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Biomedical subjects

R H Mole

Publications and source records attributed to R H Mole.

At least 55 records · Page 3Linked to original sources
PubMed1979

Radiation effects on pre-natal development and their radiological significance.

The evidence relating to pre-natal radiation exposure and the subsequent occurrence of malformations and cancer suggests that the overall risk lies in the range 0--1 cases per 1000 irradiated by one rad in utero in the first four months of pregnancy. The natural level of occurrence of serious handicaps in average pregnancies is at least 30 times higher. Is the much lower probability of radiation-induced harm sufficiently high to justify (a) concern when a woman who has been irradiated is found to have been pregnant at that time, or (b) the maintenance of restrictions on medical uses of ionizing radiation in women in the reproductive age, such as the ten day rule?

Abnormalities, Radiation-Induced↗
PubMed1977

Absorption and endogenous faecal excretion of calcium by low birthweight infants on feeds with varying contents of calcium and phosphate.

Low birthweight infants aged 4-41 days were given from birth one of three experimental milk formulae varying widely in content of calcium and phosphate. Ca and P in feed, urine, and faeces were measured between carmine markers corresponding to a metabolic period of 48 hours. Calcium enriched in 46Ca to provide a marker for the dietary Ca was added to one feed and 46Ca measured in urine and faeces. True absorption of Ca and endogenous excretion into the bowel could then be inferred. True absorption of Ca was proportional to Ca intake and independent of P intake. Endogenous faecal excretion seemed to be independent of both Ca P intakes, and varied widely between different infants in the range 4-150 mg/day. Urine Ca was low and retention was essentially the difference between true absorption and endogenous faecal excretion. Retention of Ca tended to be much greater on a high Ca intake, but the variability in retention between infants on a given intake was large, paralleling the variability in endogenous faecal excretion. The variability in plasma Ca concentrations in newborn infants may in part be a consequence of wide individual variability in endogenous faecal excretion. The 46Ca marker technique provides a means of investigating the factors determining this variability.

Calcium↗
PubMed1977

Urinary and faecal excretion of marker calcium (46Ca) by low birthweight infants.

Low birthweight infants were given calcium enriched in 46Ca in a single feed. The specific activity of successive urine samples showed that the absorption of the marker was largely complete in about 4 hours. The rate of decrease of urinary specific activity after 3 1/2 hours was exponential and very similar in 8 sets of observations in 6 infants. Its extrapolation backwards to 1 hour may indicate the size of the exchangeable calcium pool, usually about 200 mg/kg body weight. Completeness of faecal collection for estimation of 46Ca is essential for accurate determination of true absorption and endogenous faecal excretion of natural Ca. In 5 infants examined, nor marker was detectable in faeces excreted later than 48 hours after the first stool containing marker. Nevertheless, reasons are given why a collection period limited to 48 hours may sometimes involve error.

Calcium↗
PubMed1976

Skin response to X-irradiation in the guinea-pig.

Skin reaction to X-irradiation has been studied in the albino guinea-pig; early response in limited-field irradiations of the flank is comparable to that commonly seen in rodents, swine and man, and is dose-dependent with a dynamic range from mild erythema to moist desquamation. The peak early skin reaction is seen between 14 and 21 days after irradiation, and declines before 30 days except at the highest doses used. Fractionation of the X-ray dose at 24 hours results in a 'sparing' of about 340 rad. Permanent partial epilation is detectable at doses in excess of 1400 rad, and complete epilation at 1 year occurs in 50 per cent of irradiated fields at 1740 rad. Twenty-four hour two-dose fractionation results in a 'sparing' of about 500 rad for epilation. Palpable dermal 'fibrosis' is detectable at 3 months after irradiation in fields given more than 2070 rad, and at 1 year after irradiation in fields given more than 1800 rad; 50 per cent of fields showed palpable 'fibrosis' at 1 year at 1930 rad. Unlike domestic swine and man, skin fields in the guinea-pig showed no dimensional contraction after X-ray doses which produced gross early skin damage.

Animals↗
PubMed1976

Radiation cancer, safety standards and current levels of exposure.

Cancer can be induced by radiation in any tissue where cancer occurs naturally. The observation that antenatal diagnostic radiography causes a small but definit increas in childhood cancer is as good evidence as could be expected in support of the scientific expectation that there would be no threshold of dose for carcinogenesis. A linear relation between radiation dose and frequency of of induced cancer is a necessary assumption for a system of radiological protection but is not necessarily a reasonable basis for realistic assessments of cancer risk. Indeed there are radiobiological and epidemiological reasons to the contrary. If the linear hypothesis is accepted then at the present time in the UK the routine practice of medicine is of about 2 orders of magnitude more important in causing cancer than environmental pollution by discharge of radio-activity. The acceptability of radiation safety standards for occupational exposure may be justified by comparison of radiation cancer risks with risks from fatal accidents in the safer industries. The acceptability of the corresponding standards for members of the public seems to require more public discussion of the concept of negligible risk. Emotional reactions to uncontrolled releases of radio-activity are based at least in part on a failure to appreciate the hypothesis of linearity.

Air Pollution, Radioactive↗
PubMed1975

Ionizing radiation as a carcinogen: practical questions and academic pursuits The Silvanus Thompson Memorial Lecture delivered at The British Institute of Radiology on April 18, 1974.

Cancer is naturally very common, and practical questions about the possibility of radiation-induced harm are often questions about what in other contexts would be called background noise. Central to the question of whether small radiation exposures are carcinogenic is the effect of antenatal radiography. A comparison of singleton and twin births with radiography rates of 10 and 55 per cent respectively showed that radiography must be the main cause of the elevated frequency of malignant disease. In Japanese bomb survivors, most radiation-induced cancer has been found in those irradiated in adult life, less in those irradiated in childhood and adolescence, and least for exposure in utero. Specific biological differences between different kinds of malignant disease in their induction by ionizing radiation are becoming increasingly evident. When dose-response relationships for observed cancer frequencies are to be used as evidence about dose-response relationships for cancer induction, it will always be necessary to allow for the concomitant cell sterilization. When this is done, there is little support for linearity as the method of extrapolation when making predictions about possible effects of low doses but the absence of threshold seems scientifically inescapable. In cellular terms, radiation induction of cancer must be a very rare phenomenon, so rare compared with cell sterilization or mutation induction, that the general corpus of radiobiological understanding may be inapplicable.

Age Factors↗