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Biomedical subjects

J Austin

Publications and source records attributed to J Austin.

At least 91 records · Page 5Linked to original sources
PubMed1984

Carboxyatractyloside-insensitive influx and efflux of adenine nucleotides in rat liver mitochondria.

Unidirectional transport (influx and efflux) of adenine nucleotides in rat liver mitochondria was examined using carboxyatractyloside to inhibit rapid exchange of matrix and external adenine nucleotides via the adenine nucleotide translocase. Influx of adenine nucleotides was concentration-dependent. ATP was the preferred substrate with a Km of 2.67 mM and V of the preferred substrate with a Km of 2.67 mM and V of 8.33 nmol/min/mg of protein. For ADP, the Km was 14.7 mM and V was 10.8 nmol/min/mg of protein. Efflux of adenine nucleotides was also concentration-dependent, varying directly as a function of the matrix adenine nucleotide pool size. Any increase in the influx of adenine nucleotides was coupled to an increase in efflux. However, as the external ATP concentration was increased, influx was stimulated to a much greater extent than was efflux. This imbalance suggested that under certain conditions adenine nucleotide movement might be coupled to the movement of an alternate anion such as phosphate. Adenine nucleotide efflux increased as the external phosphate concentration was varied from 0.5 to 4 mM. Also, increasing the external phosphate concentration caused adenine nucleotide influx to decrease, suggesting competition. In the absence of external adenines and phosphate, no efflux occurred. Both adenine nucleotide influx and efflux were depressed if Mg2+ was omitted. Adenine nucleotide efflux in the presence of external phosphate was inhibited much less by lack of Mg2+ than was efflux in the presence of external ATP. This evidence supports a model in which either adenine nucleotides (probably with Mg2+) or phosphate can move across the mitochondrial membrane on a single carrier. Net adenine nucleotide movements can occur when adenine nucleotide movement is coupled to the movement of phosphate in the opposite direction.

Adenine Nucleotides↗
PubMed1984

Effects of water and saline irrigation during bone cutting on bone healing.

The healing of standardized bony defects prepared in the mandibles of 24 vervet monkeys with a rotating bur uncooled, or cooled with saline or water, was studied. The experiment showed no difference in healing after 56 days irrespective of the coolant used or whether the bone was cut with or without a cooling agent.

Animals↗
PubMed1984

A microcomputer system in the delivery suite.

Microcomputer systems have been installed in the delivery suites of two obstetric units which cater between them for nearly 10 000 deliveries annually. The midwifery and medical staff enter administrative, antenatal, anaesthetic and delivery details during labour and as soon after delivery as possible. The computer prints out the official Birth Notification, the entry for the Midwives Register and the record of labour and delivery for the patient's notes. Subsequently the postnatal doctor and anaesthetist, where relevant, enter details of puerperium and anaesthetic follow-up, before the production by the computer of discharge and anaesthetic summaries for the community and records. In the first 6 months of use at the Bristol Maternity Hospital (July to December 1982) 2229 patients were delivered and have had obstetric details recorded on the computer. A general obstetric audit of these patients is presented.

Adult↗
PubMed1984

Multiple sclerosis unrelated to dog exposure.

We conducted a case-control study to evaluate the possible association between exposure to dogs and MS. Seventy cases were compared with 70 age- and sex-matched neighborhood controls and 57 cases with 57 age- and sex-matched clinic controls. No association was found, by age groups or by time periods before onset of MS, between MS and presence of any dog, a small dog, a medium or large dog, or an indoor dog in the household. There was a significant negative association between MS and presence of cats in the household and MS and presence of medium and large dogs in the household, and a significant positive association, for several age groups and time periods, between MS and a history of canine distemper in a household dog. The basis for these significant associations is not clear. This study adds weight to the evidence against an association between exposure to small or indoor dogs and MS.

Adolescent↗
PubMed1983

Net adenine nucleotide transport in rat liver mitochondria is affected by both the matrix and the external ATP/ADP ratios.

The adenine nucleotide pool size of rat liver mitochondria may be regulated by a transport mechanism which allows net movement of ATP or ADP across the inner mitochondrial membrane (J. R. Aprille and J. Austin (1981) Arch. Biochem. Biophys. 212, 689-699). Since transport can occur in either direction, and ATP is the preferred substrate, variations in the matrix or external ATP/ADP ratio were examined for an effect on the direction and rate of net adenine nucleotide flux. Fastest rates of net uptake were seen when the external ATP/ADP ratio was high and the internal ratio was low. Conversely, if the external ratio was low and the internal ratio was high, net loss was observed. The rate and direction of net transport were also changed by simply varying the external ATP concentration alone between 0 and 4 mM. Concentrations of less than 1 mM produced net loss of matrix adenines, whereas higher concentrations caused a net increase. The results suggest that changes in relative concentrations of ATP in the external and internal compartments can result in changes in the adenine nucleotide pool size. Another important result was clarification of earlier ambiguous findings with carboxyatractyloside. If care was taken to avoid changes in the matrix ATP/ADP ratio, the addition of carboxyatractyloside had no effect on either net uptake or net efflux of adenine nucleotides.

Adenine Nucleotides↗
PubMed1983

Metachromatic leukodystrophy (MLD). XV. Adult MLD with focal lesions by computed tomography.

A 31-year-old woman with adult metachromatic leukodystrophy was seen for a progressive dementia. Computed tomographic scans showed four, nearly mirror-image, hypoabsorptive areas in cerebral white matter. These symmetric bifrontal and biparietal abnormalities were accompanied by mild ventricular enlargement and by a slight to moderate volume loss throughout the brain. Diffuse white-matter abnormalities of a kind that might otherwise be anticipated in the usual childhood leukodystrophy were not seen.

Adult↗
PubMed1981

Comparison of three anaesthetic scavenging devices using cuffed and noncuffed nasal endotracheal tubes during dental anaesthesia.

During maxillofacial and oral surgery the effect of three anaesthetic scavenging devices used with cuffed and non-cuffed endotracheal tubes was investigated. All the devices produced reductions in nitrous oxide concentrations in the breathing zone and peripheral air, ranging from 36% to 76%. Of the three devices evaluated, the Stellenbosch valve produced the greatest reduction in pollution compared with the control.

Air Pollution↗
PubMed1980

Early and late scavenging of anaesthetic gases.

The effectiveness of two waste gas scavenger devices, the Carstens box and the Ventex apparatus, with regard to nitrous oxide pollution was studied under comparable conditions in an operating theatre. The scavengers were brought into use in the early and late stages of induction of anesthesia, and nitrous oxide concentrations in the breathing zone and theatre peripheral air were measured. Both scavengers reduced nitrous oxide pollution at the sampling points. Similar reductions in nitrous oxide pollution in the breathing zone were obtained with both scavengers, but the Carstens box was more effective in reducing nitrous oxide pollution in the peripheral air.

Air Pollution↗
PubMed1978

Intermittent exposure of gravid rats to 1% nitrous oxide and the effect on the postnatal growth of their offspring.

Three groups of pregnant rats were exposed to 1% nitrous oxide 6 hours a day, 5 days per week for the first, first and second, and all 3 weeks of gestation. The offspring were weighed and measured at weekly intervals. The following variables were evaluated in control and experimental groups: litter size, body weight, tail length and body length. Litter sizes in animals exposed for the first and second weeks of gestation were significantly smaller than the controls. A two-way nested statistical analysis of the data revealed that over an 8-week period the experimental rats were significantly smaller than the control rats of the same age. Analysis of the 95% confidence intervals revealed no particular pattern related to the timing of the exposure to nitrous oxide.

Animals↗
PubMed1978

Experimental fractures of monkey mandibles.

Forty vervet monkey half mandibles, 20 with unerupted third molars and 20 with erupted third molars, were partially embedded in acrylic and loaded in an Instron tensiometer. Mandibles with unerupted third molars fractured at 15.8 +/- 2.5 kg while those having erupted third molars fractured at 26.4 +/- 4.2 kg. Mandibles having unerupted third molars were shown to be significantly weaker than the mandibles with erupted third molar (t = 8.45, P less than 0.001).

Animals↗