An observational study of hydrodynamic impact on water mass transport due to tidal power generation

The world's largest Sihwa Tidal Power Plant (TPP), located on the west coast of Korea, was built in 2011 for the purpose of improving water quality and producing renewable energy. After several years of actual operation, most of the original purpose was achieved, but unexpected coastal environmental changes such as tidal flat damage and sediment accumulation also occurred. In this study, in order to understand the causes of these environmental changes, field observations were conducted near TPP, and spatial and temporal variability of flow structure and water exchange process were investigated. Three-dimensional velocity data were collected along the closed line surrounding the outside of the TPP for 11 h during spring tide and analyzed according to two discharge phases: power generation phase (PGP) and drainage phase (DP). The results show that the depth-averaged maximum current velocity was more than three times greater at DP than at PGP. Jet-like flow during DP caused very high horizontal shear, whereas vertical shear was relatively weak, indicating that the horizontal and vertical flow structures were very different. The most notable result is that the mass transport patterns between PGP and DP are significantly different, i.e., during PGP, mass transport is dominated on the left side of the TPP, whereas during DP, it occurs at the front of the TPP. This means that there is a strong spatiotemporal asymmetry between the inflow from the downstream (outside of the TPP) during PGP and the outflow from the upstream (inside of the TPP) during DP. These asymmetric processes can have a significant impact on the material exchange and sediment transport near the TPP. Since observational studies on TPP are extremely rare, this study is expected to contribute to future TPP related research, such as numerical modeling.

Chinese version of the Rotator Cuff Quality of Life questionnaire: Cross-cultural adaptation and validation in rotator cuff-impaired patients in Hong Kong

Purpose:

To adapt the Rotator Cuff Quality of Life (RC-QOL) questionnaire into traditional Chinese (Chi-RC-QOL) and to evaluate the validity and reliability in patients suffering from rotator cuff pathologies in Hong Kong.

Methods:

The Chi-RC-QOL will be constructed using the forward-translation followed by the backward-translation method. Thirty consecutive patients with clinically and radiologically confirmed rotator cuff pathology were recruited. Descriptive statistics will be followed by validity assessment using comparison with the Constant Shoulder (CS) score, University of California Los Angeles (UCLA) Shoulder Rating Scale, and Western Ontario Rotator Cuff (WORC) score. Parametric data will be tested using Pearson’s correlation coefficient for the total scores. Reliability was assessed using a test–retest interval of 30 min. The Cronbach’s α and intraclass correlation coefficient were calculated.

Results:

Cronbach’s α and internal consistency scores were high for all parts of the Chi-RC-QOL, with Cronbach’s α ranging between 0.89 and 0.98. Internal consistency scores range from 0.82 to 0.92, which can be regarded as an excellent correlation. Test–retest reliability was excellent for all parts of the Chi-RC-QOL with good absolute reliability. Chi-RC-QOL correlates well with the CS score, UCLA Shoulder Rating Scale, and the WORC score, with all being statistically significant.

Conclusions:

The current study adapted the RC-QOL to traditional Chinese version. The analysis confirmed the validity and reliability of the Chi-RC-QOL questionnaire.

Level of Evidence:

III.

Familial patellar dislocation associated with t(15;20) (q24;q13.1)

Patellar instability is a common debilitating injury affecting young active individuals. It accounts for approximately 3% of all knee injuries. We report a family, of which five members across three generations, who suffered from autosomal dominant familial recurrent patellar dislocation as well as short stature. All of them have recurrent patellar dislocations before the age of 15. The affected patients in all three generations have been genetically screened. Genotypical evaluation revealed a balanced translocation of chromosomes 15 and 20.

Proliferative leukoplakia: Proposed new clinical diagnostic criteria

OBJECTIVE

We aimed to characterize proliferative verrucous leukoplakia (PVL) from a clinical and histopathological standpoint and suggest an updated classification.

SUBJECTS AND METHODS

Records of patients seen at three oral medicine centers with a clinical diagnosis of PVL were reviewed for clinical and histopathological features and malignant transformation (MT).

RESULTS

There were 42 patients (median age: 69 years [range: 36-88]; 35 females). 12.2% were current smokers. Family history of cancer was present in 43.7% of patients. Partial demarcation of lesion margins was present in 31.3% of lesions, followed by verrucous (27.5%), smooth (22.7%) erythematous (22.3%), and fissured (18.3%) appearance. Large and contiguous and multisite and non-contiguous lesions comprised 57.1% (24/42) and 35.7% (15/42) of PVL cases, respectively. 19.1% had prominent erythema (erythroleukoplakia). The most common histopathological diagnosis at first visit was hyperkeratosis without dysplasia (22/42; 56.4%). MT occurred in 71.4% patients after a median of 37 months [range: 1-210] from initial visit; erythroleukoplakia exhibited MT in 100% of cases.

CONCLUSION

The generic term "proliferative leukoplakia (PL)" may be more appropriate than PVL because 18.3% were fissured and 22.7% erythematous. We also propose the term proliferative erythroleukoplakia to more accurately describe the subset of PL with prominent erythema, which had the highest MT rate.

Scoring systems for Oral Lichen Planus used by differently experienced raters

Background

Scoring systems have been widely used to evaluate the severity and activity of oral lichen planus (OLP). The aim of the present study was to compare two existing (one modified) scoring systems in the evaluation of OLP severity and correlation with pain. Three differently experienced raters were involved.

Material and Methods

Consecutive patients with OLP were assessed for pain using the Visual Analogue Scale and examined at 10 intraoral sites before starting (T0) and three weeks after (T1) steroid therapy (Clobetasol). Three differently experienced raters evaluated photographs using two scoring systems designated White-Erosive-Atrophic (WEA) modified from an older WEA system (WEA-MOD) and Reticular-erythematous-Ulcerative (REU) systems. WEA-MOD Kendall’s W and interclass correlation coefficient were calculated and correlation between REU/WEA-MOD and pain was calculated using Spearman coefficient.

Results

Most patients showed lesions on buccal mucosa (85-93,5%) and maxillary/mandibular gingivae (31,8-31,2%), predominantly reticular. At T0, Kendall-W coefficients of 0.89 and 0.74 were obtained for the REU and WEA respectively. At T1, Kendall-W coefficients of 0.83 and 0.58 were obtained for the REU and WEA respectively. Interclass correlation coefficient ranged from 0.87 to 0.90 for REU and from 0.58 to 0.87 for WEA. REU and WEA scores significantly decreased after therapy (p<0.000) as well as VAS (p<0.05). REU score showed correlation with VAS.

Conclusions

All the raters achieved comparable measures using REU whereas WEA and WEA-MOD seem less reproducible. REU seems to correlate to disease activity and pain.

Key words:Oral lichen planus, scoring system, VAS, REU, WEA, rater.

Atypical periprosthetic femoral fracture: a case report

We report an 82-year-old woman who underwent fixation with a long-spanning cable-plate for a bisphosphonate-induced Vancouver B1 periprosthetic femoral fracture. Non-union and breakage of the plate occurred at 16 months and necessitated revision surgery using a long-stem femoral prosthesis augmented with a cable-plate construct. Bone union was achieved eventually after 10 months.

Resource utilization in cancer patients with bisphosphonate-associated osteonecrosis of the jaw

BACKGROUND AND OBJECTIVE

Bisphosphonate-associated osteonecrosis of the jaw (BONJ) is an emerging oral complication that occurs most commonly in the setting of high-dose bisphosphonate therapy for cancer. The purpose of this study was to estimate the health care-related costs associated with a diagnosis of BONJ in patients with cancer evaluated and managed at one tertiary oral medicine practice.

METHODS

This was a retrospective electronic medical record review of cancer patients with BONJ. All health care-related resources were abstracted using a structured chart abstraction tool; data captured included medications, imaging studies, laboratory investigations, procedures, and visits. Standardized references were used to assign costs in 2010 US dollars.

RESULTS

Ninety-two cancer patients with BONJ were identified who were followed for a median of 12 months. The median cost of a case of BONJ was $1667 (interquartile range from $976 to $3350). Medication costs comprised the majority (42%) of the total costs, followed by procedural interventions (22%), clinic visits (19.5%), and imaging studies (13.8%). Patient factors associated with higher median costs included a greater number of involved oral quadrants and more advanced BONJ stage.

CONCLUSION

There are considerable costs associated with the diagnosis and management of BONJ in patients with cancer, with medications accounting for nearly half of resource expenditures.

Defining the epidemiology of bisphosphonate-associated osteonecrosis of the jaw: prior work and current challenges

Bisphosphonate-related osteonecrosis of the jaw (BONJ) is an adverse effect of bisphosphonate use with a poorly described epidemiology in osteoporosis patients. We examined the literature and two new cohorts for BONJ. The literature suggests an incidence rate of 0.028 % to 4.3 %. Our cohort studies found an incidence of 0.02 % (95 % CI 0.004 %-0.11 %).

INTRODUCTION

We examined the epidemiology of BONJ associated with osteoporosis dosing of bisphosphonates.

METHODS

First, we systematically searched the literature about osteoporosis BONJ. Identified studies were abstracted by two authors. Second, we attempted to estimate the relative risk of BONJ among bisphosphonate users with osteoporosis. Two different large insurance databases, one from 2005-2007 and another from 2007-2010, combined with medical record review, were searched. The older dataset did not include the International Classification of Diagnoses (ICD) diagnosis code for osteonecrosis of the jaw (ONJ; ICD 733.45). Incidence rates and relative risks were estimated using Cox regression.

RESULTS

The literature review produced nine studies of varying quality. The incidence rates for BONJ among osteoporosis patients varied from 0.028 % to 4.3 %. Two prior studies estimated the relative risk of ONJ related to bisphosphonates and found odds ratios of 7.2 and 9.2. Our attempts to estimate the incidence rate of BONJ encompassed 41,957 in the dataset from 2005-2007 and 466,645 in a separate dataset from 2007-2010. From the older dataset, we found 51 potential cases of BONJ using a broad definition of possible ONJ. One case was confirmed by a dentist for a prevalence of 0.02 % (95 % CI 0.004 %-0.11 %) among bisphosphonate users. From the newer dataset, we found 13 possible cases, but none could be confirmed. Most subjects with the ONJ diagnosis code appeared to have had an osteoporosis-related fracture and not ONJ.

CONCLUSIONS

The literature suggests a broad range of possible values for the prevalence of BONJ; our estimate fell within the range from prior literature.

Hyaluronic acid instillation following arthroscopic anterior cruciate ligament reconstruction: a double-blinded, randomised controlled study

PURPOSE

To assess the effect of hyaluronic acid instillation after arthroscopic anterior cruciate ligament (ACL) reconstruction for improving pain, range of movement, and function of the knee.

METHODS

28 men and 4 women underwent arthroscopic ACL reconstruction for isolated ACL rupture (partial or complete) and instability after recreational sports injury 2 to 120 months earlier. They were randomised to undergo arthroscopic ACL reconstruction followed by intra-articular viscoseal instillation (13 men and 3 women) or arthroscopic ACL reconstruction alone (15 men and 1 woman). The knee injury osteoarthritis outcome score (for pain, symptoms, activities of daily living, sport and recreation function, and quality of life), range of movement, knee circumference, and analgesic use were assessed on days -1, 1, and 2, and weeks 2, 6 and 12.

RESULTS

Patient demographics were similar at baseline. At postoperative days 1 and 2, all subscales of the knee injury osteoarthritis outcome score (except for quality of life) were significantly higher in the viscoseal group. At weeks 2, 6, and 12, improvement in both groups equalised. Knee swelling (change in knee circumference) was significantly less in the viscoseal group at days 1 and 2 (p=0.009 and p=0.038, respectively, Mann-Whitney U test). Only one patient in the viscoseal group had a limited range of movement. No patient developed any adverse reaction.

CONCLUSION

Intra-articular viscoseal instillation improved pain control and swelling 2 days after arthroscopic ACL reconstruction.

A role of oral bacteria in bisphosphonate-induced osteonecrosis of the jaw

No consensus has yet been reached to associate oral bacteria conclusively with the etio-pathogenesis of bisphosphonate-induced osteonecrosis of the jaw (BONJ). Therefore, the present study examined the effects of oral bacteria on the development of BONJ-like lesions in a mouse model. In the pamidronate (Pam)-treated mice, but not control non-drug-treated mice, tooth extraction followed by oral infection with Fusobacterium nucleatum caused BONJ-like lesions and delayed epithelial healing, both of which were completely suppressed by a broad-spectrum antibiotic cocktail. Furthermore, in both in vitro and in vivo experiments, the combination of Pam and Fusobacterium nucleatum caused the death of gingival fibroblasts (GFs) and down-regulated their production of keratinocyte growth factor (KGF), which induces epithelial cell growth and migration. Therefore, in periodontal tissues pre-exposed to bisphosphonate, bacterial infection at tooth extraction sites caused diminished KGF expression in GFs, leading to a delay in the epithelial wound-healing process that was mitigated by antibiotics.

Genetics/epigenetics of oral premalignancy: current status and future research

Squamous cell carcinoma (SCC) of the oral and oropharyngeal region is the sixth most common malignancy in the world today. Despite numerous advances in treatment, long-term survival from this disease remains poor. Early detection can decrease both morbidity and mortality associated with this neoplasm. However, screening for potentially malignant disease is typically confounded by difficulty in discriminating between reactive/inflammatory lesions vs those lesions that are premalignant in nature. Furthermore, the histologic diagnosis of dysplasia can be subjective and is thus prone to a considerable range of interpretation. Similarly, no definitive, validated criteria exist for predicting which dysplastic lesions are most likely to progress to cancer over time. Given this state of science, the presence of dysplasia can only be used to indicate that an oral lesion may have an increased risk of malignant transformation. Molecular biomarkers capable of identifying the subset of lesions likely to progress to cancer are required to eliminate this clinical diagnostic dilemma. The purpose of this review is to assess the current state of knowledge regarding genetic/epigenetic alterations observed in oral mucosal premalignancy. In addition, recommendations for future research studies directed at defining the predictive capacity of specific biomarkers in this modeling are presented.

Oral epithelial dysplasia and squamous cell carcinoma following allogeneic hematopoietic stem cell transplantation: clinical presentation and treatment outcomes

Background

Late complications of allogeneic hematopoietic stem cell transplantation (HSCT) include a risk of secondary malignancies, including oral cancers. Optimization of best clinical practices for early diagnosis and treatment of oral premalignant or malignant lesions requires an assessment of potential predisposing risk factors as well as treatment outcomes.

Methods

The medical records of patients who developed oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC) following allogeneic HSCT were reviewed. Data on demographics, HSCT course, chronic graft-versus-host disease (cGVHD), smoking and alcohol consumption, oral lesion characteristics, mode of therapy and clinical outcome were recorded; landmark survival was calculated.

Results

Twenty-six patients with OED (n = 8) and OSCC (n = 18) were identified with a median follow-up of 26.5 and 21.5 months, respectively. Premalignant and malignant oral lesions were diagnosed at a median time of 2.5 and 8 years after HSCT, respectively. Chronic GVHD was present in 96% of patients and of these, 96% had oral involvement. Multifocal oral cancer was found in 28% of cases, and localized recurrence was observed in 44% of cases. Five-year overall survival was 75% and 70% for OED and OSCC, respectively.

Conclusions

These results suggest that oral cGVHD may be considered a potential risk factor for the development of OSCC following allogeneic HSCT. The observation that oral cancers were frequently multifocal and recurred locally supports the concept of field cancerization and suggests that these cancers may be more aggressive compared with the non-HSCT population. Vigilant follow-up and coordination of care between hematologists and oral health specialists are critical to minimize morbidity and mortality.

Comparison of total knee arthroplasty using computer-assisted navigation versus conventional guiding systems: a prospective study

PURPOSE

To compare knee alignments in total knee arthroplasty (TKA) using computer-assisted navigation versus conventional guiding systems.

METHODS

Five men and 49 women aged 49 to 79 years underwent TKA for primary osteoarthritis of the knee with varus deformity. All valgus knees were associated with inflammatory arthritis and thus excluded. Computer-assisted navigation was used for the first 35 TKAs, whereas conventional extramedullary tibial and intramedullary femoral guiding systems were used for the next 35 TKAs. The mechanical axis, coronal tibial and femoral angles, sagittal tibial and femoral angles in the 2 groups were compared.

RESULTS

Sagittal tibial and femoral angles aligned more optimally in TKAs using computer-assisted navigation. In the respective computer-assisted navigation and conventional guiding systems, 33 (94%) and 26 (74%) of the TKAs attained a postoperative mechanical axis of <3 degrees varus/valgus.

CONCLUSION

Computer-assisted navigation gives a more consistent alignment correction and reduces outliers during implant positioning.

The binding of zinc and copper ions to nerve growth factor is differentially affected by pH: implications for cerebral acidosis

It has recently been shown that transition metal cations Zn2+ and Cu2+ bind to histidine residues of nerve growth factor (NGF) and other neurotrophins (a family of proteins important for neuronal survival) leading to their inactivation. Experimental data and theoretical considerations indicate that transition metal cations may destabilize the ionic form of histidine residues within proteins, thereby decreasing their pK(a) values. Because the release of transition metal cations and acidification of the local environment represent important events associated with brain injury, the ability of Zn2+ and Cu2+ to bind to neurotrophins in acidic conditions may alter neuronal death following stroke or as a result of traumatic injury. To test the hypothesis that metal ion binding to neurotrophins is influenced by pH, the effects of Zn2+ and Cu2+ on NGF conformation, receptor binding and NGF tyrosine kinase (trkA) receptor signal transduction were examined under conditions mimicking cerebral acidosis (pH range 5.5-7.4). The inhibitory effect of Zn2+ on biological activities of NGF is lost under acidic conditions. Conversely, the binding of Cu2+ to NGF is relatively independent of pH changes within the studied range. These data demonstrate that Cu2+ has greater binding affinity to NGF than Zn2+ at reduced pH, consistent with the higher affinity of Cu2+ for histidine residues. These findings suggest that cerebral acidosis associated with stroke or traumatic brain injury could neutralize the Zn2+-mediated inactivation of NGF, whereas corresponding pH changes would have little or no influence on the inhibitory effects of Cu2+. The importance of His84 of NGF for transition metal cation binding is demonstrated, confirming the involvement of this residue in metal ion coordination.

A comprehensive review of oral cancer

Oral squamous cell carcinomas comprise 2-3% of all new malignancies diagnosed in the United States, making it the 10th most common malignancy. However, for the last few decades, the average five-year survival rate of 50% has not changed significantly. This article reviews the risk factors associated with the development of oral cancer and how premalignant (leukoplakia and erythroplakia) and actual cancerous lesions may appear. Diagnostic tools and aids to diagnosis are discussed, as are treatment modalities. It is imperative that all dental professionals perform a simple head and neck examination in addition to an oral examination during each new patient visit and each six-month recall appointment. Early detection saves lives.

Salivary gland changes in chronic fatigue syndrome: a case-controlled preliminary histologic study

OBJECTIVE

The purpose of this preliminary study is to compare labial salivary gland changes of 11 patients with chronic fatigue syndrome with control subjects.

STUDY DESIGN

Changes in labial salivary glands were graded from 0 to 3+ for acinar dilatation, ductal dilatation, periductal fibrosis, plasmacytic infiltrate, lymphocytic infiltrate, mast cell infiltrate, and lymphocytic aggregates or foci.

RESULTS

Four of the 11 subjects had 2+ to 3+ changes in at least 4 of the 7 parameters examined. Only the presence of mast cells was statistically significant between the 2 groups. Two of these 4 patients had 1 lymphocytic focus per 4 mm(2) of tissue.

CONCLUSIONS

The salivary gland changes in patients with chronic fatigue syndrome show varying degrees of ductal and acinar dilatation, periductal fibrosis, lymphoplasmacytic infiltrates, and occasional lymphocytic foci, all suggestive of primary gland damage. The one parameter that showed statistical significance was the presence of mast cells (Fisher exact test, 0.0125).

A TrkA-selective, fast internalizing nerve growth factor-antibody complex induces trophic but not neuritogenic signals

Nerve growth factor (NGF) is a neurotrophin that induces neuritogenic and trophic signals by binding to TrkA and/or p75 receptors. We report a comparative study of the binding, internalization, and biological activity of NGF versus that of NGF in association with an anti-NGF monoclonal antibody (mAb NGF30), directed against the C termini of NGF. NGF.mAb complexes do not bind p75 effectively but bind TrkA with high affinity. After binding, NGF. mAb complexes stimulate internalization faster and to a larger degree than NGF. NGF.mAb-induced activation of TrkA, Shc, and MAPK is transient compared with NGF-induced activation; yet NGF and NGF. mAb afford identical trophic responses. In contrast, NGF induces Suc-1-associated neurotrophic activating protein phosphorylation and neuritogenic differentiation, but NGF.mAb does not. Thus, an absolute separation of trophic and neuritogenic function is seen for NGF.mAb, suggesting that biological response modifiers of neurotrophins can afford ligands with selected activities.

Characterization of the recombinant extracellular domain of the neurotrophin receptor TrkA and its interaction with nerve growth factor (NGF)

Nerve growth factor (NGF) is the prototype of a family of neurotrophins that support important neuronal programs such as differentiation and survival of a subset of sympathetic, sensory, and brain neurons. NGF binds to two classes of cell surface receptors: p75LANR and p140TrkA. NGF binding to p140TrkA initiates the neuronal signaling pathway through activation of the tyrosine kinase activity, which subsequently results in a rapid signal transduction through a phosphorylation cascade. To examine this crucial signaling step in more detail, the TrkA extracellular domain polypeptide (TrkA-RED) was overexpressed in Sf21 insect cells and purified to homogeneity. The recombinant TrkA-RED is a 70 kDa acidic glycoprotein with a pI of 5.1, and mimics the intact TrkA receptor for NGF binding with a dissociation constant, Kd, of 2.9 nM. Thus, the recombinant TrkA-RED is functionally competent and can be used to elucidate the interaction of NGF and TrkA receptor. Circular dichroism difference spectra indicated that, upon association of NGF with TrkA-RED, a minor conformational change occurred to form a complex with decreased ordered secondary structure. Interaction between NGF and TrkA-RED was also demonstrated by size exclusion chromatography, light scattering, and chemical crosslinking with evidence for formation of a higher molecular weight complex consistent with a (TrkA-RED)2-(NGF dimer) complex. Association and dissociation rates of 5.6 x 10(5) M(-1) s(-1) and 1.6 x 10(-3) s(-1), respectively, were determined by biosensor technology. Thus, initiation of signaling may stem from NGF-induced receptor dimerization concomitant with a small conformational change.

Off-site dental evaluation program for prospective bone marrow transplant recipients

The authors evaluated the usefulness of an off-site dental evaluation program for bone marrow recipients. This evaluation packet enabled patients scheduled for bone marrow transplants to be evaluated by, and receive any treatment from, their own dentist rather than a dentist at the transplant center. The program generally was effective in achieving its goals and was well-accepted by patients and dentists alike.

Oral recrudescent herpes simplex virus infection

OBJECTIVE

The objective of this study is to determine the frequency of involvement of different intraoral sites by oral recrudescent herpes simplex virus in immunocompromised patients and whether keratinized intraoral sites are always affected by this virus.

STUDY DESIGN

The records of 30 hospitalized patients who had oral ulcers culture positive for herpes simplex virus were reviewed for the location of oral ulcers, febrile episodes, and medical diagnoses.

RESULTS

The data revealed that oral recrudescent herpes simplex virus may involve any intraoral site in immunocompromised patients with nonkeratinized sites representing approximately half of all sites; this is more frequent than has been previously reported. Twenty-six (86.7%) of 30 patients had no evidence of herpes labialis, and 13 (43.3%) of 30 patients were afebrile.

CONCLUSION

It is recommended that all oral ulcers, in immunocompromised patients should be cultured for herpes simplex virus regardless of their location. Early diagnosis reduces patient morbidity because effective treatment in the form of acyclovir is readily available.

Graft-vs.-host disease

Bone marrow transplantation (BMT) is the treatment of choice for many leukemias, lymphomas, bone marrow failure syndromes, and immunodeficiency disorders, and is the primary and salvage therapy for many solid malignancies. With the establishment of national and international marrow banks, unrelated allogeneic BMT is being performed with increasing frequency. Graft-vs.-host disease (GVHD) remains a major complication of allogeneic BMT, occurring in 25% to 70% of patients despite GVHD prophylaxis, with the skin, gastro-intestinal tract, and liver as primary target organs. Oral findings are seen in both acute and chronic GVHD. In acute GVHD, the oral lesions are often painful, erythematous, ulcerative, and desquamative. In chronic GVHD, they are lichenoid with associated erythema and ulcerations; additionally, they may be associated with a sicca syndrome characterized by xerostomia and progressive salivary gland atrophy. General principles of BMT are discussed, as are systemic and local therapeutic options for oral GVHD.

Characterization of histidine residues essential for receptor binding and activity of nerve growth factor

The role of the four histidine residues in receptor binding and activity of mouse nerve growth factor (NGF) was investigated using both site-directed mutagenesis and chemical modification with diethyl pyrocarbonate. Replacement of His-75 or His-84 with alanine resulted in decreased biological activity and decreased affinity for p140(trkA); however, with H75A only, a 5-fold increased affinity toward p75(LANR) was observed. The effect of simultaneous replacement of both His-75 and His-84 was neither additive nor synergistic. Slight perturbations in circular dichroism spectra and weakened self-association of the mutants indicated that His-75 and His-84 may be involved in stability, dimerization, and/or folding of NGF. Diethyl pyrocarbonate modification of His-4 and His-8 in the H75A/H84Q double mutant abolished neuritogenesis, binding to both receptors, and phosphorylation of p140(trkA) in PC12 cells. These chemical and mutational results confirm and clarify previous evidence for the involvement of His-75 and His-84 (Dunbar, J. C., Tregear, G. W., and Bradshaw, R. A. (1984) J. Protein Chem. 3, 349-356) or His-4 and His-8 (Shih, A., Laramee, G. R., Schmelzer, C. H., Burton, L. E., and Winslow, J. W. (1994) J. Biol. Chem. 269, 27679-27686) in receptor binding of NGF. At least three and possibly all four histidines, which are located in three spatially distinct regions, contribute to maintenance of functional sites that are essential for receptor binding and activity of NGF.

Recurrent aphthous ulcers: a review of diagnosis and treatment

Recurrent aphthous ulcers, or RAU--also called canker sores--are among the oral mucosal conditions that dentists and physicians see most commonly in their patients. Several systemic conditions are associated with oral aphthouslike ulcers, and aphthae themselves often are mistaken for recrudescent oral herpes simplex virus, or HSV, infections. This article will review RAU, describe systemic conditions associated with aphthous-like ulcerations and discuss the differences between RAU and recrudescent oral HSV infections.

Alteration of NH2-terminal residues of nerve growth factor affects activity and Trk binding without affecting stability or conformation

The role of the NH2-terminal region of nerve growth factor (NGF) was studied with an NGF delta 9/13 deletion mutant, overexpressed in a baculovirus system, and mouse NGF truncated at Met-9 by cleavage with CNBr (des-(1-9)-NGF). Structural studies have been performed on the purified proteins, in addition to biological activity assessment, in order to determine effects of such modifications on global conformation and stability. The activity of NGF delta 9/13 was reduced below detectable levels, and the activity of the des-(1-9)-NGF form was decreased by at least a 50-fold in a PC12 bioassay. Competitive binding of NGF delta 9/13 to low affinity receptors on PC12 cells was not impaired; however, the mutant was not capable of competing for the cold chase-stable, high affinity binding of NGF to the cells. The binding of NGF delta 9/13 to Sf21 cells ectopically expressing the TrkA NGF receptor was also abolished. Thus, deletion of residues 9-13 significantly altered the binding affinity for the high affinity receptors on PC12 cells and for the TrkA receptor, but not for the low affinity receptor. Neither the secondary structure, determined by circular dichroism, nor the conformational stability determined by equilibrium denaturation of NGF delta 9/13 was altered as compared with wild type NGF. Slight conformational and stability perturbations of des-(1-9)-NGF were revealed by the same analysis; however, these changes were found to reflect the influence of the formic acid treatment, not the truncation of 9 residues. Our results support the conclusion that the NH2-terminal domain encompassing residues 1-9 and 9-13 is essential for maintaining the binding capability of NGF for high affinity TrkA receptors. Moreover, conformational and stability data show that the functional results of these modifications of the NH2-terminal region are directly due to receptor binding and not to secondary effects of improper folding or other indirect structural changes.

A longitudinal study of oral ulcerative mucositis in bone marrow transplant recipients

BACKGROUND

Few longitudinal studies have investigated the onset, duration, and resolution of ulcerative mucositis in bone marrow transplant recipients. This study prospectively followed a group of such patients on a daily basis to obtain data on the incidence of ulcerative mucositis, location and duration of lesions, severity with different conditioning regimens, and the relationship of such mucositis to the absolute neutrophil count.

METHODS

Fifty-nine bone marrow transplant recipients on prophylactic acyclovir were examined daily for 26 days after marrow infusion, and all oral ulcerative lesions were recorded.

RESULTS

Oral ulcers occurred in 76.3% of patients, began at a mean of 5 days after marrow infusion (day + 5), and lasted for a median of 6 days. More than 90% of patients showed complete resolution of ulcers on or before day + 15, and all showed resolution when the absolute neutrophil count was > 500 cells/ml. Persistence of ulcers was noticed in patients who had oral graft-versus-host disease and in some patients who initially developed more severe ulcerations. Ninety-six percent of ulcers were located on nonkeratinized mucosa.

CONCLUSIONS

Ulcerative mucositis occurs in about 75% of bone marrow transplant recipients in the absence of herpes simplex virus infection. Most lesions occur on nonkeratinized mucosae which are vulnerable to trauma, especially if such mucosae are rendered atrophic by conditioning regimens. Oral ulcers may persist beyond day + 15 and after recovery of the neutrophil count in patients who initially develop more severe ulcerations or in patients who develop graft-versus-host disease.

Primary structure of the monomer of the 12S subunit of transcarboxylase as deduced from DNA and characterization of the product expressed in Escherichia coli

Transcarboxylase from Propionibacterium shermanii is a complex biotin-containing enzyme composed of 30 polypeptides of three different types: a hexameric central 12S subunit to which 6 outer 5S subunits are attached through 12 1.3S biotinyl subunits. The enzyme catalyzes a two-step reaction in which methylmalonyl coenzyme A and pyruvate serve as substrates to form propionyl coenzyme A (propionyl-CoA) and oxalacetate, the 12S subunit specifically catalyzing one of the two reactions. We report here the cloning, sequencing, and expression of the 12S subunit. The gene was identified by matching amino acid sequences derived from isolated authentic 12S peptides with the deduced sequence of an open reading frame present in a cloned P. shermanii genomic fragment known to contain the gene encoding the 1.3S biotinyl subunit. The cloned 12S gene encodes a protein of 604 amino acids and of M(r) 65,545. The deduced sequence shows regions of extensive homology with the beta subunit of mammalian propionyl-CoA carboxylase as well as regions of homology with acetyl-CoA carboxylase from several species. Two genomic fragments were subcloned into pUC19 in an orientation such that the 12S open reading frame could be expressed from the lac promoter of the vector. Crude extracts prepared from these cells contained an immunoreactive band on Western blots (immunoblots) which comigrated with authentic 12S. The Escherichia coli-expressed 12S was purified to apparent homogeneity by a three-step procedure and compared with authentic 12S from P. shermanii. Their quaternary structures were identical by electron microscopy, and the E. coli 12S preparation was fully active in the reactions catalyzed by this subunit. We conclude that we have cloned, sequenced, and expressed the 12S subunit which exists in a hexameric active form in E.coli.

Effect of deletion from the carboxyl terminus of the 12 S subunit on activity of transcarboxylase

Transcarboxylase from Propionibacterium shermanii is a biotin-containing enzyme which catalyzes the reversible transfer of a carboxyl group from methylmalonyl-CoA to pyruvate. The central hexameric 12 S subunit of the enzyme associates with six 6 S subunits in the complete enzyme complex. We have constructed a series of cloned genes which encode COOH-terminal truncations of the 12 S subunit. Five of these subunits, which remained soluble following expression in Escherichia coli and were missing from 39 to 97 COOH-terminal amino acids, were purified and compared to the full-length subunit after enzyme complexes were assembled in vitro. All of the truncated subunits were 90% as active in the transcarboxylase reaction as wild type except the reaction containing the shortest complex, TC-12 S (1-507), which had 54% of the wild type activity (TC-12 S-WT). The reduced activity was not due to a lack of CoA ester binding sites or the Km for substrate. However, TC-12 S (1-507) was slower to form than TC-12 S-WT and had more incomplete complexes as judged by high performance liquid chromatography gel filtration profiles and electron microscopy. Isolated TC-12 S (1-507) was 70-80% as active as TC-12 S-WT. We also noted that the truncated form was heat-labile compared to wild type. We conclude that the COOH-terminal region of the 12 S subunit plays a role in assembly and stability of the hexamer and also affects the binding of 6 S subunits to form enzyme complexes. Once complexes do form, the catalytic capacity of TC-12 S (1-507) is almost the same as TC-12 S-WT.

Assessment of the need for treatment of postendodontic asymptomatic periapical radiolucencies in bone marrow transplant recipients

Oral screening and treatment of existing oral disease before bone marrow transplantation have been reported to decrease the incidence of infectious complications during bone marrow transplantation. Information about the adverse sequelae of specific preexisting oral diseases during bone marrow transplantation is lacking. The presence of postendodontic periapical radiolucencies may suggest recurrent or latent infection. The purpose of this study was to compare the effect of endodontic treatment with nontreatment of asymptomatic postendodontic periapical radiolucencies on the frequency of infectious oral complications during bone marrow transplantation. The records of 276 patients undergoing bone marrow transplantation examined between July 1988 and June 1991 were reviewed retrospectively. Twenty-three postendodontic periapical radiolucencies were identified in 8 women and 15 men. The mean age of patients was 41 years (range, 25 to 58 years). Fourteen of the lesions were untreated, and nine were treated before bone marrow transplantation. When outcomes of transplant complications were compared, neither increased systemic infection as measured by neutropenic days febrile nor local oral infectious complications were significantly different. These results suggest that nontreatment of asymptomatic postendodontic periapical radiolucencies does not increase the incidence of infectious complications during bone marrow transplantation.

The role of herpes simplex virus in the development of oral mucositis in bone marrow transplant recipients

Herpes simplex virus (HSV) has been implicated as a major etiologic factor in the development of ulcerative mucositis in bone marrow transplant (BMT) recipients. In this study, 60 patients who received BMTs were evaluated for at least 30 days post-transplant for ulcerative mucositis and the presence of culturable HSV. Fifty-nine patients received prophylactic acyclovir. Forty-six patients developed ulcerative lesions and 45 of these were culture negative for HSV. Neither the source of transplant (autologous versus allogenic) nor the HSV antibody status of the patient affected the frequency of mucositis. The conditioning regimen appeared to be the most significant factor contributing to the severity of ulcerative mucositis. While the majority of ulcers occurred on movable nonkeratinized mucosa in BMT recipients, the usual sites of reactivation of intraoral HSV are nonmovable, keratinized mucosa. We conclude that HSV is probably not a major etiologic agent of mucositis in BMT recipients and that acyclovir is an effective agent in preventing HSV reactivation.

Effects of acetylene on hydrogenases from the sulfate reducing and methanogenic bacteria

The effect of acetylene on the activity of the three types of hydrogenase from the anaerobic sulfate reducing bacteria has been investigated. The (Fe) hydrogenase is resistant to inhibition by acetylene while the nickel-containing hydrogenases are inhibited by acetylene with the (NiFe) hydrogenase being 10-50 fold more sensitive than the (NiFeSe) hydrogenase. In addition the Ni(III) EPR signal (g approximately 2.3) of the "as isolated" (NiFe) hydrogenase was significantly decreased in intensity upon exposure to acetylene.

Odontogenic keratocysts in the anterior maxilla: report of two cases, one simulating a nasopalatine cyst

Two odontogenic keratocysts occurring in the anterior portion of the maxilla, an unusual location, are reported. In one instance, the clinical and radiographic features simulated a nasopalatine cyst. It is suggested that a likely origin for an odontogenic keratocyst in this location is the primordium of a mesiodens that fails to develop.

Peripheral ameloblastoma of the buccal mucosa: case report and review of the English literature

An unusual case is presented of a peripheral ameloblastoma arising on the buccal mucosa, which brings the total number of such cases to three. The occurrence and pathogenesis of peripheral ameloblastomas in general, are reviewed, especially with reference to the basal cell carcinoma.