Synteny conservation and chromosome rearrangements during mammalian evolution

An important problem in comparative genome analysis has been defining reliable measures of synteny conservation. The published analytical measures of synteny conservation have limitations. Nonindependence of comparisons, conserved and disrupted syntenies that are as yet unidentified, and redundant rearrangements lead to systematic errors that tend to overestimate the degree of conservation. We recently derived methods to estimate the total number of conserved syntenies within the genome, counting both those that have already been described and those that remain to be discovered. With this method, we show that approximately 65% of the conserved syntenies have already been identified for humans and mice, that rates of synteny disruption vary approximately 25-fold among mammalian lineages, and that despite strong selection against reciprocal translocations, inter-chromosome rearrangements occurred approximately fourfold more often than inversions and other intra-chromosome rearrangements, at least for lineages leading to humans and mice.

Vulnerability to stress: self-criticism and stress-induced changes in biochemistry

It has been hypothesized that individuals who are high on the attribute of self-criticism are particularly vulnerable to failure stress. To test this hypothesis, we examined the relationship between self-criticism and changes in plasma homovanillic acid (HVA; the metabolite of dopamine) and emotion during exposure to an induced-failure task. Participants consisted of 21 women. Plasma HVA and emotion were assessed at three time points: baseline (T1), during stress exposure (T2), and 40 minutes after cessation of the stressor (T3). We found that self-criticism was significantly and positively related to changes in plasma HVA during stress exposure. In addition, the personality attribute was significantly and positively related to subjective ratings of stress and changes in scores on the Confusion-Bewilderment scale of the Profile of Mood States during the task. To our knowledge, this is the first study to report that self-criticism is related to stress-induced changes in biochemistry.

Physiologic occlusion vs pathologic occlusion and rationale for treatment

Treatment concepts in dentistry are generally based on a preconceived normal state derived from clinical observation and theories rather than scientific evidence. Before treatment is proposed, the clinician should observe physiologic signs and symptoms to determine the presence of a particular pathology. This article presents different theories of occlusion, diagnostic characteristics that can be used to distinguish between physiologic occlusion and pathologic occlusion requiring treatment, and guidelines for reconstructive occlusal therapy.

Late-onset infections of infants in neonatal units

OBJECTIVE

To examine regional variations in the incidence of late-onset neonatal infections in Australian and New Zealand neonatal units.

METHODOLOGY

A longitudinal, prospective surveillance study of systemic sepsis (septicaemia or meningitis) in 11 neonatal units: 10 in the Australian States of the Northern Territory, New South Wales, Queensland, Victoria and Western Australia, and 1 in Christchurch, New Zealand. The results are reported of late-onset neonatal infection (defined as sepsis after 48 h) for the second year of prospective surveillance, data being collected from 1 October 1992 to 30 September 1993.

RESULTS

Data were available on 24535 live births in Australia, representing approximately 10% of all live births in the country. There were 320 episodes of sepsis in Australian units affecting 294 babies. One hundred of these episodes (31%) were early-onset; 3.0% of babies admitted to six tertiary care neonatal units attached to maternity hospitals developed late sepsis, and this rate did not differ between units. The proportion of babies infected was inversely related to birthweight: 22.6% of babies under 1OOOg, but 0.6% over 2000g. Coagulase negative staphylococci were the commonest cause of late-onset sepsis. There were 26 episodes of S. aureus septicaemia, of which only one was due to MRSA. Meningitis occurred in 13 babies (5.9%) with late-onset sepsis. The mortality from late-onset sepsis was 7.7%.

CONCLUSIONS

Coagulase-negative staphylococci are the commonest cause of late-onset sepsis of babies in neonatal units. There were no major regional differences in the incidence of, or the organisms causing, late sepsis.

Skeletal and functional effects of treatment for unilateral posterior crossbite

Unilateral posterior crossbite (UPXB) is a common malocclusion, frequently presenting a lower midline deviation, accompanied by Class II subdivision relationships in final closure and a very high prevalence of the reverse sequencing (RS) pattern of jaw movement. These features often persist even after the elimination of the crossbite. The purpose of the present study was to examine in detail the morphologic, skeletal, and functional effects of the treatment for this malocclusion category. The experimental group consisted of 24 children in the mixed dentition stage with UPXB who were treated with removable expansion plates and a control group of 10 age-matched children with normal occlusion. Longitudinal follow-up revealed a stable dental maxillary arch expansion of at least 1.5 mm but a complete elimination of crossbite in only 50% of the cases. The frequent persistence of Class II subdivision relations and lower midline deviation that were not due to functional mandibular shift was striking. The pretreatment posteroanterior (P-A) cephalograms indicated reduced facial and maxillary widths. After treatment, the achieved maxillary width increase was greater than expected with normal growth. Longitudinal assessment of the mandibular movement response revealed by the electrognathograph showed a high prevalence of RS, which was reduced after treatment. In conclusion, (1) a higher than expected prevalence of skeletal transverse aberrations at the maxillary and zygomatic levels were found in the UPXB group; (2) the removable expansion appliance induces transverse growth of the maxilla; and (3) an inherent pattern of jaw movement is characteristic to the UPXB and does not change significantly with orthodontic treatment.

Tooth contact during dynamic lateral excursion in young adults

Tooth contact in mediotrusion as well as the signs and symptoms of periodontal and mandibular dysfunction were recorded in healthy patients aged between 20 and 31 with Angle class I or II. Non-functional side contact (NFSC) was found in 94% of the patients, indicating that it is a common phenomenon. In cases of NFSC, the entire range of movement, and not only the final stage of tip-to-tip contact on the working side, should be recorded. Slight positive mobility with tooth faceting, as compared to the adjacent and contralateral teeth, was observed in 56 patients. There was no correlation between mediotrusion and mandibular dysfunction. The cumulative effects of NFSC are not well documented, and longitudinal follow-up studies should be carried out to clarify these.

Prevalence of viral antibodies in gingival crevicular fluid

The prevalence of antibodies to CMV, Mumps and Coxsackie virus strains 1, 3 and 4 was studied in 39 samples of gingival crevicular fluids (GCF) obtained from clinical healthy patients and compared to the corresponding antibodies present in the serum of each individual. In spite of the high prevalence of humoral antibodies to CMV (75%), only 24% of the gingival crevicular fluid samples exhibited IgG or IgA antibodies to this virus. The differences in the prevalence of antibodies against Mumps virus in the sera and GCF were even greater: whereas 87% of the patients exhibited serum antibodies, not even a single gingival fluid sample was found to be positive. Antibodies to Coxsackie B strains 1, 3 and 4 were found in 72%, 63% and 52% of the sera and in 25%, 19% and 33% of the gingival fluid samples (IgG only). The presence of the antibodies and their profile in GCF and serum is different. The mechanism of possible permeation is not clear but it seems that viral antibodies in this milieu are not derived from the serum solely by passive transudation, and that the antibodies are produced locally at least in some of the GCF specimens.

Urolithiasis in Australian aboriginal children

Thirty-six Australian Aboriginal children with urolithiasis were reviewed. Males dominated the series. The age distribution ranged from 8 months to 12 years and nearly 70% were 2 years or younger. Thirty-five patients had upper tract stones. Ultrasound was diagnostic in 35 patients and was falsely negative in one. Dietary factors, dehydration and recurrent diarrhoea are incriminated in the aetiology, because ammonium urate and oxalate were the main constituents of the stones. Malformations of the urinary tract were rare and known metabolic disorders were not seen. Chemical dissolution of the stones was found to be a safe and effective adjuvant in the management of urate stones.

The masticatory pattern as an adjunct for diagnosis and treatment

The sagitally-viewed masticatory pattern was investigated in 125 dentate patients. In 25 patients, the phenomenon of an incisal guided phase during mastication was observed. Clinical examination of these cases revealed slight to severe incisal attrition or various degrees of flaring. The hypothesis that the incisal guided phase contributes to this phenomenon and should therefore be taken into consideration during treatment is put forward.

Detection of herpes simplex virus in gingival tissue

The presence of herpes simplex virus (HSV) antigens was shown by immunofluorescence staining in 26 of 66 (39.3%) specimens of clinically healthy gingiva, but only one sample contained infectious virus. HSV DNA sequences were clearly identified in intact gingival cells by dot blot hybridization in one specimen, and a weak pattern in a second one. Both specimens harbored viral antigens. These findings of viral genome and protein expression suggest that the virus is present in the latent form in the gingiva.

A functional aspect of anterior attrition or flaring and mode of treatment

The phenomenon of occlusal wear has been generally reported, with no distinction being made between wear of the anterior or posterior teeth. This paper describes a group of patients without oral habits and exhibiting anterior tooth attrition or flaring with minimal posterior tooth attrition. The mandibular anterior movement patterns of the patients studied were evaluated using a Sirognathograph. These patterns appear to be the etiology for the anterior attrition or flaring present. A treatment mode allowing coexistence of this phenomenon with an anterior guidance that does not interfere with the mastication pattern is proposed. A hypothesis that might explain the clinical findings and a mode of treatment are described.

Splinting: a retrospective 17-year follow-up study

A retrospective 17-year, longitudinal study monitoring 66 patients with fixed partial denture and removable partial denture restorations revealed that perceptive splinting was beneficial and enhanced the longevity of the restoration. The study discussed the advantages and disadvantages of splinting, the survival rate of splints and splinted teeth, and the importance of oral hygiene and a periodic maintenance program.

Contribution of oral habits to dental disorders

Oral habits or parafunction may contribute to dental, periodontal, or neuromuscular damage. Such habits, of which the patient is often unaware, may cause considerable damage. Habits may be occlusal or non-occlusal, and may affect the dentition and/or the oral soft tissues. Drawing a patient's attention to the damage caused by some habits of which he or she is unaware often leads to cessation, whereas with certain conscious habits, such as nail or finger biting, success is much more limited.

Iatrogenic exfoliation of a tooth following abuse of a rubber dam: a case report

This report presents a case in which tooth exfoliation followed rubber dam abuse. A 40-year-old patient was referred to the prosthodontic clinic with complaints of mobility and discomfort in tooth 44, which had received an amalgam restoration. While this tooth was scaled, a piece of rubber dam appeared in the buccal sulcus. Removal of the rubber piece was followed by thorough scaling and tooth splinting. Tooth deterioration continued, and concern for the adjacent teeth necessitated extraction of tooth 44. To avoid such undesirable consequences, the integrity of the dam should be verified on its removal.

Effect of occlusal bite-raising splint on electromyogram, motor unit histochemistry and myoneuronal dimensions in rats

Composite resin bite-raising splints were fabricated on both sides of the upper jaw in rats. EMG activity of the deep masseter muscle was monitored continuously for 24 h before and up to 4 weeks after treatment. Together with the EMG activity, measurements of the neuromuscular junction area and muscle fibre histochemistry were made. EMG activity showed great variability immediately after splint fabrication. Some of the animals showed increased EMG activity, while others exhibited less activity 48 h after splint application. Overall, the fluctuation lasted for about 4 days, and after approximately 7 days all the animals exhibited decreased EMG activity, followed by a gradual increase in activity towards baseline levels. The neuromuscular junction territory increased significantly 5-10 days after splint application. Histochemical characterization of the deep masseter muscle revealed that it contained the three main types of muscle fibre: slow oxidative (SO), fast-oxidative-glycolytic (FOG) and fast glycolytic (FG). The frequency distribution of fibre types did not change after bite-raising splint treatment. These findings indicated that splint treatment in rats is effective in reducing EMG activity, while the muscle type characteristics remain stable. The effect of lower activity on the motor end-plates suggested that the neuromuscular junctions are quite sensitive to functional changes.

Functional and esthetic rehabilitation of an adolescent cleft lip and palate patient

Many patients with clefts that also affect the alveolar ridge present with congenital absence of the permanent maxillary lateral incisors. This paper describes the treatment of an adolescent cleft lip and palate patient whose missing and unesthetic maxillary incisors were replaced by a combination of fixed and removable partial dentures.

Severe vertical overlap: a modified method of treatment

Severe vertical overlap may predispose the patient to abnormal function, improper mastication, excessive stress, and functional problems such as bruxing, clenching, and craniomandibular disorders. This report describes the establishment of a new occlusal relationship by using the potential of posterior tooth eruption with the Hawley bite plane or the canine platform method. It was used in patients with a full complement of teeth or with some missing teeth. Patients treated by either the Hawley bite plane or the canine platform demonstrate a stable and long-lasting new occlusal relationship. The method described is efficient, inexpensive, and convenient to the patient.

Various methods in achieving anterior guidance

The anterior teeth are essential for esthetics, phoentics, and mastication and are equally involved in protecting posterior teeth. A 10-year longitudinal study of treatment modalities was conducted for overbite-overjet occlusal relationships. Comprehensive treatment combining orthodontics, occlusal adjustment, and selective restorations minimized the need for extensive restorative dentistry. The treatment of selected patients with a 10-year postoperative evaluation was discussed.

Oral cavity herpes simplex virus--a risk factor to dental personnel and patients. An overview

Herpes virus antigens were found in the sulcular epithelium of approximately 60% of patients with clinically healthy gingiva. In addition, specific antigens for herpes simplex virus (HSV) were found in the sulcular epithelial cells of patients undergoing periodontal treatment. Specific antibodies were also detected in 70-80% of the gingival fluids collected. On the basis of these data we hypothesized that the oral cavity may act as a preferential site for latent HSV. Thus, stressful events such as traumatic dental treatment and tissue damage may elicit herpetic episodes, risking dental personnel. Measures of precaution are indicated for routine dental treatment.

Rating communication behaviours in the head-injured adult

Evaluation of certain communication skills in head-injured adults has generally been limited to informal clinical impressions. A rating scale has been developed which addresses several of these communication abilities in a behaviourally based model. Preliminary data based on a sample of four head-injured adults and four trained raters revealed robust inter- and intra-rater reliability. Statistical relationships between the scale and three linguistic measures for a group of 20 head-injured adults were addressed with negative results. Individually the items selected appear to quantify aspects of complex communication behaviour.

Nonlinear directional coupler with a diffusive Kerr-type nonlinearity

We present numerical results showing the effects of a diffusive Kerr-type nonlinearity on the switching characteristics of a nonlinear directional coupler. It is found that switching can still occur even when the diffusion length is equal to the waveguide separation but that then its threshold increases and becomes less pronounced.

The cantilever fixed partial denture: a 10-year follow-up

A 10-year study of patients with cantilever fixed partial dentures suggests that these prostheses can be used for both anterior and posterior replacements. Guidelines for cantilever prostheses are described. Fixed cantilever prostheses are favorable alternatives to certain types of unilateral removable partial dentures. Proper oral hygiene is essential.

Effect of occlusal (mechanical) stimulus on bone remodelling in rat mandibular condyle

Mechanical load influences the remodelling of skeletal tissues. In the mandibular condyle, occlusal alterations and the consequent mechanical stimulus induce changes in chondrocytes and cartilage mineralization. In the present study we quantified in the mandibular condyle the effect of occlusal interference on remodelling of the subchondral bone. Computerized histomorphometry after 5-21-day exposure to the influence of a unilateral occlusal splint revealed an increased rate of trabecular remodelling, consisting of enhancement in osteoblast and osteoclast numbers and activities. The bone formation parameters reached their high values on Days 5 or 9 and remained stable thereafter. Bone resorption showed a gradual increase throughout the experimental period. These results further characterize the temporomandibular joint reaction to occlusal alterations. It is suggested that the present increase in bone turnover together with the known enhancement in chondrogenesis are part of a process of functional adaptation in response to mechanical stimulus.