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Biomedical subjects

L J Grant

Publications and source records attributed to L J Grant.

15 recordsLinked to original sources
PubMed1995

Potentiating and inhibitory effects of periodate-oxidized ATP analogs on contractions of vas deferens to ATP.

Previous studies have shown that treatment of guinea-pig isolated vas deferens with the affinity label periodate-oxidized ATP (2',3'-dialdehyde ATP), results in two irreversible effects on biphasic contractile responses to ATP, i.e., potentiation of the P2X purinoceptor-mediated first phase and inhibition of the ecto-kinase-mediated second phase. The present experiments were designed to evaluate whether periodate-oxidized ADP, periodate-oxidized AMP, and periodate-oxidized adenosine, produce similar effects. Periodate-oxidized ATP and periodate-oxidized ADP (10(-2) M) elicited contraction of the vas deferens (periodate-oxidized ATP > periodate-oxidized ADP; periodate-oxidized AMP and periodate-oxidized adenosine had no agonist activity. After incubation of the preparations for 5 min with 10(-2) M periodate-oxidized ATP, periodate-oxidized ADP, periodate-oxidized AMP or periodate-oxidized adenosine, the first phase of contraction to submaximal ATP concentrations was potentiated. Simultaneously, periodate-oxidized ATP, periodate-oxidized ADP and periodate-oxidized AMP inhibited the second contractile phase, whereas periodate-oxidized adenosine did not. The results indicate that the requirement for 5'-phosphate to produce potentiation and inhibition is different: 5'-phosphate is not needed to potentiate the first phase of contraction to ATP, but at least one 5'-phosphate is required to inhibit the second phase of contraction.

Adenosine Diphosphate↗
PubMed1995

Two miniature monitors for long-term ambulatory studies.

Two very low-power monitors are described. One typically limb-worn to record the level of physical activity of a person; the other, used with surface electrodes, to record three parameters of an EMG signal. The monitoring period can extend to days with a very accurate 'time of event' log. A novel method has been devised to double the resolution of the data gathered. A PC is used to store and process the collected data, which can be displayed or printed as one-, or four-channel, time-related histogram. The gathered data can also be analysed for trends and other statistical analysis. The hardware is relatively simple and made from low-cost components. Neither monitor uses a microprocessor for data gathering. The system is very easy to use requiring minimal operator training. Where 'no-frills' ambulatory monitoring is called for, the systems presented would compare very favourably with other commercially available monitors, either on cost, complexity of setting up, or on weight.

Circadian Rhythm↗
PubMed1990

Product liability aspects of bioengineering.

The introduction of the Consumer Protection Act 1987 brought the problems of product liability directly into hospital bioengineering and medical physics departments. This law makes great demands upon manufacturers, but also on suppliers and maintainers of medical equipment. Departments which manage medical equipment carry a responsibility for ensuring the requirements of product liability are known by all those whose actions may affect the potential of a piece of equipment to injure or damage a patient. This paper addresses these problems from a bioengineering, rather than a legal, viewpoint. The problems of design, manufacture, modification, maintenance and use are discussed and examples of potential problems are identified. The paper concludes that as long as good standards of quality control and professionalism are applied in bioengineering and medical physics departments then there is little to be feared from this piece of legislation.

Biomedical Engineering↗
PubMed1984

Assessment of child sexual abuse: eighteen months' experience at the Child Protection Center.

One hundred fifty-seven cases of alleged sexual abuse were assessed. Analysis of these data with respect to age, sex, relationship to assailant, and type of assault corroborate other published data. A 9.5% incidence of gonorrhea and 1.4% pregnancy rate were detected. Referrals were usually made through a parent. Concomitant social work and police investigation are necessary, especially in complex cases. Initial screening enables the scheduling of appointments for medical assessment in many cases.

Adolescent↗
PubMed1984

A microprocessor based instrument for the spectral analysis of the EEG in anaesthesia.

An instrument for monitoring the frequency components contained in the electroencephalogram is described. The technique uses the fast Fourier transform which is implemented in a microprocessor controlled 'black box'. The control and display of the data are organised by a conventional microcomputer. The system is designed for use by practising anaesthetists in a district general hospital environment and is, therefore, inexpensive and simple to operate. The operation of the equipment is described and some limited results from early clinical trials are presented.

Anesthesia↗
PubMed1983

A new nasal oxygen mask.

Recent interest in the benefits of long-term oxygen therapy for patients with chronic airflow obstruction and hypoxaemia should lead to an increased use of nasal prongs for prolonged (15 hours/day) oxygen administration. Because some patients find nasal prongs uncomfortable and since they may slip out of position during use, we have devised a new nasal oxygen mask and compared both its performance and comfort with conventional nasal prongs. Changes in end-tidal oxygen concentration were measured after administering oxygen at 2 litres/min through each device for 10 minutes in 15 normal subjects and for 1 hour in patients with chronic airflow obstruction and hypoxaemia. Although the prongs produced larger increases in end-tidal oxygen concentration in normal subjects, there were no significant differences between the two devices in the patients. There was also no difference in the improvement in arteriolized capillary oxygen tensions (mask 3.5 kPa; prongs 4.0 kPa). In a separate study of prolonged (22 hours) use there was no difference in reported comfort. The new mask is a useful alternative to conventional nasal prongs.

Aged↗
PubMedDate not supplied

Stray RF field strength during radiofrequency endometrial ablation.

A study has been carried out of the RF field strength around a total of 17 patients undergoing radio-frequency endometrial ablation in three hospital centres. The mean equivalent power density at the position of the surgeon exceeded 10 W m-2, which is the derived investigation level for exposure to electromagnetic fields. This value is derived from a basic restriction in the average specific absorption rate in the body to 0.4 W kg-1. This limit applies to general population as well as occupational exposure and is well below that which has been shown to be hazardous to health. Also, the working conditions did not place physical stress on the surgeon. The maximum value of the specific energy absorption rate in the head or trunk should not exceed 10 W kg-1. Measured values on the field strength suggest that this organ dose limit was not exceeded. It is concluded that staff exposure to stray RF radiation during radio-frequency endometrial ablation is not considered to be hazardous to health.

Catheter Ablation↗