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Biomedical subjects

T W Davies

Publications and source records attributed to T W Davies.

At least 19 recordsLinked to original sources
PubMed1992

Oesophageal cancer mortality in Europe: paradoxical time trend in relation to smoking and drinking.

The main risk factors for oesophageal cancer previously identified in western Europe are tobacco smoking and alcohol drinking. However, a study of the time trend from 1951 to 1985 of the mortality from oesophageal cancer in 17 European countries shows that, except among the younger age groups in men, oesophageal cancer had either decreased or increased only slightly in most countries. This trend differed from that of lung cancer, cirrhosis and alcohol consumption which had in general increased substantially during the period. The results strongly suggest that population-wide changes in certain undetermined risk/protective factor(s), one possibility of which is the consumption of fruit, had overridden the effect of tobacco and alcohol and resulted in a reduction of oesophageal cancer risk. Apart from further efforts to reduce smoking and drinking, studies to identify the factor(s) will be of great public health importance to the prevention of oesophageal cancer.

Aged↗
PubMed1992

Maternal and other factors of cryptorchidism--a case-control study in Japan.

A case-control study of cryptorchidism was undertaken in Japan. A hundred and eight mothers of children with cryptorchidism and mothers of their matched controls were surveyed. After 4 pairs which consisted of one of twin siblings either in the cases or the controls were excluded, 104 paired data of singletons were analyzed. As a result, a significantly smaller proportion of the case mothers had suffered from vomiting during the index pregnancy than that of the control mothers (odds ratio, or OR = 0.50, 95% confidence interval, or CI 0.28-0.89). A significantly larger proportion of the case mothers had delivered the index child by vacuum or breech extraction, or Caesarean section than that of the control mothers (OR = 2.09, 95% CI 1.01-3.98). A significantly larger proportion of the case mothers had never breast-fed the index child than that of the control mothers (OR = 3.50, 95% CI 1.20-10.21). Significantly larger proportions of the cases had inguinal hernia (OR = 9.00, 95% CI 1.29-62.97), or congenital cardiac diseases (OR = 8/0, p < 0.05) than those of the controls. It was inferred that endogenous hormonal milieu of a mother, rather than exogenous hormones, might be associated with the occurrence of cryptorchidism.

Birth Weight↗
PubMed1990

Body size and cancer of the testis.

In the search for possible causes for the enormous increase in testicular cancer incidence in Denmark, we tested the hypothesis that a high fat or calorie intake in adolescence and consequently relative obesity is a promotional factor for testicular cancer. A total of 438 cases and three controls for each case were included in the study. Data originated from health examination of men liable for military service. Data were analysed by logistic regression analysis. No systematic statistically significant differences in body measurements [height, weight and body-mass index (weight/height2)] could be shown. Rather than being obese a slight trend was observed towards the future victims of testicular cancer being lighter, smaller and thinner than unaffected controls.

Adolescent↗
PubMed1990

Maternal factors of testicular cancer: a case-control study in Japan.

A case-control study was undertaken in Japan to clarify maternal or prenatal factors associated with testicular cancer. Information was obtained from 37 mothers of testicular cancer patients, recruited from the discharge records of nine hospitals in Hokkaido, the northern island of Japan. Thirty-seven mothers forming a control group were then surveyed at five public health centers. Each control was selected by individually matching the sex and birth year to a testicular cancer case. Univariate analysis revealed that there were no statistically significant differences in the variables surveyed. Multivariate logistic regression analysis, however, showed that case mothers had significantly fewer live-births than control mothers when the following four variables were adjusted (adjusted relative risk per live-birth = 0.43, P = 0.025): age at indexed birth, duration of breast-feeding for indexed child, birth order, experience of induced abortion.

Abortion, Induced↗
PubMed1989

Resting length of the human soleus muscle.

The quantitative relationship between soleus muscle length and the angle of the ankle joint was studied in human cadaver lower limbs of various lengths. The ratio of soleus length to fibula length (lsol/lfib) was linearly related to ankle angle phi A. An expression for soleus resting length lr was derived from the parameters of this relationship and lr was estimated to be 0.998 lfib (S.E. of estimate = 0.004, P less than 0.0001). This gave a mean (+/- S.D.) value of lr of 361.4 (+/- 16.9) mm. The fractional change of lsol produced by rotation of the ankle joint was 0.004 lr.deg-1. The results of these analyses are used to predict lsol changes in intact subjects under varying experimental conditions.

Adolescent↗
PubMed1987

Undescended testis and hormone levels in early pregnancy.

A case-control study was carried out on mothers of boys with undescended testis to investigate the hypotheses that raised maternal levels of oestrogen or reduced levels of human chorionic gonadotrophin in early pregnancy might be factors in the environment of the fetus associated with this condition. No significant difference in the levels of either of these hormones was found, though, if anything, levels of oestrogen may have been lower in cases than in controls, and not higher as previously postulated.

Chorionic Gonadotropin↗
PubMed1986

Detection of depression and facilitation of quantal electromyographic responses in man.

Quantal EMG responses in human muscles and methods of evoking and recording them are described briefly. Techniques and statistical tests for the analysis of quantal H-reflexes are derived from probit analysis: to give a precise estimate of reflex threshold; to characterize the responding motoneurones; to assess threshold shift. With these techniques, the precision of the threshold estimate is usually better than +/- 2%. A probability profile and its associated cumulative sum chart are constructed from quantal response data to assess the latency and time course of conditioned changes in response probability. The application of these techniques is illustrated using recordings from recent experiments in man.

Adult↗
PubMed1986

Risk factors for undescended testis.

The hypothesis that undescended testis is caused by an excess of maternal oestrogen in pregnancy has been tested indirectly in a case-control study comparing mothers of boys with undescended testis (83) and mothers of normal boys (129) born on the same day. The study concentrated on the gestation of the boys, but also investigated the mother's previous obstetric history and postnatal events in the boys. The hypothesis predicted that there should be an excess of nausea, vomiting and hypertension in mothers of cases, but in fact the pregnancies of the case and control mothers were similar in all respects except one. The exception was the increased liability of the mothers of cases to threatened abortion. Mothers of cases also had an increased tendency to miscarry in previous conceptions, a reduced number of deliberate terminations and evidence of decreased fertility. An alternative hypothesis is suggested which would explain these findings. This is that placental function is impaired in the gestation of affected boys and the secretion of human chorionic gonadotrophin is reduced. This leads to changes in fetal testicular function and possible maldescent. Those born with undescended testis were more likely to present to a general practitioner with illness in the first three years after birth and this difference was mainly due to asthma, eczema, jaundice and feeding difficulties.

Adult↗
PubMed1985

Reciprocal inhibition of proprioceptive reflexes in man revealed by a threshold shift technique.

Variations in soleus H-reflex threshold following single conditioning stimuli to tibialis anterior afferents were studied in man by probit analysis of quantal electromyographic responses. The H-reflex threshold was elevated in 6 out of 7 subjects (conditioning-test interval, 2 ms) when conditioning strengths were greater than about 0.70 X tibialis anterior motor threshold: the degree of elevation was exponentially related to conditioning strength. Analysis of response variability indicated that in some cases weaker conditioning was also effective. These findings are consistent with the view that reciprocal inhibition effectively modulates the threshold, rather than the amplitude, of proprioceptive reflex discharge.

Adult↗
PubMed1985

Determination of excitability in human proprioceptive reflexes: analysis and characteristics of EMG thresholds of postural muscle.

In order to derive indirect indices of reflex excitability, human soleus (Sol) H reflex and direct M response threshold intensities (HT, MT) were determined by probit analysis of quantal responses elicited in the surface electromyogram (EMG). Within sessions, HT and MT co-varied with respect to time along a logarithmic time-course, both attaining effectively stable levels after 40-60 min of recording. The pattern of this co-variation was imposed by non-reflex factors, primarily the electrode system employed. Sampling distributions of stable thresholds were positively skewed (median values: HT, 5.20 mA, MT, 6.83 mA), and concurrently determined values were strongly correlated (r = 0.965). The Sol threshold ratio (HT/MT) was largely unaffected by non-reflex factors and was therefore stable within subjects, both within sessions (with respect to time) and between sessions. This ratio was normally distributed (mean = 0.753 +/- 0.079 S.D.). Criteria of indirect indices of reflex excitability are proposed: HT satisfies the criteria applicable to a relative index. However, the characteristics of the threshold ratio permit its use as a powerful absolute index of proprioceptive reflex excitability.

Adolescent↗
PubMed1979

Deaths from ischaemic heart disease and infant mortality in England and Wales.

Death rates from ischaemic heart disease (IHD) in English and Welsh counties are correlated, in both men and women, with the infant mortality rates of those counties when the individuals whose deaths are considered were young, thus confirming previous findings in Norway. In England and Wales, however, there is an equally good correlation between deaths from IHD and infant mortality patterns up to and including that for the same time period as the IHD deaths. The British data provide no grounds for concluding from these relationships that living conditions during early life per se bear a causal relationship to deaths from IHD.

Adult↗
PubMed1978

Travel and ischaemic heart disease.

The hypothesis that travel precipitates acute ischaemic heart disease (IHD) was tested in a case-control study of holidaymakers admitted to hospital in Great Yarmouth. The distance that patients with IHD had travelled to reach Great Yarmouth was on average greater than that travelled by patients with other diseases. I conclude that the greater distances travelled by patients with IHD may have helped to precipitate the attack.

Aged↗
PubMed1976

The application of x-ray analysis in the transmission electron analytical microscope (T.E.A.M.) to the quantitative bulk analysis of biological microsamples.

This paper describes: (a)methods for the high and low temperature ashing of biological tissue samples about 10(-4)-10(-5) g in weight; (b)a method of spraying the solubilized ash on to specimen grids which produces droplets of a size convenient for their quantitative analysis in a transmission electron analytical microscope (T.E.A.M.), but without the need to know the actual volume of individual droplets; (c)the construction of standard curves for determining the absolute concentration of Na, Mg, P, S, K, and Ca simultaneously in a given sample. For most of the elements the error in analysis was about 5% or less. It was proposed that the technique is useful for detecting local element-compartments in complex tissues, and thus may be an important aid in the interpretation of the results of point analyses performed on sections taken from adjacent micro-volumes.

Calcium↗