Genetic differentiation in spite of high gene flow in the dominant rainforest tree of southeastern Australia, Nothofagus cunninghamii

Nothofagus cunninghamii is a long-lived, wind-pollinated tree species that dominates the cool temperate rainforests of southeastern Australia. The species' distribution is more or less continuous in western Tasmania but is fragmented elsewhere. However, it is unknown whether this fragmentation has affected the species' genetic architecture. Thus, we examined N. cunninghamii using 12 nuclear microsatellites and 633 individuals from 18 populations spanning the species' natural range. Typical of wind-pollinated trees, there was low range-wide genetic structure (FST=0.04) consistent with significant gene flow across most of the species' range. However, gene flow was not high enough to overcome the effects of drift across some disjunctions. Victorian populations (separated from Tasmania by the 240 km wide Bass Strait) formed a genetic group distinct from Tasmanian populations, had lower diversity (mean allelic richness (Ar)=5.4 in Victoria versus 6.9 in Tasmania) and were significantly more differentiated from one another than those in Tasmania (FST=0.045 in Victoria versus 0.012 in Tasmania). Evidence for bottlenecking was found in small populations that were at least 20 km from other populations. Interestingly, we found little divergence in microsatellite markers between the extremes of genetically based morphological and physiological altitudinal clines suggesting adaptive differentiation is strongly driven by selection because it is likely to be occurring in the presence of gene flow. Even though the cool temperate rainforests of Australia are highly relictual, the species is relatively robust to population fragmentation due to high levels of genetic diversity and gene flow, especially in Tasmania.

Reappraisal of the historical selective pressures for the CCR5-Delta32 mutation

HIV strains are unable to enter macrophages that carry the CCR5-Delta32 deletion; the average frequency of this allele is 10% in European populations. A mathematical model based on the changing demography of Europe from 1000 to 1800 AD demonstrates how plague epidemics, 1347 to 1670, could have provided the selection pressure that raised the frequency of the mutation to the level seen today. It is suggested that the original single mutation appeared over 2500 years ago and that persistent epidemics of a haemorrhagic fever that struck at the early classical civilisations served to force up the frequency to about 5x10(-5) at the time of the Black Death in 1347.

What caused the Black Death?

For the whole of the 20th century it was believed that the Black Death and all the plagues of Europe (1347-1670) were epidemics of bubonic plague. This review presents evidence that this view is incorrect and that the disease was a viral haemorrhagic fever, characterised by a long incubation period of 32 days, which allowed it to be spread widely even with the limited transport of the Middle Ages. It is suggested that haemorrhagic plague emerged from its animal host in Ethiopia and struck repeatedly at European/Asian civilisations, before appearing as the Black Death. The CCR5-Delta32 mutation confers protection against HIV-1 in an average of 10% of the people of European origin today. It is suggested that all the Deltaccr5 alleles originated from a single mutation event that occurred before 1000 BC and the subsequent epidemics of haemorrhagic plague gently forced up its frequency to 5 x 10(-5) at the time of the Black Death. Epidemics of haemorrhagic plague over the next three centuries then steadily raised the frequency in Europe (but not elsewhere) to present day values.

Human population dynamics

Time-series analysis of parish register series can be used to study human population dynamics at three different levels: (i) The metapopulation of preindustrial rural England. A short wavelength, exogenous oscillation in the burials series of 404 parishes can be detected which, it is suggested, was driven by a cycle of malnutrition associated with wheat prices. (ii) Individual populations, where long-term endogenous oscillations in baptisms and burials of wavelength 30-32 years or 43-44 years can be detected. Their characteristics and causes are explored and elucidated by matrix modelling. (iii) The separate neonatal, post-neonatal, child and adult mortalities in an individual population each show an exogenous short wavelength oscillation and a model is presented to show how these cycles were driven by an oscillation in grain prices and how they interacted. Together, they formed the feedback in a saturated, density-dependent population which was fundamental in controlling the characteristics of the longer wavelength endogenous oscillations in the population dynamics described above.

Modelling the dynamics of scarlet fever epidemics in the 19th century

Annual deaths from scarlet fever in Liverpool, UK during 1848-1900 have been used as a model system for studying the historical dynamics of the epidemics. Mathematical models are developed which include the growth of the population and the death rate from scarlet fever. Time-series analysis of the results shows that there were two distinct phases to the disease (i) 1848-1880: regular epidemics (wavelength = 3.7 years) consistent with the system being driven by an oscillation in the transmission coefficient (deltabeta) at its resonant frequency, probably associated with dry conditions in winter (ii) 1880-1900: an undriven SEIR system with a falling endemic level and decaying epidemics. This period was associated with improved nutritive levels. There is also evidence from time-series analysis that raised wheat prices in pregnancy caused increased susceptibility in the subsequent children. The pattern of epidemics and the demographic characteristics of the population can be replicated in the modelling which provides insights into the detailed epidemiology of scarlet fever in this community in the 19th century.

Protection against cellular damage in the rat heart by iodoacetate

In this comparative study, rat hearts were perfused at 37 degrees C with three clearly defined protocols: the Ca2+ paradox, the O2 paradox, and with 20 mM caffeine. Each protocol involved an initial priming (Ca2+o depletion or anoxia; stage 1) and subsequent full activation (Ca2+o repletion, caffeine or reoxygenation; stage 2) of the damage system of the sarcolemma. Iodoacetate (1 mM) provided complete protection in the O2 paradox and over 80% protection in the Ca2+ paradox and caffeine protocols against creatine kinase release when present throughout the experiment (P < 0.001). Almost identical protection was found when iodoacetate was present only in stage 2 (P < 0.001). However, it was concluded that iodoacetate had limited protective effects when present only in stage 1 in any of the three protocols and that its action is to inhibit the activity of the transsarcolemma damage system in stage 2 when it has been activated in stage 1. It is suggested that iodoacetate interacts with thiol groups on the damage system of the sarcolemma.

A new indanone from the marine cyanobacterium Lyngbya majuscula that inhibits hypoxia-induced activation of the VEGF promoter in Hep3B cells

A new indanone (1) has been isolated from the filamentous marine cyanobacterium Lyngbya majuscula, and its structure determined spectroscopically. Vascular endothelial growth factor (VEGF) is an important regulator of tumor angiogenesis. Compound 1 inhibits hypoxia-induced activation of the VEGF gene promoter in Hep3B human liver tumor cells, in vitro.

Interacting effects of nutrition and social class differentials on fertility and infant mortality in the pre-industrial population

Inadequate nutrition of both the mother and her offspring at each stage of its development - before pregnancy, in the womb, in infancy and during early childhod - played an important role in the patterns of subfertility and infant mortality in a saturated, marginal, preindustrial community. It is suggested that the three social classes had different diets but all were deficient in some essential constituents. Differences in nursing practices in the social groups contributed to differential exogenous mortality and to malnourishment and maternal depletion in the subsistence and (paradoxically) in the elite classes, producing an interacting web of effects and generating a vicious circle from which they could not escape for 150 years. Although the population apparently preferred daughters, the persistent generation effect of low birthweight girls bearing low birthweight daughters probably contributed to the steady-state conditions in this compromised community.

Nutrition, fertility and steady-state population dynamics in a pre-industrial community in Penrith, northern England

The effect of nutrition on fertility and its contribution thereby to population dynamics are assessed in three social groups (elite, tradesmen and subsistence) in a marginal, pre-industrial population in northern England. This community was particularly susceptible to fluctuations in the price of grains, which formed their basic foodstuff. The subsistence class, who formed the largest part of the population, had low levels of fertility and small family sizes, but women from all social groups had a characteristic and marked subfecundity in the early part of their reproductive lives. The health and nutrition of the mother during pregnancy was the most important factor in determining fertility and neonatal mortality. Inadequate nutrition had many subtle effects on reproduction which interacted to produce a complex web of events. A population boom occurred during the second half of the 18th century; fertility did not change but there was a marked improvement in infant mortality and it is suggested that the steadily improving nutritional standards of the population, particularly during crucial periods in pregnancy (i.e. the last trimester), probably made the biggest contribution to the improvement in infant mortality and so was probably the major factor in triggering the boom.

Protection against cellular damage in the rat heart by hyperosmotic solutions

In this comparative study, rat hearts were perfused at 37 degrees C with three clearly defined protocols: the Ca2+ paradox, the O(2) paradox, and with 20 mM caffeine. Each protocol involved an initial priming (Ca(2+)(0) depletion or anoxia; stage 1) and subsequent full activation (Ca(2+)(0) repletion, caffeine or reoxygenation; stage 2) of the damage system of the sarcolemma. Creatine kinase release in stage 2 was completely inhibited (P < 0.001) in all three protocols when 420 mOsm was added to the perfusion medium throughout the experiments, or only during stage 1, or only during stage 2. Increasing the perfusion pressure in the Ca2+ paradox significantly (P < 0.001) exacerbated creatine kinase release, although this was still completely inhibited at 28 degrees C. Amiloride (1 mM) inhibited creatine kinase release completely at 40 cm of water pressure but only some 50% at 80 cm of water pressure. It is suggested that the transmembrane damage system needs to be uncoupled or deactivated by modifying its relationship with the cytosol or with the underlying cytoskeleton by hyperosmotic cell shrinkage for only one of the stages in all three protocols to block the damage pathway. Increased perfusion pressure has the opposite effect and exacerbates damage.

The effects of population density and malnutrition on the dynamics of whooping cough

Liverpool, a seaport in NW England, suffered severely from lethal infectious diseases in the second half of the 19th century: the population was densely crowded and malnourished and life expectancy was low. Time-series analysis shows that the epidemics of whooping cough (i) had an interepidemic interval of 2.9 years, 1863-85, which lengthened to 3.4 years, 1885-1900 (ii) were strongly coherent with wheat prices (P < 0.001) and (iii) also correlated with cycles of seasonal weather conditions. It is suggested from mathematical modelling that the epidemics in this compromised population were maintained (i.e. the system was driven) by an oscillation of malnutrition and by seasonal weather conditions. A model that incorporates both the dynamics of whooping cough and the demographic characteristics of the population is presented. It has been shown to replicate the dynamics of the epidemics and has been used to predict the changes with time of (i) the force of the infection and (ii) the proportion of those infected with whooping cough who died.

Normal adaptive function with learning disability in duplication 8p including band p22

Duplication 8p usually results in a syndrome characterized by profound mental retardation, mild facial anomalies, and malformations of hand, heart, and brain. We report on a large kindred segregating a Y;8 translocation in whom several individuals have duplication 8p22-->8pter. These individuals have normal adaptive function despite their unbalanced karyotype. The family was studied with G-banding and fluorescent in situ hybridization (FISH) using probes to chromosomes 8 and Y. Comparison of this family with other reported cases defines a mild clinical outcome for trisomy 8p22-->8pter in contrast to the severe findings when the duplication involves a longer, more proximal segment.

The interacting effects of prices and weather on population cycles in a preindustrial community

The exogenous cycles and population dynamics of the community at Penrith, Cumbria, England, have been studied (1557-1812) using aggregative analysis, family reconstitution and time series analysis. This community was living under marginal conditions for the first 200 years and the evidence presented is of a homeostatic regime where famine, malnutrition and epidemic disease acted to regulate the balance between resources and population size. This provides an ideal historic population for an investigation of the direct and indirect effects of malnutrition. Throughout the period studied, a short wavelength oscillation in grain prices was apparently the major external factor that drove exogenous cycles in mortality, birth rate, and migration. In particular, the different responses of children to variations in food supply are emphasised; fluctuations in poor nutrition correlated significantly with the variations in mortality rates for infants (probably indirectly during pregnancy and directly during the first year of life) and for young children (via susceptibility to lethal infectious diseases). Migratory movements contributed to the maintenance of homeostasis in the population dynamics. A medium wavelength cycle in low winter temperatures was associated with a rise in adult mortality which, in turn, promoted an influx of migrants into this saturated habitat. A model incorporating these interacting associations between vital events and exogenous cycles is presented: grain prices were an important density-dependent factor and constituted the major component of the negative feedback of this population and drove the exogenous, short wavelength mortality cycles. Cycles of births and immigration provide a positive feedback for the build-up of susceptibles and the initiation of smallpox epidemics and increased population size.

Migration to the New South Wales North Coast 1986-1991: lifestyle motivated counterurbanisation

"Some of [Australia's] most rapid population growth rates have been recorded on the North Coast of New South Wales. The paper sets this migration flow in an international context and looks in detail at the profile, decision-making, and experience of 150 households who moved to the North Coast in the 1986-1991 intercensal period. Results corroborate earlier findings that many coastal migrants are motivated by non-economic considerations. ¿Pull' factors are much more important than ¿push' factors, with the influence of the physical environment, climate and relaxed lifestyle dominant."

The dynamics of measles epidemics

The interepidemic interval (T) of measles in London from 1647 to 1837 evolved progressively from 5-yearly to 2-yearly by 1800. Measles mortality was significantly ( p<0.001) cross-correlated with the annual wheat prices, a good index of nutrition although at a 2-year lag. Epidemics correlated with low autumn temperatures (p<0. 001). A linearised model of the dynamics of epidemics shows that T is determined by the product of population (N) and susceptibility (beta) and that the system will settle at its steady state unless the epidemics are driven. It is suggested that (i) the progressive change in T was caused by a rise in population size (N) and an increased susceptibility (beta) related to malnutrition and (ii) epidemics were driven by oscillations in low autumn temperature (p<0. 001) and by cycles of susceptible young children produced by malnutrition during pregnancy.

Protection against cellular damage in the perfused rat heart by lowered pH

In this comparative study, rat hearts were perfused at 37 degrees C with three clearly defined protocols: the Ca2+ paradox, the O2 paradox and with 20 mM caffeine. Each protocol involved an initial priming (Ca2+(o) depletion or anoxia; stage 1) and subsequent full activation (Ca2+(o) repletion or reoxygenation; stage 2) of the damage system of the sarcolemma. Creatine kinase release in stage 2 was completely inhibited (P < 0.001) in all three protocols when pH was reduced to 6.5 throughout the experiments, or only during stage 1, or only during stage 2. The inhibitor of the Na+/H+ antiporter, amiloride (1 mM), completely prevented creatine kinase release in the Ca2+ paradox (P < 0.001) and markedly reduced damage in the caffeine protocol. Amiloride had no significant effect on creatine kinase release in the O2 paradox. The possible role of Na+(i) was studied in the caffeine protocol: ouabain (5 x 10(-6) M) had little effect whereas substitution of choline for Na+ in the perfusion medium reduced creatine kinase release by about 50%. It is suggested that the same damage system is activated in stage 1 in all three protocols and that a key event is the intracellular production of H+ which are exported via Na+(o)/H(i) exchange. Prevention of H+ efflux by lowered pH(o), even during stage 2, protected against creatine kinase release. The possible role of Na+ movements in the genesis of sarcolemma damage is discussed.

Interacting factors affecting illegitimacy in preindustrial northern England

Illegitimacy in a historic, single community at Penrith, Cumbria (1557-1812), has been studied using aggregative analysis, family reconstitution and time series analysis. This population was living under extreme conditions of hardship. Long, medium and short wavelength cycles in the rate of illegitimacy have been identified by time series analysis; each represents a different response to social and economic pressures. In a complex interaction of events, the peaks of the cycles in wheat prices were associated with rises in adult mortality which promoted an influx of migrants and a concomitant rise in illegitimacy. The association between immigration and illegitimacy was particularly noticeable after the mortality crises of the late sixteenth and early seventeenth centuries. Children of immigrant families also tended to produce illegitimate offspring. Native and immigrant families responded differently to extrinsic fluctuations, and variations in their reproductive behaviour were probably related to access to resources.

Oscillatory dynamics of smallpox and the impact of vaccination

The evolution of smallpox epidemics in London, 1647-1893, was studied by time series analysis of deaths from the disease in the Bills of Mortality. The interepidemic interval (T) evolved progressively from 4 years to 2 years at 1800. The dynamics of epidemics during 1647-1800 are explicable in terms of the transmission of viral diseases which shows that (i) T is determined by the product of population size (N) and susceptibility (beta), (ii) T determines the mean age of catching the disease, (iii) the system will settle at its steady-state, endemic level unless the epidemics are driven. It is suggested that (i) the progressive change in T was initially caused by a rise in N and later by an increased beta related to malnutrition and (ii) the epidemics were driven by an oscillation in delta beta associated with seasonal dry conditions. The effects of variolation and vaccination became apparent after 1800: the endemic level fell progressively, the epidemics were reduced in amplitude and they were not driven. The dynamics of the disease can now be described by an SEIR model: severe outbreaks of smallpox are followed by decaying epidemics. Endemic smallpox mortality also interacts with the dynamics of the population so that a long wavelength oscillation (associated with recovery after the plague) and a 5/6 year (associated with immigration) oscillation are generated.

Extracellular K+ and protection against cellular damage in the rat heart

Rat hearts were perfused at 37 degrees C with three clearly-defined protocols: the Ca2+ paradox, the O2 paradox and with 20 mM caffeine. Each protocol involved an initial priming (stage 1) and a subsequent full activation (stage 2) of the damage system of the sarcolemma. Raising [K+]o from 5.4 to 6.5 mM in the Ca2+ paradox had no significant effect, but creatine kinase release was significantly inhibited (P < 0.001) at 7.5, 10.8 or 16.2 mM. Raising [K+]o to 16.2 mM only during stage 1 or only during stage 2 also inhibited creatine kinase release (P < 0.001); protection was greater than when 16.2 mM [K+]o was present throughout. [K+]o at 10.8 mM exacerbated creatine kinase release in the O2 paradox (P < 0.001) and also when present only during stage 1. However, significant protection was provided when [K+]o was raised only during stage 2 (P < 0.001). Creatine kinase release in the caffeine protocol was significantly inhibited (P < 0.001) at 10.8 mM [K+]o and when [K+]o was raised only during stage 1 or stage 2. It is concluded that raised [K+]o has two opposing effects: prevention of the activation of the membrane damage system and an exacerbation of damage via an increased Ca2+ influx.

The dynamics of scarlet fever epidemics in England and Wales in the 19th century

There was a marked rise in scarlet fever mortality in England and Wales in the mid-nineteenth century and spectral analysis of the registration details, 1847-80, shows that the interepidemic interval was 5-6 years, but after 1880 the endemic level fell and the fatal epidemics disappeared. The dynamics of the scarlet fever epidemics can be represented by a linearized mathematical model and because the system is lightly damped, it could be driven by an oscillation in susceptibility. Epidemics were significantly correlated with dry conditions in spring/summer (P < 0.001), suggesting that these produced a low amplitude oscillation in susceptibility which drove the system. Epidemics also correlated (P < 0.001) with an oscillation in wheat prices but at a lag of 3 years, suggesting that malnutrition during pregnancy caused increased susceptibility in the subsequent children which interacted synergistically with seasonal dry conditions. Scarlet fever mortality was sharply reduced after 1880 in parallel with falling wheat prices suggesting that the remarkable period of high scarlet fever mortality (1840-80) was dependent on poor nutritive levels during that time.

Whooping cough epidemics in London, 1701-1812: infection dynamics, seasonal forcing and the effects of malnutrition

Time series analysis of the London Bills of Mortality, 1701-1812, reveals that whooping cough appeared as a lethal endemic disease after 1700 with epidemics of progressively increasing amplitude after 1720. The interepidemic period changed from 5 years (1720-1750) to 3 years (1750-1785) before returning to 5 years during 1785-1812. The epidemiology of whooping cough can be described by the mathematics of linearized dynamic systems and the interepidemic interval is determined by population size and susceptibility. The latter was governed by fluctuating levels of malnutrition, which were directly associated with oscillations in the wheat prices. It is suggested that the epidemics were driven in 1720-1785 by fluctuating seasonal temperatures which interacted with oscillations in wheat prices to produce an oscillation in susceptibility, but after 1785 the dynamics escaped from the pattern predicted by mathematical theory and the epidemics were apparently driven only by the wheat prices which generated a regular oscillation in susceptibility. The results emphasize the importance of an adequate nutritive level in combating whooping cough in the Third World today where it remains a lethal disease in children because of immunodeficiency linked to fluctuating and severe malnutrition which is often a consequence of crop cycles.

Membrane damage and the Ca(2+)-paradox in the perfused rat kidney

Lactate dehydrogenase (LDH) leaks from the perfused rat kidney under the artificial conditions of a Ca(2+)-paradox protocol, namely Ca(2+)-repletion following a 20 minute period of Ca(2+)-depletion. LDH leakage was markedly suppressed by perfusion at 25 degrees C or with 0.1 mM dibucaine or 2 mM lidocaine. Lidocaine inhibited leakage only during Ca(2+)-depletion. Lowering the perfusion rate significantly reduced LDH escape. No LDH loss occurred if the osmotic pressure of the perfusion fluid was raised by 420 mOsm during either Ca(2+)-depletion or Ca(2+)-repletion. Amiloride (2 mM) significantly reduced LDH leakage to 43%. Reduction of the pH of the perfusion fluid to 6.8 significantly inhibited LDH loss, and at pH 6.4 this leakage was almost completely suppressed. LDH loss was equally suppressed at pH 6.4 only during Ca(2+)-depletion, whereas pH 6.4 was markedly less effective when perfused only during Ca(2+)-repletion. Ouabain (5 x 10(-6) M) had only a limited effect in exacerbating LDH leakage. Raising [K+]o significantly protected against LDH leakage, which fell to 36% at 16 mM [K+]. These features correspond with the Ca(2+)-paradox of the perfused rat heart an it is suggested that: (i) a Ca(2+)-paradox can be produced in the rat kidney; (ii) a similar mechanism governs the release of cytosolic proteins in these two preparations; and (iii) the damage mechanism of the plasmalemma is a transmembrane oxidoreductase-diaphorase molecular complex which generates H+ when activated by Ca(2+)-depletion.

The plague in Penrith, Cumbria, 1597/8: its causes, biology and consequences

Using a family reconstitution study the biology of the plague in Penrith, Cumbria in 1597/8 is described in detail; it was an explosive epidemic that spread rapidly within families and 606 individuals died of the plague, some 40% of the population. The age-specific mortality corresponded with the calculated age structure of the population and infection appeared to be random. The sex ratio of victims was 1.37 females to 1 male. The plague spread from the northeast via Richmond and then exploded in the Eden valley, appearing almost simultaneously in Penrith, Kendal and Carlisle. The details of the epidemics and the location and the climate of these widely separated small market towns show that bubonic plague was not the causative agent, and the possibility that anthrax was responsible for the drastic mortality is briefly considered. The population rapidly built up after the plague, largely by immigration and not by increased fertility, and steady-state conditions were re-established within 5 years and continued for 150 years. This severe mortality crisis of the plague had a profound effect on the population at Penrith, triggering long wavelength oscillations in both baptisms and burials in this population living under marginal conditions and maintained in steady-state by density-dependent factors.

Protective effect of lidocaine on cell damage in the perfused rat heart

The effect of lidocaine (2 mM) on cell damage in the perfused rat heart is compared in three experimental protocols: the Ca(2+)-paradox, the O2-paradox and perfusion with caffeine. Lidocaine protected against creatine kinase (CK) release when perfused throughout or only during the priming stage in all three protocols. Lidocaine also protects against CK release in the Ca(2+)-paradox when present only during Ca(2+)-reperfusion. Lidocaine protects against myofilament damage in the Ca(2+)-paradox but not in the O2-paradox and caffeine protocols, even though CK release is inhibited. Analysis of these different effects of lidocaine on the priming and full activation stages in the three protocols suggests the sequence of the underlying biochemical events of the two separate damage pathways associated with the release of cytosolic proteins and the degradation of the myofilament apparatus.

The protective effect of lowered temperature on the oxygen paradox in the rat heart

The isolated rat heart was completely protected against creatine kinase (CK) release in the standard Ca2+ or O2 paradoxes when perfused at 28 degrees C instead of 37 degrees C, as previously reported. Hearts subjected to the O2 paradox at 28 degrees C recovered normal contractile activity, and electron microscopy revealed normal, undamaged ultrastructure. The mitochondria remained contracted and showed no signs of Ca2+ uptake following a rise in Ca2+ concentration in the cytosol that would be expected following the prolonged period of anoxia. It is concluded that the rise in [Ca2+]i that results from a perturbation of Ca2+ homeostasis during anoxic perfusion in the O2 paradox is not sufficient to cause either CK release or myofilament degradation which follow only on reoxygenation in the second phase of the paradox. Since both the Ca2+ and O2 paradoxes are completely protected when the first stage is carried out at 28 degrees C, it is concluded that the initial activation of the sequence of damage events is prevented at this temperature.

Infant mortality and famine: a study in historical epidemiology in northern England

OBJECTIVE

To examine whether periodic variations in annual infant mortality were associated with malnutrition and the poor quality of the food supply available to the community.

DESIGN

Retrospective study of historical epidemiology of infant mortality by time series analysis and family reconstitution of parish registers of burials and baptisms.

SETTING

Penrith, Cumbria, England, 1557-1812.

SUBJECTS

A total of 17,500 births during 1557-1812.

RESULTS

This community in the Eden Valley, Cumbria, close to the Scottish borders, was living under marginal conditions with high mortality and low fertility. Clear oscillations in infant mortality synchronise with the oscillations in the wheat price index which is regarded as a measure of the availability of food to the community, and to pregnant and nursing mothers in particular. Input-output analysis showed that the relationship between the wheat price index (input) and infant mortality (output) was highly significant (p < 0.001). Events during the famine of 1623 have been analysed in detail: high wheat prices during pregnancy caused subsequent severe infant mortality but did not have indirect effects on the subsequent mortality of the surviving children over the age of 1 year. Non-stationary oscillations in neonatal and post neonatal mortality were strongly coherent (p < 0.001) with the wheat price index throughout the period.

CONCLUSIONS

Infant mortality is particularly sensitive to famine and also to the quality of the food supply available to pregnant and nursing mothers. The lags between neonatal and post-neonatal mortalities and wheat prices, together with the analysis of the famine of 1623, support the hypothesis that neonatal mortality was related to malnutrition in pregnancy whereas post-neonatal mortality was primarily directly dependent on exogenous causes in the first year of life.

The action of phenazine methosulphate in causing cellular damage in the isolated mouse soleus muscle preparation

Exposure of the isolated mouse soleus preparation to 1.0 mM phenazine methosulphate (PMS) caused (i) a slow and modest release of creatine kinase (CK) that was exacerbated by removal of extracellular Ca2+, (ii) a specific type of ultrastructural damage, namely a characteristic spacing of the myofibrils, (iii) swelling of the mitochondria, indicating a modest rise in [Ca2+]i, and (iv) swelling of the sarcoplasmic reticulum (SR). It is suggested that PMS (i) activates a sarcolemma oxidoreductase which synergistically interacts with raised [Ca2+]i to cause modest CK efflux and (ii) activates an oxidoreductase on the SR, thereby generating electrons which directly modify the integrity and organisation of the contractile apparatus.

Modelling the different smallpox epidemics in England

Time series analysis has revealed two different patterns of smallpox epidemics in Britain in the seventeenth and eighteenth centuries: in large conurbations (exemplified by London) the disease was endemic whereas medium-sized rural towns (exemplified by Penrith, Cumbria) suffered from 5 year epidemics with no cases of smallpox in the inter-epidemic years. The oscillations (epidemics) persisted for over 150 years and it is suggested that both systems were pumped up by regular fluctuations in susceptibility (delta beta). Modelling suggests that: (i) the natural frequency of oscillations in large cities is two years and the system is pumped up by a 1 year, seasonal input; (ii) it takes five years to build up a pool of susceptibles in medium-sized towns by new births and epidemics are then triggered by a 5 year input. The equations represent a system that has two components, a basic linear element with the remainder of the system being nonlinear; modelling a progressive increase in delta beta in London illustrates theoretically how a predominantly linear response changes to a nonlinear response and ultimately to chaos. A variation in susceptibility is a theoretical condition for inducing chaos; the undriven system cannot become chaotic. Modelling populations of progressively increasing size/density and applying a 1 year or 5 year sinusoidal oscillation in delta beta illustrates the fundamental distinction in the response of medium-sized rural towns and large cities.

Ultrastructural changes in rat kidney mitochondria in response to the oxygen- or calcium-paradox

Isolated, perfused rat kidney released lactate dehydrogenase in response to the protocol of a standard oxygen-paradox or calcium-paradox. The results are comparable to those found with rat heart. The mitochondria of the proximal tubule cells at the end of the calcium-paradox were swollen, had mitochondrial bars and were subdivided with internal septa; after the oxygen-paradox they exhibited, in addition, many myelin figures. Such ultrastructural changes were characteristic of the mitochondria of skeletal and cardiac muscles damaged by a rise in [Ca2+]i. It is concluded (i) that typical calcium- and oxygen-paradoxes can be produced in kidney, (ii) that these are associated with a rise in [Ca2+]i and (iii) the proximal tubules, in particular, are damaged.

Are oxygen radicals implicated in the calcium paradox of the rat heart?

No reduction in creatine kinase (CK) release during standard Ca2+ paradox in the Langendorff-perfused rat heart was afforded by anoxic perfusion, nor by addition of the radical scavengers superoxide dismutase (150,000 U/L), catalase (150,000 U/L), mannitol (15 or 50 mM), dimethylthiourea (DMTU, 10 mM), the antioxidant vitamin E (0.25 or 0.75 mM), or the iron chelator desferrioxamine (0.8 mM). Even under mild Ca(2+)-paradox conditions, achieved by (a) reducing the duration of the Ca(2+)-free period, (b) increasing [Ca2+]0 during the "Ca(2+)-free" period, or (c) reperfusing with 0.1 mM Ca2+, no protection was achieved by mannitol, DMTU, or desferrioxamine. Perfusion with N2 did not cause a reduction in CK release caused by caffeine or dinitrophenol or Ca2+ paradox. We conclude that no evidence supports the hypothesis that oxygen radicals are implicated in release of CK in Ca2+ paradox.

The dynamics of smallpox epidemics in Britain, 1550–1800

Time-series analysis, a valuable tool in studying population dynamics, has been used to determine the periodicity of smallpox epidemics during the seventeenth and eighteenth centuries in two contrasting representative situations: 1) London, a large city where smallpox was endemic, and 2) Penrith, a small rural town. The interepidemic period was found to be two years in London and five years in Penrith. Equations governing the dynamics of epidemics predict 1) a two-year periodicity and 2) that oscillatory epidemics die out quickly. It is suggested that epidemics were maintained by a periodic variation in susceptibility linked either to a five-year cycle of malnutrition or to an annual cycle. Computer modeling shows how the very different patterns of epidemics are related to population size and to the magnitude of the oscillation in susceptibility.

Biochemical pathways of cell damage during the oxygen paradox of the rat heart

1. The standard O2-paradox has been studied in the Langendorff-perfused rat heart. 2. Perfusion of glucose-free saline under anoxia did not cause release of creatine kinase (CK) although, it is suggested, there was a progressive rise in [Ca2+]i. 3. Ca(2+)-depletion after anoxia caused CK release. 4. Prolonged anoxic perfusion (55 min) produced a markedly reduced release of CK on Ca(2+)-depletion because, it is suggested, of the reduction in substrates for the release mechanism. 5. No protection against the O2-paradox was found with oxygen radical scavengers and inhibitors. 6. Lowering [Ca2+]o during reoxygenation to 0.1 mM did not reduce CK release. 7. Neither 1 mM amiloride (Na+/H+ antiporter inhibitor) nor 2 x 10(-6) M 1-(5-isoquinolinesulphonyl) piperazine (protein kinase C inhibitor) reduced CK release, unlike their effects in the Ca(2+)-paradox. 8. An hypothesis for events in the O2-paradox in presented: anoxia causes a loss of Ca(2+)-homeostasis and a rise in [Ca2+]i thereby activating a transmembrane NAD(P) oxido-reductase/diaphorase (stage 1); the return of O2 synergistically activates this molecular complex and causes CK release (stage 2).

The dynamics of smallpox epidemics in Britain, 1550-1800

Time-series analysis, a valuable tool in studying population dynamics, has been used to determine the periodicity of smallpox epidemics during the seventeenth and eighteenth centuries in two contrasting representative situations: 1) London, a large city where smallpox was endemic, and 2) Penrith, a small rural town. The interepidemic period was found to be two years in London and five years in Penrith. Equations governing the dynamics of epidemics predict 1) a two-year periodicity and 2) that oscillatory epidemics die out quickly. It is suggested that epidemics were maintained by a periodic variation in susceptibility linked either to a five-year cycle of malnutrition or to an annual cycle. Computer modeling shows how the very different patterns of epidemics are related to population size and to the magnitude of the oscillation in susceptibility.

Does the protein kinase C pathway modulate sarcolemma damage and the release of cytosolic proteins in the rat heart?

1. The release of creatine kinase (CK) in the Langendorff-perfused rat heart during the Ca(2+)-paradox, was critically dependent on the duration and [Ca2+]o of the initial Ca(2+)-depletion phase. 2. When [Ca2+]i was raised by perfusion with caffeine or under N2, activation of the protein kinase C pathway (PKC) produced a small but significant release of CK. PKC stimulation is therefore able to substitute for the Cao(2+)-depletion of the Ca(2+)-paradox. 3. The PKC inhibitor, 1-(5-isoquinolinyl sulphonyl)-2-methyl piperazine, (2 x 10(-6) M) inhibited both the Ca(2+)-paradox and caffeine-induced release of CK. 4. It is concluded that the PKC pathway has a regulatory role for the damage system of the sarcolemma that is responsible for the release of cytosolic proteins.

Cellular damage in the rat heart caused by caffeine or dinitrophenol

1. Langendorff-perfusion of rat hearts with either 10 mM caffeine or 1 mM 2,4-dinitrophenol (DNP) caused severe ultrastructural damage to the myofilaments and mitochondria that was similar to that found in a standard Ca(2+)-paradox. 2. This damage occurred in the presence and absence of extracellular Ca2+. 3. Creatine kinase (CK) release (indicative of sarcolemma breakdown) was not recorded unless the caffeine- or DNP-perfusion was preceded by Ca(2+)0-depletion. 4. It is concluded that: (i) the pathways leading to damage to the myofilaments and sarcolemma are independent; (ii) the CK release mechanism requires dual activation of Ca(2+)0-depletion plus a rise in [Ca2+]i; and (iii) current theories concerning the mechanisms underlying the genesis of the Ca(2+)-paradox are incorrect or incomplete.

An hypothesis for the periodicity of smallpox epidemics as revealed by time series analysis

Parish registers have been studied by time series analysis to detect smallpox epidemics in England during 1600-1800. Confirmatory evidence was provided by the seasonality of child mortality. A 5-year cycle in smallpox epidemics was detected in medium-sized, rural towns. Consideration of the mathematics of the dynamics of viral diseases suggests that the true interepidemic period where smallpox is endemic should be 2-3 years and it is concluded that, in the towns studied, the disease was not endemic but that the oscillations were established by 5-year cycles of periods of famine associated with high wheat prices. The cross-correlation function between the two cycles shows zero lag and the input-output function shows significant coherence. Another epidemic follows only when a sufficient density of susceptibles has been established by births, so that the cycles become phase-locked. It is predicted that smallpox (i) was endemic in London and other large cities, with 2-3 year epidemics, (ii) was epidemic with a 5-year oscillation in rural towns, (iii) did not reach epidemic proportions in scattered communities.

Interaction of H2O2 and dithiothreitol and the genesis of cellular damage in the perfused rat heart

1. H2O2 (0.3 mM) causes release of creatine kinase (CK) from the perfused rat heart, but only when activated by removal of extracellular Ca2+. 2. Dithiothreitol (DTT), 2 mM, provides partial protection against this damage induced by artificially-introduced O2 radicals. 3. Paradoxically, DTT triggers CK release by H2O2 in the presence of extracellular Ca2+. The interaction of these agents in stimulating and protecting against this damage to the sarcolemma is discussed.

Fra(X) prenatal diagnosis: are endoreduplicated and polyploid cells useful diagnostic criteria?

Cytogenetic and molecular protocols for prenatal ascertainment of the fragile X syndrome and the associated fragile site at Xq27.3 are relatively reliable. Any new diagnostic method which becomes available still elicits much interest. Kimchi-Sarfaty et al. [1991] reported an increase in frequency of endoreduplication and polyploidy in fra(X) lymphoblasts and amniocytes when cultured with methotrexate (MTX) or fluorodeoxyuridine. Recently we analyzed the endoreduplication/polyploidy system using amniotic fluid, chorionic villus, and fibroblasts from fra(X) positive abortus cell cultures and from control samples. We observed no increased expression of endoreduplicated or polyploid cells in fra(X) positive amniocytes after exposure to MTX. The data presented here clearly dispute the value of endoreduplication/polyploid scoring as a diagnostic aid in prenatal fra(X) analysis.

Dialyzed fetal bovine serum increases cytogenetic fragile X expression

Short-term whole blood cultures from 9 unrelated male individuals with the fragile X [fra(X)] syndrome were exposed to 5-fluorodeoxyuridine (FUdR). The fra(X) frequency was higher in 8 of 9 cases where the complete medium contained dialyzed fetal bovine serum (DFBS). In 3 of the cases, the fra(X) frequency nearly tripled (e.g., 12/100 to 33/100) while in 2 others, it nearly doubled (e.g., 15/100 to 29/100). When DFBS cultures from 2 other fra(X) individuals were exposed to increasing folic acid concentrations ranging from 2 to 4,000 x 10(-6) M, there was virtually no change in fra(X) expression. In 6 of 9 DFBS cultures, the mitotic index decreased, and it increased in 3. Therefore, although the fra(X) frequency increased, in most DFBS cultures the mitotic index decreased. Whether the reduction in mitotic index indicates an inverse correlation between reduced mitotic index and increased fra(X) expression, at least in cultures from some individuals, will be determined by additional studies.

IN CONCLUSION

(1) medium supplementation with dialyzed fetal bovine serum should be considered when using FUdR for fra(X) identification in order to avoid potentially false negative results; (2) there appears to be no direct correlation between increased mitotic index and increased fra(X) expression in whole blood cultures; (3) increased folic acid concentrations do not affect fra(X) expression when FUdR fra(X) induction is employed; therefore requesting people to refrain from taking vitamins, including folic acid, before fra(X) testing (a practice that still persists in some places) appears unnecessary.

Fra(X)(q27.2), the common fragile site, observed in only one of 760 cases studied for the fragile X syndrome

Cell cultures from 760 whole blood, amniotic fluid, chorionic villus sample, and peripheral umbilical blood sample specimens were exposed to multiple fra(X)(q27.3) induction systems (none had aphidicolin). Fifty-three exhibited the rare fragile site, fra(X)(q27.3) or FRAXA, none of which demonstrated the common fragile site or FRAXD at band Xq27.2. Only one cell in one of the negative whole blood FUdR-treated cultures from a mentally retarded male showed FRAXD. Therefore, it appears that FRAXD occurs very rarely in cultures treated to induce FRAXA since only one positive cell was observed in over 88,000 analyzed. It appears that very low frequencies of fra(X)(q27) can be accounted for only in part by the presence of the common fragile site since only one of 9 cases, each with one fra(X)(q27) positive cell, exhibited FRAXD and the others were FRAXA. After confirmation of FRAXA with direct DNA testing in a large number of low frequency cases, it should be possible to rely on the detection of very low frequencies of fra(X)(q27.3), e.g., 1% with at least 2 positive cells.

SV40-transformed fragile (X) amniocytes

We report SV-40 transformation of female and male fragile X [fra(X)] amniocytes. In the transformants, fra(X) (q27.3) was detected in the 7th passage (9 cell generations) in fra(X) female amniocytes. It was conserved until at least the 20th passage (42 cell generations) although the frequency was reduced or became difficult to detect due to karyotypic evolution in the later generations. Similarly, for the male fra(X) amniocyte line, fra(X) was demonstrated at the 2nd passage (3 cell generations) and persisted until at least the 13th passage (29 cell generations). The prolonged period of reproductive potential of these transformed lines ranging from at least 29-42 generations suggests that the cryopreservation of significant quantities of early passage fra(X) transformed amniocytes will assure a reliable and continuous supply of positive control cells. These lines may be used for fra(X) prenatal diagnostic studies thereby improving the ability to quality control the particular fra(X) induction system being used.