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Biomedical subjects

J F Fowler

Publications and source records attributed to J F Fowler.

At least 145 records · Page 8Linked to original sources
PubMed1989

Repair kinetics in mouse lung: a fast component at 1.1 Gy per fraction.

Four experiments to measure the half-time of repair of radiation damage in mouse lung are described. Three of these experiments used two or four doses per fraction of 3.6-9 Gy. Half-times of approximately 0.6 h were found. The fourth experiment investigated repair between the two doses in pairs of small doses given daily (26F x 1.1 Gy in 13 days). Evidence was obtained of more rapid repair between these small fractions, with a half-time of 0.30 h. Using the best methods of analysis appropriate to each experiment, the 95 per cent confidence limits for the T1/2 values at 1.1 Gy per fraction did not overlap with those for the large doses per fraction.

Animals↗
PubMed1989

Allergic contact dermatitis from glutaraldehyde exposure.

A hospital maintenance employee developed an airborne contact dermatitis when cleaning respiratory therapy equipment. Patch-testing determined that she is allergic to glutaraldehyde, an ingredient in a popular commercial germicidal product. The increasing concern over acquired immunodeficiency syndrome (AIDS) and other infectious diseases has resulted in more intensive cleaning, sterilizing, and disposal procedures in health care facilities. This, in turn, may lead to an increased risk of contact dermatitis among health care workers. Glutaraldehyde is commonly used as a sterilizing agent in medical facilities. It is effective against most micro-organisms, including viruses, and is generally harmless to medical equipment. This report concerns a case of airborne allergic contact dermatitis caused by glutaraldehyde.

Aldehydes↗
PubMed1989

First interim progress report on the second British Institute of Radiology Fractionation Study: short versus long overall treatment times for radiotherapy of carcinoma of the laryngopharynx.

Preliminary data from a second British Institute of Radiology Fractionation Trial comparing short (less than or equal to 4 weeks) and long (greater than 4 weeks) overall treatment times are reported. The intake of patients ran from January, 1975 to December, 1985 when 611 patients with carcinoma of the laryngo-pharynx were registered in this prospective, randomized, multicentre clinical trial. No significant differences have, so far, been demonstrated between the two arms of the trial with respect to observed survival rates, tumour-free or laryngectomy-free rates. Further long-term follow-up is continuing.

Clinical Trials as Topic↗
PubMed1988

Repair kinetics in mouse lung after multiple X-ray fractions per day.

The potential advantage for sparing normal tissue damage by hyperfractionation of low-LET radiation may be limited by the repair kinetics of tissues in the irradiated field. Tissues with slow repair kinetics will limit the number of fractions that may be given on the same day. Results are presented for mouse lung treated with a range of doses per fraction using either two or three fractions per day in multiple X-ray fractionation schedules. The results are analysed to determine whether the repair kinetics follow a single exponential function of time. The calculated repair rate (T1/2) was about 1.2 h for two fractions per day of 2 Gy (10F/5d) but slightly less (T1/2 = 0.8 h) for two fractions of 9 Gy (2F/1d). For smaller doses per fraction of 1.1 Gy, given three times per day (39F/13d), the T1/2 was not significantly less (T1/2 = 0.3-0.7 h). For three fractions per day of 1.1 Gy per fraction an unsatisfactory fit is achieved using a single exponential function of time, and a better fit is obtained using two components of repair. The repair kinetics are slow for lung, in comparison to acute reacting tissues (except skin), and may require that 6-8 h (i.e. four or five half-times) should be allowed between fractions on the same day so that more than 95 per cent of the repairable dose is repaired. At present the variation in repair kinetics with doses per fraction between 1.1 and 9 Gy are not significantly different, so no reduction of interfraction interval should be proposed.

Animals↗
PubMed1988

Radiotherapy employing three fractions on each of twelve consecutive days.

In order to achieve the greatest advantage of accelerated hyperfractionated radiotherapy, treatment has been given 3 times each day for 12 consecutive days without a rest period. A total tumour dose of 50.4 Gy was well tolerated in a series of 38 patients with bronchial, head and neck and oesophageal carcinomas. A further 14 patients have now received an elevated dose of 54 Gy, again with satisfactory tolerance. The tumour responses at all these sites have been very promising and further work is proceeding.

Bronchial Neoplasms↗
PubMed1988

Intervals between multiple fractions per day. Differences between early and late radiation reactions.

Assuming the linear quadratic model for dose-response curves enables the proportion of repairable damage to be calculated for any size of dose per fraction. It is given by the beta (dose squared) term, and represents a larger proportion of the total damage for larger doses per fraction, but also for late-reacting than for early-reacting tissues. For example at 2 Gy per fraction, repairable damage could represent nearly half the total damage in late-reacting tissues but only one fifth in early-reacting tissues. Even if repair occurs at the same rate in both tissues, it will obviously take longer for 50% of the damage to fade to an undetectable level (3 or 5%) than for 20% to do so. This means that late reactions require longer intervals than early reactions when multiple fraction per day radiotherapy is planned, even if the half-lives of repair are not different.

Humans↗
PubMed1987

Survival of mouse type B spermatogonia for the study of the biological effectiveness of 1 MeV, 2.3 MeV and 5.6 MeV fast neutrons.

The most radiation-sensitive cells in the testis are B and intermediate spermatogonia. We have used a histological scoring technique to compare three neutron beams of different mean energies (1 MeV at the ECN, Petten, 2.3 MeV at the Gray Laboratory, Northwood, and 5.6 MeV at the Oncological Centre, Krakow). CBA inbred mice, 14-20 weeks old, were exposed to whole-body irradiation with single doses of either X-rays (0.1-1 Gy) or neutrons (0.2-0.25 Gy). Relative biological effectiveness values, calculated at the level of 50 per cent reduction in survival of B spermatogonia, were 5.7 at the ECN, Petten, 4.6 at the Gray Laboratory and 3.0 at the Oncological Centre in Krakow. The Do value for the B spermatogonia after X-rays was 0.34 +/- 0.02 Gy when the data from the three centres were combined. Do values for neutrons for the examined spermatogonia were 0.08 Gy, 0.09 Gy and 0.11 Gy at the ECN, Petten, the Gray Laboratory and the Oncological Centre, respectively.

Animals↗