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Biomedical subjects

S R Duncan

Publications and source records attributed to S R Duncan.

59 records · Page 4Linked to original sources
PubMedDate not supplied

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.

England↗
PubMedDate not supplied

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.

Age Factors↗
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Distinguishing between infection, rejection, and the adult respiratory distress syndrome after human lung transplantation.

The adult respiratory distress syndrome, bacterial pneumonia, cytomegalovirus pneumonitis, acute rejection, or a combination thereof were the primary causes of radiographic infiltrates or gas exchange abnormalities that occurred early after lung transplantation. The time of occurrence after transplantation, standard measures of clinical assessment as for nontransplant patients (i.e., vital signs, weight, white blood cell count, sputum, and cultures, etc.), bronchoalveolar lavage, and transbronchial lung biopsy were the primary tools used to analyze these situations. Bacterial pneumonia always occurred after postoperative day 2, acute rejection after postoperative day 5, and cytomegalovirus pneumonitis after postoperative day 16. Although cultures of bronchoalveolar lavage fluid were useful to detect pneumonia caused by bacteria, virus, and fungus, the types of cells recovered by bronchoalveolar lavage were not diagnostic of any type of disorder. Transbronchial lung biopsy was necessary to detect acute rejection and cytomegalovirus pneumonitis. Thus the cause of an early radiographic infiltrate or impairment of gas exchange was almost always reliably determined by using standard tools of clinical assessment, knowledge of the usual temporal sequence of the complications, and judicious use of bronchoalveolar lavage and transbronchial lung biopsy.

Biopsy↗
PubMedDate not supplied

Donor cerebral emboli as a cause of acute graft dysfunction in lung transplantation.

Early graft dysfunction in lung transplantation has many causes, most commonly preservation injury. This report details a more unusual cause of graft failure and respiratory decompensation in the early postoperative period donor cerebral emboli occluding segments of the pulmonary arterial tree in the implanted lung allografts of two patients who had received single lung implants from a common donor in whom massive cerebral trauma had been incurred in a motor vehicle accident. The incidence, complications, and clinical manifestations of cerebral emboli are discussed.

Adolescent↗