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Biomedical subjects

B L Stewart

Publications and source records attributed to B L Stewart.

17 recordsLinked to original sources
PubMed1998

Effects of age, season, and fertility status on plasma and intratesticular immunoreactive (IR) inhibin concentrations in stallions.

The nature of the relationship between inhibin and reproductive function in the stallion is yet to be elucidated. Blood and testes from 51 light horse stallions ranging in age from 2 mo to 25 years were collected during the breeding and nonbreeding seasons to study the effects of testicular maturation, aging, season, and fertility status on peripheral and intratesticular concentrations of Ir inhibin and other reproductive hormones. Of the 51 stallions, 12 age-matched stallions (6 fertile, 3 subfertile, and 3 infertile) were used in the fertility study. Blood samples were taken before castration and plasma stored at -20 degrees C for analysis of Ir inhibin, luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone (T), estradiol (E2), and estrogen conjugates (EC) by radioimmunoassay (RIA). Testes were homogenized and testicular extracts prepared and frozen at -70 degrees C for analysis of Ir inhibin, T, E2, and EC by RIA. Plasma concentrations of Ir inhibin, LH, FSH, T, E2, and EC and intratesticular concentrations of Ir inhibin, T, E2, and EC increased with age (P < 0.01). The most dramatic effect appeared to be during testicular maturation. An aging effect was not observed in adult stallions. A seasonal effect was not detected for any of the plasma hormones, whereas for the intratesticular hormones the only change noted was an increase in T in the nonbreeding season (P < 0.05). Plasma Ir inhibin, E2, and EC were lower (P < 0.01) and gonadotropins higher (P < 0.05) in infertile stallions. Plasma T levels did not change. Intratesticular Ir inhibin concentrations tended to be lower (P < 0.1) in subfertile stallions and significantly lower (P < 0.01) in infertile stallions, whereas intratesticular steroid levels were not different among the three groups. In conclusion, plasma and intratesticular Ir inhibin concentrations seem to be affected by testicular maturation and fertility status.

Aging↗
PubMed1992

Self-efficacy for recovery from a lapse after smoking cessation.

Self-efficacy for avoiding any lapse after smoking cessation has often been found to predict maintaining abstinence. We measured recent ex-smokers' self-efficacy for recovery of abstinence (SER) after an initial lapse by using the articulated thoughts during simulated situations (ATSS; Davison, Robins, & Johnson, 1983) paradigm. Subjects with moderate SER maintained abstinence nonsignificantly longer than did those with high SER, significantly longer than those with low SER. This result is consistent with Bandura's (1986) hypothesis that SER should be high enough that ex-smokers do not become hopeless if a lapse occurs, yet not so high that they are tempted to experiment with smoking. The discussion focuses on measurement and conceptualization of SER, in particular its distinctiveness from response-outcome expectations.

Adaptation, Psychological↗
PubMed1992

Survey of dental practice/dental education in Victoria. Part V. One-year follow-up survey of 1988 graduating class.

A follow-up survey of the 1988 graduating class was carried out in order to compare views of the same cohort after 12 months of dental practice. The most significant finding was that there were few changes in opinion in respect to those subjects where 60 per cent or more respondents in the 1988 survey had judged the practical and/or theoretical components to have too little emphasis. These included fixed prosthodontics, occlusion, orthodontics, endodontics, aesthetic dentistry, oral surgery, conservative dentistry and care of the special patient. Recent changes to the undergraduate curriculum were high-lighted and the need for further development in continuing education courses was re-emphasized.

Attitude of Health Personnel↗
PubMed1991

Relationship of intelligence with cognitive therapy outcome.

Theorists have speculated that intelligence is positively associated with the capacity to benefit from cognitive-behavioral therapies. We evaluated this notion by relating pre-treatment measures of fluid and crystallized intelligence to self-reported symptom reduction in a naturalistic study (n = 106) of cognitive therapy for outpatients with principal diagnoses of major depression, dysthymia, or generalized anxiety disorder. Intelligence measures did not significantly predict outcome, and nonsignificant relationships were in the opposite direction from the theoretical prediction. Discussion centered on possible limitations to the generalizability of these results and on the logical interpretation of prediction studies in psychotherapy research.

Anxiety Disorders↗
PubMed1990

Survey of dental practice/dental education in Victoria. Part II. Recent graduates/graduating students.

The views of recent graduates and graduating students from the University of Melbourne, School of Dental Science, were sought in regard to their training for registration as dentists. Respondents were requested to indicate the emphasis placed on a number of subjects taught in the dental curriculum over the past ten years in relation to their preparedness for general practice. The priorities to be given to basic science and medical subjects, as indicated by the recent graduates in another section of the survey, were related to the judgment of emphasis given in the undergraduate curriculum. With respect to dental subjects, there were some for which a substantial number of respondents (over 60 per cent in each case) indicated that there was insufficient emphasis given during the undergraduate course. These included both 'Theory' and 'Hands on' aspects of aesthetic dentistry, fixed prosthodontics, occlusion and orthodontics, 'Hands on' aspect of care of the special patient, conservative dentistry, endodontics, medical emergencies and oral surgery and, finally the 'Theory' aspect of equipment design. Students also considered both aspects of ethics and legal matters, 'Hands on' experience for oral function and disorders of oral function and the theoretical aspect of implant dentistry to be deficient. Appreciable numbers of graduates (over 40 per cent for both 'Theory' and 'Hands on') indicated insufficient emphasis on implant dentistry, patient management, equipment design, ethics and legal matters, practice management/administration, practice promotion and professional relationships.(ABSTRACT TRUNCATED AT 250 WORDS)

Curriculum↗
PubMed1990

Survey of dental practice/dental education in Victoria. Part IV. Specialist dental practice.

A survey of dentists registered with the Dental Board and resident in the State of Victoria included two sections, one for specialist/restricted practitioners and the other for practitioners, who had gained a postgraduate degree from the University of Melbourne between December 1982 and 1987. The responses of the former suggested that demand for most specialist services appears to be reasonably healthy at the moment and the majority of the latter indicated that they had been adequately trained for specialist practice. It was suggested that there are several market forces which could influence the number of applicants seeking specialist training in future. Strongest demand was likely to be sustained for oral surgery and orthodontics. This is despite evidence of a decline in demand for specialist orthodontic services in private practice. Attention was drawn to the 1986 Ministerial Review of Dental Services in Victoria, in which concern was expressed for the lack of access to orthodontic services for low income families. It was proposed that more cost-effective methods of deploying orthodontic personnel could be used, as in other countries, to provide this access. Demand for specialist services in endodontics, paediatric dentistry, periodontics and prosthodontics could decline in future as general practitioners steadily broaden their range of services through continuing education courses.

Dentists↗
PubMed1990

Determination of adhesive bond strength to dentine. A new method.

Specimens for the determination of adhesive bond strength to dentine were prepared using suitable surfaces of freshly extracted teeth from 15 patients who were having immediate dentures fitted. As soon as possible after extraction, shallow cavities were cut into the dentine to a depth of 1 mm using a high-speed round bur (diameter 4.2 mm) under water coolant. The cavities were restored using dentine bonding agents and single increments of light activated composite resin. The restored teeth were cut down to approximately 5 mm in diameter and 3 mm thick and were either placed in previously prepared sites in the buccal or occlusal surfaces of their respective dentures or in containers of tap water. Patients were instructed to remove their dentures only for cleaning with a soft nylon brush and toilet soap, while the laboratory specimens were stored at ambient temperature. After one week, the tensile force needed to dislodge each restoration from its cavity was determined using a universal testing machine. Previously reported laboratory methods for bond strength determination have usually employed a flat dentine surface. However, this study more closely resembled the clinical situation in that the smear layer was produced by a rotary cutting instrument, and the effects of polymerization shrinkage when curing the composite resin were simulated. Furthermore, it was easier to confine the bonding agent to the desired dentine surface.

Adhesives↗
PubMed1990

Survey of dental practice/dental education in Victoria. Part III. Trends in general dental practice.

The responses of practising dentists in regard to clinical time spent and demand trends in dental practice were combined with recent graduates' views of the emphasis given to various disciplines during their undergraduate training in order to provide information which might assist the undergraduate curriculum review. The greatest proportion of clinical time spent by general practitioners on various clinical disciplines was reported to be restorative, preventive, diagnostic and endodontic services. There was evidence to suggest that there is an increasing demand for a broad range of clinical services, particularly in country locations, and that general practitioners appear to be expanding their range of services, including those traditionally offered by specialists. Highest increasing demand over the past five years were for recent advances in 'aesthetic dentistry', endodontics, preventive services, orthodontics, periodontics and fixed prosthodontics. High rates of referral were reported only for fixed orthodontics and major oral surgery. Almost twice as many practitioners overall reported an increase (44 per cent) rather than a decrease (26 per cent) in volume of patients over the last five years. This trend was much more evident in country practices, however, with 55 per cent and 22 per cent compared with Melbourne city, 37 per cent and 29 per cent, increasing and decreasing, respectively. Although dental educators are challenged to ensure that graduates are adequately prepared clinically to meet the demands of dental practice there is mounting pressure to support the introduction of an intern year prior to full registration.

Curriculum↗
PubMed1990

Relationship between hopelessness and ultimate suicide: a replication with psychiatric outpatients.

A prospective study of 1,958 outpatients found that hopelessness, as measured by the Beck Hopelessness Scale, was significantly related to eventual suicide. A scale cutoff score of 9 or above identified 16 (94.2%) of the 17 patients who eventually committed suicide, thus replicating a previous study with hospitalized patients. The high-risk group identified by this cutoff score was 11 times more likely to commit suicide than the rest of the outpatients. The Beck Hopelessness Scale thus may be used as a sensitive indicator of suicide potential.

Adolescent↗
PubMed1990

Dental materials in Papua New Guinea: a survey of dental clinics.

Questionnaires were distributed to 55 Public Health and Defence Force dental clinics throughout Papua New Guinea in order to ascertain storage and clinical conditions, as well as information related to the type, consumption and performance of alginate and elastomeric impression materials and composite restorative materials. Of the 39 respondents, representing a 71% return, few reported any problems with either of the two types of impression materials. However, complaints associated with the use of paste-paste composites, Adaptic and Concise, were a major concern. It was assumed that the problems were caused by exposure to excessively high temperatures during shipment, distribution and storage of these materials throughout Papua New Guinea. Alternative materials, which are less sensitive to heat, were proposed for use in Papua New Guinea. These were a light-activated composite (Durafill), a powder-liquid composite (Powderlite) and a powder-water glass ionomer (Chemfil II).

Dental Clinics↗
PubMed1989

Shelf-life of tooth-coloured restorative materials in Papua New Guinea.

A survey of Dental Officers and Dental Therapists in Government Health and Defence Force Clinics throughout Papua New Guinea indicated that the problem of slow setting and even failure to set is a frequent occurrence with composite resin materials. This is because these materials tend to deteriorate at high temperatures to which they may be subjected during transport, initial storage and clinical storage awaiting use. Eight brands of composite resin, including paste-paste, powder-liquid and light-activated systems, as well as three glass ionomer cements were evaluated over a period of twelve months with respect to shelf-life and suitability for use in a tropical environment. Preliminary results indicated that, although a light-activated composite resin appeared to be the material of choice, it may not be suitable because it is relatively expensive and requires a curing light which is electrically operated. A powder-liquid composite resin was, therefore, the recommended product. On the other hand, it was also suggested that a powder-water glass ionomer cement, Chemfil II, might be a suitable alternative for a developing, tropical country such as Papua New Guinea.

Chemical Phenomena↗
PubMed1989

Survey of dental practice/dental education in Victoria. Part I. Questionnaire/general aspects.

A questionnaire was designed to canvass the opinions of dentists registered with the Dental Board and resident in the State of Victoria, with a view to assessing the present undergraduate curriculum in relation to clinical dental practice. All respondents were requested to provide information about age, sex, registration, type/location of practice and qualifications. The questionnaire sought opinions from all respondents regarding the priority to be given to basic sciences and medical sciences as well as the introduction of topics not presently included in the undergraduate course. Questions were also posed in relation to physical assessment of applicants for the dental course, the timing of introduction to clinical procedures and the desirability of an intern year (Section A). Other sections were designed to ascertain the current trends and busyness of general dental practice (Sections B and C) and of restricted/specialist practice (Sections C and E), the views of recent graduates and postgraduates with respect to the appropriateness of their training for clinical practice (Sections D and F, respectively) and, in a separate questionnaire, the perceived views of graduating students with respect to their training for registration as dentists. The results of the survey were prepared in the form of four papers, namely, General aspects (Part I). Recent graduates/graduating students (Part II), Current trends in general dental practice (Part III) and Specialist dental practice (Part IV). This paper deals with the results of Section A of the survey which, it is suggested, need to be considered in any review of the curriculum.

Adult↗
PubMed1976

Changes in nasal airway resistance associated with rapid maxillary expansion.

Records consisting of nasal resistance measurements, postero-anterior radiographs, and dental casts were obtained on seventeen patients before they underwent rapid maxillary expansion. These records were retaken after maximum expansion of the appliance and after 3 months of retention. Measurements of nasal resistance, binasal cavity width, and maxillary first molar width were made for each subject at each stage of treatment. The following conclusions were derived: 1. Rapid maxillary expansion produced a significant reduction in nasal resistance measured at both 0.50 L. per second and 0.25 L. per second air flow. The reduction of nasal resistance by maxillary expansion was stable through a 3-month period of retention. 2. There was very low correlation between the amount of maxillary first molar expansion and change in nasal resistance. Also, changes in nasal resistance showed low correlation with the amount of nasal cavity widening which occurred during the expansion procedure. 3. Changes in nasal cavity width was not closely related to the amount of maxillary first molar expansion. 4. The patient's subjective opinion of changes in his ability to breathe through the nose was not closely related to the amount his nasal resistance was reduced. 5. The change in nasal resistance of subjects who noticed an improvement in their ability to breathe through the nose was not significantly different from nasal resistance change in children who did not notice any change in their breathing. 6. When subjects treated with an all-wire expansion appliance were compared to subjects treated with a wire-and-acrylic appliance, the two groups were not significantly different with respect to maxillary first molar expansion, nasal cavity widening, or changes in nasal resistance. Differences in amount of molar tipping or alveolar bending were not investigated. 7. Patients requiring rapid maxillary expansion treatment for constricted maxillary arches have significantly higher nasal resistance than other orthodontic patients and nonorthodontic subjects. The rapid maxillary expansion procedure reduced the nasal resistance of those treated to a level which was not significantly different from that of subjects with maxillary arches of normal dimensions. 8. The reduction in nasal resistance achieved with the expansion procedure was not lost after 3 months of retention. 9. Where indicated, rapid maxillary expansion is not only an effective method for increasing the width of narrow maxillary arches but also reduces nasal resistance from levels associated with mouth breathing to levels compatible with normal nasal respiration.

Adolescent↗
PubMedDate not supplied

Removable partial denture design: a photoelastic study.

Quantifiable frozen-stress photoelastic techniques were used to analyze stresses induced in mandibular models by a conventional free-end saddle removable partial denture. Four quasi-anatomical mandibular models were constructed for processing, together with their respective calibration specimens, through identical time/temperature stress-freezing cycles. After processing and slicing, an unloaded control model demonstrated some low-order fringes adjacent to the coronal third of the abutment tooth roots, but was otherwise stress free. A lower bilateral free-end saddle partial denture was constructed and fitted in turn to each of the remaining three models. Each denture/model combination was then loaded and processed through a stress-freezing cycle. After processing, 6-mm slices were cut from selected regions for analysis for the presence of stresses. Using a polariscope with circular polarized, monochromatic light, values for maximum shear stress were calculated at selected points in the slices taken from the three loaded models. Variations up to 28% of the mean were obtained for the three experimental models as compared with the consistent results for the material fringe values obtained from the calibration specimens. The study pointed out the problems involved in using photoelastic stress analysis on complicated anatomical models. The interpretation of the results from such studies should be approached with caution.

Denture, Partial↗