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Biomedical subjects

M Nelson

Publications and source records attributed to M Nelson.

At least 361 records · Page 20Linked to original sources
PubMed1988

Inhibition of cell-mediated immunity by tumour cell products: depression of interleukin-2 production and responses to interleukin-2 by mouse spleen cells.

Supernatants from cultures of mouse and human tumour cells inhibited the production of interleukin-2 (IL-2) by stimulated mouse spleen cells. The tumour cells tested, all of which were active, included a mouse and a human melanoma, three methylcholanthrene-induced fibrosarcomas of mice, and human HeLa cells. Supernatants from normal mouse and human fibroblasts were inactive. Inhibition was dose-dependent. Spleen cells from aged mice were more susceptible to inhibition than spleen cells from young mice. When tumour cell culture supernatants were fractionated on Sephacryl S-300, two peaks of activity were found, with apparent molecular weights of approximately 50 and 18 kD. Supernatants from tumour cell and fibroblast cultures caused variable, but generally weak, inhibition of responses of lymphoblasts to IL-2. It is suggested that inhibition of IL-2 production may be an important mode of action of tumour cell products that inhibit cell-mediated immunity.

Animals↗
PubMed1988

Rehabilitation concerns in electrical burn patients: a review of the literature.

Patients with electrical burns have problems which are unique to their type of injury. In the acute stage, amputations, peripheral neuropathy, and entrapment syndromes occur more commonly in electricity-induced trauma than in thermal burns. In addition, clinicians must be vigilant because peripheral neuropathy, quadriplegia, paraplegia, and entrapment syndromes may have an insidious onset and become manifest days to months after the original injury. Both electrical and thermal burn patients are subjected to two types of trauma: the insult caused by the acute event, and complications which occur because of poor positioning, bulky dressings, intramuscular injections, and neurotoxic medications.

Burns, Electric↗
PubMed1988

Iodine in milk and the incidence of thyrotoxicosis in England.

Because iodine is added to cattle feed, milk and dairy products have become a major source of dietary iodine in Britain. The mean iodine concentrations of milk supplied to seven towns in England were measured each month throughout 1 year. Values were more than twice those recorded 20 years ago. There were large differences between the towns, with average annual concentrations ranging from 130 to 200 micrograms/l. Within the towns there were up to four-fold variations between the peak values in February/March and lowest values in June. The similarity between the monthly variations in milk iodine and seasonality in the onset of thyrotoxicosis suggests that iodine concentrations in milk and dairy products may now have reached harmful levels. Control of high winter levels in areas of Britain which were previously iodine deficient may now be necessary.

Animals↗
PubMed1988

Urinary iodine excretion correlates with milk iodine content in seven British towns.

In February and May 1986, weekly samples of whole pasteurised milk were collected from the 24 dairies supplying seven British towns. A random sample of 96 women aged 25-64 was drawn from general practitioners' lists in each town, and catch specimens of early morning urine were collected by post from 194 subjects in February and from 186 subjects in May. Median milk iodine concentration was significantly greater in February (235 micrograms/l) than in May (119 micrograms/l). The median urine iodine concentration (expressed per g of creatinine) was also greater in February (106 micrograms/g) than in May (78 micrograms/g). There was a strong and statistically significant correlation between milk and urine iodine concentrations in the seven towns in February (Spearman's r = 0.79, p = 0.04). Within the towns, the change in milk iodine levels between February and May was positively associated with the change in the iodine:creatinine ratio over the same period. There is concern that an excess of dietary iodine may be harmful to some individuals. Should it prove desirable to reduce iodine intakes at the community level, the present results suggest that this could be achieved by a reduction in milk iodine levels, which can be readily brought about by adjusting the levels of iodine in cattle feed.

Adult↗
PubMed1987

Restriction endonucleases for pulsed field mapping of bacterial genomes.

Fundamental to many bacterial genome mapping strategies currently under development is the need to cleave the genome into a few large DNA fragments that can be resolved by pulsed field gel electrophoresis. Identification of endonucleases that infrequently cut a genome is of key importance in this process. We show that the tetranucleotide CTAG is extremely rare in most bacterial genomes with G+C contents above 45%. As a consequence, most of the sixteen bacterial genomes we have tested are cleaved less than once every 100,000 base pairs by one or more endonucleases that have CTAG in their recognition sequences: Xba I (TCTAGA), Spe I (ACTAGT), Avr II (CCTAGG) and Nhe I (GCTAGC). Similarly, CCG and CGG are the rarest trinucleotides in many genomes with G+C content of less than 45%. Thus, Sma I (CCCGGG), Rsr II (CGGWCCG), Nae I (GCCGGC) and Sac II (CCGCGG) are often suitable endonucleases for producing fragments that average over 100,000 base pairs from such genomes. Pulsed field gel electrophoresis of the fragments that result from cleavage with endonucleases that cleave only a few times per genome should assist in the physical mapping of many prokaryotic genomes.

Base Composition↗
PubMed1987

Depression of cell-mediated immunity by tumour cell products: induction of resistance by immunotherapeutically active extracts of bovine ocular squamous cell carcinoma.

Tumours produce substances that inhibit the expression of cell-mediated immunity, in the form of delayed-type hypersensitivity in mice. Phenol-saline extracts of bovine ocular squamous cell carcinoma (BOSCC) which have immunotherapeutic activity in cattle were able to immunize mice against this depressive effect. Such immunization was effective against products of BOSCC, a spontaneous rat tumour, three of four human tumour cell lines and (in other experiments) mouse tumours. Phenol-saline extracts of mouse tumour cell lines were immunogenic (protective against depression of delayed-type hypersensitivity) in mice. Fractions of BOSCC phenol-saline extracts which were immunotherapeutically active in cattle were generally also protective in mice. The protective activity was lost after treatment with proteinase K, and was present in the supernatant after precipitation with 55% ammonium sulphate. It was not affected by treatment with RNase or DNase or by heating to 50 degrees C for 2 h. It was present in gel filtration fractions with an apparent molecular weight of 10,000-37,000 daltons. The immunogenic factor in mice and the immunotherapeutic factor in cattle may be related to each other.

Adjuvants, Immunologic↗