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Biomedical subjects

G Dunn

Publications and source records attributed to G Dunn.

At least 145 records · Page 8Linked to original sources
PubMed1981

Bacteriophage T5 growth in Escherichia coli containing PstI fragments of the colicin Ib plasmid.

PstI restriction fragments of the colicin Ib (ColIb) plasmid have been cloned into the Apr gene of the pBR322 vector. Colicin-producing clones (Col+) all contained two common PstI (L and U) fragments, 2000 and 800 bp long, respectively. All of these colicin producers were found to permit the normal growth of bacteriophage T5; the presence of the whole ColIb plasmid causes an abortive T5 or BF23 phage infection. None of the other clones selected for their inability to propagate T5 produced colicin. The clones (Abi+) that permitted only an abortive infection by T5 contained a single restriction fragment, O (1600 bp), which was not found in any of the colicin producers. Likewise, the specific fragments (L and U) found in the Col+ clones were not found in the Abi+ clones. These data are very hard to reconcile with the hypothesis of a colicin-induced cell deterioration after T5 phage infection.

Bacteriocin Plasmids↗
PubMed1981

The natural history of depression in general practice: stochastic models.

Three statistical models are presented to describe different aspects of the natural history of depression (as recognized by a general practitioner) during a 20-year study of a single general practice. After controlling for age, the prevalence of recognized depression in men increased during the 20 years of the study (1957-76), but there was little change in women. In any given year, however, women are both more likely to become depressed than men, and are less likely to recover. The changes in prevalence are shown to be due to changes in observed incidence and recovery rates. Taking into account attendances over the previous 5 years at which a diagnosis of depression was made, the models enable one to predict, for example incidence rates for 'first episodes' of recognized depression, and recovery rates for 'chronic' patients. In all situations there is a significant sex difference (women always being more likely to be recognized as depressed), but this difference is smaller at the end than at the beginning of the 20 years.

Adult↗
PubMed1981

Factors affecting the consumption of psychotropic drugs.

This paper presents some results from a survey conducted in West London in 1977. The 2-week prevalence of psychotropic drug consumption was found to be 10.9% and almost identical figure to that obtained in an earlier survey conducted 8 years previously. The reasons for the absence of the expected rise in prevalence of consumption are discussed. Consumption was found to be strongly associated with various measures of health, and there was a marked sex difference in drug consumption (females greater than males) which was independent of health.

Adolescent↗
PubMed1981

The role of linear models in psychiatric epidemiology.

The aim of this paper is to explain and to stress the importance of mathematical models and, in particular, linear models in the field of psychiatric epidemiology. An awareness of linear models is essential in contemplating the use of statistics of analyse epidemiological survey data, and in many cases the appropriate linear model is by far the most effective way of summarizing such data.

Adult↗
PubMed1980

Statistical analysis of the patterns of spore formation in Bacillus subtilis.

A description of the patterns of sporulation in chains of Bacillus subtilis cells has been obtained by fitting a statistical model to data obtained from a resuspended culture. The underlying assumptions of this model are: (a) resuspension causes an immediate response in the growing bacteria which is necessary for subsequent sporulation; (b) the probability of this response occurring is the same for all the bacteria present at the time of resuspension; (c) after resuspension some of the bacteria pass through a single round of cell division to produce a pair of sporulating bacteria, while the rest divide twice to produce four; and (d) the two sub-populations described in (c) differ in their ability to complete sporulation.

Bacillus subtilis↗
PubMed1980

Caring for old people in New York and London: the "nurses' aide' interviews.

As part of a comparative study of the institutionalized elderly in London and New York, random samples of nurses' aides, nursing assistants and care assistants were interviewed. It is shown that the two long-term care `systems' employ very similar people to provide basic care services, but far more in-service training is provided for New York staff. A detailed analysis of tasks performed suggests that New York staff may be more likely than their London counterparts to carry out technical `nursing' procedures and to be actively involved in physical rehabilitation. The preferences of staff in caring for more or less dependent people showed considerable cross-national agreement, almost half of the total respondents reporting that they preferred immobile patients. Some of the reasons they gave are presented and the implications of this finding discussed.

Aged↗
PubMed1978

Maternal age related pre- and post-implantation fetal mortality: a strain survey.

Pre and post-implantation mortality were examined as a function of maternal aging in six inbred mouse strains. These strains were chosen to evaluate the effects of altered immunity (A/J and NZB/J) and premature reproductive aging (CBA). The decline in litter size observed with maternal aging does not appear to be the result of a decrease in the number of ova produced. The frequency of both pre- and post-implantation mortality increases with maternal age in all strains examined. Although the highest levels of pre- and post-implantation mortality were found in the NZB/J strain, which features altered immune responses, results from the A/J females, which also display immune dysfunction were at the other end of the spectrum. Thus, no consistant relationship was seen between altered immune function and fetal mortality. The CBA strain which is characterized by premature reproductive decline and marked maternal age-related fetal aneuploidy also demonstrated high levels of pre- and post-implantation mortality, even in the young maternal age range.

Animals↗
PubMed1976

Order of expression of genes affecting septum location during sporulation of Bacillus subtilis.

The mean volumes of stationary-phase cells of wild-type and asporogenous mutants of Bacillus subtilis have been measured. Mutants blocked at stage 0 of sporulation either produced cells that had the same volume as the developing sporangium or they divided to produce cells of one-half this volume. The order of expression of the genes affected by the mutations in these strains was determined by biochemical characterization and by construction of double sporulation mutants. Mutants that produced small cells were blocked at an earlier stage of sporulation than those that produced large cells. It is suggested that the following dependent sequence must occur before the formation of the prespore spetum: (i) the initiation of sporulation, (ii) a signal to block the final central division site, and (iii) a signal to activate a polar septum site.

Anti-Bacterial Agents↗
PubMed1976

Resporulation of outgrowing Bacillus subtilis spores.

Germinated spores of Bacillus subtilis were incubated in outgrowth medium and tested periodically for capacity to sporulate when suspended in sporulation medium. Concurrent measurements were made of deoxyribonucleic acid (DNA) content and numbers of cell division septa and nucleoids. Sporulation potential is shown to reach a peak at about 110 min at which time the chromosomes are probably well into the second round of replication. Experiments with nalidixic acid show that sporulation potential can be generated in the outgrowth medium even when DNA synthesis is largely prevented. Further experiments show that nalidixic acid apparently does not prevent the formation of DNA initiation complexes, which can subsequently function after resuspension in the sporulation medium. The results support those previously obtained with a temperature-sensitive DNA mutant which indicated that sporulation could only be induced at a specific stage of chromosome replication, and then only if the cells are in a state of nutritional "step-down".

Bacillus subtilis↗
PubMed1975

The limit dextrinases from ungerminated oats (Avena sativa L.) and ungerminated rice (Oryza sativa L.).

The limit dextrinases from ungerminated oats and rice have been purified, and their substrate specificity compared with a bacterial isoamylase preparation. Both cereal enzymes could hydrolyse (1 yields6)-alpha-D-glucosidic linkages in oligosaccharide alpha-dextrins, pullulan, amylopectin, and the beta-limit dextrins of amylopectin and glycogen. However, under comparable conditions, they were unable to attack glycogens.

Amylases↗
PubMed1973

Observations of the action of limit dextrinases on amylopectin-like polysaccharides.

The rate of hydrolysis of amylopectin by three different limit dextrinase preparations is only about 15-23% of that of amylopectin beta-limit dextrin under similar conditions. On dilution of the enzymes there was no change in specificity. The factors controlling the specificity of the enzyme and the possible significance in vivo of the results are discussed.

Chromatography, Gel↗
PubMedDate not supplied

Death by homicide, suicide, and other unnatural causes in people with mental illness: a population-based study.

BACKGROUND: People with mental illness are at great risk of suicide, but little is known about their risk of death from other unnatural causes. No study has commented on their risk of being victims of homicide; public concern is pre-occupied with their role as perpetrators. We aimed to calculate standardised mortality ratios (SMRs) and directly standardised rate ratios for death by homicide, suicide, and accident in people admitted to hospital because of mental illness. METHOD: We did a population-based study in which we linked the data for 72208 individuals listed in the Danish Psychiatric Case Register between 1973 and 1993, and who died before Dec 31, 1993, with data in the Danish National Register of Causes of Death. FINDINGS: 17892 (25%) patients died from unnatural causes. Our results show raised SMRs for homicide, suicide, and accident for most psychiatric diagnoses irrespective of sex. The all-diagnosis SMRs for women and men, respectively, were: 632 (95% CI 517-773) and 609 (493-753) for homicide, 1356 (1322-1391) and 1212 (1184-1241) for suicide, and 318 (305-332) and 466 (448-484) for accident. We recorded an increased risk of dying by homicide in men with schizophrenia and in individuals with affective psychosis. The highest risks of death by homicide and accident were in alcoholism and drug use, whereas the highest risks of suicide were in drug use. INTERPRETATION: People with mental disorders, including severe mental illness, are at increased risk of death by homicide. Strategies to reduce mortality in the mentally ill are correct to emphasise the high risk of suicide, but they should also focus on other unnatural causes of death.

Accidents↗