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Biomedical subjects

R M Anderson

Publications and source records attributed to R M Anderson.

At least 343 records · Page 19Linked to original sources
PubMed1981

Progressive multifocal leukoencephalopathy.

Three cases of progressive multifocal leukoencephalopathy have occurred in one hospital in a 3-year period. The 3 patients had been receiving chemotherapy for chronic myeloid leukaemia, lymphocytic lymphoma and acute myeloid leukaemia respectively, and developed progressive neurological illnesses which resulted in their deaths. The routine neurological investigations were unhelpful and although the diagnosis was suspected in 2 cases, treatment was not given. It is felt that the disease is not as rare as originally believed and that brain biopsy should be more readily considered since progressive multifocal leukoencephalopathy is potentially treatable.

Astrocytes↗
PubMed1980

The use of repeatedly prescribed medicines.

The use of prescribed medicines was investigated by interviewing a random sample of 836 people aged 18 and over, living in England and Wales. Two fifths of respondents had taken some prescribed medicine, excluding an oral contraceptive, in the two weeks before the interview; nearly a quarter of all people were taking some medicine first prescribed one year or more previously. Medicines from two therapeutic classes, psychotropics and diuretics or preparations acting on the cardiovascular system, made up half of all the long-term prescriptions. It seems that the number of people taking long-term prescriptions of diuretics or medicines acting on the cardiovascular system has trebled since 1969, although the general distribution of long-term prescribed medicines, in age and sex groups, has remained much the same as it was in 1969. People classified as working-class were more likely than middle-class people to be taking some medicine on a long-term prescription.

Adolescent↗
PubMed1979

Population biology of infectious diseases: Part II.

In the first part of this two-part article (Nature 280, 361--367), mathematical models of directly transmitted microparasitic infections were developed, taking explicit account of the dynamics of the host population. The discussion is now extended to both microparasites (viruses, bacteria and protozoa) and macroparasites (helminths and arthropods), transmitted either directly or indirectly via one or more intermediate hosts. Consideration is given to the relation between the ecology and evolution of the transmission processes and the overall dynamics, and to the mechanisms that can produce cyclic patterns, or multiple stable states, in the levels of infection in the host population.

Bacterial Infections↗
PubMed1979

Population biology of infectious diseases: Part I.

If the host population is taken to be a dynamic variable (rather than constant, as conventionally assumed), a wider understanding of the population biology of infectious diseases emerges. In this first part of a two-part article, mathematical models are developed, shown to fit data from laboratory experiments, and used to explore the evolutionary relations among transmission parameters. In the second part of the article, to be published in next week's issue, the models are extended to include indirectly transmitted infections, and the general implications for infectious diseases are considered.

Animals↗
PubMed1979

A sequential study of changes in the brain and cerebrospinal fluid of the rat following triethyltin poisoning.

Following a single intravenous (i.v.) injection of triethyltin (10 mg/kg) in rats, vacuoles appeared in the myelin sheath within 3 h and they progressively increased in size between 6 and 24 h. Their development was closely correlated with a progressive increase in water, sodium, and chloride content of the brain, and of cerebrospinal fluid (CSF) pressure. Oedema was more extensive in tissues consisting predominantly of white matter rather than grey matter. The sustained increase in CSF pressure did not precede the development of lesions and was the result of, rather than the cause of, brain oedema and swelling. These findings indicate that triethyltin has a direct effect on the myelin sheath.

Animals↗
PubMed1979

Prevalence of schistosome infections within molluscan populations: observed patterns and theoretical predictions.

The paper draws together a large and scattered body of empirical evidence concerning the prevalence of snail infection with schistosome parasites in field situations, the duration of the latent period of infection in snails (and its dependence on temperature), and the mortality rates of infected and uninfected snails in field and laboratory conditions. A review and synthesis of quantitative data on the population biology of schistosome infections within the molluscan host is attempted and observed patterns of infection are compared with predictions of a schistosomiasis model developed by May (1977) which incorporates differential snail mortality (between infected and uninfected snails) and latent periods of infection. It is suggested that the low levels of prevalence within snail populations in endemic areas of schistosomiasis are closely associated with high rates of infected snail mortality and the duration of the latent period of infection within the mollusc. In certain instances, the expected life-span of an infected snail may be less than the duration of the latent period of infection. Such patterns generate very low levels of parasite prevalence. A new age prevalence model for schistosome infections within snail populations is developed and its predictions compared with observed patterns. The implications of this study of observed and predicted patterns of snail infection within molluscan populations are discussed in relation to the overall transmission dynamics of schistosomiasis.

Animals↗
PubMed1979

The dynamics of infection of Tribolium confusum by Hymenolepis diminuta: the influence of infective-stage density and spatial distribution.

The mean parasite burden of a population of Tribolium confusum is shown to rise to a plateau as the exposure density of infective eggs of Hymenolepis diminuta increases. The level of this plateau is shown to be dependent on the nutritional status of the host population, being depressed from approximately 18 cysticeroids/beetle in hosts which have been starved prior to experimentation, to approximately 2 cysticercoids/beetle in satiated hosts. A simple model is used to describe the shape of this infection functional response in terms of the predator-prey interaction between hosts (T. confusum) and parasite infective stages (H. diminuta eggs). The distribution of successful infections/host is shown to be over-dispersed, even when hosts are exposed to infective stages arranged in a uniform spatial pattern. The over-dispersion of parasite numbers/host is shown to become more severe as the spatial pattern of infective stages changes from under-dispersed, through random, to over-dispersed. Experimental results are discussed in relation to the dynamics of parasite-host interactions, in which infection takes place by host ingestion of a free-living infective stage.

Feeding Behavior↗
PubMed1979

A rational approach to ligation of patent ductus arteriosus in the neonate.

During a 23-month period, 25 premature infants underwent ligation of a patent ductus arteriosus performed in the neonatal intensive care unit utilizing a limited posterolateral muscle-retracting incision. This approach afforded adequate exposure with minimal surgical time and trauma. All infants manifested severe respiratory distress and congestive heart failure. Both standard and contrast echocardiographic studies were used for noninvasive preoperative evaluation. Echocardiographic study proved to be a highly reliable and sensitive indicator of ductal patency. Eight infants (32 percent) died at 8 to 225 days of age. The primary cause of death was progressive pulmonary disease with subsequent failure of multiple organ systems. Seventeen (68 percent) of the 25 infants survived to leave the hospital. Advantages of ligation of a patent ductus arteriosus in the neonatal intensive care unit include the elimination of problems of transportation (thermoregulation, ventilation, and loss of lines) and continuity of ongoing care and monitoring. The standard facilities of the neonatal intensive care unit proved completely satisfactory for ligation of a patent ductus arteriosus. Ligation in the neonatal intensive care unit is suggested to minimize potential complications of care in the operating room and transport of these critically ill infants.

Ductus Arteriosus, Patent↗
PubMed1978

Experimental studies of infection dynamics: infection of the definitive host by the cercariae of Transversotrema patialense.

The number of cercariae of Transversotrema patialense which attach to the fish host Brachydanio rerio, during a fixed exposure period, is shown to be directly proportional to cercarial density within an experimental infection arena. The distribution of successful infections/host is shown to change from a random pattern to an over-dispersed form as cercarial exposure density or duration of host exposure to infection increases. A stochastic simulation model is used to demonstrate that small differences in host susceptibility to infection, within a population of hosts, can generate patterns of dispersion in parasite numbers/host similar to those observed in the experimental studies. Differences in host behaviour, during the period of exposure to infection, are thought to generate variability in host susceptibility to cercarial infection.

Animals↗
PubMed1978

Population dynamics of snail infection by miracidia.

The essential biological features of snail infection by miracidia are incorporated into a simple model which describes the rate of change with respect to time of the number of miracidial infections/host. The model is based on the assumption that the net rate of infection is directly proportional to the density of both miracidia and hosts. Empirical evidence is provided to support this assumption. The basic framework of the model is expanded to take into account demographic stochasticity in infection and is used to predict the percentage of snails that become infected after exposure to a known number of miracidia for a set period of time. The influence of miracidial mortalities and age-dependent infectivity are examined and theoretical predictions are compared with a range of experimental results. Underlying heterogeneity in the distribution of the number of infections/snail is shown to generate an artifactual decrease in infection rates as exposure density rises, if rate estimation procedures are based on an assumption of randomness. Empirical evidence is presented to illustrate the generation of over-dispersion in the number of miracidial infections/snail under tightly controlled laboratory conditions, using supposedly homogeneous snail populations. Biological causes for underlying patterns of heterogeneity are discussed in relation to snail susceptibility to infection and 'attractiveness' to infective stages.

Animals↗
PubMed1978

Severely handicapped children in the public schools. A new frontier for the physical therapist.

Recent court decisions are currently generating the need for the development of a more humane, school-based system of educational options for severely and profoundly handicapped children. This natural commitment, which includes provisions for various ancillary services, has major implications for the profession of physical therapy. This paper includes the problems, issues, and trends related to the development of public school physical therapy programs and presents some guidelines and suggestions which might be helpful in the implementation of such programs.

Activities of Daily Living↗