PD-L1-positive circulating endothelial progenitor cells associated with immune response to PD-1 blockade in patients with head and neck squamous cell carcinoma

A number of the inhibitors against programmed death protein 1 (PD-1) have been approved to treat recurrent or metastatic squamous cell carcinoma of head and neck (HNSCC). The interaction between PD-1 and its ligand (PD-L1) serves as an immune checkpoint that governs cytotoxic immune effectors against tumors. Numerous clinical trials of PD-1/PD-L1 inhibitors have so far been discordant about having sufficient PD-L1 expression in the tumor as a prerequisite for a successful anti-PD-1 treatment. On the other hand, vascular endothelial cells modulate immune activities through PD-L1 expression, and thus it is possible that the expressions of circulating endothelial cells (CECs) and circulating endothelial progenitor cells (CPCs) could affect antitumor immunity as well as neoangiogenesis. Here we investigated the potential involvement of PD-L1+ CECs and PD-L1+ CPCs in PD-1 blockade treatments for HNSCC patients. We measured CD8+ T cells, CECs, and CPCs in the peripheral blood of the HNSCC patients treated by anti-PD-1 therapies. We found that their PD-L1+ CPC expression before anti-PD1 therapies was strongly correlated with treatment responses and overall survival. Moreover, if the first infusion of PD-1 inhibitors reduced ≥ 50% PD-L1+ CPCs, a significantly better outcome could be predicted. In these patients as well as in an animal model of oral cancer, Pd-l1+ CPC expression was associated with limited CD8+ T-cell infiltration into the tumors, and anti-PD-1 treatments also targeted Pd-l1+ CPCs and increased CD8+ T-cell infiltration. Our results highlight PD-L1+ CPC as a potential regulator in the anti-PD-1 treatments for HNSCC.

Wasabi Component 6-(Methylsulfinyl)hexly Isothiocyanate and Derivatives Improve the Survival of Skin Allografts

We tested the effect of 6-(Methylsulfinyl)hexyl Isothiocyanate (6-MITC) and derivatives (I7447 and I7557) on the differentiation and maturation of human myeloid dendritic cells (DCs) in vitro, and skin transplantation in vivo. Triggering of CD14⁺ myeloid monocyte development toward myeloid DCs with and without 6-MITC and derivatives to examine the morphology, viability, surface marker expression, and cytokine production. Stimulatory activity on allogeneic naive T cells was measured by proliferation and interferon-γ production. The skin allograft survival area model was used to translate the 6-MITC and derivatives’ antirejection effect. All of the compounds had no significant effects on DC viability and reduced the formation of dendrites at concentrations higher than 10 μM. At this concentration, 6-MITC and I7557, but not I7447, inhibited the expression of CD1a and CD83. Both 6-MITC and I7557 exhibited T-cells and interferon-γ augmentation at lower concentrations and suppression at higher concentration. The 6-MITC and I7557 prolonged skin graft survival. Both the 6-MITC and I7557 treatment resulted in the accumulation of regulatory T cells in recipient rat spleens. No toxicity was evident in 6-MITC and I7557 treatment. The 6-MITC and I7557 induced human DC differentiation toward a tolerogenic phenotype and prolonged rat skin allograft survival. These compounds may be effective as immunosuppressants against transplant rejection.

Dual blockade of PD-1 and PD-L1 is effective but causes severe pneumonitis in lung metastasis: Syngeneic mice study for validation of clinical observation

e14115

Background: In clinical practice, the shifting use of PD-1 inhibitors and its ligand PD-L1 inhibitors due to ineffectiveness or toxicity is becoming more common and has distinct responses. To validate clinical observation, we examined the anti-cancer effect, tumor microenvironment (TME) modulation and toxicity of dual blockade of PD-1 and PD-L1 in mice. Case Presentation: Three patients with metastatic lung adenocarcinoma received nivolumab (5, 5 and 11 doses); after the initial response and subsequent progression, they were shifted to receive atezolimumab (1, 1 and 4 doses) at intervals of 70, 38 and 43 days, respectively. All 3 patients obtained partial response according to iRECIST. Two of the 3 patients developed pneumonitis at days 3 and 15 after the first dose of atezolimumab and pneumonitis subsided by methylprednisolone injection for 7 and 4 days. Methods: The Balb/c mice bearing lung metastasis of CT26 colon cancer cells were treated. Assessments included optical imaging for tumor burden, multi-parameter flow cytometry for TME, pathology and immuohistochemistry. Results: The pathology of lung showed that all the mice (100%, n = 3 for each group) treated with a combination of anti-PD-1 and anti-PD-L1, either sequential or simultaneous, developed severe clustered inflammatory infiltrates, mucus filling in bronchus and thrombi in small vessels. Among infiltrating leukocytes, combinatorial blockade increased LyC6+ inflammatory monocytes and NKG2D+ T cells and reduced tumor-associated macrophages in lung. Peripheral leukocytes in spleen had no such alteration. In lung metastatic foci, the expression of PD-1 was noted mainly within tumors, and this expression was reduced by combinatorial blockade. PD-L1 expression had no change. For control of lung metastasis, the combinatorial treatments exhibited better control, and anti-PD-L1 followed by anti-PD-1 was the most effective. No significant pneumonitis was noted in single blockade groups. Conclusions: The combination of PD-1 and PD-L1 blockade, either sequential or concurrent, may have better tumor control but cause severe pneumonitis. Dual blockade of PD-1 and PD-L1 should be used with caution.

Sequential Blockade of PD-1 and PD-L1 Causes Fulminant Cardiotoxicity-From Case Report to Mouse Model Validation

The combined administration of programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) inhibitors might be considered as a treatment for poorly responsive cancer. We report a patient with brain metastatic lung adenocarcinoma in whom fatal myocarditis developed after sequential use of PD-1 and PD-L1 inhibitors. This finding was validated in syngeneic tumor-bearing mice. The mice bearing lung metastases of CT26 colon cancer cells treated with PD-1 and/or PD-L1 inhibitors showed that the combination of anti-PD-1 and anti-PD-L1, either sequentially or simultaneously administered, caused myocarditis lesions with myocyte injury and patchy mononuclear infiltrates in the myocardium. A significant increase of infiltrating neutrophils in myocytes was noted only in mice with sequential blockade, implying a role for the pathogenesis of myocarditis. Among circulating leukocytes, concurrent and subsequent treatment of PD-1 and PD-L1 inhibitors led to sustained suppression of neutrophils. Among tumor-infiltrating leukocytes, combinatorial blockade increased CD8⁺ T cells and NKG2D⁺ T cells, and reduced tumor-associated macrophages, neutrophils, and natural killer (NK) cells in the lung metastatic microenvironment. The combinatorial treatments exhibited better control and anti-PD-L1 followed by anti-PD-1 was the most effective. In conclusion, the combinatory use of PD-1 and PD-L1 blockade, either sequentially or concurrently, may cause fulminant cardiotoxicity, although it gives better tumor control, and such usage should be cautionary.

Moscatilin Inhibits Growth of Human Esophageal Cancer Xenograft and Sensitizes Cancer Cells to Radiotherapy

Esophageal cancer prognosis remains poor in current clinical practice. We previously reported that moscatilin can induce apoptosis and mitotic catastrophe in esophageal cancer cells, accompanied by upregulation of polo-like kinase 1 (Plk1) expression. We aimed to validate in vitro activity and Plk1 expression in vivo following moscatilin treatment and to examine the treatment's radiosensitizing effect. Human esophageal cancer cells were implanted in nude mice. Moscatilin was intraperitoneally (i.p.) injected into the mice. Tumor size, body weight, white blood cell counts, and liver and renal function were measured. Aberrant mitosis and Plk1 expression were assessed. Colony formation was used to measure survival fraction after radiation. Moscatilin significantly suppressed tumor growth in mice bearing human esophageal xenografts without affecting body weight, white blood cell counts, or liver and renal function. Moscatilin also induced aberrant mitosis and apoptosis. Plk1 expression was markedly upregulated in vivo. Moreover, moscatilin pretreatment enhanced CE81T/VGH and BE3 cell radioresponse in vitro. Moscatilin may inhibit growth of human esophageal tumors and sensitize esophageal cancer cells to radiation therapy.

Morphometric analysis of the maxillary root apex positions according to crowding severity

OBJECTIVES

To determine differences in arch forms derived from the root apices locations between individuals with <2 mm maxillary crowding and controls.

SETTING AND SAMPLE POPULATION

The Department of Orthodontics, Pusan National University. Cone-beam computed tomography (CBCT) images of 102 patients in the control group and 95 patients in the crowding group.

MATERIALS AND METHODS

X, Y and Z coordinates of the tip of the crowns and the apex of the root of the maxillary teeth (except second molars) were determined on the CBCT images. The acquired three-dimensional (3D) coordinates were converted into two-dimensional (2D) coordinates via projection on the palatal plane, and the Procrustes analysis was employed to process the converted 2D coordinates. The mean shape of the arch form derived from the location of the tip of the crowns and the apex of the root was compared between groups using the statistical shape analysis.

RESULTS

There was a statistically significant difference (P = .046) between the groups for the mean shape of the root apex arch form, but the difference was small and clinically irrelevant as it is minor compared to the degree of crowding.

CONCLUSIONS

Maxillary arch from at the level of the maxillary apices only shows minor differences between crowded and non-crowded dentitions.

A microwave applicator for uniform irradiation by circularly polarized waves in an anechoic chamber

Microwave applicators are widely employed for materials heating in scientific research and industrial applications, such as food processing, wood drying, ceramic sintering, chemical synthesis, waste treatment, and insect control. For the majority of microwave applicators, materials are heated in the standing waves of a resonant cavity, which can be highly efficient in energy consumption, but often lacks the field uniformity and controllability required for a scientific study. Here, we report a microwave applicator for rapid heating of small samples by highly uniform irradiation. It features an anechoic chamber, a 24-GHz microwave source, and a linear-to-circular polarization converter. With a rather low energy efficiency, such an applicator functions mainly as a research tool. This paper discusses the significance of its special features and describes the structure, in situ diagnostic tools, calculated and measured field patterns, and a preliminary heating test of the overall system.

Recombinant biglycan promotes bone morphogenetic protein-induced osteogenesis

The aim of this study was to determine the effects of glutathione-S-transferase-fused recombinant biglycan (GST-BGN) on craniofacial bone regeneration. We recently demonstrated a positive effect of tissue-derived BGN on bone morphogenetic protein 2 (BMP-2) function, which is exerted likely via the BGN core protein. Here, we investigated the effects of GST-BGN lacking any posttranslational modifications on BMP-2 function in vitro and in vivo. In the C2C12 cell culture system, BMP-2-induced Smad 1/5/8 phosphorylation and alkaline phosphatase activity were both enhanced by the addition of GST-BGN. For the in vivo effect, we employed a Sprague-Dawley rat mandible defect model utilizing 1 µg (optimal) or 0.1 µg (suboptimal) of BMP-2 combined with 0, 2, 4, or 8 µg of GST-BGN. At 2 weeks post-surgery, newly formed bone was evaluated by microcomputed tomography and histologic analyses. The results revealed that the greatest amounts of bone within the defect were formed in the groups of suboptimal BMP-2 combined with 4 or 8 µg of GST-BGN. Also, bone was well organized versus that formed by the optimal dose of BMP. These results indicate that recombinant BGN is an efficient substrate to promote low-dose BMP-induced osteogenesis.

Zoledronic acid, an aminobisphosphonate, prolongs survival of skin allografts

Purpose: Zoledronic acid (ZOL), an effective nitrogen-containing bisphosphonate used to prevent excessive bone loss in clinical practice, has been shown to affect the development of dendritic cells by redirecting differentiation toward a state of atypical maturation. The study was aimed to examine whether ZOL can reduce acute rejection of skin allografts. Methods: A skin transplantation model using C57BL/6 to BALB/c mice was used. ZOL was injected intraperitoneally into transplant recipients post-surgically. Graft survival, body weight, leukocyte count, hepatic and renal functions were assessed. Results: ZOL treatment significantly prolonged skin allograft survival in mice. In terms of toxicity, there were no significant differences in body weight, leukocyte count, plasma alanine aminotransferase or creatinine levels between the ZOL-treated and control groups. Histopathology showed that the loss of skin integrity seen in control group was prevented by ZOL treatment. In draining lymph nodes and spleen, the number and clustering extent of mononuclear cells were markedly declined by ZOL treatment. The plasma IL-6 levels were reduced by treatment of ZOL. Conclusion: ZOL can prolong skin allograft survival without major toxicity.

Functional characterization of the human placental fusogenic membrane protein syncytin 2

Fusion of cytotrophoblasts into the multinucleated syncytiotrophoblast layer is essential for the development of a functional placenta. The envelope protein of a human endogenous retrovirus W (HERV-W) family member, syncytin 1, has been shown to mediate placental cell fusion. Recently, the envelope protein of another HERV family member (HERV-FRD), syncytin 2, has been identified and shown to be highly expressed in the placenta. To better understand the biology of syncytin 2, in this study we first investigated syncytin 2 gene expression in normal and preeclamptic placentas and then characterized the functions of syncytin 2. The expression of syncytin 2 gene was decreased in preeclamptic placentas and could be stimulated by the cAMP stimulant forskolin. The endoprotease furin was found to be involved in the posttranslational cleavage of syncytin 1 and 2 polypeptides into surface and transmembrane subunits. In addition, proper association of the subunits of syncytins 1 and 2 is probably required for the functional integrity of each protein, because subunit swapping of syncytins 1 and 2 failed to generate fusogenic chimeras. Finally, we demonstrated that the disulfide bridge-forming CX(2)C and CX(7)C motifs found in syncytins 1 and 2 are essential for their fusogenic activities, because mutations in the CX(2)C motif not only abolished fusogenesis but also functioned as dominant-negative mutants. Our results suggest that syncytin 2 may function as a second fusogenic protein for placental cell fusion.

Elasticity of alveolar bone near dental implant-bone interfaces after one month's healing

Information is scarce about Young's modulus of healing bone surrounding an implant. The purpose of this preliminary study is to quantify elastic properties of pig alveolar bone that has healed for 1 month around titanium threaded dental implants, using the nanoindentation method. Two 2-year-old Sinclair miniswine were used for the study. Nanoindentation tests perpendicular to the bucco-lingual cross section were performed on harvested implant-bone blocks using the Hysitron TriboScope III. Nomarski differential interference contrast microscopy was used to identify pyramidal indentation measurements that were from bone. Reduced moduli, averaged for all anatomical regions, were found to start low (6.17 GPa) at the interface and gradually increase (slope=0.014) to a distance of 150 microm (7.89 GPa) from the implant surface, and then flatten to a slope of 0.001 from 150 to 1500 microm (10.13 GPa). Mean reduced modulus and its relationship to distance did not differ significantly by anatomic location (e.g., coronal, middle, and apical third; P>/=0.28 for all relevant tests) at 1 month after implantation.

Effects of implant healing time on crestal bone loss of a controlled-load dental implant

The universally accepted concept of delay-loaded dental implants has recently been challenged. This study hypothesizes that early loading (decreased implant healing time) leads to increased bone formation and decreased crestal bone loss. We used 17 minipigs to study implants under a controlled load, with non-loaded implants for comparison. Radiographic and histological assessments were made of the osseointegrated bone changes for 3 healing times (between implant insertion and loading), following 5 months of loading. The effect of loading on crestal bone loss depended on the healing time. Early loading preserved the most crestal bone. Delayed loading had significantly more crestal bone loss compared with the non-loaded controls (2.4 mm vs. 0.64 mm; P < 0.05). The histological assessment and biomechanical analyses of the healing bone suggested that loading and bioactivities of osteoblasts exert a synergistic effect on osseointegration that is likely to support the hypothesis that early loading produces more favorable osseointegration.

New organosilicon maxillofacial prosthetic materials

OBJECTIVES

The silicone elastomer A-2186 is a widely used maxillofacial prosthetic material. It is a pourable two-component silicone rubber cured by a platinum catalyst. Used as a prosthetic material, A-2186 has short working time and because of its hydrophobic nature, poor adhesion to non-silicone based adhesives. The purpose of this study is to evaluate the physical properties of new prosthetic materials based on methacryloxypropyl-terminated polydimethylsiloxane (MPDS-MF), and to compare the properties with those of A-2186.

METHODS

Hardness, tensile strength, ultimate elongation, tear strength and adhesive bonding strength of MPDS-MF and A-2186 with and without additives were determined and compared. The bonding strengths of the extrinsic colorant carrier with the prosthetic materials were also determined. Statistical analyses were done using a two-way analysis of variance (ANOVA). For significant effects, post-hoc tests were done using the Bonferroni correction.

RESULTS

The hardness of MPDS-MF is similar to A-2186. However, tensile strength, tear strength, ultimate elongation, and adhesive bonding strength of MPDS-MF are higher than those of A-2186.

SIGNIFICANCE

MPDS-MF is cured by free radical thermal polymerization and crosslinking. The working time of MPDS-MF, unlike A-2186, is long. The presence of methacrylate groups in MPDS-MF enhances its adhesion to non-silicone based adhesive. Based on the present study, it appears that MPDS-MF is suitable for use in fabricating of clinical prostheses.

Local capsaicin application to the stellate ganglion and stellatectomy attenuate neurogenic inflammation in rat bronchi

The present study investigated the contributions of vagal and nonvagal sensory nerve fibers on neurogenic inflammation in rat bronchial airways. A surgical procedure was developed via the rat mediastinum ventral intercostal space to prepare an intercostal opening without causing pneumothorax for performing stellate ganglionectomy alone, thoracic vagus nerve section alone, and stellatectomy plus thoracic vagotomy, and for injecting capsaicin (2 microl, 10 mg/ml) and 6-hydroxydopamine (2 microl, 50 mg/ml) into the ganglion. One week later in our procedure, we investigated if neurogenic inflammation induced by an intravenous injection of capsaicin (300 nmol/ml/kg) and innervation density of substance P-immunoreactive sensory axons could be decreased after chronic denervation in the rat lower airways. The major findings were that surgical removal of the right stellate ganglion and local capsaicin application resulted in a significant attenuation of neurogenic plasma extravasation in the right bronchial tree evoked by systemic capsaicin application. Reduction of neurogenic plasma extravasation was totally abolished by combined stellatectomy and thoracic vagotomy. The number of substance P-containing axons was also greatly decreased following these surgical and capsaicin treatments. It is concluded that sensory nerve fibers from both vagal source and nonvagal (spinal) source, which associated with the stellate ganglion, contributed significantly to neurogenic inflammation in the bronchial airways with a slightly higher contribution from the vagus nerve.

Multifactorial analysis of an MOD restored human premolar using auto-mesh finite element approach

The use of an mesial-occlusal-distal (MOD) restoration in repairing a large carious lesion depends on many factors. Biomechanical performance is one of the most important. It has been recognized that resistance to restoration failure is not solely a biological concern (e.g. toxicity), but that the cavity shape, dimensions, and the state of stress must all be taken into account. In the present study, a newly developed auto-mesh program was used to generate 30 three-dimensional (3D) finite element (FE) models simulating the biomechanics for multiple factorial design of the MOD gold restoration in a maxillary second premolar. Stress levels were related to individual design factors (e.g. pulpal wall depth [P], isthmus width [W] and interaxial thickness [T]) and to their interactions under the worst physiological scenario: a concentrated bite force acting on lingual cusp with debonded interfaces between cavity walls and restorations. The results showed that enlarging the volume of the MOD cavity significantly increased stresses in enamel but did not intentionally affect stresses in dentin. The alternation of individual design parameters significantly changed the peak stresses (P < 0.05). For all three parameters, except for the width, the peak stress increased as the cavity dimension increased. Stress elevation rate (termed as 'volumetric stress rate'--stress elevation by increasing one unit volume of the restored materials) was different among three design factors. Depth was the most critical factor governing the stress elevation in enamel (1.76 MPa mm(-3)) while length (interaxial thickness) was the most important parameter in dentin (0.49 MPa mm(-3)). Width was the least compromising factor to the remaining tooth, 0.32 MPa mm(-3) for enamel and -0.23 MPa mm(-3) for dentin. The findings, at its core, did not fully agree with the traditional concept that the preservation of tooth substances will reduce risk of tooth fracture. This study leaves open possibility for the structural optimization of the MOD restoration.

Numerical investigation of the factors affecting interfacial stresses in an MOD restored tooth by auto-meshed finite element method

Many researches have addressed the high correlation between the fracture of restored teeth and the prepared cavity geometry. In addition, concerns about bonding versus debonding dental materials from cavity walls and different occlusal force conditions could also alter the mechanical responses in a restored tooth. This study employed an automatic mesh procedure to investigate the mechanical interactions between different interfacial conditions and cavity parameters such as pulpal wall depth under different chewing functions. The results indicated that when occlusal force was applied directly on the tooth, it could increase unfavourable stress dramatically. When interfacial fixation was simulated as the contact condition between the tooth tissue and restorative material, it might increase the fracture potential exponentially compared with the bonded interface. For pulpal wall depth analyses, greater risks of fracture for the remaining tooth were observed in deeper cavity of mesio-occlusal-distal (MOD) restorations and the existence of a pulpal wall is essential even it is only 1 mm above the gingival wall.

Factors influencing optical 3D scanning of vinyl polysiloxane impression materials

PURPOSE

Future growth in dental practice lies in digital imaging enhancing many chairside procedures and functions. This revolution requires the fast, accurate, and 3D digitizing of clinical records. One such clinical record is the chairside impression. This study investigated how surface angle and surface roughness affect the digitizing of vinyl polysiloxane impression materials.

MATERIALS AND METHODS

Seventeen vinyl polysiloxane impression materials were digitized with a white light optical digitizing system. Each sample was digitized at 3 different angles: 0 degrees, 22.5 degrees, and 45 degrees, and 2 digitizer camera f-stops. The digitized images were rendered on a computer monitor using custom software developed under NIH/NIDCR grant DE12225. All the 3D images were rotated to the 0 degrees position, cropped using Corel Photo-Paint 8 (Corel Corp, Ottawa, Ontario, Canada), then saved in the TIFF file format. The impression material area that was successfully digitized was calculated as a percentage of the total sample area, using Optimas 5.22 image processing software (Media Cybernetics, LP, Silver Spring, MD). The dependent variable was a Performance Value calculated for each material by averaging the percentage of area that digitized over the 3 angles. New samples with smooth and rough surfaces were made using the 7 impression materials with the largest Performance Values. These samples were tested as before, but with the additional angle of 60 degrees. Silky-Rock die stone (Whip Mix Corp, Louisville, KY) was used as a control.

RESULTS

The Performance Values for the 17 impression materials ranged from 0% to 100%. The Performance Values for the 7 best materials were equivalent to the control at f/11 out to a surface angle of 45 degrees; however, only Examix impression material (GC America Inc, Alsip, IL) was equivalent to the control at f/11/\16. At the 60 degrees surface angle with f/11/\16, the Performance Values were 0% for all the impression materials, whereas that for the control was 90%. The difference in the Performance Values for the smooth and rough surface textures was 7%, which was not significant.

CONCLUSIONS

The digitizing performance of vinyl polysiloxane impression materials is highly material and surface angle-dependent and is significantly lower than the die stone control when angles to 60 degrees are included. It is affected to a lesser extent by surface texture.

Correlation of noncarious cervical lesion size and occlusal wear in a single adult over a 14-year time span

STATEMENT OF PROBLEM

Noncarious cervical lesions are described as having a multifactorial cause, with occlusal trauma and toothbrush abrasion frequently mentioned as major factors. Finite element modeling studies have demonstrated a relocalization of occlusal stresses to the cervical area due to flexure of the crown. This may cause microcracking, especially under tensile stresses, that will lead to a loss of enamel and dentin in the cervical region. Clinical confirmation of an occlusal cause for noncarious cervical lesions has been difficult to obtain.

PURPOSE

This study investigated whether occlusal wear was correlated with an increase in the size of noncarious cervical lesions.

MATERIAL AND METHODS

Loss of contour at occlusal and cervical sites on 3 teeth of a single individual was measured using digital and visualization techniques at 3 time intervals over a 14-year time span. The 1983 baseline casts and 1991, 1994, and 1997 clinical impressions of a single adult patient with existing noncarious cervical lesions were replicated in epoxy. Surfaces of all replicas were digitized with a contact digitizing system. Sequential digitized surfaces were fit together and analyzed using AnSur-NT surface analysis software. Clinical losses of surface contour by volume and depth of the left mandibular first molar and first and second premolars were recorded.

RESULTS

Nine measurements of cervical volume loss (range 0.9 to 11.5 mm(3)) and 9 corresponding measurements of occlusal volume loss (range 0.39 to 7.79 mm(3)) were made. The correlation between occlusal and cervical volume loss was strong (r(2)=0.98) and significant (P<.0001).

CONCLUSION

For the single adult patient in this study, there was a direct correlation between occlusal wear and the growth of noncarious cervical lesions.

Optical scattering power for characterization of mineral loss

Mineral loss in early caries cannot be measured without invasive procedures. To quantify mineral loss without sectioning the tooth, one must determine the optical scattering of the enamel. Using enamel white-spot lesions, we hypothesize that the optical scattering power (Sp) of the demineralized enamel would provide a quantitative estimate of mineral loss. Enamel slabs were demineralized to produce artificial white spots. The data were acquired by means of a Charge-Coupled Device (CCD) camera and image-processing software. For the purpose of comparison, mineral loss (deltaZ) of the demineralized samples was determined by the use of a microhardness approach after the samples were sectioned. The scattering power correlated well with deltaZ (r2 = 0.82). In contrast, simple reflectance of the demineralized samples correlated poorly with deltaZ (r2 = 0.22). The validity of using scattering power to measure demineralization has been confirmed by a three-dimensional Monte Carlo Simulation.

Spatial chemical analysis of dental stain using wavelength dispersive spectrometry

Six extracted human teeth with naturally-formed neglected stain were analyzed for chemical constituents using wavelength dispersive spectrometry (WDS), an electron microprobe technique. Spatial distribution, within a few microm resolution, of the compositional elements was obtained by line and map analyses, which provided relative concentrations of the elements in stain-enamel complex. Absolute concentrations at different locations across a specimen were obtained from quantitative analysis. Results showed that these neglected stains were highly calcified and contained a significant amount of organic matter (C, N, O, S), with traces of Fe and Cu. The tooth surface underneath the stain layer could be easily distinguished by the higher Ca and P content, as well as by finite amounts of C and S. Corresponding areas of high concentrations between S and Fe/Cu were observed, which suggested the complex of sulfur and metal ions as possible color-forming species. S was found to diffuse into surface enamel in the range of 10 microm.

Stain removal efficacy: an in vitro evaluation using quantitative image analysis

OBJECTIVE

This study developed a computer image analysis technique as a quantitative means to measure changes in dental stain after brushing with various dentifrices.

METHOD AND MATERIALS

Enamel specimens with naturally occurring mature stain were cut from bovine incisors. The specimens were subjected to in vitro toothbrushing with one of the four tested groups, consisting of two dentifrices that make claims of stain removal (Aquafresh Whitening and Rembrandt Sensitive), a regular dentifrice, (Aquafresh Triple Protection), and water. Digital images of stain specimens were recorded under standardized lighting conditions and analyzed with an image analysis software. The area-intensity stain determinant, which accounted for the reflected intensity and the corresponding areas of stain, was computed. Stain removal efficacy was calculated based on the difference in area-intensity stain determinant before and after brushing.

RESULTS

Brushing with any of the tested dentifrices removed more stain than did brushing with water alone. The finding that brushing with a regular dentifrice resulted in higher stain removal efficacy than brushing with water seems to indicate a role for abrasivity. Aquafresh Whitening had a higher stain removal efficacy than did Rembrandt for the removal of mature calcified stain used in this study. However, there were certain stains that none of the dentifrices removed.

CONCLUSION

Computer image analysis provides an objective and quantitative measurement to distinguish in vitro stain removal efficacy of dentifrices.

Multiresolution registration of coronary artery image sequences

Registration of coronary arterial images taken at different times is very important for obtaining better visibility of differences between sequential images. A typical image registration algorithm often employs a similarity measure to detect the differences generated from the relative motion or gray level changes between these images. Although a number of image registration approaches have been proposed to resolve the registration problem of digital angiography, they are either computationally expensive or not very robust in the application to practical images. This paper presents a feature-based sum of absolute values of difference (SAVD) using a coarse-to-fine strategy. The proposed algorithm was demonstrated to be capable to automatically registering the arterial structures in the areas of interest selected from a pair of sequential images as well as providing fractional pixel precision in registration. Compared to other existing methods, the algorithm improves the speed and the reliability of registration when a pair of coronary arterial images are acquired at the same or almost the same phase of cardiac motion.

Upright postures and isoproterenol infusion for provocation of neurocardiogenic syncope: a comparison of standing and head-up tilting

Head-up tilt testing has proved to be useful in provocation of neurocardiogenic syncope. The purpose of this study was to examine whether simply assuming an upright posture by standing can be an alternative to the head-up tilt testing for diagnosis of neurocardiogenic syncope. Eighty-four patients with recurrent unexplained syncope and 22 normal volunteers were recruited into the study. Forty-seven patients with syncope and all normal volunteers received the standing test. Thirty-seven of the patients with syncope received head-up tilt testing (90 degrees). All subjects lay down for 5 minutes and then assumed an upright posture until syncope or presyncope occurred or until a maximum of 10 minutes was reached in each stage of the test. The tests included four stages: baseline and infusion of 1, 2, or 3 micrograms/min isoproterenol in each of the successive stages. Five subjects could not tolerate the procedure, and further testing was terminated. Overall, the standing test was positive in 83% of the patients with syncope, and its specificity was 74%. The head-up tilt testing was positive in 75% of the patients with syncope. The duration of assuming an upright posture before occurrence of syncope or presyncope was significantly longer in the syncope-tilting group in the third stage (p < 0.01) and the fourth stage (p < 0.05) compared with the syncope-standing group. However, the curves of the time course for cumulative positive rates were not significantly different (p = 0.0739) in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Three-dimensional reconstruction of biliary tract from biplane projections

Over the past few years, very little has been done in the area of 3-D reconstruction of the bile duct. Since the system in use for 3-D visualization of the biliary tree is built by surgical or autopsy materials, it generally cannot be applied to clinical diagnosis. In this paper, an algorithm for three-dimensional reconstruction of the biliary tree from two mutually orthogonal is presented to provide accurate and reproducible 3-D information of the biliary tree structure. It has been proven to be useful in diagnosis prior to operation or non-surgical treatment, particularly, obstructive stones can be visualized by using a transparency technique. As experiments demonstrated, the proposed method can be used as a useful tool for the visualization of 3-D structure of biliary tree in clinical applications.

Three-dimensional reconstruction of the biliary tract from two-dimensional biliary images

To make conventional two-dimensional cholangiography easier and more precise to read, we used techniques in computer vision to reconstruct the images in three dimensions. A 72-year-old man and a 70-year-old woman suffering from acute cholangitis were treated using endoscopic nasobiliary drainage. Their cholangiograms, from two orthogonal views, were used for three-dimensional reconstruction. We used video image-grabber and film scanner methods to digitize the original conventional biliary radiographs, and applied two different image processing methods to show the biliary structure. Both methods of three-dimensional reconstruction of the biliary tract were highly useful in evaluating the biliary tracts in these two patients, especially when a semitranslucence overlapping display technique was applied in the second patient. With this technique, the biliary tree itself and the stones inside the common bile duct can be clearly delineated. The technique of three-dimensional reconstruction of biliary images can make the conventional cholangiographs more lifelike and has great potential in surgical simulation in the near future.

A fully automated identification of coronary borders from the tree structure of coronary angiograms

The accurate assessment of variations in coronary arterial dimensions plays an important role in the evaluation of ischemic heart disease and the effectiveness of treatment. Although there exist a variety of edge detection algorithms in the literature, most of them are human interactive and may provide a poor estimate on coronary lesion. In this paper, we present a new method for automatic identification of arterial borders. The proposed algorithm makes use of mathematical morphology to segment blood vessels which follow a tree structure, based on a priori knowledge of coronary anatomy. Finally, an adaptive tracking strategy is applied to automatically identify 2-D arterial borders along both sides of the vessels. This is accomplished by using an edge detection model at a branching point, matched filters, and the tree structure of the coronary artery. Experimental results show that our approach not only is insensitive to the intensity variations of background and noise, but also can extract the boundary of the coronary artery accurately.

Pacing may not prevent neurocardiogenic syncope: the importance of correct diagnosis

A 28-year-old female with frequent attacks of syncope showed high degree atrioventricular (AV) block in Holter's electrocardiographic monitoring. A permanent pacemaker (VVIR) was implanted. However, the syncope recurred despite the normally-functioning pacemaker. The syncope associated with hypotension and bradycardia was reproduced by upright posture for 8 min. This neurocardiogenic syncope was prevented by propranolol (30 mg/day). Neurocardiogenic syncope should be ruled out before pacemaker implantation in patients with syncope, particularly in young adults with no apparent symptom/electrocardiography correlation.

A computer system for skeletal growth measurement

In this paper, we have presented a new image-processing system for the measurement of skeletal growth in pediatric radiology. From a standard posterior and anterior view radiograph, taken from a left hand, the proposed system first automatically locates the phalangeal region of interest, and then measures the geometrical parameters associated with skeletal maturity. Finally, the bone age is estimated by using the standard phalangeal length table. Clinical studies reveal that the computer processing has resulted in an objective and accurate assessment of skeletal age. It greatly improves the shortcomings, including inter- and intraobserver variations and inaccuracy, reported in other research by manual methods. In conclusion, it is an inexpensive and useful tool for the evaluation of short-term abnormalities in the skeletal growth of children.

[A pilot study of nursing activities on the Chest Medicine Ward at KMCH]

The current study sought to establish a preliminary patient classification system by determining how much time nurses spend each shift on their various activities. In this way we hoped to determine the direct care needs of the patient. From August 11 through the 17, snap-shot observations on the Chest Medicine Ward of Kaohsiung Medical College Hospital were taken every five minutes throughout the day to evaluate nursing activities and health care needs of patients. After employing such statistical techniques as percentage comparison, One-way ANOVA on the collected data, we gained a preliminary understanding of the distribution, characteristics, extent and nature of nursing activities. The results demonstrated that the average working hours of the day shift and the evening shift are 8.13 and 8.05 hours respectively. The night shift may be as long as 8.52 hours. Our studies also revealed that the most demanding nursing activity is indirect care (50.73%), direct care (29.39%), individual time (13.73%) and related activities (6.15%) follow. In the direct care of patient, nurses devoted most of their time monitoring vital signs, administering medication, assisting in examination and treatment, caring for, and communicating with patients. On hygiene, physical movements and the clean up of body discharges were mostly devoted by patients and families.

[A study of patient severity classification and nursing hours]

The purpose of this study utilizing the patient classification system was to investigate the distribution of categories of patient severity in medical departments in relation to the nursing hours required for each patient according to the severity of illness. In addition, Work distribution among nursing personnel and evaluation for the feasibility of this program were also considered. As per a proto-type index, patient severity was recorded by the observer; a factor-type nursing requirement table was designed by the nursing personnel. There were 621 samples collected from sub-specialized medical departments. Snapshot observations were taken to survey the allocation of nursing care time. The total of 88 samples of nursing personnel data were analyzed. The results showed that most categories of patient severity were distributed among B II, B III, C III, C IV while the average nursing hours required daily fluctuated between 1.21-10.38 hours. Because of the few samples in A III, B IV, C II, the average nursing hours among three categories were no significance in statistics, and other categories were significant. The researcher may use the nursing hour model as an approach to determine ideal nursing manpower.

Effects of posts on dentin stress distribution in pulpless teeth

A finite element analysis was carried out to study the roles of posts in reducing dentin stress in pulpless teeth. Two-dimensional plane strain models of the midlabiolingual section of a human maxillary central incisor were first analyzed. The results showed that the gold alloy post reduced maximal dentin stress by as much as 30%. However, the integrity of the dentin was compromised and the effects of the post were likely to be exaggerated in such models. In an effort to correct for these problems, plane stress models with side plates and axisymmetric models were analyzed. Posts were found to reduce maximal dentin stress by only 3% to 8% when the teeth were subjected to masticatory and traumatic loadings in these latter models. Although posts reduced maximal dentin stress by as much as 20% when the teeth were loaded vertically, teeth such as incisors and canines normally are not subjected to vertical loadings. Thus the reinforcement effects of posts seem to be doubtful in these teeth.

[Primary treatment of contaminated syringes and needles in a ward]

Body fluid transmitted viruses become the major enemies of human health. These viruses have been reported as occupational hazards for health care personnel, and they may become environmental hazards as well. We conducted this study to examine the primary treatment of used syringes and needles in a ward, and to evaluate the effects of re-education. For questions such as "The used syringes with bloody contamination should isolated from those without" and "The cover of used needles should not be put back on", we recorded error rates during the 1st one-week observation. A lecture about the standard treatment methods of discarding instruments was given to all nurses in this ward after the 1st observation. The 2nd and 3rd one-week observations were repeated one day and one month after the lecture, respectively. The misclassification rates of discarded syringes were 4.4% (33/758), 1.4% (9/661) and 3.9% (18/616). There was a significant decrease between the 1st and 2nd observations (p less than 0.05), but no significant difference between the 1st and 3rd observations (p greater than 0.05). The rates of covered discarded needles were 50.4% (287/569), 44.3% (198/447) and 38.5% (269/699), respectively. These rates showed a trend to decrease (p less than 0.05). The misclassification rates of discarded syringes were low. Although re-education achieved only temporary effects, self-protective education on not re-covering used needles was effective. However, about 40% of all discarded syringes were still being covered after use. Based on our finding, some improvements have been made in this ward.

[The correlating factors affecting nursing personnel resignation in an university hospital]

Demographic characteristics of 1080 university hospital nursing personnel were studied from January 1979 to December 1987. These characteristics included age, marital status, number of children and educational background. Among them, 457 nurses have resigned, while others remain in service. We evaluated the correlations between resignation and various demographic characteristics and the reasons for resignation. This would provide valuable references for nursing recruitment and hospital administration. Our analysis revealed that the reasons for resignation are in the following order: Transfer to governmental hospital, advanced study, marriage, change of occupation, transfer to teaching, personal problems, medical corps to Saudi-Arabia, family responsibilities, and relocation to other cities. Regarding to demographic characteristics, both educational background and marital status affected the reasons for resignation. The average length of service time for nurses who resigned was 30.0 +/- 29.59 months. There are significant differences among the age, marital status, number of children and educational background. The nurses between the age of 21 and 30 years old, (79%) had the highest rate of resignation (45.64%). Those below the age of 20 had the shortest service time, while those above 30 years old had the longest service time. The married nurses also had a longer service time than the single ones. Those who had children had a longer service time compared to those without children. In view of their educational background, those with a bachelor degree had the shortest service time (16.8 +/- 10.3 months) and the highest rate of resignation (71.1%). Our analysis indicates that professional license and location of residence also affected the reasons for resignation.(ABSTRACT TRUNCATED AT 250 WORDS)