Search PubMed⌕ Search

Biomedical subjects

J R Cain

Publications and source records attributed to J R Cain.

At least 19 recordsLinked to original sources
PubMed2001

A custom impression tray made with the aid of an existing prosthesis: a clinical technique.

Prostheses for patients with intraoral defects usually have complex contours. The replacement of a successful prosthesis is more readily accomplished with the aid of a custom impression tray that reproduces the contours of the existing prosthesis. In the technique presented, an irreversible hydrocolloid impression is made of the intaglio surface of the prosthesis to be replaced. Autopolymerizing acrylic resin tray material is poured into the impression, creating a custom impression tray. This procedure can simplify the impression process and reduce the need for multistep impression techniques.

Acrylic Resins↗
PubMed2001

Development of a push-pull ventilation system to control solder fume.

Hand soldering using rosin core solder wire is common in the electronics industry and several studies have implicated the aerosol produced when rosin flux is heated in causing respiratory sensitisation. Control of solder fume is generally achieved using local exhaust hoods, simple blowers with a filter or low-volume high-velocity (LVHV) ventilation systems. None of these provide an ideal control system and so a push-pull ventilation design was developed as an alternative. Laboratory tests of the system's capture efficiency were carried out using nitrous oxide tracer gas. Capture efficiency was generally greater than 90% with the push airflow operating. However, without the push airflow, capture efficiency decreased sharply with increasing distance from the exhaust hood (between 38 and 58% at 420 mm from the front of the exhaust hood with the same exhaust airflow used by the push-pull system). The push-pull system was found to be relatively insensitive to obstructions placed in the path of the air flow or the influence of cross draughts. The system was tested in five electronics factories and the effectiveness was compared to their existing ventilation systems. Where only a small amount of soldering was carried out both the in-house and push-pull systems seemed to provide adequate control of inhalation exposure to rosin-based solder flux fume measured as total resin acids. However, the push-pull system provided more consistent control than the existing ventilation systems when larger quantities of solder were used. In these situations the mean personal exposure level was reduced to below the UK Maximum Exposure Limit (MEL) of 0.05 mg/m(3) 8-h time weighted average in most instances. The corresponding mean personal exposure level with the in-house systems in operation was about three to four times the long-term MEL. Interpretation of these data is complicated because of high background contribution to exposure from poorly controlled soldering operations elsewhere in the factories. However, this study suggests that the in-house systems were relatively inefficient.

Air Pollutants, Occupational↗
PubMed2000

Sterilization of reusable implant components: a pilot study.

STATEMENT OF PROBLEM: The placement and restoration of dental implants require the use of numerous reusable instruments and components. The adequate sterilization of reusable instruments and components is essential to prevent cross contamination between patients. Sterilization usually is accomplished with single-use sterilization envelopes. A reusable sterilization vehicle would reduce costs as well as the waste generated in patient care. PURPOSE: This study was designed to determine the efficacy of a 10-cc Pyrex test tube as a sterilization vehicle for reusable dental implant instruments and components. MATERIAL AND METHODS: In this study, a reusable dental implant component was placed in a Pyrex test tube, along with a biologic test strip. A control biologic test strip was kept for each test tube. The test tube was closed with a cotton roll folded in half and placed in the opening. Twenty test tubes were prepared. five sets of 4 test tubes were placed in an autoclave in different locations with varying orientations. The autoclave completed a standard sterilization cycle. RESULTS: The biological monitoring service indicated that the biologic test strips in 100% of the test tubes were sterile, whereas the control strips were 100% nonsterile. CONCLUSION: A Pyrex test tube sealed with a cotton roll can serve as a sterilization vehicle for reusable dental implant instruments and components.

Bacillus subtilis↗
PubMed2000

A survey of exposure to diesel engine exhaust emissions in the workplace.

Forty sites were visited during a survey of exposures to diesel engine exhaust emissions. Personal and background exposure to gaseous components, respirable dust, elemental carbon, organic carbon and total carbon were measured and details of control systems were recorded. The results show a wide spread in exposure patterns reflecting the different work practices, job categories of employees and the control methods used. However, sites where fork-lift trucks were in use consistently produced the highest exposures. The survey results suggest that the measurement of elemental carbon could be used as an indicator of exposure to diesel engine exhaust emissions.

Air Pollutants, Occupational↗
PubMed1987

Effects of dietary and parenteral estrogens on bobwhite reproduction.

Bobwhites were fed one of several doses (.01 to 1,000 micrograms/day) of estriol (E3), beta-estradiol-3-benzoate (E2B), diethylstilbestrol (DES), or biochanin-A (BA) during two 10-week trials. The initial 2 weeks of each trial were short day length (10L:14D) followed by 8 weeks of long day length (16L:8D). In addition, female bobwhites were given daily injections containing dosages (.01 to 10 micrograms/day) of E2B, E3, and DES while housed on the same light regimen. Reproductive performance as assessed by onset of lay, egg production, and egg fertility was depressed in a dose-dependent manner and was inhibited by dietary dosages of 1,000 micrograms/day of E3, DES, and E2B. No consistent effects on reproductive performance were observed in bobwhites fed up to 1,000 micrograms/day of the phytoestrogen BA. Injected estrogens appeared approximately 100 times more potent than dietary estrogens. It was concluded that both dietary and parenteral estrogen can inhibit reproduction, but in order for phytoestrogen (BA) in natural feedstuffs to impair reproduction in bobwhites it would have to be consumed in excess of 1 mg/day.

Animal Feed↗
PubMed1987

Production, physiological, and behavioral responses of laying hens in different management environments.

Responses of commercial laying hens to 16 management systems were examined for 10 laying periods of 28 days each. Twelve cage treatments consisted of housing three, four, or five hens in deep and shallow cages of different dimensions which provided .035 and .046 m2/hen. Four floor treatments housed 35 hens or 32 hens and three roosters at densities of .094 or .373 m2/bird, in two replicated pens each. Quantitative data were collected simultaneously for 23 production, physiological, and behavioral characteristics throughout the study. When comparing all caged with floor pen hens, caged hens had better (P less than .05) egg production rates (76.3 vs. 73.9%), gained more weight, had better feed efficiency, and had greater egg and egg shell weights than floor hens. All floor pen hens had higher (P less than .01) viability (98.9 vs. 95.0%), higher (P less than .01) plasma corticosterone levels (595.0 vs. 445.4 pg/ml), a greater (P less than .01) response to adrenocorticotropin (ACTH) challenges, and lower (P less than .01) antibody titers to Salmonella pullorum challenges than all caged hens. Caged hens preened, stood, crouched, and feather pecked more than floor hens, while floor hens drank and moved about more than caged hens. This study attempted to quantify production, physiological, and behavioral traits, all on the same flock of hens, in order to separate stressful from nonstressful management environments. Integration of all measurements indicates that properly managed caged hens were subjected to significantly fewer stressors than laying hens housed in floor pens, although the hens' well-being in the two environments could not be quantitatively compared.

Animals↗
PubMed1986

Corticosterone sampling of laying hens in different management systems.

Plasma corticosterone was measured as a stress indicator of laying hens in different management conditions. Laying hens housed in cages and floor pens were sampled repeatedly in the morning and the afternoon. Plasma corticosterone concentrations of afternoon samples of hens from floor treatments were significantly higher than those from cage treatments, but morning values were not different. These results suggest that management systems, producing subtle adverse conditions for laying hens, are associated with elevated baseline corticosterone levels during the nadir of the diurnal response, whereas peak values may not be affected.

Animals↗
PubMed1985

Prosthetic treatment for chemical burns of the oral cavity.

Chemical burns of the mouth, pharynx, and digestive passages have been reviewed in regard to the nature of the injury and wound description. Fabrication of custom mouth protectors to minimize oral scar contracture and its sequelae has been described. Mouth protectors provide flexible but active resistance to the forces of scar contracture and avoid a constant unyielding force that could cause pressure necrosis. Protectors are easy to fabricate and adjust, and permit movement and function of the injured area.

Burns, Chemical↗
PubMed1985

The influence of exogenous estradiol on bobwhite quail (Colinus virginianus) reproductive systems.

Mean plasma 17-beta-estradiol (E2) concentrations of nonphotostimulated adult bobwhite quail were less than 31.2 and 119.9 pg/ml for males and females, respectively. Dietary beta-estradiol-3-benzoate (E2 beta) dosages of 10, 100 or 500 micrograms/bird/day caused mean plasma E2 concentrations of females to increase by 1.2, 2.0 or 5.6 times. Oviduct weights were significantly increased in females fed E2 beta dosages of greater than 100 micrograms/bird/day for five days. Gonad weights were not significantly effected in either sex. Ten- to fifty-fold greater doses of dietary E2 beta were required to induce oviduct growth responses equivalent to those produced by injected E2 beta.

Animals↗
PubMed1984

Grower diets and bird density effects on growth and cannibalism in ring-necked pheasants.

The effects of bird density and dietary protein and energy level on growth rate and feather pecking in Ring-Necked pheasants were investigated in two experiments. After brooding, pheasants in Experiment 1 were housed at densities of .19, .38, or .74 m2/bird and fed grower diets containing 16, 19, or 22% protein. Experiment 2 pheasants were housed at .4 m2/bird and fed diets containing 16 or 22% protein with energy levels of 2530, 2750, 2970, or 3190 kcal/kg. Body weight was not affected by bird density differences, but feather pecking was significantly reduced by increasing floor space per bird. Body weight, cannibalism, and feed conversion were poorer in groups fed the 16% protein diet than those fed the 19 or 22% protein diets. Body weight gains, feed efficiency, and feather pecking scores improved as the energy content of grower diets increased. Significant interactions existed between dietary protein and bird density and between dietary protein and energy for feather picking in pheasants. Total performance was best for groups fed a grower diet of 22% protein and 2970 kcal/kg metabolizable energy level with a floor space of .38 m2 or greater per bird.

Animals↗
PubMed1984

Performance, behavior, plasma corticosterone, and economic returns of laying hens in several management alternatives.

Production, physiological, and behavioral data were collected simultaneously on commercial hens housed for 10 months of lay in housing alternatives of cages, deep litter floor pens, and outside range pens. Treatments consisted of housing 1, 2, or 3 hens in small cages 3, 4, 5, or 6 hens in large cages, floor pens housing 51 hens each at three densities, and range pens with 50 hens at .74 m2 (8 ft2) per hen. Egg production rates were greater for all caged hen treatments than for any floor or range groups. Egg numbers favored 2 hens per cage, but economic benefits favored 5 hens per cage. Viability was highest for 1 hen per cage and range pen groups. Feed efficiency was poorer in floor and range groups; however, body weight was generally greater for caged hens. Plasma corticosterone levels did not differ among any cage or range groups, but floor pen hens had significantly elevated levels. Behavioral data for walking and object pecking showed clear differences between cage and floor management alternatives. Preening, standing, and drinking activities were different between some treatments but not clearly different between management alternatives. Feeding activity did not differ among any groups. Although correlations between stress and well-being have not been well elucidated, the sum of the stressors of cage confinement appeared to be less than those from floor pens. Therefore, it was concluded that the well-being of hens in cages was equal to or better than that for free ranging hens or those in floor pens.

Animal Husbandry↗
PubMed1983

Custom ocular prosthesis with dilating pupil.

The manually adjustable pupil has two diameters: one constricted, the other dilated. The patient may select the appropriate diameter for the existing light conditions by moving a small magnet over the surface of the prosthesis. In the discerning patient this prosthesis will eliminate the need for two separate prostheses, which are commonly provided today. Patient privacy and hygiene are maintained because the prosthesis need not be removed to alter pupil size.

Eye, Artificial↗