Rate and reasons for peritoneal dialysis dropout following haemodialysis to peritoneal dialysis switch: a systematic review and meta-analysis

BACKGROUND

Patient experiences and survival outcomes can be influenced by the circumstances related to dialysis initiation and subsequent modality choices. This systematic review and meta-analysis aimed to explore the rate and reasons for peritoneal dialysis (PD) dropout following haemodialysis (HD) to PD switch.

METHOD

This systematic review conducted searches in four databases, including Medline, PubMed, Embase, and Cochrane. The protocol was registered on PROSPERO (study ID: CRD42023405718). Outcomes included factors leading to the switch from HD to PD, the rate and reasons for PD dropout and mortality difference in two groups (PD first group versus HD to PD group). The Critical Appraisal Skills Programme (CASP) checklist and the GRADE tool were used to assess quality.

RESULTS

4971 papers were detected, and 13 studies were included. On meta-analysis, there was no statistically significant difference in PD dropout in the PD first group (OR: 0.81; 95%CI: 0.61, 1.09; I2 = 83%; P = 0.16), however, there was a statistically significant reduction in the rate of mortality (OR: 0.48; 95%CI: 0.25, 0.92; I2 = 73%; P = 0.03) compared to the HD to PD group. The primary reasons for HD to PD switch, included vascular access failure, patient preference, social issues, and cardiovascular disease. Causes for PD dropout differed between the two groups, but inadequate dialysis and peritonitis were the main reasons for PD dropout in both groups.

CONCLUSION

Compared to the PD first group, a previous HD history may not impact PD dropout rates for patients, but it could impact mortality in the HD to PD group. The reasons for PD dropout differed between the two groups, with no statistical differences. Psychosocial reasons for PD dropout are valuable to further research. Additionally, establishing a consensus on the definition of PD dropout is crucial for future studies.

Explanation-visualised deep learning model for accessory pathway localisation using 12-lead electrocardiography

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): British Heart Foundation Imperial Centre of Research Excellence

Background/Introduction

ECG algorithms for identifying accessory pathway (AP) locations are inaccurate and difficult to use. Human expert interpretation is poorly reproducible. Artificial intelligence (AI) techniques such as machine learning can improve accuracy in classification tasks by eschewing theory-driven predictions. More reproducible and accurate AP localisation could shorten procedure time and personalise ablation consent.

Purpose

We developed a neural network to perform AP localisation using 12-lead ECGs. Its decision-making process was analysed to enable explainability of the neural network.

Methods

A convolutional neural network was trained on raw, digital, intra-procedural 12-lead ECGs of patients with manifest APs who underwent successful ablation. ECGs were labelled with AP locations as left-sided, septal or right-sided using procedure reports, fluoroscopy and electro-anatomical maps. Accuracy of the neural network was assessed via 4-fold cross-validation and was compared to the Arruda algorithm. Five cardiologists were also assessed for their accuracy in determining locations in sub-groups of cases. The neural network was retrospectively analysed to identify areas of ECGs most influential to its predictions using importance mapping.

Results 

In 156 cases, accuracy of the neural network (92.9%) was significantly higher than the Arruda algorithm (76.9%; p < 0.0001) and all five cardiologists (37.5% to 65.9%; p = 0.0001 to 0.0290). Importance mapping demonstrated that the QRS complexes of leads aVL and V1 were perceived as most influential, indicating interrogation of the lateral and anterior-posterior axes respectively.

The figure shows (A) architecture of the neural network, (B) accuracy of the neural network, Arruda algorithm and five cardiologists, (*, p = 0.05 – 0.01; **, p = 0.01 – 0.001; ***, p = 0.001 - 0.0001; ****, p < 0.0001; as compared to the neural network) and (C) example importance maps for 12-lead ECGs of left-sided, septal and right-sided APs (in order from left to right), with darker regions corresponding to greater relative importance. 

Conclusion 

AI ECG interpretation allows accurate, reproducible prediction of AP locations, superior to conventional algorithms and human interpretation. Although AI decision-making is thought of as a ‘black box’, explanation visualisation techniques such as importance mapping allow humans to understand aspects of how a neural network make decisions. A prospectively validated neural network could be integrated into clinical practice to improve pre-procedural AP localisation. Abstract Figure. Summary of results

Risk Factors for Development of Acute Kidney Injury in COVID-19 Patients: A Retrospective Observational Cohort Study

INTRODUCTION

Acute kidney injury (AKI) in coronavirus infection disease (COVID-19) is associated with disease severity. We aimed to evaluate risk factors associated with AKI beyond COVID-19 severity.

METHODS

A retrospective observational study of COVID-19 patients admitted to a tertiary hospital in Singapore. Logistic regression was used to evaluate associations between risk factors and AKI (based on Kidney Disease Improving Global Outcomes criteria). Dominance analysis was performed to evaluate the relative importance of individual factors.

RESULTS

Seven hundred seven patients were included. Median age was 46 years (interquartile range [IQR]: 29-57) and 57% were male with few comorbidities (93%, Charlson Comorbidity Index [CCI] <1). AKI occurred in 57 patients (8.1%); 39 were in AKI stage 1 (68%), 9 in stage 2 (16%), and 9 in stage 3 (16%). Older age (adjusted odds ratio [aOR] 1.04; 95% confidence interval [CI]: 1.01-1.07), baseline use of angiotensin-converting enzyme inhibitor (ACE-I) or angiotensin receptor blocker (ARB) (aOR 2.86; 95% CI: 1.20-6.83), exposure to vancomycin (aOR 5.84; 95% CI: 2.10-16.19), use of nonsteroidal anti-inflammatory drugs (NSAIDs) (aOR 3.04; 95% CI: 1.15-8.05), and severe COVID-19 with hypoxia (aOR 13.94; 95% CI: 6.07-31.98) were associated with AKI in the multivariable logistic regression model. The 3 highest ranked predictors were severe COVID-19 with hypoxia, vancomycin exposure, and age, accounting for 79.6% of the predicted variance (41.6, 23.1, and 14.9%, respectively) on dominance analysis.

CONCLUSION

Severe COVID-19 is independently associated with increased risk of AKI beyond premorbid conditions and age. Appropriate avoidance of vancomycin and NSAIDs are potentially modifiable means to prevent AKI in patients with COVID-19.

Adherence of nurses to annual seasonal influenza vaccination over a 5-year period

BACKGROUND

Healthcare workers (HCWs) are at risk of influenza infection with associated nosocomial transmission. Sustained adherence to seasonal influenza vaccination uptake each year is important in epidemic control.

AIM

To assess the adherence of nurses to seasonal influenza vaccination over 5 years and its associated factors.

METHODS

A cross-sectional study was conducted among nurses after the winter influenza season in Hong Kong in March 2019. Based on influenza vaccine uptake rates in the 2014/15-2018/19 seasons, respondents were stratified into three groups: 'full adherence' (vaccine uptake in five seasons), 'partial adherence' (vaccine uptake in one to four seasons) and 'non-adherence' (no vaccine uptake). Stepwise multi-variable logistic regression was performed to determine the associations between adherence to annual influenza vaccination, respondents' characteristics and considerations for vaccination.

FINDINGS

Of 1306 nurses recruited, the majority were female (88%) with a median age of 36 years (interquartile range 30-46 years). The influenza vaccination uptake rate increased from 36% in the 2014/15 season to 47% in the 2018/19 season. After stratification, 39%, 40% and 21% of respondents were non-adherers, partial adherers and full adherers, respectively. Full adherence was significantly associated with female gender [adjusted odds ratio (aOR) 0.60], age ≥40 years (aOR 2.92), long-term care facility nurse (aOR 0.56), uptake during studentship (aOR 3.83), local prevalence of seasonal influenza (aOR 0.51) and expert opinion (aOR 4.04).

CONCLUSIONS

A limited proportion of nurses were fully adherent to seasonal influenza vaccination. Monitoring adherence, improving access to vaccines, and interventions targeting less-adherent HCWs are crucial.

P2838The impact of anesthesia depth on catheter ablation for atrial fibrillation: a systematic review and meta-analysis of observational studies

Objectives

This meta-analysis and systematic review seeks to compare both characteristic parameters and procedural outcomes of catheter ablation in patients under GA/deep sedation and mild/moderate sedation.

Background

Catheter ablation has become a widely applied intervention for treating symptomatic AF and arrhythmias that are refractory to medical therapy. It can be conducted through from mild sedation to general anesthesia.

Methods

PubMed and Embase were searched up to July 2018 for randomized controlled trials, cohort and observational studies that assessed the outcomes of catheter ablation under GA/deep sedation or mild/moderate sedation. 12 studies were included in this meta-analysis after screening with the inclusion and exclusion criteria. Heterogeneity between studies and publication bias was evaluated by I2 index and Egger's regression, respectively.

Results

Our meta-analysis found catheter AF ablation with GA/deep sedation to be associated with reduced risk of recurrence (RR: 0.79, 95% CI: 0.56 to 1.13, P=0.20) and complications (RR: 0.95, 95% CI: 0.64 to 1.42, P=0.82), though statistically insignificant. In terms of procedural parameters, there was non-significant difference between the two groups when both procedural time (SMD: −0.13, 95% CI: −0.90 to 0.63, P=0.74) and fluoroscopy time (SMD: −0.41, 95% CI: −1.40 to 0.58, P=0.41) were considered. Multivariate meta-regression demonstrated hypertension as an independent moderating factor for complication risk.

Complications Comparison

Conclusion

Apart from an increased likelihood of procedural success, ablation by GA/deep sedation was found to be non-significantly different from the mild/moderate sedation approach in both procedural parameters and outcome measures.

Does statin increase the risk of intracerebral hemorrhage in stroke survivors? A meta-analysis and trial sequential analysis

Background:

It remains debatable whether statin increases the risk of intracerebral hemorrhage (ICH) in poststroke patients.

Methods:

We systematically searched PubMed, EMBASE, and CENTRAL for randomized controlled trials. Trial sequential analysis (TSA) was conducted to assess the reliability and conclusiveness of the available evidence in the meta-analysis. To evaluate the overall effectiveness, the net composite endpoints were derived by totaling ischemic stroke, hemorrhagic stroke, transient ischemic attack (TIA), myocardial infarction, and cardiovascular mortality.

Results:

A total of 17 trials with 11,576 subjects with previous ischemic stroke, TIA, or ICH were included, in which statin therapy increased the risk of hemorrhagic stroke (risk ratio [RR], 1.42; 95% confidence interval [CI], 1.07–1.87), but reduced the risk of ischemic stroke (RR, 0.85; 95% CI, 0.75–0.95). For the net composite endpoints, statin therapy was associated with a 17% risk reduction (95% CI, 12–21%; number needed to treat = 6). With a control event rate 2% and RR increase 40%, the TSA suggested a conclusive signal of an increased risk of hemorrhagic stroke in stroke survivors taking statin. However, with the sensitivity analysis by changing assumptions, the conclusions about hemorrhagic stroke risk were less robust.

Conclusions:

Statin therapy in poststroke patients increased the risk of hemorrhagic stroke but effectively reduced ischemic stroke risk. Weighing the benefits and potential harms, statin has an overall beneficial effect in patients with previous stroke or TIA. However, more studies are required to investigate the conclusiveness of the increased hemorrhagic stroke risk revealed in our study.

Three Cases of Aconite Root Poisoning Due to Bikhama in a Hong Kong Nepalese Family

Aconite is one of the most toxic plants. Aconite is used by herbalists for pain relief. Toxicity occurs due to misidentification, contamination, adulteration and mis-processing. Patients usually present with classical symptoms of aconite poisoning such as perioral paraesthesia, gastrointestinal upset, and generalised burning sensation. Cardiac manifestations include hypotension and ventricular tachycardia. Since aconite is a life-threatening herb commonly used in all cultures, every clinician should be aware of this poison. This report recorded three cases of aconite poisoning in a Nepalese family who were managed in a major urban hospital in Hong Kong. They all presented with variable severity of aconite poisoning after mistakenly ingesting aconite. Management was performed basing on the clinical features, as laboratory confirmation of aconite poisoning was not immediately available. All three patients survived and did not suffer from any consequences.

Should lidocaine spray be used to ease nasogastric tube insertion? A double-blind, randomised controlled trial

OBJECTIVE

To investigate the efficacy and safety of lidocaine nasal spray before nasogastric tube insertion in an emergency department.

DESIGN

Double-blind, randomised controlled study.

SETTING

Emergency department of a major regional hospital in Hong Kong.

PATIENTS

A total of 206 adult patients, for whom nasogastric tube insertion was indicated.

MAIN OUTCOME MEASURES

Primary outcome was discomfort gauged on a visual analogue scale, and Likert scale addressing difficulty of nasogastric tube insertion.

RESULTS

Compared with placebo spray use, lidocaine spray use was associated with less patient discomfort, and less difficulty in nasogastric tube insertion, both difference being statistically significant.

CONCLUSION

Intranasal lidocaine spray before nasogastric tube insertion was safe and effective in reducing patient discomfort related to the procedure.

The first novel influenza A (H1N1) fatality despite antiviral treatment and extracorporeal membrane oxygenation in Hong Kong

We report the first fatality caused by novel influenza A (H1N1) infection despite having the diagnosis confirmed and being given antiviral treatment after hospitalisation. This patient was also the first with influenza A (H1N1) to be supported with extracorporeal membrane oxygenation in Hong Kong. Although extracorporeal membrane oxygenation is an effective means of supporting patients with refractory hypoxaemia on high mechanical ventilatory support, it is labour-intensive and technically demanding. We also discuss the challenges faced when managing this case.

Factors affecting the palpability of breast lesion by self-examination

INTRODUCTION

This study aims to assess the accuracy of detection of breast lesion by breast self-examination and to assess different factors affecting the accuracy.

METHODS

All consecutive Chinese female patients, who attended our breast imaging unit in 2001, completed our questionnaire, had retrievable hard copy films, and had more than three years clinical follow-up, were recruited for this study. Different factors, such as age, menopausal status, previous experience of breastfeeding, family history of breast cancer, previous history of mastectomy or lumpectomy, hormonal therapy, oral contraceptive pills and previous history of mammography, were correlated with accuracy in self-detection of breast lesions retrospectively. The nature, size and location of the lesion, and breast size based on imaging, were also correlated with the accuracy in self-detection of breast lesions.

RESULTS

A total of 163 questionnaires were analysed. 111 patients detected a breast lesion themselves and 24 of these lesions were false-positives. A total of 173 lesions (27 cancerous, 146 benign lesions) were documented by either ultrasonography and/or mammography, and confirmed by either histology or three-year clinical follow-up. The overall sensitivity in detecting both benign and malignant breast lesions was 71% when number of breast lesions was used as the denominator, and up to 78% sensitivity was achieved when number of patients was used as the denominator. History of mastectomy, and size and nature of the lesions were found to affect the accuracy of self-detection of breast lesions.

CONCLUSION

Overall, breast self-examinations were effective in the detection of breast lesions and factors such as size of lesion, nature of the lesion and history of mastectomy affect the accuracy of the detections. Breast self-examination should be promoted for early detection of breast cancer.

Antioxidant and pro-oxidant properties of chlorhexidine and its interaction with calcium hydroxide solutions

AIM

To evaluate the antioxidant and pro-oxidant properties of chlorhexidine (CHX).

METHODOLOGY

The scavenging and generation of reactive oxygen species (ROS) by CHX in the presence or absence of saturated Ca(OH)(2) solutions was evaluated. The reaction emitted chemiluminescence in the presence of lucigenin thus was determined by a luminometer to evaluate the levels of ROS production. Changes in DNA conformation were analysed by agarose gel electrophoresis. Paired Student's t-test was used to compare the difference between groups.

RESULTS

Chlorhexidine (0.00002-0.02%) effectively scavenged 56-88% of the superoxide radicals generated by the xanthine/xanthine oxidase reaction. Through analysis of PUC18 DNA conformation changes, CHX was shown to be a mild scavenger of hydroxyl radicals generated by H(2)O(2) plus FeCl(2). However, CHX (>0.083%) decreased the mobility of PUC18 plasmid DNA with potential production of DNA-DNA cross-link and severe DNA breaks (presence of DNA smear) at further higher concentrations. Furthermore, CHX induced ROS production including H(2)O(2) and superoxide radicals in 0.1N NaOH (pH = 12.76) or Ca(OH)(2) (pH = 12.5) solutions.

CONCLUSION

Chlorhexidine exhibited both antioxidant and pro-oxidant properties under different conditions. These events are possibly involved in the killing of root canal and periodontal microorganisms when CHX and Ca(OH)(2) were used in combination or separately. Potential genotoxicity and tissue damage when extruded into the periradicular tissue and at higher concentrations should be considered during periodontal and endodontic practice.

Effects of TGF-beta s on the growth, collagen synthesis and collagen lattice contraction of human dental pulp fibroblasts in vitro

Transforming growth factor-beta (TGF-beta) is important in regulating the repair and regeneration of damaged dental pulp. For further elucidating the roles of different isoforms of TGF-beta in the healing and inflammatory processes of human dental pulp, we found that TGF-beta1, TGF-beta2 and TGF-beta3 inhibited the growth of two human dental pulp cell strains in vitro by 19-29, 18-25 and 23-26%, respectively, at a concentration of 0.5 ng/ml. TGF-beta also differentially stimulated the collagen synthesis of pulp cells. Collagen synthesis increased by 1 ng/ml of TGF-beta1 and TGF-beta2 by 42 and 51%, respectively. TGF-beta3 (0.1-1 ng/ml) lacked of stimulatory effect on collagen synthesis of pulp cells. Pulp cells have the intrinsic capacity to contract collagen lattice, leading to decreasing of lattice diameter. An 8 h exposure to TGF-beta1 and TGF-beta2 enhanced the pulp cell-populated collagen lattice contraction at concentrations ranging from 0.2 to 3 ng/ml. At similar concentrations, TGF-beta3 lacked of this stimulatory effect. When collagen lattice were detached after 24 h of exposure, TGF-beta1 and TGF-beta2 (0.6-3 ng/ml) induced the pulp cells-populated collagen lattice contraction within 4-8h of gel detachment. These results indicate that TGF-beta-induced collagen lattice contraction is a late cellular event. These in vitro results indicate that effects of TGF-beta isoforms on the growth, collagen synthesis and collagen lattice contraction of pulp cells may play crucial roles in the pathobiological processes of dental pulp.

Scavenging property of three cresol isomers against H2O2, hypochlorite, superoxide and hydroxyl radicals

Formocresol has long been used for pulpotomy of primary teeth and as an intracanal medicament. Little is known, however, about the pharmacological effect of tricresols. This study showed that three cresol isomers, o-cresol, m-cresol and p-cresol, are H2O2 scavengers with a 50% inhibitory concentration (IC50) of 502, 6.7 and 10.16 microM, respectively. o-, m- and p-cresol were also shown to be effective scavengers of superoxide radicals generated by xanthine/xanthine oxidase with an IC50 of 282, 153 and > 4000 microM, respectively, as analyzed by luminometer. o-, m- and p-cresol showed protective effects on the DNA breaks generated by H2O2/FeCl2 and FeCl3/ascorbate/H2O2 systems at concentrations ranging from 70 microM to 1.43 mM, o-, m- and p-cresol also showed differential protective effects against DNA breaks induced by 0.17% NaOCl with 100% inhibitory concentration (IC100) of about 10, 1 and 10 mM, respectively. In addition, reaction with 3% H2O2 and 0.17% NaOCl completely prevented NaOCl-induced DNA breaks. The results indicate that the three cresol isomers are effective ROS scavengers and may prevent ROS induced damage when used as pulpotomy agents or as intracanal medicaments. Owing to the difference in the position of the functional hydroxyl group in the three cresol isomers, m-cresol is the most effective ROS scavenger. Concomitant use of H2O2 for root canal irrigation may diminish both the tissue dissolving capacity of NaOCl and NaOCl-induced DNA damage.

Myxoma of the gingiva: a case report and literature review

Soft tissue myxomas of the oral and para-oral tissue are extremely rare. Only two cases of myxoma of gingiva have been reported in the literature. The histogenesis of these lesions remains obscure. We report a case of gingival myxoma in a 37-year-old man. A firm ovoid soft tissue mass measuring 1.5 x 1.2 x 1 cm in size was noted at the mesio-lingual gingiva of a partially impacted right mandibular third molar. Radiographic examination revealed an impacted mandibular third molar with normal radiographic bony consistency of the mandible. Excisional biopsy was performed with no evidence of recurrence after 8 months. Histological examination showed stromal mass composed of myxoid-like fluid in fibrovascular stroma and scanty inflammatory cell infiltration, suggesting myxomas of the oral soft tissues and jaws. Immunohistochemical stains with S-100 protein, desmin and smooth muscle specific actin yielded negative results, and those with alcian blue, periodic-acid-Schiff, mucicarmine, vimentin and reticulin were positive. Tumor cells of mesenchymal origin without neurogenic or muscular derivations and myxoid matrix composed of acid mucopolysaccharides in this lesion further confirmed the diagnosis of myxoma. Periodontal ligament origin cannot be completely excluded due to tumor location and its association with an impacted molar. However, further study is necessary to clarify the origin and histogenesis of these lesions.

Noisy speech recognition using de-noised multiresolution analysis acoustic features

This paper describes a novel application of multiresolution analysis (MRA) in extracting acoustic features that possess de-noising capability for robust speech recognition. The MRA algorithm is used to construct a mel-scaled wavelet packet filter-bank, from which subband powers are computed as the feature parameters for speech recognition. Wiener filtering is applied to a few selected subbands at some intermediate stages of decomposition. For high-frequency bands, Wiener filters are designed based on a reduced fraction of the estimated noise power, making the consonant features much more prominent and contrastive. The proposed method is evaluated in phone recognition experiments with the TIMIT database. In the presence of stationary white noise at 10-dB SNR, the de-noised MRA features attain a phone recognition rate of 32%. There is a noticeable improvement compared with the accuracy of 29% and 20% attained by the commonly used mel-frequency cepstral coefficients (MFCC) with and without cepstral mean normalization (CMN), respectively. The effectiveness of the MRA features is also verified by the fact that they exhibit smaller distortion from clean speech.

Implications of organizational learning for nursing managers from the cultural, interpersonal and systems thinking perspectives

This paper discusses the implications of organizational learning to healthcare administrators, in particular nursing managers, from the cultural, interpersonal and systems thinking perspectives. In the various perspectives the reasons for organizational ineffectiveness and remedies are presented. There is little doubt that pressure for nurses to perform is escalating as healthcare institutions attempt to improve the quality of service through restructuring and change, which leads to greater job dissatisfaction, higher turnover, lower morale and increased industrial actions of nurses. An integrated approach to organizational learning is arguably important for the effective management of nurses during periods of transition.

Areca nut extract and arecoline induced the cell cycle arrest but not apoptosis of cultured oral KB epithelial cells: association of glutathione, reactive oxygen species and mitochondrial membrane potential

There are 600 million betel quid (BQ) chewers in the world. BQ chewing is a major etiologic factor of oral cancer. Areca nut (AN) and arecoline may inhibit the growth of oral mucosal fibroblasts (OMF) and keratinocytes. In this study, AN extract (100-800 microg/ml) and arecoline (20-120 microM) inhibited the growth of oral KB cells by 36-90 and 15-75%, respectively. Exposure to arecoline (> 0.2 mM) for 24 h induced G(2)/M cell cycle arrest of OMF and KB cells. Areca nut extract (> 400 microg/ml) also induced G(2)/M arrest of KB cells, being preceded by S-phase arrest at 7-h of exposure. No evident sub-G(0)/G(1) peak was noted. Marked retraction and intracellular vacuoles formation of OMF and KB cells were observed. Glutathione (GSH) level, mitochondrial membrane potential (Deltabetam) and H(2)O(2) production of KB cells were measured by flow cytometry. GSH level [indicated by 5-chloromethyl-fluorescein (CMF) fluorescence] was depleted by 24-h exposure of KB cells to arecoline (0.4-1.2 mM) and AN extract (800-1200 microg/ml), with increasing the percentage of cells in low CMF fluorescence. By contrast, arecoline (0.1-1.2 mM) and AN extract (800-1200 microg/ml) induced decreasing and increasing H(2)O(2) production (by 2',7'-dichloro- fluorescein fluorescence), respectively. Hyperpolarization of Deltabetam (increasing of rhodamine uptake) was noted by 24-h exposure of KB cells to arecoline (0.4-1.2 mM) and AN extract (800-1200 microg/ml). AN extract (100- 1200 microg/ml) and arecoline (0.1-1.2 mM) induced little DNA fragmentation on KB cells within 24 h. These results indicate that AN ingredients are crucial in the pathogenesis of oral submucous fibrosis (OSF) and oral cancer by differentially inducing the dysregulation of cell cycle control, Deltabetam, GSH level and intracellular H(2)O(2) production, these events being not coupled with cellular apoptosis.

The prevalence and distribution of bone defects in patients with moderate to advanced periodontitis

BACKGROUND

Alveolar bone defect is one of the common features of periodontitis and may vary in its form, extent, and distribution among teeth and individuals. The purpose of this study was to analyze the prevalence and distribution of different forms of bone defects in Taiwanese patients with moderate to advanced periodontitis.

METHODS

One hundred and thirty-seven Taiwanese patients with moderate to advanced periodontitis comprising a total sample of 3542 teeth were studied. During periodontal surgery, osseous defects were explored and classified as interproximal crater, 1-wall, 2-wall, 3-wall, hemiseptal and circumferential defects. Among them, some were also recorded as complicated defects.

RESULTS

Among 3542 existing teeth, 1376 were examined surgically and 483 teeth had bone defects. There was an increase in bone defects from anterior to posterior. The frequencies of defects in anterior and posterior segments were significantly different. More defects were found on the right side than on the left side. Yet there was no difference between the maxillary and mandibular arch. Interproximal surfaces of the first and second molars had the highest prevalence of bone defects. Crater was the most common defect type (26.50%), followed by circumferential (23.40%) and 3-wall defect (20.08%). More than 40% also presented with complicated defects.

CONCLUSIONS

There was an increase in bone defects from anterior to posterior. Interproximal aspects were more frequently involved than buccal or lingual aspects. Crater, circumferential and 3-wall defects were more common than other defect types. The treatment of complicated defects, which comprise over 40% of all defects, presents a challenging task for periodontists.

Thrombin-stimulated growth, clustering, and collagen lattice contraction of human gingival fibroblasts is associated with its protease activity

BACKGROUND

Thrombin is a serine protease produced following gingival tissue injury or inflammation. It regulates the functional behavior of injury-neighboring cells via the activation of specific protease-activated receptors (PAR). Thrombin's role in gingival tissue healing and inflammatory response processes is not yet well understood.

METHODS

We investigated the effects of thrombin on gingival fibroblast (GF) growth [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay], collagen lattice contraction, and associated morphological changes.

RESULTS

Thrombin (>1 U/ml), but not thrombin receptor (PAR-1) agonist peptide (SFLLRN, single letter amino acid code, abbreviated as TRAP, 1 to 50 microg/ml), stimulated the growth and clustering of cultured human GF in vitro. Growth-stimulatory effects of thrombin were inhibited by D-Phe-Pro-ArgCH2Cl (PPACK), a serine protease inhibitor. By contrast, trypsin (>10 microg/ml), a PAR-2 activator, suppressed the growth of GF. Thrombin (>0.2 U/ml) and TRAP (10 to 25 microg/ml), but not trypsin, prostaglandin E2 (0.01 to 0.5 microg/ml), or bovine serum albumin (BSA) (1 to 80 microg/ml), induced the GF-populated collagen lattice contraction within 30 to 60 minutes of exposure. The thrombin-induced collagen lattice contraction was inhibited by PPACK (20 microg/ml) and an actin filament polymerization inhibitor, cytochalasin B (1 microg/ml). The collagen lattice contraction induced by TRAP was also inhibited by cytochalasin B, but not by PPACK. Using a reverse-transcriptase polymerase chain reaction (RT-PCR), the expression of PAR-1, and to a lesser extent PAR-3, was observed for human GF, although little PAR-2 and PAR-4 expression was noted.

CONCLUSIONS

These results indicate that thrombin is important in periodontal wound healing and inflammatory processes by promoting the growth and contraction of GF. The stimulatory effects of thrombin are associated with its protease activation of thrombin receptors.

TRADD domain of Epstein-Barr virus transforming protein LMP1 is essential for inducing immortalization and suppressing senescence of primary rodent fibroblasts

Mutation analysis of latent membrane protein 1 (LMP1) in Epstein-Barr virus (EBV)-induced B-cell immortalization revealed two transformation effector sites, TES1 and TES2. TES2 mediates the interaction with tumor necrosis factor receptor-associated death domain protein (TRADD) and plays a key role in transactivating NF-kappa B and AP-1. Recombinant EBV containing LMP1 with TES2 deleted induces a limited proliferation of B cells. The present study shows that a mutant with an LMP1 site-specific mutation at TES2, LMP1(TRADD), initially stimulates cell growth and significantly extends the life span of MEF. However, it is not sufficient for the immortalization of MEF, and MEF-LMP1(TRADD) cells eventually enter growth arrest. Further analysis reveals that although LMP1(TRADD) promotes cell growth, it does not prevent the eventual onset of senescence and the expression of tumor suppressor p16(Ink4a).

Double-coping technique in prosthesis fabrication for osseointegrated teeth implantation: case report

Reconstruction of segmental mandibular defects resulting from trauma, infection, or tumor resection still remains difficult. Although cosmetic improvement was seen in patients who had immediate reconstruction of the mandibular continuity, normal mastication and deglutition could not be achieved by conventional removable dentures. Since 1988, the treatment protocol has been modified to use endosseous root-form implants to support dental prostheses instead of the conventional removable prostheses in these patients. There are 2 types of prostheses that can be constructed over dental implants: (1) a removable implant overdenture and (2) a fixed detachable prosthesis. Although the latter better meets in patients' psychological needs, it may present problems such as phonetic discrepancies, food impaction, difficult home care, and poor esthetics if the patient has a high lip line. In addition, it is not easy to fabricate accurately in the laboratory. To overcome these problems, a case is presented to illustrate the use of another fixed-type prosthesis, a double-coping technique, for fabricating dentures so that any discrepancy between the inner and outer copings can be filled by cement. The technique not only improves the shortcomings of fixed detachable prostheses but also satisfactorily meets patients' desire for normal mastication and deglutition. Follow-up after 4 years showed no significant changes around the implants by clinical and radiographic examinations.

Undergraduate medical education: comparison of problem-based learning and conventional teaching

OBJECTIVE

To review the literature on studies comparing all aspects of problem-based learning with the conventional mode of teaching.

DATA SOURCES

Medline literature search (1980 through 1999) and the references cited in retrieved articles.

DATA SELECTION

Studies and meta-analyses that compared the newer problem-based learning curriculum and the conventional lecture-based mode of teaching undergraduate medical students. Areas of comparison included the academic process; programme evaluation; academic achievement; graduates' performance, specialty choices, and practice characteristics; and the attitude of students and teachers towards the programmes.

DATA EXTRACTION

Data were extracted independently by multiple authors.

DATA SYNTHESIS

Students of the problem-based learning curriculum found learning to be "more stimulating and more humane" and "engaging, difficult, and useful", whereas students of the conventional curriculum found learning to be "non-relevant, passive, and boring". Students who used the problem-based learning method showed better interpersonal skills and psychosocial knowledge, as well as a better attitude towards patients. Students using the conventional model, however, performed better in basic science examinations. Teachers tended to enjoy teaching the newer curriculum. Although the two curricula encourage different ways of learning, there is no convincing evidence of improved learning using the problem-based learning curriculum.

CONCLUSION

A combination of both the conventional and newer curricula may provide the most effective training for undergraduate medical students.

Areca nut extract up-regulates prostaglandin production, cyclooxygenase-2 mRNA and protein expression of human oral keratinocytes

There are about 600 million betel quid (BQ) chewers in the world. BQ chewing is associated with increased incidence of oral cancer and submucous fibrosis. In this study, areca nut (AN) extract (200-800 microg/ml) induced the prostaglandin E(2) (PGE(2)) production by 1. 4-3.4-fold and 6-keto-PGF(1 alpha) production by 1.1-1.7-fold of gingival keratinocytes (GK), respectively, following 24 h of exposure. Exposure of GK to AN extract (>400 microg/ml) led to cell retraction and intracellular vacuoles formation. At concentrations of 800 and 1200 microg/ml, AN extract induced cell death at 21-24 and 32-52% as detected by MTT assay and cellular lactate dehydrogenase release, respectively. Interestingly, AN-induced morphological changes of GK are reversible. GK can still proliferate following exposure to AN extract. Cytotoxicity of AN extract cannot be inhibited by indomethacin (1 microM) and aspirin (50 microM), indicating that prostaglandin (PG) production is not the major factor responsible for AN cytotoxicity. PGE(2) exhibited little effect on the growth of GK at concentrations ranging from 100-1000 pg/ml. Stimulating GK production of PGs by AN extract could be due to induction of cyclooxygenase-2 (COX-2) mRNA expression and protein production. These results suggest that AN ingredients are critical in the pathogenesis of oral submucous fibrosis and oral cancer via their stimulatory effects on the PGs, COX-2 production and associated tissue inflammatory responses. AN cytotoxicity to GK is not directly mediated by COX-2 stimulation and PG production.

Extracoronal resilient attachments in distal-extension removable partial dentures

Esthetics is often compromised in patients who wear removable partial dentures with metal clasps placed on anterior teeth. Clinical procedures are presented for a new design of a removable partial denture that improves esthetics and function through a new dental attachment. The extracoronal resilient attachment system offers vertical resiliency and universal stress relief for use where a resilient prosthesis is indicated. The removable partial denture retained by these attachments provides esthetics, vertical resiliency, and easy replacement of worn attachments.

Successful treatment of pulpal-periodontal combined lesion in a birooted maxillary lateral incisor with concomitant palato-radicular groove. A case report

Palato-radicular groove (PRG) is a common developmental anomaly of maxillary incisors, whereas PRG associated with a birooted maxillary incisor is relatively infrequent. The clinical significance of PRG is related to the incidence of localized periodontitis with or without pulpal pathosis, depending on the depth, extent, and complexity of the groove. Successful treatments of PRG in single-rooted incisors have been reported in the literature. However, treatment of PRG in birooted incisors has often been ineffective. This case report describes a pulpal-periodontal combined lesion occurring on a birooted maxillary left lateral incisor with concomitant PRG in a 13-year-old boy which was successfully treated by conventional endodontic therapy in combination with periodontal treatment including accessory root resection, radiculoplasty and bone grafting. Seven-year follow-up is included in this report. The basis of a successful result is accurate diagnosis and elimination of inflammatory irritants and contributory factors. Awareness of the existence of this abnormality by the clinician is important.

Effects of Butyrate and Propionate on the Adhesion, Growth, Cell Cycle Kinetics, and Protein Synthesis of Cultured Human Gingival Fibroblasts

BACKGROUND

Various periodontal and root canal pathogens, such as the Bacteroides species, can produce significant amounts of short chain fatty acids (SCFA). The roles of SCFA in the pathogenesis of periodontal disease are still not fully understood.

METHODS

We therefore investigated 2 main SCFA, butyrate and propionate, on the functional behavior of cultured human gingival fibroblasts (GF) such as cell growth, protein synthesis, cell adhesion capacity, and cell cycle progression.

RESULTS

Butyrate and propionate inhibited the growth of healthy (HGF) and inflamed gingival fibroblasts (IGF) in a dose dependent manner. At concentrations of 4, 8, and 16 mM, butyrate suppressed the cell growth by 11 to 58%, 16 to 60%, and 50 to 71%, respectively. The response of cultured gingival fibroblasts to SCFA showed individual differences. Morphologically, GF became larger and more flattened in appearance following exposure to butyrate (>8 mM) and propionate (>24 mM) for 5 days. Inhibitory effects of butyrate (>2 mM) and propionate (>8 mM) on the growth of GF were due possibly to their inhibition of cell-cycle progression. At concentrations of 2 and 8 mM, butyrate led to G0/G1 arrest. Elevation of the exposure concentration to 8 to 24 mM further result in G2/M phase arrest of GF. On the other hand, propionate, at concentrations ranging from 4 to 24 mM, led to G0/G1 arrest. Butyrate (>2 mM) inhibited the proline-rich protein synthesis of GF. At concentrations of 4, 8, 16, and 24 mM, butyrate inhibited the protein synthesis of HGF-1 by 42%, 43%, 51%, and 54%, respectively. In all strains of cultured GF, the suppressive effect of propionate is less than that of butyrate. At concentration range of 4 to 24 mM, propionate suppressed the protein synthesis of HGF-1 by 23 to 43%. However, both butyrate and propionate (4 to 48 mM) exerted little effects on the adhesion of GF to type I collagen within 3 hours of incubation.

CONCLUSIONS

These results suggested that SCFA released by pathogenic microorganisms can contribute to the gingival tissue dysfunction and breakdown through their actions on specific biological functions of GF.

Soft tissue management using palatal mucosa around endosteal implants in vascularized composite grafts in the mandible

Excessive thickness and mobility of the skin flap and lack of a vestibular sulcus in composite vascularized bone grafts for mandibular reconstruction limit the usefulness of endosteal implants to support a prosthetic device. Palatal mucosal grafts and a simple acrylic stent are an excellent means to overcome these problems. The technique is presented in this paper.

Identification of linear surface epitopes on the guinea pig sperm membrane protein PH-20

The sperm plasma membrane protein PH-20 has previously been shown to be an effective immunogen for protection against fertilization in guinea pigs. To identify immunodominant regions on gpPH-20 that may be related to this contraceptive effect, we used several high-titer immune sera obtained from animals rendered infertile by gpPH-20 injections to screen a set of overlapping peptides that cover the entire 494-residue sequence. Multiple clusters of peptide sequences exhibited specific reactivity. Some of these sequences were then constructed as octameric synthetic peptides and tested for immunogenicity in female guinea pigs. Our results indicated two regions (res. 94-119 and res. 424-444) to be highly immunogenic and both are surface accessible when native gpPH-20 is in solution or anchored on sperm surface. Both anti-peptide antibodies are specific for gpPH-20 and one of them inhibited hyaluronidase activity partially. These monospecific antibodies should be useful probes for further molecular definition of gpPH-20 structure-function relationships.

The effects of extracellular citric acid acidosis on the viability, cellular adhesion capacity and protein synthesis of cultured human gingival fibroblasts

Root surface demineralization is widely used as an adjunct to periodontal treatment. To clarify the influence of citric acid root conditioning on periodontal wound healing, the effects of citric acid and associated extracellular acidosis on the viability (MTT assay), attachment and protein synthesis ([3H]-proline incorporation into trichloroacetic acid-precipitated proteins) of human gingival fibroblasts (GF) were investigated. A concentration of 47.6 mmol/L of citric acid (pH 2.3) in water led to total cell death within three minutes of incubation. Media containing 23.8 mmol/L and 47.6 mmol/L of citric acid exerted strong cytotoxicity (47 to 90 per cent of cell death) and inhibited protein synthesis (IC50 = 0.28 per cent) of GF within three hours of incubation. Incubation of cells in a medium containing 11.9 mmol/L of citric acid also suppressed the attachment and spreading of fibroblasts on culture plates and Type I collagen, with 58 per cent and 22 per cent of inhibition, respectively. Culture medium supplemented with 11.9, 23.8 and 47.6 mmol/L of citric acid also led to extracellular acidosis by decreasing the pH value from 7.5 to 6.3, 5.2 and 3.8, respectively. In addition, it was confirmed that the toxic effect of media containing citric acid was due to their acidity rather than the citrate content. Most of the citric acid-induced cell death could be prevented by adjusting the pH value of the culture medium to pH 7.5. Sodium citrate, at a concentration of 47.6 mmol/L, also exerted little cytotoxicity. The results suggested that toxicity of citric acid in specific stages of the healing process must be considered prior to its clinical application. Careful management of citric acid in order to avoid contact with tissue or the development of other demineralizing agents is important in enhancing periodontal wound healing.

Morphological alterations associated with the cytotoxic and cytostatic effects of citric acid on cultured human dental pulp cells

Citric acid exerts potential harmful effects on the pulp when used for root surface demineralization, smear layer removal, and dentin etching. Using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay, we found that incubation of cultured human dental pulp cells in medium containing 0.5% (pH 4.74) or 1.0% (pH 3.42) of citric acid for 2 h lead to 25% and 48% of cell death, respectively. Cytotoxicity of citric acid was associated with its acidity. Exposure of cells to pure 1% citric acid (pH 2.26) for 60 s lead to immediate cell death. Cytotoxicity was usually preceded by cell retraction, cell surface blebbing, and finally uptake of trypan blue, implicating the presence of cell membrane damage. A medium containing 0.05% citric acid can retard the growth of pulp cells. These results indicate that adequate protection of the pulp is important, especially when the remaining dentin is thin in deep carious lesions or in the presence of accessory canals on the root surface.

Vertical root fracture in endodontically versus nonendodontically treated teeth: a survey of 315 cases in Chinese patients

OBJECTIVE

The purpose of this study was to compare endodontically versus nonendodontically treated teeth with respect to clinical features, including patient age and gender and tooth types of vertical root fractures.

STUDY DESIGN

A total of 315 consecutive cases of vertical root fracture occurring in 274 Chinese patients during a 1 3-year period were reviewed. Age and gender, as well as tooth type and root distribution of vertical root fractures, were presented and compared in endodontically versus nonendodontically treated teeth.

RESULTS

Most patients (87%) had 1 fractured tooth; the others had 2 or 3 fractured teeth. Of all vertical root fractures, 40% occurred in nonendodontically treated teeth. In comparison with those in endodontically treated teeth, vertical root fractures in nonendodontically treated teeth tended to occur in patients with a higher mean age (55 years vs. 51 years) and were more frequent in male patients (78% vs. 58%). Vertical root fractures occurred in nonendodontically treated teeth more often in molars (84% vs. 53%), less often in premolars (16% vs. 33%), and seldom in anteriors (1 tooth vs. 27 teeth).

CONCLUSIONS

Vertical root fractures in nonendodontically treated teeth are not uncommon and comprise a large proportion of such fractures in Chinese patients. Differences between endodontically and nonendodontically treated teeth in patient age and gender, as well as in tooth types of vertical root fractures, were demonstrated.

Effects of areca nut, inflorescence piper betle extracts and arecoline on cytotoxicity, total and unscheduled DNA synthesis in cultured gingival keratinocytes

Betel quid (BQ) chewing has a strong correlation with oral leukoplakia, submucous fibrosis and oral cancer. For elucidation of its pathogenesis, we investigated the effects of areca nut (AN) and inflorescence piper betle (IPB) extracts and arecoline on the growth, total DNA synthesis (TDS) and unscheduled DNA synthesis (UDS) of cultured human gingival keratinocytes (GK). Arecoline and AN extract suppressed the growth of GK over 5 days of incubation in a dose-dependent fashion. At concentrations of 100, 200 and 400 microg/ml, AN extract suppressed the growth of GK by 31%, 46% and 90%, respectively. The IPB extracts exerted less inhibitory effect on the growth of GK. IPB extract (200-400 microg/ml) decreased cell numbers by 20-40% over 5 days of incubation. Moreover, at a concentration of 0.1, 0.2 and 0.4 mM, arecoline suppressed cell growth by 44%, 77% and 96%, respectively. However, only AN extract induced TDS and UDS in cultured GK within 6 h of exposure. Induction of UDS by AN extract was concomitant with the presence of apparent intracellular vacuolization. Arecoline was also toxic to GK, but did not induce intracellular vacuolization. At a concentration range of 200-1600 microg/ml, AN extract induced TDS by 2.1- to 6.5-fold. Furthermore, at a concentration of 400-1600 microg/ml, AN extract elevated the UDS by 2.4- to 5.5-fold more than that of untreated control. On the contrary, IPB extract (200-1600 microg/ml) and arecoline (0.2-1.6 mM) inhibited the TDS and UDS of GK to a different extent. Simultaneous exposure of confluent GK to AN extract, IPB extract and arecoline for 1 to 5 days led to different degrees of cytotoxicity that was dose- and time-dependent. These results indicate that AN, IPB and arecoline take part in the pathogenesis of BQ chewing-related oral mucosal lesions, possibly through both genotoxic and non-genotoxic mechanisms.

Effects of thrombin on the growth, protein synthesis, attachment, clustering and alkaline phosphatase activity of cultured human periodontal ligament fibroblasts

Previous studies have indicated that thrombin can activate pulp cells, including fibroblasts. Because pulp cells and periodontal ligament (PDL) fibroblasts can express thrombin receptor mRNA, the specific aim of this study was to determine whether thrombin can activate the growth, attachment, protein synthesis, alkaline phosphatase activities and cellular clustering of cultured human PDL fibroblasts. Thrombin can stimulate the growth of PDL fibroblasts in a dose dependent manner (as analyzed by MTT assay). At concentrations of 5 and 10 U/ml, thrombin increased the cell numbers to 141% and 153% greater than that of the control after 5 days of incubation, respectively. Thrombin (5-20 U/ml) also stimulated the protein synthesis rate (assayed by [3H]proline incorporation) to 1.88-2.13 fold that of the control. However, pretreatment of PDL fibroblasts with thrombin (1-20 U/ml) could not promote the attachment of PDL fibroblasts to type I collagen and fibronectin. Moreover, thrombin could induce clustering of PDL fibroblasts within a concentration range of 5-20 U/ml. However, thrombin (1-20 U/ml) exerted neither stimulatory nor inhibitory effect on cellular alkaline phosphatase activities. In conclusion, it appears that the presence of thrombin seems to have effects on PDL fibroblasts in terms of cell growth, protein synthesis and cell clustering. This suggests that thrombin might be important in the early healing process of periodontium following periodontal surgery.

Vertical root fracture in nonendodontically treated teeth--a clinical report of 64 cases in Chinese patients

Vertical root fractures (VRFs) in teeth without endodontic treatment are uncommon. A clinical study was done on 64 cases of VRFs in 61 Chinese patients to define better the clinical characteristics, diagnostic signs, and possible causes. Results showed that fractures occurred most often in first molars of patients between 40 and 69 yr of age, and the incidence was two times higher in males than in females. Flat roots with smaller mesiodistal diameters were more prone to fracture. The majority (79%) of patients had intact dentition with less than four teeth missing. Fractured teeth were frequently attrited with no restorations. VRFs may result from excessive or repetitive masticatory force due to damaging chewing habits exerted on flat roots of smaller mesiodistal diameter. Nonendodontic VRFs seem to occur more frequently than earlier believed and may represent an underdiagnosed clinical entity deserving of our attention.

Cutaneous sinus tracts of dental origin: clinical review of 37 cases

Cutaneous sinus tracts in the face and neck region are often dental in origin. The purpose of this study was to characterize the clinical features and treatment of 37 consecutive cases of odontogenic cutaneous sinus tracts, collected and reviewed in a 15-year period. More than half of the patients (21 cases, 57%) were referred from medical doctors, particularly plastic surgeons and dermatologists. The sinus tracts were associated with caries (26 cases), incomplete endodontic treatment (7), crown fracture (2), vertical root fracture (1) and impacted mandibular third molar (1). They occurred most often in adolescents and adults (30 cases, 81%). The most common causative teeth were mandibular teeth (34 teeth, 85%). The chin, submental, and cheek areas were the most common sites of sinus tracts (30 cases, 81%). The majority of causative teeth (32 teeth, 80%) were treated endodontically. All fistulas healed uneventfully after proper dental treatment, without cosmetic surgery. In 63% (20 cases) of the recorded cases, complete resolution occurred within 8 weeks. Half of the patients had had fistulas for more than 6 months before receiving dental treatment, demonstrating that delays in proper diagnosis and treatment were common. As most patients suffered from unnecessary medication or surgery due to the delay of dental treatment, early dental consultation and treatment is important. Conventional endodontic treatment should be the treatment of choice if the tooth is salvageable. The increasing incidence of incomplete endodontic treatment in association with the occurrence of sinus tracts indicates that standardized endodontic therapy should be emphasized for prevention.

Primary insertion of osseointegrated dental implants into fibula osteoseptocutaneous free flap for mandible reconstruction

Twelve patients with segmental mandibular defects were reconstructed with fibula osteoseptocutaneous flaps and simultaneous placement of osseointegrated implants. Decision to perform this procedure was based on the facts that all patients had benign diseases, did not require postoperative radiotherapy, were in good general and oral conditions, and were psychologically motivated. A total of 34 fixtures was inserted in the first stage. Eight patients underwent second stage surgery, which consisted of connection of the implant abutments to the fixtures and the use of palatal mucosal grafts around the implants. Final dental prostheses were fixed 1 month later in seven patients, at this time. All flaps survived after surgery, and no implant failure was observed after a mean follow-up period of 25 months. Only one fixture was not used during the subsequent stage and was left as a sleeper. Fixed dental prostheses were used in five patients and removable overlay prostheses in the other two. Chewing function was recovered between 4 and 6 weeks after the start using the definitive dental prosthesis. In contrast to previous results, we conclude that excellent results can be achieved when this combined procedure is used in carefully selected patients. In addition, it is confirmed that the fibula osteoseptocutaneous flap is a versatile, reliable composite tissue that facilitates primary placement of osseointegrated dental implants during mandible reconstruction, thus allowing full oral rehabilitation in a shorter period of time.

Serine protease activity is essential for thrombin-induced protein synthesis in cultured human dental pulp cells: modulation roles of prostaglandin E2

Irritations and injuries to the dental pulp usually lead to different degrees of pulpal inflammation. To investigate the roles of thrombin and prostaglandins in the healing and inflammatory processes of dental pulp as well as their effects on pulpal protein synthesis, human dental pulp cell cultures were established and their protein production was measured with or without the presence of exogenous thrombin and prostaglandins. At concentrations of 1-25 U/ml, alpha-thrombin increased the protein synthesis to 1.4-2.3 fold over the vehicle control. On the contrary, 0.1 microg/ml of prostaglandin E1 (PGE1) suppressed protein synthesis by 60%. Prostaglandin E2 (PGE2) also inhibited protein synthesis with an IC50 of 0.4 microg/ml. The stimulatory effects of thrombin (10 U/ml) can be inhibited by antithrombin III (2 U/ml) (a natural thrombin inhibitor) with heparin (2 U/ml), PPACK (D-Phe-Pro-ArgCH2Cl) (20-50 microg/ml) (a serine protease inhibitor), and PGE2 (0.5-1.0 microg/ml). Moreover, TRAP (20-40 microg/ml), a thrombin receptor agonist peptide, also exerted a stimulatory effect (1.21-1.37 fold). In conclusion, thrombin-induced protein synthesis by pulp cells is dependent on proteolytic activity, but not on binding to receptors. Both PGE1 and PGE2 exert suppressive effects on protein synthesis, indicating that interactions between thrombin and prostaglandins are important in regulating the inflammation, repair and regeneration of pulp tissue following injury.

Cutaneous sinus tract caused by vertical root fracture

This report presents a rare case of odontogenic cutaneous sinus tract caused by a vertical root fracture. The root-fractured molar was probably caused by an accidental blow by a cow 3 years ago. Despite all treatments by physicians and surgeons for nearly 1 year, the sinus tract recurred repeatedly. After diagnosis and extraction of the fractured molar by the dentist, the sinus tract healed uneventfully in a month.

Ganglion cyst and synovial cyst of the temporomandibular joint. Two case reports

Ganglion cysts and synovial cysts are lesions rarely associated with the temporomandibular joint. Ganglion cysts arise from myxoid degeneration of the connective tissue of the joint capsule, are filled with viscoid fluid or gelatinous material, and have a fibrous lining. Synovial cysts also contain gelatinous fluid and are lined with cuboidal to somewhat flattened cells consistent with a synovial origin. One case of a ganglion cyst and one case of a synovial cyst of the temporomandibular joint are presented, and their differential diagnosis and management are discussed.

Recombinant human monoclonal antibody IgG1b12 neutralizes diverse human immunodeficiency virus type 1 primary isolates

The CD4-binding domain of human immunodeficiency virus type 1 (HIV-1) gp120 elicits antibodies that are present in infected human sera. Monoclonal antibodies that recognize the HIV-1 gp120 CD4-binding domain have been isolated. Some of these antibodies can neutralize laboratory-adapted strains of HIV-1 and probably mediate neutralization by interfering with virus binding to its cellular CD4 receptor. However, most anti-CD4 binding domain antibodies do not neutralize primary HIV-1 isolates. We used primary HIV-1 isolates in an infectivity reduction assay to test the uniquely derived anti-CD4 binding domain recombinant human monoclonal antibody, IgG1b12. All of the tested HIV-1 isolates were neutralized by this antibody. Additional studies indicated that neutralization of a primary isolate with MAb IgG1b12 did not require continuous exposure of human peripheral blood mononuclear cell cultures to the antibody. Finally, a complete IgG1 molecule of an in vitro-selected b12 FAb mutant with a > 400-fold increase in affinity was assembled, expressed in mammalian cells, and evaluated in the infectivity reduction assay in comparative studies with the parent IgG1b12 antibody. The mutant did not retain the level of primary isolate neutralization potency that was a property of the parent molecule. Thus, we confirm that recombinant IgG1b12 has a unique specificity, and that it can neutralize all primary isolates tested in human PBMC cultures in vitro.

Intentional replantation of a mandibular molar with calcified canal: a case report

Intentional replantation is an accepted endodontic technique for treating teeth in which both conventional and/or surgical endodontic treatments are not recommended. A rare case using intentional replantation technique on one mandibular molar has been successfully treated. This procedure was used owing to inaccessible calcified canal and pain intolerance of the patient. A thirty month post-operative evaluation revealed an asymptomatic, functional tooth with no radiographic signs of pathosis. The favorable results obtained in this case might be attributed to certain factors, such as occlusal adjustment prior to replantation, maintaining asepsis during replantation, no-damaging pressure during extraction, use of noneugenol periodontal packing, preservation of the vitality of the periodontal ligament, a minimal extraoral period, non-rigid splinting, apicoectomy and retrograde amalgam filling were done for hermetic apical seal. Intentional replantation may be limited to those cases when conventional endodontic therapy is not possible, but may be a treatment alternative to maintain the dentition and save an otherwise hopeless tooth.

Intentional replantation for iatrogenic perforation of the furcation: a case report

Intentional replantation is an accepted endodontic procedure for treatment of teeth in which conventional surgical endodontic treatment is contraindicated. This article presents a rare case of intentional replantation of a mandibular molar that had severe periodontal destruction resulting from iatrogenic perforation of the furcation. A 17-month follow-up evaluation revealed an asymptomatic and functional tooth with no radiographic signs of pathosis. The favorable results obtained might be attributed to the preservation of the vitality of the periodontal ligament; the absence of damaging pressure during extraction; the minimal extraoral treatment time; the use of nonrigid splinting; and the immediate repair of the perforation during a one-visit endodontic procedure. The results obtained with this tooth may indicate the possibility of a successful surgical technique for this otherwise hopeless complication of endodontic therapy.

Implant-retained mandibular overdentures: a simplified effective treatment option

The use of implant-retained mandibular overdentures is a treatment option for compromised patients. The combination of using a bar and intracoronal attachments to connect two implants provides cross-arch stabilization, good retention and stability for the overdenture which is still mainly supported by soft tissue. However, connecting the component parts of an internal attachment to the removable overdenture requires numerous laboratory and clinical procedures and the resulting errors can prevent proper seating of the prosthesis. A simple, direct technique, totally controlled by the operator, is presented to increase the precision of the assemble of the component parts and contribute to the precise fit if the implant-retained overdenture. The advantages, disadvantages and the rational treatment are discussed.

Gingival mass as the primary manifestation of multiple myeloma: report of two cases

Two cases of multiple myeloma with primary manifestations in the oral cavity are reported, both presenting as a mandibular gingival/alveolar mass with hypermobility of the adjacent teeth. Roentgenographic examination demonstrated concomitant "punched-out" osteolytic jawbone lesions. After biopsy of the gingival mass was performed, multiple myeloma was subsequently diagnosed in both cases. Systemic bone scanning revealed multiple osteolytic bone lesions involving the skull and various skeletal bones. Hematologic screening showed a monoclonal gammopathy in both cases. A bone marrow biopsy confirmed the diagnosis of multiple myeloma. Awareness of the maxillofacial manifestations of multiple myeloma is important for early detection of the disease, especially in patients with initial oral involvement.

Induction of superoxide dismutase isozymes by tumor necrosis factor-alpha and lipopolysaccharide in cultured normal and hyperplastic gingival fibroblasts

To determine whether lipopolysaccharide (LPS) and tumor necrosis factor-alpha (TNF-alpha) are involved in the induction of superoxide dismutase (SOD) in gingival tissue, we examined their effect on induction of SOD isozymes in cultured normal (NGF) and phenytoin-induced hyperplastic (PHF) gingival fibroblasts. Treatment of both NGFs and PHFs with 10 to 50 ng/mL TNF-alpha for 24 hours increased the level of manganese SOD (MnSOD) to as much as four times the level of untreated cultures. PHFs, but not NGFs, were shown to be responsive to TNF-alpha in eliciting a significant increase in copper-zinc SOD (Cu/ZnSOD), albeit in a lesser amount than MnSOD. Additionally, treatment of both types of cells with 5 to 50 mg/mL of LPS for 24 hours also elicited an increase in the levels of MnSOD. Again, an LPS-induced increase in Cu/ZnSOD levels could only be demonstrated in PHFs, but not in NGFs. These observations were further confirmed by comparing the achromatic bands associated with SOD isozymes exhibited in the electrophoretogram using a nondenaturing polyacrylamide electrophoresis technique. These results indicate that TNF-alpha and LPS were capable of inducing both MnSOD and Cu/ZnSOD simultaneously in PHF fibroblasts. PHFs may be inherently more capable than NGFs in combating oxidative stress.

[Hereditary gingival fibromatosis: a case report]

Hereditary gingival fibromatosis is an uncommon congenital anomaly of undetermined etiology, the condition is manifested as a dense, diffuse, smooth or nodular overgrowth of the gingival tissue, usually begins with the eruption of the permanent incisors. However, it may happen as early as the eruption of the deciduous teeth. The case, a 30 years old woman with normal stature, visited our dental clinic because of "overgrown gum" which greatly affected mastication and appearance. A review of her past medical history revealed no relevant diseases. Oral examination showed gross fibrous enlargement of gingival without inflammation or swelling. Her father, two sisters and one daughter also suffered from this disease. Microscopically, there is a obvious increase in the amount of connective tissue that is relatively avascular and consists of densely arranged collagen bundles and numerous fibroblasts. The surface epithelium is thickened and acanthotic with elongated rete pegs. Gingivectomy with flap operation were performed to correct the gingival overgrowth. After periodontal treatment, two fixed partial dentures were constructed to replace the missing right upper and lower first molars. One year after operation, no obvious recurrence was noted clinically.

Primary extramedullary plasmacytoma in cyclosporine-induced gingival overgrowth. A case report

An unusual solitary extramedullary plasmacytoma developed in the gingiva of a 28 year-old male renal transplant patient with cyclosporine (CyA)-induced gingival overgrowth. On initial presentation, there was no suspicion of a tumor within the lesion. One year later, however, the lesion had increased progressively in size, and its surface was ulcerated. At this time, the lesion was excised by gingivectomy, and histopathological examination revealed plasmacytoma. CyA was discontinued and the patient has been closely observed for 4 years with no recurrence of the gingival lesion.