Studies on artificial cryptorchidism: compensatory changes in the scrotal testes of unilaterally cryptorchid rats.
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Animals↗
Biomedical subjects
E J Clegg
Publications and source records attributed to E J Clegg.
Studies on artificial cryptorchidism: the histological appearances of unilateral and bilateral abdominal testes in the rat.
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Animals↗
Infectious disease mortality in two Outer Hebridean islands: 1. measles, pertussis and influenza.
OBJECTIVES: The purpose of the study was to examine changes in mortality from measles, pertussis (whooping cough) and influenza (all epidemic diseases) in Harris and Barra, two Outer Hebridean islands, from 1855 to 1990, and to compare the findings with those from Scotland as a whole over the same period. It was also intended to relate changes in mortality to those in social and economic factors. MATERIALS AND METHODS: Ages and causes of death in Harris and Barra were ascertained from copies of death certificates held at the General Register Office, Edinburgh, and for Scotland as a whole from the Annual Reports of the Registrars General for Scotland. Data were standardized by calculating the Proportionate Mortality Ratio (PMR), the proportion of deaths due to a particular cause to all deaths over a given period. Spectral analysis was employed to examine the durations of epidemic cycles. RESULTS: Ages at death increased slightly over the period of the study. For measles and pertussis, other than for the former in Harris, there were significant relationships between numbers of deaths per decade, and numbers of new susceptibles, estimated as the numbers of births. Epidemics of measles and pertussis in the islands occurred at intervals, usually separated by years of no mortality. The highest PMRs were generally during the later decades of the 19th and first decade of the 20th centuries; this may have been related to the economic problems of agriculture and fishing, and to increasing population density. Influenza epidemics were more frequent than those of the other two diseases. For all three diseases in both islands, there were significant negative power relationships between epidemic size and frequency of occurrence; those in Harris were the stronger. The relationships between length and frequency were significant only in Harris. Generally, epidemic lengths seemed less variable than sizes, possibly because of the rather 'coarse' units of length (quarters) employed. Spectral analysis of the 'detrended' data for the period before the introduction of specific immunoprophylaxis revealed that for measles the main epidemic cycle in all three populations was between 7.3 and 7.8 years' duration. Barra and Scotland had additional 2.5- and 2-year cycles, respectively. For pertussis, Harris and Barra had main cycles of 7.4 years. Harris had an additional cycle of 3.2 years. Scotland had cycles of 4 and 2 years. For influenza, Harris had a main cycle length of 7.4 years, and a less-defined one of about 2.6 years. Barra had a main cycle of 6.9 years, and a subsidiary one of 2 years. Scotland has a single cycle of 8 years. Cubic regressions of the spectral densities on cycle frequencies showed large coefficients for Harris and Barra, but small ones for Scotland. Measles coefficients were closely similar in the two islands, but not those for pertussis. CONCLUSIONS: The findings demonstrate the episodic occurrence of epidemics of these three diseases in the two islands, as against their continual presence in the much larger population of Scotland. They reveal also the decreasing importance of these causes of death in all three populations. The data from Harris and Barra suggest that measles is a more epidemiologically 'stable' disease than pertussis. Both islands appear to obey Hamer's law of 'mass action'. The relatively long intervals between epidemics in the islands may be due partly to their isolation, and partly to the slow accumulation of sufficient numbers of susceptibles to enable an epidemic to occur.
Adolescent↗
Infectious disease mortality in two Outer Hebridean islands: 2. pulmonary tuberculosis.
OBJECTIVE: To examine mortality from pulmonary tuberculosis (PTB) in the Outer Hebridean islands of Harris and Barra, and to compare it with that in Scotland as a whole. DESIGN: Ages and dates of death from PTB in Harris and Barra between 1855 and 1990 were ascertained from copies of death certificates. For Scotland, annual numbers of deaths in 5-year age-groups were extracted from Annual Reports of the Registrars General. Proportionate mortality ratios (PMRs) were calculated for each population in the 1-14 and 15 or over age-groups, and the 'detrended' PMRs were subjected to spectral analysis. For this purpose the data were divided into the pre-antibiotic (1855-1950) and antibiotic/chemo-therapeutic (1951-1990) periods. RESULTS: PTB was predominantly a disease of adolescence and early adulthood, although ages at death increased towards the end of the period of study. While PMRs for Scotland decreased steadily after the mid-1870s, apart from increases during the 1940s, those for the two islands increased during the late 19th century, and did not decrease markedly until the 1930s. In the younger age-groups the pattern of mortality was similar to that of an acute infectious disease, while in the older age-group the pattern was largely endemic. Spectral analysis of pre-1951 data from both islands showed marked periodicities in mortality, mostly among the younger age-group. The introduction of effective therapy in the 1950s appeared to lengthen inter-epidemic intervals. There appeared to be no relationship in either island between mortality and socio-economic deprivation, as indicated by numbers of new poor registrations. In Harris, mortality was higher in colder and wetter years. This was not the case in Barra. CONCLUSIONS: The findings are reasonably consistent with a hypothesis that PTB was relatively uncommon in the Outer Hebrides until the later 19th century, and that it behaved epidemiologically like an acute infectious disease. This was not the case with Scotland as a whole, where the disease appeared to be largely endemic.
Adolescent↗
Blood groups and reproduction in Hebridean women.
The distribution of ABO and RH blood groups was studied in 910 fertile women from the Isles of Lewis and Harris. The frequencies of group O mothers fell and of RH-mothers rose with increasing parity, but there were no significant changes in the ABO and RH blood group distributions among their offspring when they were subdivided according to their mothers' parity. When mother-offspring pairs classified according to their ABO and RH compatibility status it was found that RH incompatibility was associated with greater number of previous pregnancies and of abortions. Regression coefficients of birth weight on maternal stature and maternal age were significant only for doubly compatible female offspring and on number of previous pregnancies only for doubly compatible offspring of both sexes. When offspring were classified according to their own and their mothers' ABO blood groups, considerable variations in sex ratio were found. However, the only statistically significant finding was a deficit of A females among the offspring of O mothers. It is suggested that for the ABO blood groups system incompatibility selection, which favours homozygotes rather than heterozygotes, can be counterbalanced by selection for greater maternal tolerance of incompatible offspring with increasing parity. Hence the loss of heterozygotes in lower parity mothers may be compensated by an increase production in higher parity mothers. For the Rh system the same mechanism may occur, but there is evidence additionally of reproductive compensation.
ABO Blood-Group System↗
ABO and Rh blood groups in the Outer Hebrides.
ABO and Rh (D--,dd) phenotype frequencies and gene frequencies are reported on 1547 pregnant women from different populations in the Outer Hebrides. There was significant heterogeneity of ABO gene frequencies in the Isle of Lewis, but not in or between other populations. More heterogeneity was apparent at the Rh locus, significant amounts being present between the populations of rural Lewis, between Lewis and Harris and between Lewis, Harris and the combined populations of North and South Uist, Benbecula and Barra. There was no evidence of heterogeneity due to religion in Benbecula or South Uist. Data on exogamy and endogamy suggest that migration between the various populations has been at a level sufficient to prevent or correct any tendency to genetic diversification. It is suggested tentatively that the heterogeneity observed may be the result of the massive emigration from the islands which has occurred over the last 150 years.
ABO Blood-Group System↗
Blood group variation in the Isle of Lewis.
Blood groups and protein and enzyme polymorphism distributions were studied in 285 residents on the Isle of Lewis, in the Outer Hebrides. As well as gene frequency calculations for individual loci, genetic distance estimations were made and a phylogenetic tree was constructed. The results indicated several major differences from North-west European populations, with high values of R2(CDe), Rz(CDE) and P1. Among protein and enzyme polymorphisms Hp1, EAPA and PGM1(1) had very high frequencies. Genetic distances show Lewis to be unlike both Western and Eastern North European populations, while the phylogenetic tree shows a common, but rather distant, ancestry with Icelanders. This genetic uniqueness of Lewis as a whole is accompanied by a considerable degree of heterogeneity within the island itself, especially in the ABO and Rh systems. Stornoway, with a greater proportion of residents descended from immigrant stock, shows a greater degree of similarity with neighbouring populations. The reasons for both the overall uniqueness and the heterogeneity within Lewis are discussed, but in the absence of a large time-depth and adequate vital records, the various roles of selection, drift and migration in producing them are difficult to establish.
ABO Blood-Group System↗
The use of parental isonymy in inbreeding in two Outer Hebridean populations.
The use of isonomic associations between the parents of spouses is described. Scottish marriage registers contain information on the natal surnames of all four parents of spouses and enable all the four possible types of isonymy between pairs of parents to be identified. Thus assumptions about the sex labelling of pedigrees may be tested and inbreeding coefficients calculated using either each type of isonymy singly or by pooling all types to give 'overall' coefficients. By this latter method the number of potential isonomous events is increased to four times the number of marriages. Assumptions about the randomness of migration with regard to sex may also be tested by comparing coefficients of relationship by isonymy calculated using either paternal or maternal natal surnames. Within populations the coefficients should be lower for the more migrant sex: between populations the reverse should be the case. Similarly the intergenerational 'fluxes' of surnames in parents of either sex may be compared as may be similar variation in surname frequencies. Two small Outer Hebridean islands, Scalpay and Berneray were used to test these assumptions. It was concluded that while the sex labelling of pedigrees appeared to be at random, there was considerable variation in the isonymy inbreeding coefficients and that because of the 4 X greater amount of data, 'overall' coefficients are more reliable. In both islands there appeared to be a greater lability in migrational terms of the female population, although it was impracticable to examine all marriages involving residents of the two islands.
Analysis of Variance↗
Birth dimensions in Melanesian and Indian Fijians and their relationships with maternal and socio-economic factors.
Fifty-nine Melanesian (MF) and 39 Indian (IF) Fijian full-term newborns were studied within 5 days of birth. Dimensions recorded included birthweight, length, crown-rump length, head circumference, upper limb length, bycondylar humeral and femoral diameters and four skinfolds (triceps, subscapular, suprailiac and thigh). Data from previous pregnancies of the presenting newborns' mothers were added to presenting birthweights, giving a total of 160 MF and 84 IF birthweights. In all birthweight and linear dimensions MFs were the bigger. Sex differences were significant in respect only of head circumference and the two bicondylar diameters. Multiple regression analysis showed dimensions in MF newborns to have few significant relationships with the maternal and socio-economic variables of age, parity, stature and years of education, but IFs had many more significant relationships. When covariance correction was made for the significant maternal and socio-economic variables (maternal age and parity) little effect on racial differences was seen. All linear dimensions except length could be subsumed into birthweight. MFs had greater triceps and subscapular skinfold thicknesses than IFs, a difference which was not much changed by covariance correction for significant maternal and socio-economic variables (maternal stature and years of education). Measurements of shape, expressed as ratios of linear dimensions, showed few racial differences but males had relatively broader limbs. For upper limb shape only, this difference was maintained after covariance correction for significant maternal and socio-economic variables (parity, stature and education). The greater size of MF infants at birth is associated with lower peri- and neonatal death rates. However this advantage is reversed during the remainder of the first year of life. It is suggested that better standards of infant care among IFs are responsible for this change.
Birth Weight↗
The growth of Melanesian and Indian children in Fiji.
A cross-sectional study was made of the growth of Melanesian and Indian children residing in or near Suva, the capital of Fiji. Melanesians numbered 283 males and 269 females, Indians 201 males and 216 females. Melanesian ages ranged from 6 to 20; Indian from 6 to 15. Generally Melanesians were larger than Indians at all ages and the most significant discriminating measurements were calf circumference and nose breadth for males, and face height and nose breadth for females. The most significant shape indexes were nasal index, ponderal index and relative sitting height, with Melanesians having relatively broader noses and less linear build. Puberty indicators (breast development, age at menarche) showed Indians to be significantly in advance of Melanesians with the exception of age at B2. In particular menarche was earlier by approximately two years. With a median value of 11.80, Indian menarcheal age appeared to be extremely low. Socioeconomic factors (social class, sibship size, position in sibship) appeared to have a comparatively small effect on growth in the two populations, the exception being age at menarche, which was greater among lower social status children, but earlier in girls from larger families. There was evidence for a secular trend to greater size among Melanesians over the last 15-20 years, but little evidence of a trend during 1930-70. However, the differences between the samples used necessitate caution in the interpretation of the data.
Adolescent↗