

One hundred children 3 years of age or younger received a complete ophthalmologic examination and were photographed using the Medical Technology Innovations (MTI) photoscreener. Twenty-six children had normal examination results, and the remaining 74 children had conditions that are of interest for pediatric screening, including strabismus, refractive error, media opacities, and ptosis. Eighteen volunteers, including pediatric ophthalmologists, pediatricians, ophthalmic technicians, health department nurses, Prevention of Blindness Society personnel, and Lions Club volunteers, graded each of the 100 photoscreening photographs.

MAIN OUTCOME MEASURES

Sensitivity and specificity of vision screening and of photograph grading were measured.

RESULTS

Results from various graders yielded sensitivities ranging from 37% to 88% and specificities ranging from 40% to 88%. No single grader achieved sensitivity and specificity both greater than 70%. The grading of the manufacturer's representative had a sensitivity of 43% and a specificity of 85%. Sensitivity decreased to 31% for strabismus and 18% for refractive error when the correct type of strabismus or refractive error was required to be considered true-positives. Results were not positively correlated with the ophthalmologic knowledge of the participant.

CONCLUSIONS

The wide variability in sensitivities and specificities among graders indicates inconsistent photograph interpretation skills or deficient screening guidelines or both. For off-axis photoscreening as implemented by the MTI system to become a useful vision-screening method, additional photograph interpretation skill transfer may be beneficial, although not necessarily sufficient.

Comparison of tetrazolium colorimetric and 51Cr release assays for cytotoxicity determination of dental biomaterials

OBJECTIVES

The purpose of this study was to compare a methylthiazole tetrazolium (MTT) dye colorimetric method with the standard 51Cr assay as methods of assessing cytotoxicity of dental materials.

METHODS

Two MTT-based colorimetric formats, test tube and 96-well microplate methods, were compared to the 51Cr release assay. A series of eight dental materials were evaluated. Cytotoxicity profiles were determined for each test material. A TC50 value (Toxic Concentration required to kill 50% of the cells) was determined for each biomaterial, and these results were used to make statistical comparisons between the methods.

RESULTS

The three methods were statistically correlated (p<0.005) by comparison of the eight samples tested. That is, the same rank in toxicity was given by the two tetrazolium sample formats and the 51Cr method.

SIGNIFICANCE

The MTT assay was found to have several advantages in comparison to the current standard 51Cr release assay. Optimized in the 96-well format, complete dose response curves and greater sample comparisons can be made rapidly, making the MTT method more economical in time and cost. Furthermore, the MTT method is based on intracellular biochemical changes, measuring cell viability rather than cell morbidity, and has lower detectable limits than the 51Cr release method. There is also less detector chemical binding interference than encountered in the 51Cr release method.

The effect of spiroorthocarbonate volume modifier co-monomers on the in vitro toxicology of trial non-shrinking dental epoxy co-polymers

A major improvement in dental restoratives is possible through the development of biomaterials that do not shrink upon polymerization, hence, avoid leakage and subsequent breakdown. Polymers containing spiroorthocarbonates (SOCs) show promise in this respect, but their toxicology in copolymerized materials has not been explored. In this study, the in vitro toxicology of these materials in homopolymer form and in two trial non-shrinking epoxy co-polymers was evaluated for cytotoxicity and mutagenicity. Cytotoxicity was determined by the MTT test to measure the lethality effect on mouse L929 cells. Mutagenicity was evaluated using the Ames-Salmonella Test. For comparison, commercial composite and adhesive materials as well as several other materials of current interest in dentistry were also evaluated. Epoxy resin samples containing 5% of either T/T SOC or Dp SOC reduced the cytotoxicity (TC50) from approximately 400 to 800 micrograms/200 microliters. The epoxy-spiro copolymers had more favorable TC50 values than the commercial product Super-Bond. They showed TC50 values on the order of 35% greater than Super-Bond and 45% less than Scotchbond 2, the latter two being materials currently used in the clinic. These two comparatives demonstrated dose response curves with lower doses at maximum cell kill values than the spiro materials. The epoxy formulations all showed weak mutagenesis, but this is attributed to the epoxy formulation and not the SOCs. Although considerable toxicology is yet be conducted, these in vitro results suggest that biocompatible copolymer formulations for spiroorthocarbonates are a developmental reality.

Effect of esterase on methacrylates and methacrylate polymers in an enzyme simulator for biodurability and biocompatibility testing

Current in vitro biocompatibility methods do not evaluate the degradation of biomaterials after contact with enzymes that might be present in the oral or systemic environment. In this study, two methods of in vitro enzyme degradation and a method for the separation of the degradative products by high performance thin-layer chromatography (HPTLC) are reported. In the first method two dental adhesives, Scotchbond and Scotchbond II, and two dental composites, Heliomolar and P-50, were evaluated. These materials were incubated with four different enzymatic preparations for periods of up to 72 h. The enzymes were lipase, esterase, and liver enzyme extracts from both mouse and rat. Chloroform soluble products extracted from the aqueous phase were examined by HPTLC for decomposition products resulting from enzyme activity. The second method was similar, but analyzed the aqueous fraction directly without chloroform extraction. In this method five dental restorative materials, P-50, P-30, Scotchbond II, Silux, and Silux Plus, were incubated with a nonspecific porcine liver esterase. In addition to the polymerized biomaterials, monomers containing methacrylic acid units were also hydrolyzed with esterase and analyzed by ion chromatography to establish the sensitivity of the enzyme simulator. Each biomaterial presented thin-layer zones not present before enzymatic action. These experiments provide support that aqueous enzymatic action may facilitate the hydrolytic weakening of polymeric biomaterials.

Ligand interactions of the cation-independent mannose 6-phosphate receptor. The stoichiometry of mannose 6-phosphate binding

The interaction of the bovine cation-independent mannose 6-phosphate receptor with a variety of phosphorylated ligands has been studied using equilibrium dialysis and immobilized receptor to measure ligand binding. The dissociation constants for mannose 6-phosphate, pentamannose phosphate, bovine testes beta-galactosidase, and a high mannose oligosaccharide with two phosphomonoesters were 7 X 10(-6) M, 6 X 10(-6) M, 2 X 10(-8) M, and 2 X 10(-9) M, and the mol of ligand bound/mol of receptor monomer were 2.17, 1.85, 0.9, and 1.0, respectively. We conclude that the cation-independent mannose 6-phosphate receptor has two mannose 6-phosphate-binding sites/polypeptide chain.

Ligand interactions of the cation-dependent mannose 6-phosphate receptor. Comparison with the cation-independent mannose 6-phosphate receptor

The interactions of the bovine cation-dependent mannose 6-phosphate receptor with monovalent and divalent ligands have been studied by equilibrium dialysis. This receptor appears to be a homodimer or a tetramer. Each mole of receptor monomer bound 1.2 mol of the monovalent ligands, mannose 6-phosphate and pentamannose phosphate with Kd values of 8 X 10(-6) M and 6 X 10(-6) M, respectively and 0.5 mol of the divalent ligand, a high mannose oligosaccharide with two phosphomonoesters, with a Kd of 2 X 10(-7) M. When Mn2+ was replaced by EDTA in the dialysis buffer, the Kd for pentamannose phosphate was 2.5 X 10(-5) M. By measuring the affinity of the cation-dependent and cation-independent mannose 6-phosphate receptors for a variety of mannose 6-phosphate analogs, we conclude that the 6-phosphate and the 2-hydroxyl of mannose 6-phosphate each contribute approximately 4-5 kcal/mol of Gibb's free energy to the binding reaction. Neither receptor appears to interact substantially with the anomeric oxygen of mannose 6-phosphate. The receptors differ in that the cation-dependent receptor displays no detectable affinity for N-acetylglucosamine 1'-(alpha-D-methylmannopyranose 6-monophosphate) whereas this ligand binds to the cation-independent receptor with a poor, but readily measurable Kd of about 0.1 mM. The spacing of the mannose 6-phosphate-binding sites relative to each other may also differ for the two receptors.

The cation-independent mannose 6-phosphate receptor binds insulin-like growth factor II

The bovine cation-independent mannose 6-phosphate receptor (CI-MPR) and the human insulin-like growth factor II (IGF-II) receptor have recently been shown to be 80% identical in their amino acid sequences as deduced from cDNA clones (Morgan, D. O., Edman, J. C., Standring, D. N., Fried, V. A., Smith, M. C., Roth, R. A., and Rutter, W. J. (1987) Nature 329, 301-307). We have studied the binding of IGF-II to affinity-purified CI-MPR in order to obtain direct evidence that the same protein binds mannose 6-phosphate-containing ligands and IGF-II. In equilibrium binding studies, the CI-MPR bound 0.95 mol of IGF-II/mol of receptor with a Kd of 0.2 nM. The pH optimum of binding was 7.4. The addition of mannose 6-phosphate did not affect binding, indicating that the two ligands interact with different binding sites on the receptor. IGF-I bound to the receptor with a much lower affinity (Kd of 0.4 microM), and insulin binding could not be detected. IGF-II did not bind to the cation-dependent mannose 6-phosphate receptor. We conclude that the cation-independent mannose 6-phosphate receptor and the IGF-II receptor are the same protein.