Microhabitat use affects goby (Gobiidae) cue choice in spatial learning task.

This study investigated whether spatial learning ability and cue use of gobies (Gobiidae) from two contrasting habitats differed in a spatial task. Gobies were collected from the spatially complex rock pools and dynamic, homogenous sandy shores. Fishes were trained to locate a shelter under the simulated threat of predation and it was determined whether they used local or extra-maze (global) and geometric cues to do so. It was hypothesized that fishes from rock pools would outperform fishes from sandy shores in their ability to relocate shelter and the two groups would differ in their cue use. It was found that rock-pool species learnt the location of the correct shelter much faster, made fewer errors and used a combination of all available cues to locate the shelter, while sand species relied significantly more on extra-maze and geometric cues for orientation. The results reported here support the hypothesis that fishes living in complex habitats have enhanced capacity for spatial learning and are more likely to rely on local landmarks as directional cues than fishes living in mundane habitats where local cues such as visual landmarks are unreliable.

Expression and intracellular distribution of stress fibers in aortic endothelium.

Immunofluorescence microscopy was used to determine the number of endothelial cells with stress fibers for three age groups, and for three distinct anatomical locations within the descending thoracic aorta of both normotensive and spontaneously hypertensive rats. For each age group examined, hypertensive rats consistently demonstrated greater stress fiber expression than did normotensive rats. Neither age nor blood pressure was the predominant influence on stress fiber expression in aortic endothelium. In the normotensive rats, stress fiber expression remained unchanged for all age groups examined. For both strains, however, more endothelial cells with stress fibers were found in those regions where fluid shear stresses are expected to be high, when compared with those regions where the fluid shear stresses are expected to be low. This observation suggests that anatomical location, with its implied differences in fluid shear stress levels, is a major influence on stress fiber expression within this tissue. Electron microscopy was used to determine the intracellular distribution of stress fibers for both strains. Most stress fibers in both strains were located in the abluminal portion of the endothelial cells. This result is consistent with a role for stress fibers in cellular adhesion. However, the hypertensive rats had a higher proportion of stress fibers in the luminal portion of their cytoplasm than the normotensive rats. This increased presence of stress fibers in the luminal portion of the cell may be important in maintaining the structural integrity of the endothelial cell in the face of elevated hemodynamic forces in situ.

Factors influencing the expression of stress fibers in vascular endothelial cells in situ.

The organization of actin and myosin in vascular endothelial cells in situ was studied by immunofluorescence microscopy. Examination of perfusion-fixed, whole mounts of normal mouse and rat descending thoracic aorta revealed the presence of axially oriented stress fibers containing both actin and myosin within the endothelial cells. In both species, the proportion of cells containing stress fibers varied from region to region within the same vessel. Some endothelial cells in mouse mesenteric vein and in rat inferior vena cava also contained stress fibers. Quantitative studies of the proportion of endothelial cells containing stress fibers in the descending thoracic aorta of age-matched normotensive and spontaneously hypertensive rats revealed significant differences. When animals of the same sex of the two strains were compared, the proportion was approximately two times greater in the spontaneously hypertensive rats. The proportion of endothelial cells containing stress fibers was about two times greater in males than in females of both strains. These observations suggest that multiple factors, including anatomical, sex, and hemodynamic differences, influence the organization of the endothelial cell cytoskeleton in situ.

Multiple positive and negative 5' regulatory elements control the cell-type-specific expression of the embryonic skeletal myosin heavy-chain gene.

To identify the DNA sequences that regulate the expression of the sarcomeric myosin heavy-chain (MHC) genes in muscle cells, a series of deletion constructs of the rat embryonic MHC gene was assayed for transient expression after introduction into myogenic and nonmyogenic cells. The sequences in 1.4 kilobases of 5'-flanking DNA were found to be sufficient to direct expression of the MHC gene constructs in a tissue-specific manner (i.e., in differentiated muscle cells but not in undifferentiated muscle and nonmuscle cells). Three main distinct regulatory domains have been identified: (i) the upstream sequences from positions -1413 to -174, which determine the level of expression of the MHC gene and are constituted of three positive regulatory elements and two negative ones; (ii) a muscle-specific regulatory element from positions -173 to -142, which restricts the expression of the MHC gene to muscle cells; and (iii) the promoter region, downstream from position -102, which directs transcription initiation. Introduction of the simian virus 40 enhancer into constructs where subportions of or all of the upstream sequences are deleted (up to position -173) strongly increases the level of expression of such truncated constructs but without changing their muscle specificity. These upstream sequences, which can be substituted for by the simian virus 40 enhancer, function in an orientation-, position-, and promoter-dependent fashion. The muscle-specific element is also promoter specific but does not support efficient expression of the MHC gene. The MHC promoter in itself is not muscle specific. These results underline the importance of the concerted action of multiple regulatory elements that are likely to represent targets for DNA-binding-regulatory proteins.

Polyethylene ribbon fibers: a new alternative for restoring badly destroyed primary incisors.

Dentistry has advanced to the point where it is undesirable for children to be partially edentulous or to have unattractive anterior teeth. With the introduction of new materials and adhesive systems the use of polyethylene fibers as post and core offer a new reconstructive alternative for severely destroyed primary anterior teeth. These fibers offer root and coronal retention, stability and esthetics, and it is done chair side. The present study compared two different types of fibers and analyzed the fracture resistance between the two of them. Two groups were formed. Group I used non pre-impregnated resin fibers (glasSpan) and group II used pre-impregnated resin fibers (Splint-it). Both types of fibers have been used as post and core in the restoration of primary teeth and clinical studies have been published. Our results indicated that the mean fracture resistance for group I was 71.346 and for group II 97.952 (p = 0.004). During the observation of the fractured samples, adhesive failures were noted for group I at the junction between the fiber and its core to the interior wall of the root canal. In group II, the fibers were dislodged out of the canal and the core part of the canal remained intact. It can be concluded that pre-impregnated fibers offer a better fracture resistance when used as post in endodontically treated primary anterior teeth.

Orthopedic approach in the treatment of a skeletal class II division 1 malocclusion with an anterior open bite.

The patient presented with a skeletal class II malocclusion characterized by an anterior open bite and maxillary midline deviation. This mixed dentition case was treated orthopedically with MRI appliance to rotate and impact the maxilla. A Bionator was used advance the mandible. The case was completed using Occlus-O-Guide. The result showed that the facial bones and teeth appear in the correct position.

An in vitro evaluation of microleakage in class I preparations using 5th, 6th and 7th generation composite bonding agents.

The intent of this study was to evaluate microleakage of newer generations of dentinal bonding systems of Class I restorations filled with the same resin based composites. Eighty extracted human premolar and molar teeth were randomly assigned to four groups for bonding: the 5th generation bonding system (Optibond Solo), the 6th generation bonding system (Prompt-L-Pop) and the 7th generation bonding system (iBond), and a control group that was used with no dentinal bonding system. Cavities were prepared 3 mm in width, 2 mm in depth and 2 mm in length. Margins of the cavities were chamfered using a high-speed hand piece with water spray and a #1/2 round diamond bur. The cavities were restored with resin based composites after the application of the dentinal bonding systems according to the instructions of the manufacturer. Upon drying of the teeth, two coats of nail varnish were applied covering the surface of the tooth, excluding the tooth-restoration interface. Samples were thermocycled and immersed in methylene blue dye (0.05%). Each sample was sectioned with an Isomet and evaluated, for microleakage using light microscopy under a measuring microscope at 50x magnification Statitical significance was determined using the Chi-Square Test. Among the three dentinal adhesive systems used in this study the 5th generation outperformed both the 6th and 7th generation bonding systems.

Reversible changes in stress fiber expression and cell shape in regenerating rat and rabbit aortic endothelium.

The influence of intimal de-endothelialization on stress fiber expression in regenerating rat and rabbit aortic endothelium was studied using immunofluorescence microscopy. Rat thoracic and abdominal aortae were balloon de-endothelialized, and endothelial cell shape and stress fiber expression was studied in both uninjured and de-endothelialized animals. In control animals, the majority of thoracic endothelial cells did not contain stress fibers while the majority of abdominal endothelial cells did. One week after injury, all the endothelial cells distal to the regenerating edge contained very prominent stress fibers. In areas directly adjacent to the still de-endothelialized surface, the endothelial cells had an intense, diffuse cytoplasmic staining without stress fibers. Regenerating endothelium also had a substantially higher length-to-width ratio, but smaller cell areas. Six weeks after injury, the endothelium had completely regenerated, and stress fibers were lost from the majority of the thoracic endothelial cells. Changes in abdominal aorta stress fiber expression were not as marked. In the rabbit, all the control thoracic endothelial cells had stress fibers; however, cells at the leading edge of a narrow region of de-endothelialization had few stress fibers. The results suggest that stress fibers do not play a primary role in cellular migration in situ. The transient increase in stress fiber expression in the rat may result from a temporary demand for greater adhesive capabilities until the subendothelial extracellular matrix is remodeled.

Electrical resistance correlation with tactile examination on occlusal surfaces.

Electrical resistance of the tooth was measured through the dental pulp by a relatively simple method. The primary resistance is in the enamel, and the total resistance drops severalfold as dental caries develop. This resistance has been measured on the occlusal surfaces of 122 teeth of children. The differences between explorer categories showed statistically different resistance values (P greater than 0.9995, excluding the offscale sound-tooth category). After 3 to 4 months, 9 of the 32 teeth of the incipient caries category became obviously carious, while none of the caries-free teeth became carious.

Early detection of occlusal caries by measuring the electrical resistance of the tooth.

The tooth resistance measuring instrument was compared to the traditional method of the explorer examination for the detection of occlusal carious lesions. The findings of the instrument were more sensitive as compared to the traditional method when verified by a histological examination.

Continuous culture studies on the growth and physiology of Streptococcus mutans.

We examined the effects of nutritional limitations on the production of lactic acid by Streptococcus mutans grown at low growth rates in continuous culture. Lactic acid production was greater in nitrogen- and phosphate-limited continuous cultures than in glucose-limited conditions. These results are correlated with the release of calcium from enamel in cellfree broths from various fermentations.

Social and sexual contact between general practitioners and patients in New Zealand: attitudes and prevalence.

BACKGROUND: Doctor-patient social and sexual contact is increasingly acknowledged as an issue of importance for the medical profession. However, there is little research concerning general practitioners on this topic. AIM: A study was undertaken to obtain data on social and sexual contact between general practitioners and their patients. METHOD: An anonymous questionnaire was mailed to a nationwide randomized sample of 217 general practitioners in New Zealand. RESULTS: A response rate of 86% was obtained. Dating and sexual contact with patients was considered to be sometimes or usually acceptable to 35% and 10% of general practitioners, respectively. Of respondents, 6% reported having dated a patient, 4% reported having had sexual contact with a patient at some point during their career and 2% reported having engaged in sexual contact with a former patient. General practitioners who had personally known of a colleague who had engaged in sexual contact with a patient were more likely to believe this behaviour had negative consequences than general practitioners who themselves reported having engaged in sexual contact with a patient. CONCLUSION: The study results have implications for developing behavioural guidelines and educational interventions for general practitioners.

Nutrition in the practice of pediatric dentistry.

Nutrition is an important aspect of the total environment of a growing child. The dentist should evaluate the nutrition of pediatric patients from the physical parameters of the child including growth, general appearance, posture, muscle control, oral findings, and dietary history. Some common malnutrition problems of the pediatric age group include deficiencies of iron, calcium, vitamins A, C, and D, protein and/or calories, and excess ingestion of calories. The causes of and means of preventing nursing-bottle syndrome are easily preventable in this form of dental caries which has many dental, systemic, and economic consequences. The use of group dynamics as an effective and enjoyable method of teaching preventive dentistry is discussed.

Metal-ceramic bridges from commercial dental laboratories: alloy composition, cost and quality of fit.

The quality of construction of fixed bridge prostheses directly affects their long-term survival. The cost, alloy composition and marginal fit of bridges made by 30 commercial dental laboratories is assessed. Duplicate models of a three unit bridge preparation were sent to 30 different laboratories, as if required for a patient receiving treatment under the General Dental Service. Material was sent via general dental practitioners, requesting metal-ceramic bridges made from 45% Au alloy, precious metal or non-precious metal. Proximal contacts were overbuilt at 65% of sites and pontic tissue contacts were excessive in all but one bridge. Eight laboratories did not use alloys corresponding to the request made. The mean marginal gaps of non-precious metal bridges (145 microns) were significantly greater than those for 45% gold alloy (106 microns). Marginal fit was poor and a number of factors have been observed, with other postulated, which may have contributed to this problem.

Attitudes toward sexual contact between general practitioners and their patients.

AIMS: To examine attitudes toward sexual contact with patients including seductive and sexually demeaning verbal behaviour. METHODS: Anonymous questionnaire mailed to a nationwide randomised sample of 217 general practitioners. A response rate of 88% was obtained. MAIN OUTCOMES MEASURES: Attitudes were appraised through responses about the acceptability of sexual contact with current and former patients. Knowledge of colleagues engaging in sexual contact, seductive or sexually demeaning behaviour was also assessed. Disposition toward reporting colleagues was explored. RESULTS: Ninety per cent of general practitioners indicated that it was never permissible to have sexual contact with a current patient. Twenty per cent agreed that it was never permissible to have sexual contact with a patient even when treatment had been terminated. While only 4% and 6% respectively knew of a general practitioner who had engaged in seductive or sexually demeaning verbal behaviour, 32% had personally known of a colleague who had engaged in sexual contact with a patient. Participants were divided in their attitudes toward reporting colleagues for sexual misdemeanours with patients. CONCLUSION: The results have implications for the development of guidelines and the training of general practitioners.

General practitioner attitudes toward mandatory reporting of doctor-patient sexual abuse.

AIM: To explore general practitioner attitudes toward mandatory reporting of doctor-patient sexual abuse. METHODS: Anonymous questionnaire mailed to a randomised sample of 217 New Zealand general practitioners. Attitudes toward mandatory reporting of doctor-patient sexual contact, seductive or sexually demeaning behaviour were appraised including an indication of whom the perceived appropriate reporting body should be. RESULTS: Forty-seven per cent of respondents supported the notion of mandatory reporting for doctor-patient sexual contact, 42% for sexually demeaning behaviour and 35% for seductive verbal behaviour. These respondents indicated that the most appropriate body to report to was a Doctor's Health Advisory Service. CONCLUSION: There was a lack of strong consensus on mandatory reporting of doctor-patient sexual abuse.

Increasing the uptake of cervical smears: strategies implemented among general practitioners in Auckland.

AIM: To evaluate three strategies designed to increase the uptake of cervical smears among specified groups of women through a collaborative partnership between the Auckland Area Health Board and selected Auckland general practitioners. METHOD: Using action-based research general practitioners and practice nurses were engaged to initiate ways of inviting women in their practices to have cervical smears. Both formative and process evaluations were made. Concurrently, outcomes were measured in terms of call/recall systems, uptake rates and cost barriers. RESULTS: Where financial incentives were given to establish call/recall systems for older women, overall uptake rates increased by 21%, and by 154% for women over 45 years. Over one third of a targeted group of women aged between 60 and 70 years responded to an invitation to have a free smear. Of these 109 women, fourteen, with a median age of 67 years, had their first smear. Almost two thirds indicated that cost had never been a barrier. CONCLUSIONS: The determining factor for women having a cervical smear in all three strategies was a personal invitation from their general practitioner or practice nurse. Invitations were dependent upon having accurate call/recall systems. This evaluation of the collaborative process between Auckland Area Health Board and local general practitioners demonstrated how manager and provider partnerships can benefit the consumer.

The prevalence of bad headaches including migraine in a multiethnic community.

AIM: Overall and ethnic specific prevalences of bad headache including migraine, for the New Zealand population, are unknown. A study was carried out in South Auckland to estimate prevalence and to explore ethnic differences in doctor attendance for the diagnosis and management of bad headaches. METHODS: Telephone interviews were administered to respondents selected by random digit dialing of households. RESULTS: 40.6% of the respondents suffered from bad headaches. 54.5% of these had the characteristics of bad headache with features symptomatic of migraine. Trends in the prevalence of bad headache with features symptomatic of common migraine, peaked between the ages of 30-49 years in both men and women. A difference was seen in the prevalence of bad headache with aura, with or without common migraine features, when ethnic groups and gender were examined. The difference in prevalence of aura was particularly noticeable between Pacific Island men and women. Although there was no difference between ethnic groups in doctor attendance, headaches were more likely to be labelled as migraine in Europeans than in the Polynesian groups. CONCLUSION: Ways in which people perceive and report their bad headaches have a bearing on management by general practitioners. Although no overall ethnic predominance was seen, there was a gender difference amongst Pacific Island people in reporting bad headaches with aura. The labelling process, and thus the management by general practitioners does demonstrate likely ethnic differences.

The importance of occlusal balance in the control of complete dentures.

OBJECTIVE: The importance of occlusal balance to the control of complete dentures during function was assessed. METHODS AND MATERIALS: The complete dentures of five patients who were having difficulty controlling their prostheses were accurately duplicated. The artificial teeth were replaced with occlusally balanced teeth. No other changes were made. Patients were asked to report their experiences with the new dentures after 1 week, 3 weeks, and 6 weeks. RESULTS: By the end of 6 weeks, improvement in denture stability and eating comfort were reported by all patients. CONCLUSION: Improvements occurred when the occlusion was balanced, despite existing jaw relationship errors, fitting inaccuracies, and peripheral extension errors.

Intraoral craniofacial manipulation.

This case report demonstrates how to use intraoral mechanics to correct facial planes that are not parallel, namely the eye plane, ear plane and occlusal plane. Currently, our protocol states that the cranial and occlusal planes are treated first, followed by expanding (transversely or sagittally), if necessary, the maxillary arch to accommodate the dentition. This creates the template from which the remaining treatment will be rendered, which would include, proper TMJ position, correction of mandibular facial asymmetries that result from ramus growth deficiencies, (both frontal and profile), and determining the correct posterior vertical. At this point the case is in a Class I osseous relationship with all expansion completed. The teeth are then erupted into the correct positions for the orthodontic finishing of the case.