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C Berg

Publications and source records attributed to C Berg.

25 records · Page 2Linked to original sources
PubMed1986

Aqueous and serum-based materials compared for use as simulated calibrators for three ionized calcium analyzers.

To determine if bias between different ionized calcium analyzers could be decreased, we analyzed 10 control fluids during a study in which ionized calcium was measured in more than 150 serum and whole-blood samples. After calibrating three ionized calcium analyzers (Radiometer ICA 1, Nova 8, and AVL 980) with the manufacturers' respective calibrators, we used the between-instrument differences of the control fluids to simulate recalibration of the analyzers during each analytical run. A filtered human serum pool containing ionized calcium at 1 mmol/L concentration, with CO2 removed and having no added buffer, was the only material that consistently decreased between-analyzer bias of both serum and whole blood. Another human serum pool containing about 1.3 mmol of ionized calcium and about 10 mmol of bicarbonate per liter was even better at minimizing analyzer biases for serum samples, but was not as effective for whole-blood samples. Some additives used to buffer pH apparently adversely affected both the accuracy and precision of some, but not other, calcium ion electrodes. We conclude that if a reference material is developed for calibration of ionized calcium analyzers, it should be tested on several analyzers for use with both serum and whole blood, and it should be at least as effective as a human serum material, such as that used here.

Calcium↗
PubMed1986

The combined use of interferon and radiotherapy in cancer management.

Preclinical studies have suggested combination therapy with interferon and radiation results in an enhanced cytotoxic effect. Both additive and synergistic effects have been reported in mammalian cells in tissue culture. A phase I trial was designed to determine patient tolerance to concomitant Schering interferon alfa-2b (Intron A) and radiation therapy (RT). RT was delivered in standard fashion (five times a week in 180 rad fractions). Interferon was injected subcutaneously 2 hours prior to irradiation. Sixteen patients, divided into groups of three, received interferon at dose levels of 2 X 10(6) to 30 X 10(6) IU/m2 given five or three times a week. Planned dose escalations were stopped at 5 X 10(6) IU/m2 by patient tolerance. We observed a significant difference in tolerance to treatment between the patients receiving interferon three times a week and those receiving interferon five times a week. Eight of nine patients treated five times a week developed grade III-IV toxicity resulting in hospitalization and discontinuation of interferon; radiation was not discontinued. Only two of seven patients treated three times a week were hospitalized, with grade II toxicity (anorexia), but both were subsequently able to continue treatment with both interferon and radiation. We have identified a maximum tolerated dose and schedule of interferon (5 X 10(6) IU/m2 three times a week) for use in future combined modality trials to assess the potential clinical effectiveness of interferon in combination with RT.

Adult↗
PubMed1985

Antagonism of Ca2+-induced contractions of K+-depolarized smooth muscle by local anaesthetics.

Drugs known to interact with Na+ channels were compared as antagonists of Ca2+-induced contractions of K+-depolarized taenia preparations from guinea-pig caecum. Tetracaine (apparent pA2 5.3 +/- 0.2), quinidine (5.2 +/- 0.1) quinine (5.1 +/- 0.1), d-propranolol (4.7 +/- 0.1), 1-propranolol (4.7 +/- 0.1), lignocaine (4.0 +/- 0.1) and procaine (3.6 +/- 0.1) displaced cumulative concentration-response curves to Ca2+ to the right without depression the maximal response. The slopes of Arunlakshana and Schild plots were close to unity for quinidine, quinine, lignocaine and procaine. These drugs relaxed the established Ca2+-induced contractions rapidly and thus the effects of these drugs resembled the effects of low concentrations of verapamil. However, the effects of the local anaesthetics were increased in the presence of sodium salicylate (5-10 mM) which increases the negative surface charge. In contrast the effects of verapamil were decreased by salicylate. Veratridine (10-100 microM), which activates Na+ channels, had only depressant effects on Ca2+-induced contractions. Thus, drugs acting on Na+ channels can also interact with Ca2+ channels but there are qualitative as well as quantitative differences between the effects of these drugs and those of drugs such as verapamil. These findings indicate different mechanisms of action for the inhibition of Ca2+-induced contractions by local anaesthetics and verapamil.

Anesthetics, Local↗
PubMed1984

Interactions between a "calcium channel agonist", Bay K 8644, and calcium antagonists differentiate calcium antagonist subgroups in K+-depolarized smooth muscle.

The proposal that calcium antagonists have different sites of action has been tested by attempting to reverse their inhibitory effects with a dihydropyridine which augments Ca2+ entry into cells, Bay K 8644. Bay K 8644 (1-1000 nmol/l) increased the sensitivity to Ca2+ of K+-depolarized taenia preparations from the guinea-pig caecum. Thus Bay K 8644 augmented established submaximal Ca2+-induced contractions and also shifted cumulative concentration-response curves to Ca2+ to the left, even in the presence of an optimal K+-depolarization. The inhibitory effects of nifedipine (10 nmol/l), verapamil (0.2 mumol/l), diltiazem (1 mumol/l) and diclofurime (1 mumol/l) on Ca2+-induced contractions were reversed by Bay K 8644 (1-1000 nmol/l). In contrast, Bay K 8644 did not reverse the effects of cinnarizine (1 mumol/l), flunarizine (1 mumol/l), fendiline (3 mumol/l), prenylamine (3 mumol/l), pimozide (1 mumol/l), bepridil (3 mumol/l), perhexiline (10 mumol/l) or the calmodulin antagonist W-7 (200 mumol/l). Bay K 8644 (1-100 nmol/l) was less effective at reversing the effects of nisoldipine (10 nmol/l), a slowly dissociating dihydropyridine, than the effects of nifedipine. However, preincubation with Bay K 8644 (1 mumol/l) protected the taenia from the inhibitory effects of nisoldipine (10 nmol/l). These findings are compatible with interactions of nisoldipine and Bay K 8644 at a common site. Taenia preparations incubated with Bay K 8644 (1 mumol/l) were protected from the inhibitory effects of nifedipine (10 nmol/l), nisoldipine (10 nmol/l) and to a lesser extent verapamil (0.2 mumol/l) and diltiazem (1 mumol/l).(ABSTRACT TRUNCATED AT 250 WORDS)

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1977

Paget's disease.

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Aged↗
PubMed1976

Alcoholics' perception of leisure.

The attitudes of alcoholics and a norm group toward leisure were compared. The alcoholics differed from the norm consistently in seeing themselves as having more leisure than they wanted, in being more work-oriented, in preferring highly structured free time, and in viewing leisure negatively.

Age Factors↗