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Biomedical subjects

D Scott

Publications and source records attributed to D Scott.

At least 361 records · Page 20Linked to original sources
PubMed1982

Evaluation of radiation-induced chromosomal aberrations in human peripheral blood lymphocytes in vitro: result of an IAEA-coordinated programme.

The results of an IAEA coordinated programme on radiation induced chromosomal aberrations in human peripheral blood lymphocytes in vitro are presented. In a master experiment, a whole blood sample from one donor was irradiated with 200 R of X-rays. Different fixation times from 46 to 82 h were used. The progression of cells into mitosis was monitored by BrdUrd incorporation. 14 investigators took part in the scoring of chromosomal aberrations. The main conclusions of this study are: (1) The mean frequencies of aberrations changed with fixation time. (2) The number of cells scored as aberrant by different laboratories was very similar, but there was variability in the number of aberrations scored per aberrant cell. (3) The differences in the frequencies of aberrations between laboratories were minimal when the scoring was restricted to the first major peak of mitotic activity and sufficient cells were scored. It is concluded that using controlled experimentals conditions, human peripheral blood lymphocytes can effectively be used as a reliable biological dosimeter for absorbed radiation dose.

Argentina↗
PubMed1982

Man-made lakes and man-made diseases. Towards a policy resolution.

Throughout the tropical world, in Africa. Asia and Latin America, the construction of water impoundments, for irrigation and other purposes. in areas of endemic water-related diseases, has inexorably intensified community levels of infection, and also created new areas of transmission. The clearest 'indicator' disease is a schistosomiasis, but other are involved such as malaria and the filariases. An assessment for the future suggests a worsening situation because of population growth, the demand for food production, and the increased technological capacity of the "bulldozer revolution' to effect earth impoundments. The typical sectoral dichotomy in which a department of agriculture creates a disease outbreak through its development activity, leaving its counterpart department of public health to cope on he curative basis, where possible, is strongly deplored. A policy position is offered whereby disease prevention measures are integrated with development projects from the beginning, and infrastructural investment and operational costs for health maintenance are identified and incorporated in the total benefit-cost analysis. The need for the communications network on ecological and health effects is pointed out; and a typology for registration of dams is offered in support of policy implementation.

Ecology↗
PubMed1982

Proctalgia fugax.

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Anus Diseases↗
PubMed1982

Cell cycle dependence of mitotic delay in X-irradiated normal and ataxia-telangiectasia fibroblasts.

The delay in progression of X-irradiated cells through the cell cycle, which is more pronounced in normal (N) than in A-T fibroblasts, is greatest for cells in G2 at the time of irradiation. The greater effect of radiation on the initiation of DNA synthesis in N than in A-T cells is reflected in the shape of the percent labelled mitosis curves after 3H-thymidine treatment. The duration of the S phase in unirradiated A-T cells is greater than in N cells. Any explanation of the underlying defect in A-T must account not only for the reduced radiosensitivity of DNA synthesis but for the lesser delay in G2. Our data support the hypothesis that DNA is the principal target for radiation-induced G2 delay.

Ataxia Telangiectasia↗
PubMed1982

Therapeutic progress--review VI. Treatment of rheumatoid arthritis.

Anti-rheumatic drugs used in rheumatoid arthritis fall into two distinct groups: non-steroidal anti-inflammatory and second-line drugs. Non-steroidal anti-inflammatory drugs give early symptomatic improvement and reduce the degree of acute inflammatory synovitis. Second-line drugs such as gold or D penicillamine exert an anti-inflammatory effect only after two to three months and act by suppressing disease activity: these reduce the ESR and other acute phase responses. However, the evidence that any of these drugs halt the progression of radiological changes or can be used as long-term agents to control the disease over a period of years is weak. The current use of anti-rheumatic drugs follows a general pattern with non-steroidal anti-inflammatory drugs used alone in patients with mild disease, whereas patients with severe disease also receive second-line drugs. As yet the long-term effect of this policy is not known. Cytotoxic drugs should be restricted to patients with severe disease who either fail to respond to conventional second-line drugs or have active extra-articular disease, particularly those with vasculitis.

Anti-Inflammatory Agents↗
PubMed1982

A quantitative comparison of cytogenetic effects of anti-tumor agents.

The relative potency of different anti-tumor agents in inducing structural and numerical chromosome abnormalities and SCEs was assessed by making comparisons at equitoxic doses, measured in terms of colony forming ability, in cultured diploid human fibroblasts. At approximately 20% survival the relative potency of X-rays, daunorubicin, nitrogen mustard, adriamycin, and actinomycin D in inducing structural aberrations was 1.0, 0.85, 0.26, 0.22, and zero, respectively. SCE induction was quantitatively unrelated to the induction of chromosome aberrations. No numerical changes were observed. Accurate assessment of the yields of chromosome aberrations requires the use of multiple sampling times in asynchronous populations.

Antineoplastic Agents↗
PubMed1982

Epidemiology of human Schistosoma haematobium infection around Volta Lake, Ghana, 1973-75.

There was a dramatic rise in the prevalence of urinary schistosomiasis around Volta Lake within a year of its full impoundment in 1968. Research was undertaken to investigate the epidemiology of the disease in preparation for a control programme. The interplay of three factors-age, sex, and ethnic affiliation-largely defined the demographic patterns of the prevalence and the intensity of infection. Both of these increased in young children up to a peak at age 10-14 years, and then declined, the intensity of infection more rapidly than the prevalence. The prevalence and intensity of infection were both greater in males than females (above ages 15-24 years and 5-9 years, respectively), and differences between the two main ethnic groups were related to differences in their lake-related activities. Differences between the patterns of prevalence and intensity of infection are attributed to the greater sensitivity of the latter measurement in indicating changes in the level of transmission. Practical difficulties were encountered in obtaining a precise measurement of incidence, the most important being the considerable degree of population movement. A field cohort study showed a seasonality of transmission, greatest between January and April, during the period of high level of the lake and in the early part of the draw-down.Research on the intermediate snail host (Bulinus truncatus rohlfsi) and lakeside ecology established the focality of transmission at human water-contact sites serving the shore-line communities and, in conjunction with parasitological surveys, its seasonality: variations in ecology that accompanied the annual rise and fall of the lake led to high levels of transmission when the water level was high and lower levels during the draw-down.The geographical distribution of the infection was also affected by differences in ecology, specifically by variations in the distribution and abundance of the aquatic weed Ceratophyllum demersum. A non-seasonal decline in transmission observed in one locality during the period from 1973 to 1975 resulted from a local decrease in the amount of Ceratophyllum.

Adolescent↗
PubMed1982

Pregnancy following gastric bypass for the treatment of morbid obesity.

Of the patients undergoing gastric bypass for treatment of morbid obesity, 75 per cent are female. A common question both pre-and postoperatively concerns the advisability of a pregnancy following surgically-induced weight loss. Of all patients, 45 became pregnant on 54 occasions following gastric bypass and 46 infants were delivered. There were two spontaneous abortions (4.0%) and six early terminations of an undesired pregnancy. Seven infants were delivered prematurely. One child was born microcephalic and has developed severe retardation in both growth and development. In contrast to reports of infants born to mothers with jejunoileal bypass, 12 of the babies that were born to mothers after gastric bypass were heavier at birth than older siblings. An additional ten infants were the first born to women who had lost more than 100 pounds following gastric bypass. All but one of the women became pregnant more than six months following surgery. This corresponds to the period of maximum weight loss and reversal of menstrual abnormalities associated with massive obesity. Pregnancies were well tolerated by the mothers, with no excessive increase in weight loss or development of metabolic deficiencies. Since the gastric bypass is modeled on the Billroth II gastrectomy, additional iron supplementation was recommended during the pregnancy. While we cannot recommend pregnancy during the period of rapid weight loss in the initial postoperative period, our data indicate that neither the mother nor the developing fetus is unduly endangered by a pregnancy which develops after the period of rapid postoperative weight loss.

Adult↗
PubMed1981

Criteria audit of surgery for carcinoma of the large intestine in Melbourne teaching hospitals.

A criteria audit of patients undergoing surgery for carcinoma of the large intestine in three Melbourne teaching hospitals revealed a considerable variation in the degree of compliance with individual criteria, and a high complication rate with approximately two-thirds of the patients suffering one or more complications. The uniform system of data gathering used provides a baseline for future studies.

Aged↗
PubMed1981

Comparison of abdominal circumference measurements by real-time and B-scan techniques.

In an effort to evaluate the efficacy of measuring abdominal circumference with real-time ultrasound, 53 patients were scanned with both contact scanning and linear array real time. Image measurements were made blindly from both types of equipment. Abdominal circumference measurements with real time compared favorably with those obtained from contact images (r = +0.984).

Abdomen↗
PubMed1981

Cell death, chromosome damage and mitotic delay in normal human, ataxia telangiectasia and retinoblastoma fibroblasts after x-irradiation.

We recently showed (Scott and Zampetti-Bosseler 1980) that X-ray sensitive mouse lymphoma cells sustain more chromosome damage, mitotic delay and spindle defects than X-ray resistant cells. We proposed that (a) chromosome aberrations contribute much more to lethality than spindle defects, and (b) that DNA lesions are less effectively repaired in the sensitive cells and give rise to more G2 mitotic delay and chromosome aberrations. Our present results on human fibroblasts with reported differential sensitivity to ionizing radiation (i.e. normal donors and patients with ataxia telangiectasia and retinoblastoma) support the first hypothesis since we observed a positive correlation between chromosome aberration frequencies and cell killing and no induced spindle defects. Our second hypothesis is however not substantiated since X-ray sensitive fibroblasts from the ataxia patient suffered less mitotic delay than cells from normal donors. A common lesion for mitotic delay and chromosome aberrations can still be assumed by adopting the hypothesis of Painter and Young (1981) that the defect in ataxia cells is not in repair but in a failure of DNA damage to initiate mitotic delay. In contrast to other reports, we found the retinoblastoma cells to be of normal radiation sensitivity (cell killing and aberration).

Adolescent↗
PubMed1980

Growth of factor-dependent hemopoietic precursor cell lines.

Cell lines have been produced from long-term cultures of mouse bone marrow that require a factor, present in WEHI-3 conditioned medium (CM) or in spleen CM, for their sustained growth. The cell lines were obtained from nonvirus-treated cultures, are nonleukemic, maintain a normal karyotype, and form colonies showing granulocyte maturation when plated in soft agar. Granulocyte/macrophage (GM) colony-stimulating factor is not the inductive moiety involved in the maintenance of proliferation of these cells. It is suggested that the cell lines represent a self-renewing population of cells ancestral to GM colony-forming cells, which may be responding to a hitherto unrecognized regulator.

Animals↗
PubMed1980

Cytodifferentiation of the supraoptic nucleus correlated with vasopressin synthesis in the rat.

This study demonstrates that neurons in the supraoptic nucleus attain many of the prerequisites for functional activity prior to birth. Immunoassayable vasopressin (VP) was detected in the hypothalamo-neurohypophyseal system (HNS) of the rat as early as 17 days post-coitus (dpc). Vasopressin concentrations increased 3--6-fold daily from an average of 21 pg/animal on 17 dpc to 5984 pg/animal at 21 dpc. The daily increases were highly significant (P less than 0.001). Between 21 dpc and the morning of the day of birth on 22 dpc, a further significant increase (P less than 0.05) occurred to a mean level of 9672 pg VP/animal. Birth usually occurred on the afternoon of the 22nd day. Parturition did not seem to deplete VP stores in the HNS. Differentiation of the magnocellular neurons in the supraoptic nucleus closely paralleled the appearance and increases in VP. It was first possible to dintinguish a supraopic nucleus in the 17 dpc rat and to identify dense core granules in the developing neurons of the nucleus. Cytodifferentiation of the magnocellular neurons was essentially complete by 21 dpc. Synaptic contacts could not be found on the soma and dendrites of the supraoptic neurons until 21 dpc and were extremely rare throughout the period examined.

Age Factors↗