Expression of regeneration-associated cytoskeletal proteins reveals differences and similarities between regenerating organs

The unique events which allow regeneration of an entire organ to occur are formation of a specialized wound epidermis and accumulation of progenitor cells (blastemal cells) at the amputated surface to form a blastema. In order to identify some of the molecular events underlying the early stages of the regenerative process which are either common to different systems or specific to one of them, we have investigated whether molecules which are induced in limb blastemas are also expressed in skin repair and during regeneration of other complex body structures (lower jaws, upper jaws, and tails). In addition, we have addressed the issue of the identity of progenitor cells during jaw development and regeneration by analyzing the expression of limb blastemal markers in the developing head and face. We have focused on cytoskeletal components, and particularly on the epidermal keratin NvKII, the simple epithelial keratins 8 and 18 and 22/18, because they are among the few molecules which have been shown to be associated with regeneration in the limb and may play significant roles in various developmental processes. Some important findings emerge from this study: 1) Expression of the epidermal keratin NvKII, unlike that of its mammalian homologue K6, is not simply induced in response to wounding, but is associated with regeneration of specific organs. In fact, NvKII is expressed in regenerating limbs and tails, but not in upper or in lower jaw regenerates, demonstrating the existence of molecular differences in the composition of the wound epidermis in these systems. This, together with the fact that NvKII mRNA is regulated by retinoic acid, which differentially affects patterning of limbs and jaws, argues for distinct inductive abilities of the wound epidermis in different organs. 2) In contrast to the differential expression of the epidermal keratin NvKII, the regeneration-associated cytoskeletal molecules identified in limb blastemal cells are expressed in a similar fashion in jaw and tail blastemas. Therefore, it appears that similar cellular events lead to the establishment of an actively proliferating population of progenitor cells from the stump of different organs. Finally, the mesenchyme of the facial rudiments, unlike that of developing limb buds, expresses simple epithelial keratins. Thus, it appears that mesenchymal progenitor cells of developing and regenerating jaws are alike in regard to their intermediate filament content, and this may be related to nerve-dependent growth control of progenitor cells in different developing and regenerating systems.     

C2 domain conformational changes in phospholipase C-delta 1

The structure of the PH-domain truncated core of rat phosphoinositide-specific phospholipase C-delta 1 has been determined at 2.4 A resolution and compared to the structure previously determined in a different crystal form. The stereochemical relationship between the EF, catalytic, and C2 domains is essentially identical. The Ca2+ analogue Sm3+ binds at two sites between the jaws of the C2 domain. Sm3+ binding ejects three lysine residues which bridge the gap between the jaws and occupy the Ca2+ site in the apoenzyme, triggering a conformational change in the jaws. The distal sections of the C2 jaws move apart, opening the mouth by 9 A and creating a gap large enough to bind a phospholipid headgroup.     

Osteomyelitis of the jaws: a 50-year perspective

The incidence of osteomyelitis of the jaws has decreased dramatically, except for a few subsets of individuals. This has been due, in no small part, to the availability of bacteriocidal antimicrobial therapy. The pathogenesis of osteomyelitis of the jaws is predominately due to odontogenic microorganisms rather than the classic skin contaminant, Staphylococcus. This causative relationship relegates the classification of osteomyelitis of the bimaxillary skeleton to predominately that of contiguous foci. These may be regionally progressive, secondary to microvascular compromise brought about by inherent flaws in regional anatomic calcified tissue vascular perfusion as well as by inflammatory metaplastic processes. Diagnosis is based on the presence of painful sequestra and suppurative areas of tooth-bearing jaw bone unresponsive to debridement and conservative therapy. This is usually accompanied by regional or systemic compromise of the immune response, microvascular decompensation, or both. Treatment of both acute and chronic forms of the disease, as outlined in Table 5, is successful if surgically supported. Sustained bacteriocidal antibiotic therapy is pertinent, especially in the face of potentially refractory virulent microorganisms and compromised regional vascular penetrance. The use of adjunctive hyperbaric oxygen therapy also may be included in the more refractory forms of osteomyelitis of the jaws to enhance the local and regional immune response of the jaws as well as to produce microvascular neoangiogenesis for reperfusion support. With resolution of infection, hard and soft tissue reconstruction may be necessary to augment the reparative process.     

Cuticular metals: quantification and mapping by complementary techniques

Metal-replete cuticle was characterised by back-scattered electron imaging, secondary ion mass spectrometry, proton induced X-ray emission and SEM-X-ray microanalysis. Each technique was found to have singular advantages and limitations for localising and quantifying metal content. Manganese and zinc were found coincident at the mandibular cutting edge of the leaf-cutting ant Atta sexdens; these two metals were found in different zones within jaws of the ragworm, Nereis virens; while only manganese was found in the jaws of the termite C. cumulans. Copyright 1997 Academic Press     

Isoxaben soil biodegradation in pear tree orchard after repeated high dose application

Dose uniformity within the treatment volume for tangent breast irradiation can be significantly improved through dynamic compensating collimation using all four independent jaws to define a superposition of sequentially reduced Enhanced dynamic wedge fields. The enhanced dynamic wedge angle is determined which optimizes dose uniformity in the central axis transverse plane, then the sequential reduction of the superior and inferior jaws is determined to optimize the sagittal dose uniformity. This technique could be applied under computer control through a record and verify system.     

Familial florid cemento-osseous dysplasia--a case report and review of the literature

Cemento-osseous dysplasia is a fairly common lesion of the jaws originating from the elements of the periodontal ligament. Most lesions do not have a hereditary basis, however a few familial cases have been documented. This is the first report of the florid form of cemento-osseous dysplasia in an African family. The mother, son and one daughter exhibited multiple sclerotic cemental masses of the jaws with large tumour-like swellings in the symphyseal area of the mandible. In the case of the mother the lesions had become infected. The familial form of cemento-osseous dysplasia differs from the non-hereditary type in that the lesions present in children, all cases are florid in nature, there is no predilection for black females, the rate of growth appears to be more rapid and the symphyseal area of the mandible is most severely affected. The mode of transmission appears to be autosomal dominant with variable phenotypic expression.     

99MTc-diphosphonate bone imaging and uptake in healing rat extraction sockets

Clinically positive bone scans of the jaws may result from a variety of benign dental conditions. An experimental system for studying radionuclide imaging and uptake in the jaws of rats was developed. Sequential 99mTc-diphosphonate bone scans and radionuclide uptake determinations were performed on rats after standardized extractions of their mandibular left first molars. Positive bone scans were seen 4-16 days after molar extraction, and increased radionuclide uptake was found in the healing extraction wounds 4-42 days after the extraction. Conventional radiography and histology fail to show unusual bony architecture in extraction sockets at such times. These results correlate with clinical findings in patients and suggest that human beings may have positive bone scans for several months after dental extraction.     

Nurse 98 awards. A touching story. Interview by Anna Minton

A clinical example of effective treatment of an adult patient with combined deformations of the jaws (upper prognathism of the third degree and open occlusion of the second degree) is reported. Fragmented osteotomy of the maxilla at the level of symmetrical removal of second molars is performed. Due to Engle's arches soldered with Vasil'ev's splint and compression, a maxillary fragment was shifted 10 mm backward and downward at the expense of compressing the inter-root septae; the first molars were preserved. Diastemata and tremata between incisors of both jaws were eliminated by the same method.     

The effect of levamisole on experimental gingivitis in the beagle dog

The effect of Levamisole on gingivitis development was studied in three beagle dogs. Plaque accumulation was first allowed on one side of the jaws whereas the other side was subjected to careful tooth cleaning procedures. After 2 weeks' experimental gingivitis the dogs were given Levamisole and plaque accumulation was permitted on the other side of the jaws for another two weeks. The following parameters were investigated in the two gingivitis experiments: Plaque and Gingival Indices, Gingival Exudate measurements and histologic measurements. The biopsies were prepared both for light and electron microscopy. The clinical parameters did not show any differences between the two gingivitis experiments. The biopsies, however, demonstrated a larger area of infiltrated connective tissue and an increased number of leukocytes in the junctional epithelium in Levamisole-treated compared to normal animals.     

A method for implementing dynamic photon beam intensity modulation using independent jaws and a multileaf collimator

A mathematical model is derived for digitally controlled linear accelerators to deliver a desired photon intensity distribution by combining collimator motion and machine dose rate variations. It shows that, at any instant, the quotient of the machine dose rate and the speed of collimator motion is proportional to the gradient of the desired in-air photon fluence distribution. The model is applicable for both independently controlled collimator jaws and multileaf collimators and can be implemented by controlling different parameters to accommodate linear accelerators from different manufactures. For independent jaws, each pair of jaws creates photon fluence variations along the direction of the jaw movement. For multileaf collimators, where each leaf is independently controlled, any two-dimensional (2D) photon fluence distribution can be delivered. The model has been implemented for wedged isodose distributions using independent jaws, and 2D intensity modulation using a multileaf collimator. One-dimensional (1D) wedged isodose distributions are created by moving an independent jaw at constant speed while varying machine dose rate. 2D intensity modulation has been implemented using a 'dynamic stepping' scheme, which controls the leaf progression during irradiation at constant machine dose rate. With this automated delivery scheme, the beam delivery time for dynamic intensity modulation, which depends on the complexity of the desired intensity distribution, approaches that of conventional beam modifiers. This paper shows the derivation of the model, its application, and our delivery scheme. Examples of 1D dynamic wedges and 2D intensity modulations will be given to illustrate the versatility of the model, the simplicity of its application, and the efficiency of beam delivery. These features make this approach practical for delivering conformal therapy treatments.     

UNIFOLIATA regulates leaf and flower morphogenesis in pea

Signs and symptoms of craniomandibular dysfunction (CMD) and social medical history were reported in 29 subjects, aged 23-68 years, with longstanding (5 years or more) bruxing behaviour. The subjects were selected from answers to an advertisement in the local newspaper. The subjects presented many symptoms of a general character including somatic and psycho-social problems, sleep disorders (72%), and pain (86%). More than half of the subjects (55%) had symptoms every day. Frequent aches in the neck, back, throat or shoulders were reported by 69% and frequent headache by 48% of the subjects. The most common symptoms of CMD were pain in the face or jaws (48%), stiffness in the jaws in the morning (44%), temporomandibular joint (TMJ) sounds (34%) and fatigue in the jaws during chewing (38%) and the most common clinical signs were more than three muscles tender on palpation (76%), TMJ-sounds (55%) and tenderness of TMJ on lateral palpation (66%). There was a statistically significant correlation between frequent tooth clenching and headache, pain in the neck, back, throat or shoulders, sleep disorders and high scores of the clinical dysfunction index (Di). The frequent clenchers had higher score values than the 'non-clenchers' for pain in the face and the jaws; headache; pain in the neck, back, throat or shoulders and the clinical dysfunction index (Di). These findings indicate a causal relationship between frequent tooth clenching and signs and symptoms of CMD, including headache and pain in the neck, back, throat or shoulders and high pathogenicity for frequent clenching. However, the material in this study is small and some precaution must be taken prior to generalized conclusions. More studies are required, especially sleep laboratory investigations, which could perhaps give answers to some of the numerous questions in this unexplored field of odontology.     

Florid cemento-osseous dysplasia in a young Chinese man. Case report

Florid cemento-osseous dysplasia refers to a group of fibro-osseous lesions which are exuberant, multiquadrant and arise from the tooth-bearing area of the jaws. It is classically described as a condition occurring almost exclusively in middle-aged black women. A case of florid cemento-osseous dysplasia occurring in a young Chinese male is reported which was rare in regard to race and sex. This 20 year old Chinese man presented with huge symmetrical bony lesions in all four quadrants of the jaws. Clinical presentation, radiological findings and histological features of the excised specimens are described. Treatment of the lesions was unusual. Curettage was first done with minimal benefit and it was followed by mandibular recontouring to improve facial appearance. The outcome of these procedures will be discussed.     

The use of attachments for the fixation of removable dentures

A new design of OT-cap system attachment for removable denture fixation is offered improving fixation reliability, functional and esthetic characteristics of dentures. Establishment of attachments when the jaws are maximally tightly compressed helps evenly distribute the masticatory loading of the underlying tissues and abutment teeth individually for each patient.     

Networking with Internet

In forensic odontology, registration of dental characteristics is crucial in the identification procedure. It has been found that the most common errors made are incorrect registration of restorations and confusion about premolars and molars in both jaws. In an earlier study, dental students were observers and the charting was made without radiographs. However, in practical forensic work dentists make the registrations and radiographs are usually available. In this investigation eight dental students and eight dentists made registrations on ten excised macerated jaws with the aid of radiographs. The mean number of errors for each jaw for the students and the dentist was 4 and 3 respectively. The most common error among the dentists was incorrect registration of restorations, while errors on registrations of missing teeth were most common among the students. Even though the material in this study was limited, the results indicate the importance of re-examining of postmortem findings before the comparison with the antemortem data is done. Additionally, the forensic work should be performed by specialists.     

Intracerebroventricular administration of neuropeptide Y to normal rats increases obese gene expression in white adipose tissue

Dose planning programs originally intended for use with symmetric fields have been adapted for use with asymmetric fields. An accurate representation of the change in primary beam quality with off-axis distance and depth is essential for accurate dose calculation and is usually represented in the computer as a primary radiation profile or primary off-center ratio (POCR). The original field edge correction (FEC) method described by Cadman [Med. Phys. 22, 457 (1995)] to determine POCRs has been extended to allow accurate POCR values to be obtained to an off-axis distance defined by the corners of the largest field, typically at an off-axis distance of 28.3 cm. This technique requires only routine symmetric field measurements including beam profiles, TMRs, and collimator and phantom scatter factors. The POCRs obtained using the FEC technique were used to generate off-center ratios (OCRs) using the boundary factor technique of Chui et al. [Med. Phys. 15, 92 (1988)]. Excellent agreement with measured values was obtained for cross-beam OCRs using a 10 x 10-cm2 field defined by a single set of asymmetric jaws with a field center offset of 15 cm and for diagonal OCRs using a 20 x 20-cm2 field with each pair of jaws in a half-blocked configuration.     

Diagnosis of infra-alveolar bony lesions in the dentate alveolar process with high-resolution computed tomography. Experimental results

RATIONALE AND OBJECTIVES: Conventional intraoral radiography was compared with axial computed tomography (CT) scans for identification and classification of bony pockets in dentate jaw segments. METHODS: Fifty-five artificial bone defects were produced in six dentate jaw segments. The jaws were examined radiographically using a dental x-ray unit and by contiguous axial CT scans. Identification, classification, and vertical depth of the bony defects were compared among the specimens, radiographs, and CT scans. RESULTS: On the intraoral radiographs, 38 (69%) bony lesions were identified, and the vertical depth was underestimated by a mean of 2.2 mm, compared with the objective measurements on the jaws. In contrast, all artificial bony lesions (100%) were identified and classified on the axial CT scans and the vertical depth was underestimated by a mean of 0.5 mm. CONCLUSIONS: High-resolution CT improves the identification and metric assessment of the vertical dimension of infra-alveolar bony lesions compared with conventional intraoral x-ray films and allows these defects to be classified according to the number of existing walls into one-walled, two-walled, and three-walled bony pockets. In patients with apically extended metallic restorations, the image quality could be limited by artifacts.     

A historical review of dental and facial skeletal trauma

It is only in the past 100 years that dentists have embraced the concept of occlusion as the guide for reducing and stabilizing fractures involving the jaws. Through early history and into the middle ages, there were two schools of thought regarding the management of jaw fractures. Often overlooked is the influence wars have had on the evolution of treatment of maxillofacial injuries.     

Tooth wear and temporomandibular joint morphology in a skull material from the 17th century

Skeletal remnants from the skulls of 69 subjects from the 17th century have been studied focusing on TMJ morphology and tooth wear. Several of the skulls were damaged and altogether 68 condyles and 28 temporal components of the TMJ, and 97 dentate jaws could be examined. Tooth wear was extensive and most of the first molars in both jaws had lost most of their occlusal morphology. This is remarkable with respect to the fact that the great majority of the subjects had died before the age of 35 years, according to the age determination performed. The TMJs showed frequent remodelling but only rarely deformative changes. The frequent observation of a broken up compact bone layer on the condyle was interpreted as a post-mortem artefact. The results indicate adaptive response of the TMJs to the probably heavy masticatory function but do not support the suggested relationship between tooth wear and TMJ osteoarthrosis.     

Diagnostic difficulties in a case of ectopic pregnancy]

The authors propose a device for measuring plaster models of patients' jaws with normal occlusion in order to evaluate the distance from the coordinate point to the point between the incisors (i), points of contact of the canines (p) and of contact of the first molars of the maxilla and mandible (m). It is possible to assess the position of the upper and lower dentition in the skull space in relation to the universal parameter--the coordinate point common for both dentitions and parameters of the skull.     

热轧平整线卷取机卷筒故障分析与对策

通过对热轧平整线卷取机卷筒扇形板、棱锥轴及钳口机构的故障分析,提出了保证卷筒精度的检测、判断与计算方法以及部件优化配置时的工艺改进.