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Biomedical subjects

D Forman

Publications and source records attributed to D Forman.

At least 181 records · Page 10Linked to original sources

Geographic and social class variation within the UK in levels of salivary nitrates and nitrites. A preliminary report.

In the study, the first results of which are reported here, salivary nitrate and nitrite levels were examined in populations drawn from regions of the UK which differ in mortality rates for gastric cancer. The aims were to see, firstly, whether there was an equivalent geographic variation for nitrate and nitrite levels and, secondly, whether within each region any socio-economic or dietary characteristics correlated with the salivary levels. The results show that the nitrate and nitrite levels are significantly higher in residents from the Oxford region (low gastric cancer incidence area) than in residents from the north-east of England and north Wales (high-incidence areas). Further, within each area there is a noticeable relationship between nitrate and nitrite levels and age and social class. The social class trend is, as with the geographic trend, the inverse of that for stomach cancer risk. It is felt that the explanation of these results is probably a greater consumption of fresh, nitrate-containing vegetables by people in the Oxford region and by those in higher socio-economic groups. The implications that these results have for the nitrate hypothesis in relation to gastric cancer is discussed.

Adolescent↗

Trends in mortality from carcinoma of the liver and the use of oral contraceptives.

There is increasing concern that contraceptive pill usage may increase the risk of hepatocellular carcinoma. As primary malignant liver cancer is very rare in this country, any effect due to oral contraceptives should be apparent in national mortality statistics. An analysis of mortality rates over the last 24 years shows a small but consistent increase for young women starting to occur during the end of the last decade. However no such trend is apparent in data from other countries where pill usage is comparable to that in the U.K. Overall liver cancer remains an extremely uncommon cause of death in developed countries, but it will be particularly important to monitor trends in this disease in the future.

Adult↗

Determination and cellular commitment in the embryonic amphibian mesoderm.

In classical embryology, the term 'determination' was used to describe the process by which a region of the embryo became committed to form a particular part of the body and it was understood that there was a particular stage of development at which determination occurred with respect to each decision. Some authors insisted that only an irreversible commitment should be described as determination, but this leaves undefined the nature of the preceding events involved in its establishment. We show here that there may be several stages of commitment for an organ rudiment that can be distinguished from one another by the use of different methods for altering the pathway of development. We have investigated the region of the amphibian mesoderm that is destined to become somitic muscle in the course of normal development and applied to it a variety of isolation and grafting techniques. The results, which show an extensive period of lability within this region, can be used to explain how pattern formation might occur within the dorsoventral axis of the mesoderm.

Ambystoma↗

An interaction between dorsal and ventral regions of the marginal zone in early amphibian embryos.

When small explants from early gastrulae of Xenopus laevis are allowed to develop in a buffered salt solution there is a considerable difference between the patterns of differentiation obtained from different dorsoventral levels of the marginal zone. These patterns of differentiation correspond to the fates of the different regions in the course of normal development. They are not altered if several explants of the same type are fused before culture. If a ventral marginal zone explant from Xenopus is cultured in contact with a piece of dorsal marginal zone from the axolotl, it forms structures more dorsal in character than it would in isolation or in normal development. This behaviour is shown only feebly with other regions of the axolotl gastrula. A piece of dorsal marginal zone from Xenopus is not affected in its development by culture in contact with an explant of ventral marginal zone from the axolotl. The dorsalization of ventral marginal zone explants is shown only if there is a large area of direct contact with the dorsal explant and if the pieces remain in contact for a period of 48 h or more. It is proposed that this in vitro interaction is the same as the dorsoventral component of action of the 'organizer' graft discovered by Spermann and Mangold.

Ambystoma↗

Enzyme immunoassay of serum thyroxine with the "Autochemist" multichannel analyzer.

We have modified the homogeneous enzyme immunoassay of thyroxine and have adapted it to the AutoChemist. Both enzyme immunoassay and radioimmunnoassay procedures were performed on 2016 patients' sera on which thyroxine determinations had been ordered. We find the automated enzyme immunoassay to be precise and accurate, and for the first time it permits total automation of an immunoassay on a multichannel biochemical-profiling instrument. More importantly, it represents the first time that a thyroid-function test has been included in a multitest biochemical screening profile performed on a single automated instrument.

Autoanalysis↗

Nitrates, nitrites and gastric cancer in Great Britain.

Nitrate and nitrite were measured in the saliva of two populations who differed in their risk of developing gastric cancer. Surprisingly, the levels of both ions were significantly higher in the low-risk group.

Adolescent↗