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Biomedical subjects

J C Austin

Publications and source records attributed to J C Austin.

At least 73 records · Page 4Linked to original sources
PubMed1980

Effects of low concentrations of nitrous oxide on rat fetuses.

The long-term inhalation of air polluted with nitrous oxide has been implicated in spontaneous abortions and fetal abnormalities in operating room personnel. Studies with 1% and 0.5% N2O in air have confirmed the adverse effects of dilute concentrations of N2O in pregnant rats. The present study was designed to determine the threshold concentration of nitrous oxide necessary to produce adverse responses in pregnant rats. Wistar albino rats were mated in an environmental chamber and conception confirmed by vaginal smears. Immediately thereafter, the rats were randomly divided into control and experimental groups. The control rats were exposed for 19 days to oil-free compressed air in an environmental chamber at a flow rate of 8.5 air changes per hour. Experimental animals were exposed continuously under identical conditions to concentrations of 0.0, 0.1%, 0.5%, or 0.025% N2O. On day 19 the gravid rats were killed. The corpora lutea of pregnancy were counted and related to the number of fetuses in the uterus. Fetuses were fixed, cleared, and their skeletons stained with alizarin red. Litter size, frequency of fetal resorption, and fetal crown rump measurements were significantly different following exposure to 0.1% N2O than they were in control rats or in rats exposed to 0.05% or 0.025% nitrous oxide, neither of which had any fetal effects. The suggested threshold level of 30 ppm (0.03%) N2O in humans may be unrealistically low.

Abnormalities, Drug-Induced↗
PubMed1978

Histologic response of replanted teeth pretreated with acidulated sodium fluoride.

Central incisors in the vervet monkey were extracted, endodontically treated, and replanted into their original sockets after immersion in a 2 per cent acidulated sodium fluoride solution (pH 5.5) for 30 minutes. Histologic examination at 1, 2, 4, and 8 weeks postoperatively showed that by the second week resorption had taken place and that ankylosis, first seen by the fourth week, along both the buccal and palatal root surfaces, was well established by the eighth week. Under the conditions of the study, pretreatment of the tooth roots with 2 per cent acidulated sodium fluoride did not reduce root resorption and ankylosis.

Acids↗
PubMed1978

Nitrous oxide contamination in dental surgeries using relative analgesia.

The concentrations of nitrous oxide were determined at various positions in four dental surgeries in which nitrous oxide sedation was used without scavenging. Contamination was present in all the surgeries, the greatest concentration being recorded at the dentist's nose and the least in the peripheral air. The reception area adjoining the surgeries was found also to be contaminated by nitrous oxide.

Air Pollutants↗
PubMed1978

Comparison of sampling techniques for studies of nitrous oxide pollution.

The retention of nitrous oxide in samples of nitrous oxide in air held in disposable plastic syringes, glass syringes and custom-made nylon film bags was studied by means of gas chromatography at intervals of 90 min, 24, 48 and 120 h after filling the containers. After 24 h the nylon bags retained a mean concentration of 94.5% of the original concentration of nitrous oxide. The disposable plastic syringes and glass syringes were unsatisfactory and retained only 80% of the original concentration of nitrous oxide after 90 min. These values decreased to 51% and 31% of the original concentration of nitrous oxide respectively at 24 and 48 h.

Air Pollution↗
PubMed1978

The role of laboratory animals in dental research.

In dental research, in common with other forms of scientific research, the use of laboratory animals is necessary to carry out many investigations that may not be undertaken on man, and to control biological variability. In South Africa the main experimental animals used in dental research are rats and vervet monkeys, although other species such as dogs and baboons have been used. This paper lists examples of published dental research carried out in laboratory animals in South Africa in the fields of bone healing, dental caries, dental materials, growth studies, oral cancer, oral mucosa and periodontal disease investigations.

Animals↗
PubMed1978

Current status and future options for the development of laboratory animal technology and the training of laboratory animal technicians.

Laboratory animal technology has evolved into a specialised field of expertise which is associated with the production, care and use of laboratory animals in biomedical teaching and research. A survey of laboratory animal facilities and supporting personnel was undertaken to assess the uses of laboratory animals in relation to the administrative and technical staffing of animal facilities. The results of this study indicate that there is a need for training in laboratory animal science at both the technical and professional levels. Options for the development of formal training in laboratory animal technology are reviewed.

Academies and Institutes↗
PubMed1978

The Japanese quail (Coturnix coturnix japonica) as a laboratory animal.

The use of the Japanese quail as a laboratory animal was first reported in 1959. Since then this species has been increasingly used as an avian model for biomedical research. A quail colony was recently established in the Dental Research Institute to provide adult birds for teratogenicity and toxicity studies. These birds are not widely used for biological research in South Africa at present. The housing, husbandry, breeding and nutrition of this species is described, together with the biomethodology which is applicable to this species.

Animal Husbandry↗
PubMed1978

Design and use of an inhalation chamber for air pollution studies in small animals.

Environmental chambers provide a convenient means of studying the toxicology of gases in experimental animals. The specialised equipment needed for these studies is not commercially available. This paper reports on the design, construction and performance of a simple, and inexpensive, inhalation chamber and gas mixing unit for air pollution studies in small laboratory animals. Provision has been made for controlling the mixing of gases, the ventilation rate, the even distribution of gases in the chamber and for the removal of vented gases to prevent the hazard of air pollution in the laboratory animal facility. No significant differences were found between the food and water consumption and body mass gain of a group of rats housed in the chamber for 5 days and a control group housed im similar cages located in a rodent room and managed under conventional laboratory conditions. The chamber fulfills all the requirements for an animal inhalation system.

Air Pollutants↗
PubMed1977

The effect of a proteolytic enzyem mixture (Orenzyme-Forte) on experimentally induced pulpitis.

A proteolytic enzyme mixture, Orenzyme-Forte, containing trypsin, chymotrypsin, and ribonuclease was used to treat experimentally induced pulpitis in the teeth of three monkeys. Assessment by means of the criteria of Stanley showed that the enzyme mixture induced better healing than a zinc oxide--eugenol dressing. When the two were used simultaneously, a synergistic effect was seen. We suggest that this enzyme mixture may be useful in clinical practice in the treatment of pulpitis.

Animals↗