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Biomedical subjects

T W Anderson

Publications and source records attributed to T W Anderson.

At least 55 records · Page 3Linked to original sources
PubMed1978

Staircase in frog ventricular muscle. Its dependence on membrane excitation and extracellular ionic composition.

Staircase was studied in frog ventricle strip preparations where it was possible to alter extracellular ionic composition extremely rapidly in the diastolic interval between beats. Several findings strongly indicate that staircase in this tissue is a result of progressively increasing calcium influx per beat, rather than a beat-by-beat augmentation of an intracellular calcium pool which contributes to activation. After a steady state of force development, the very next beat could be graded, from approximately zero force to the steady state value attained during the staircase progression, by grading the calcium concentration of a new Ringer's solution switched to perfuse the muscle in the diastolic period immediately before that beat. Also, action potentials, elicited during the "quiescent" period in the virtual absence of contraction (in 0.025 mm calcium Ringer's solution), markedly increase force development and accelerate the staircase seen upon return to normal Ringer's solution. Staircase is augmented and accelerated by prior exposure of the muscle, during the quiescent period, to calcium-poor media and markedly suppressed by prior exposure to sodium-poor media. Tetrodotoxin, in a dose that markedly slows the action potential upstroke, has no effect on staircase. Finally, staircase is seen to occur during a train of depolarizations (by voltage clamp) to inside positive levels greater than the equilibrium potential for sodium. It is concluded that changes in intracellular sodium concentration will alter the staircase response and may contribute to its genesis, but that this cannot be the sole cause of staircase.

Action Potentials↗
PubMed1977

Large scale studies with vitamin C.

The combination of a regular daily supplement of vitamin C with extra dosage at the time of illness has been shown to reduce the disability due to common colds and other winter illness, but we have seen little effect on frequency of infections, sense of (well-being), or levels of serum cholesterol. The variable results that have been obtained from some other trials of vitamin C may be due in part to variation in the initial nutritional state of the subjects, with the greatest effects to be expected where there is most room for improvement. Because of the great variation in individual susceptibility to infection large numbers of subjects are required in these trials and they must be strictly double-blind. Although we have seen no clear evidence of harmful side-effects, occasional sensitivity to large doses of vitamin C cannot be ruled out, and the withdrawal depression of blood levels could conceivably interfere with a patient's ability to handle stress.

Ascorbic Acid↗
PubMed1975

Letter: Ischemic heart disease, water hardness and myocardial magnesium.

In 54 cases of accidental death in cities with water hardness of 60 parts per million (ppm) or less, the mean myocardial magnesium concentration was 918 mug/g of dry tissue. This was 7% lower than the corresponding figure of 982 mug/g among 29 cases of accidental death in cities with water hardness of 300 ppm or more, and this difference was significant (P less than 0.01). There were no significant differences between the cities with soft and hard water in the mean myocardial concentrations of calcium, zinc, copper, chromium, lead or cadmium. These results are compatible with the belief that the relatively high death rates in some soft-water areas may be due to a suboptimal intake of magnesium, and that water-borne magnesium exerts a protective effect on the residents of hard-water areas.

Adult↗
PubMed1975

Treatment of chronic pain with acupuncture.

We performed 979 acupuncture treatments in 261 patients with chronic pain. A substantial number of patients stated that they had relief immediately following a series of four acupuncture treatments. It did not matter whether the needles were placed in the traditional meridian locations of in arbitrary fixed control points. Four weeks following treatment, 65% of the patients reported little or no reduction in the intensity of their pain, 17% reported a 50% reduction, and 18% at least a 75% reduction.

Acupuncture Therapy↗
PubMed1975

Winter illness and vitamin C: the effect of relatively low doses.

After their random -llocation to one of three treatment aroups, 622 volunteers received either vitamin C or placebo in a maintenance dose of 500 mg once weekly and a therapeutic dose of 1500 mg daily on the 1st day and 1000 mg on the next 4 days of any illness. Two forms of vitamin C were employed: a sustained-release capsule containing ascorbic acid and a regular tabet containing a mixture of sodium and calcium ascorbate. In the 448 subjects who completed an average of 15 weeks in the study of total of 635 episodes of illness were recroded. Respiratory symptoms were recorded on at least 1 day in 92 per cent of these episodes. There were no consistent or significant differences in the sickness experience of the subjects receiving the sustained-release vitamin capsules compared to those receiving the vitamin tablets, but subjects in both vitamin groups experienced less severe illness than subjects in the placebo group, with approximately 25 per cent fewer days spent indoors because of the illness (P smaller than 0.05). These results are compatible with the belief that supplementary vitamin C can reduce the burden of winter illness, but the intake need not be as high as has sometimes been claimed.

Adolescent↗
PubMed1974

The effect on winter illness of large doses of vitamin C.

Between December 1972 and February 1973, 2349 volunteers participated in a double-blind trial to assess the effect of large doses of vitamin C on the incidence and severity of winter illness. In addition, records were kept but no tablets taken during March. Subjects were randomly allocated to eight treatment regimens: three prophylactic-only (daily dose 0.25, 1 or 2 g), two therapeutic-only (4 or 8 g on the first day of illness), one combination (1 g daily and 4 g on the first day of illness), and two all-placebo. None of the groups receiving vitamin C showed a difference in sickness experience that was statistically significant from that of the placebo groups, but the results obtained were compatible with an effect of small magnitude from both the prophylactic and therapeutic regimens, and an effect of somewhat greater magnitude from the combination regimen. The combination regimen was associated more with a reduction in severity than frequency of illness, although the extra dosage was limited to the first day of illness. In spite of the eightfold range in daily dose, the three prophylactic-only regimens showed no evidence of a dose-related effect, but the 8 g therapeutic dose was associated with less illness than the 4 g therapeutic dose. There was no evidence of side effects from the 1 and 2 g prophylactic doses of vitamin C, and no evidence of a rebound increase in illness during the month following withdrawal of the daily vitamin supplements. On the basis of this and other studies it is suggested that the optimum daily dose of vitamin C is less than 250 mg, except possibly at the time of acute illness, when a larger daily intake may be beneficial.

Administration, Oral↗