Detection of extracellular calcium gradients with a calcium-specific vibrating electrode.

We have developed a vibrating calcium-specific electrode to measure minute extracellular calcium gradients and thus infer the patterns of calcium currents that cross the surface of various cells and tissues. Low-resistance calcium electrodes (routinely approximately 500 M omega) are vibrated by means of orthogonally stacked piezoelectrical pushers, driven by a damped square wave at an optimal frequency of 0.5 Hz. Phase-sensitive detection of the electrode signal is performed with either analogue or digital electronics. The resulting data are superimposed on a video image of the preparation that is being measured. Depending on the background calcium concentration, this new device can readily and reliably measure steady extracellular differences of calcium concentration which are as small as 0.01% with spatial and temporal resolutions of a few microns and a few seconds, respectively. The digital version can attain a noise level of less than 1 microV. In exploratory studies, we have used this device to map and measure the patterns of calcium currents that cross the surface of growing fucoid eggs and tobacco pollen, moving amebae and Dictyostelium slugs, recently fertilized ascidian eggs, as well as nurse cells of Sarcophaga follicles. This approach should be easily extendable to other specific ion currents.

Hypoglycemic activity of several seaweed extracts.

The hypoglycemic activity of several seaweed extracts on rabbits was studied. Ethanol extracts of Laminaria ochroleuca, Saccorhiza polyschides and Fucus vesiculosus were administered orally to normal animals and their effects on glycemia and triglyceridemia evaluated. Crude polysaccharides and protein solutions from Himanthalia elongata and Codium tomentosum were also assayed. Polysaccharides and proteins from H. elongata caused a significant reduction in blood glucose 8 h after intravenous administration. A case of 5 mg/kg of crude polysaccharide lowered glycemia about 18% in normal rabbits and by about 50% in alloxan-diabetic animals, while the protein solution lowered glycemia in diabetic rabbits by about 30%.

Effect of pretazettine and viva-natural, a dietary seaweed extract, on spontaneous AKR leukemia in comparison with standard drugs.

Antileukemic activity of pretazettine hydrochloride (PTZ: a narcissus alkaloid) and Viva-Natural (a seaweed extract) has been confirmed against spontaneous AKR T cell leukemia in mice containing 20% of advanced leukemia. The activity of both agents has been compared with selected standard cytotoxic drugs, vincristine (VCR), methotrexate (MTX), 6-thioguanine (6-TG), and adriamycin (ADR), and immunomodulators, pyran copolymer (MVE-2), isoprinosine, levamisole and tilorone. PTZ activity seems to be superior (90% increase in life span, ILS) to those of MTX (71% ILS), 6-TG (60%), and ADR (49%), and inferior to VCR (114% ILS). Viva-Natural has been found to be the only immunomodulator (61%) active against AKR T cell leukemia, while all standard immunomodulators tested were not active. Combination treatment of PTZ with VCR, or 6-TG, or ADR, or Viva-Natural were synergistic, but combination of PTZ with MTX was not beneficial. PTZ or VCR has been found to be therapeutically very effective (323 or 347% ILS, respectively) against mice in advanced stage of leukemia, and induced complete clinical remissions. Also, PTZ has been found to reverse the leukemia-enhancing effect of ciclosporin in AKR mice at preleukemic stage.

Human intake of arsenic and iodine from seaweed-based food supplements and health foods available in the UK.

A number of seaweed-based products were analysed for total and 'reducible' arsenic and total iodine. Maximum potential intakes of the two elements were estimated using the manufacturers' recommended does. The levels of reducible arsenic found were generally low and, with one exception, ingestion of the products is unlikely to lead to the Joint Expert Committee on Food Additives (JECFA) Tolerable Daily Intake being exceeded. Iodine levels varied widely even between different samples of the same product. In a number of these cases the potential iodine intake is very high.

Anticancer activity of a natural product, viva-natural, extracted from Undaria pinnantifida on intraperitoneally implanted Lewis lung carcinoma.

A natural product, named Viva-Natural, extracted from a dietary seaweed Undaria pinnantifida has been found to be therapeutically active against Lewis lung carcinoma (LLC). Viva-Natural also demonstrated moderate prophylactic activity against LLC in allogeneic mice. The active principle(s) which was concentrated in the water-insoluble fraction of Viva-Natural was essentially noncytotoxic in KB cell cultures, and probably a polysaccharide. Viva-Natural was found to be significantly effective in enhancing the natural cytolytic activity of peritoneal macrophages against KB cells as targets in in vitro assay, suggesting that the antitumor action of Viva-Natural might be indirect through the activation of nonspecific immune systems. A combination therapy of Viva-Natural and standard anticancer drugs was additively or synergistically effective.

Copper poisoning in sheep from North Ronaldsay maintained on a diet of terrestrial herbage.

Copper toxicity occurred in North Ronaldsay sheep fed on a diet of terrestrial herbage relatively high in molybdenum. Five sheep were taken from the island of North Ronaldsay, Orkney to the veterinary investigation centre at Thurso and fed solely on the herbage of the laboratory paddocks, supplemented in winter by hay made from these paddocks. The level of copper, molybdenum, zinc and total sulphur in the terrestrial herbage was analysed, together with the seaweeds which form the major part of the diet on North Ronaldsay. Serum copper, vitamin B12 and serum aspartate aminotransferase levels were obtained. Four of the five sheep died on this diet of terrestrial herbage and had liver copper levels of 1379, 1723, 2279 and 2281 mg/kg. The susceptibility of the North Ronaldsay breed of Orkney sheep to copper poisoning when first introduced to a diet of purely terrestrial herbage is demonstrated by the high liver copper levels of the four dead sheep compared to the normal serum copper levels and unimpaired health of two other breeds of sheep and a north country Cheviot cross North Ronaldsay ram.