Muscle metabolism and red cell ATP/ADP concentration during bicycle ergometer in patients with AMPD-deficiency

Dr, Wagner; Felbel, Jochen; Gresser, Ursula; Zöllner, N.

doi:10.1007/bf01666850

Cited by 10 publications

(8 citation statements)

References 14 publications

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“…From these experiments it may be concluded that in AMPD deficiency large amounts of adenosine may be lost by myo cytes into plasma during exercise, phosphorvlated compounds remaining in the cells. This conclusion is consistent with the data of Wagner et al [4] which show a higher ATP concentration in red cells of AMPD-defi cient patients during exercise, probably due to higher plasma adenosine concentrations. In that case, ribose could enhance the de novo synthesis of purine nucleotides lost in form of adenosine.…”

Section: Discussionsupporting

confidence: 83%

“…The muscular performance was normal in comparison with the muscular performance of control subjects obtained by Wagner et al [4]. On day 2, after exercise with oral ribose.…”

Section: Resultsmentioning

confidence: 73%

“…patient 1 had no more mus cular symptoms, whereas patient 2 still com plained of muscle stiffness and cramps. On day 1 (without ribose), patient 3 who suf fered from severe muscular dystrophy was not able to perform a normal muscular exer cise compared with the control subjects [4], His maximum capacity was 80 W (controls of the same age: 100-160 W). After exercise, he complained of muscle fatigue and Plasma lactate concentrations increased during exercise on day 1 (without ribose) from 0.7 (range 0.7-0.8) to 4.1 mmol/1 (range 1.5-5.5).…”

Section: Resultsmentioning

confidence: 99%

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Effects of Oral Ribose on Muscle Metabolism during Bicycle Ergometer in AMPD-Deficient Patients

Wagner¹,

Gresser²,

Zöllner³

1991

Ann Nutr Metab

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Three patients with AMP deaminase deficiency (AMPD deficiency) performed exercise on a bicycle ergometer with increasing work load without and with administration of ribose (3 g p.o. every 10 min, beginning 1 h before exercise until the end). The patients performed exercise until heart rate was 200 minus age. Maximum capacity was not increased by administration of ribose, but postexertional muscle stiffness and cramps disappeared almost completely in 2 of 3 AMPD-deficient patients. Plasma concentrations of lactate and inosine were increased in AMPD-deficient patients after oral administration of ribose. Our data suggest that ribose may both serve as an energy source and enhance the de novo synthesis of purine nucleotides.

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Section: Discussionsupporting

confidence: 83%

“…The muscular performance was normal in comparison with the muscular performance of control subjects obtained by Wagner et al [4]. On day 2, after exercise with oral ribose.…”

Section: Resultsmentioning

confidence: 73%

Section: Resultsmentioning

confidence: 99%

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Effects of Oral Ribose on Muscle Metabolism during Bicycle Ergometer in AMPD-Deficient Patients

Wagner¹,

Gresser²,

Zöllner³

1991

Ann Nutr Metab

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“…A higher increase in serum lactate level after bicycle exercise with increasing work load was also reported in four out of six MAD deficient patients compared to healthy subjects although these four patients performed less work than most controls [18].…”

Section: Discussionmentioning

confidence: 93%

“…However, an exerciseinduced increase in plasma ammonia level in MAD-deficient patients was found in an aerobic forearm test [I1] and in bicycle exercise with increasing work load[18] although the increase in ammonia level was always lower in patients than in control subjects. In this bicycle test[18], the increase in hypoxanthine level in plasma after exercise was similar in patients and controls (1.52 and 1.96 gmol/1, respectively). In part, these differences may be due to the type of exercise, with strongly reduced degradation of adenine nucleotides in MAD-deficient patients in ischemic isometric exercise[15] or in ischemic forearm test [11], both short-term modes of exercise.…”

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confidence: 99%

Ergometer exercise in myoadenylate deaminase deficient patients

Gross

Gresser

1993

Clin Investig

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Three patients with primary myoadenylate deaminase deficiency were subjected to exercise on a bicycle ergometer at 125 W for 30 minutes. Blood samples prior to, during, and at the end of exercise were analyzed for lactate, ammonia, and hypoxanthine. In addition, urinary hypoxanthine excretion was measured. In these patients the serum lactate level increased to concentrations between 7.9 and 9.0 mmol/l at the end of exercise whereas the mean lactate level in nine control subjects at the end of exercise was 3.3 mmol/l (range 1.1-8.1 mmol/l). There was no difference to control subjects in the exercise-induced increase in plasma levels of ammonia and hypoxanthine or in the increase in urinary hypoxanthine excretion. The findings support the hypothesis of a reduced substrate supply to the citric acid cycle in myoadenylate deaminase deficiency. The normal formation of ammonia and hypoxanthine excludes a marked loss of adenine nucleotides in working muscles in these patients.

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Clinical trials of agents that reverse multidrug resistance. A literature review

Raderer

Scheithauer

1993

Cancer

215

103

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Background. The discovery of the P‐170 glycoprotein as a mediator of multidrug resistance (MDR) represents one of the most important research accomplishments in antineoplastic pharmacology during the last decade. Demonstration of P‐170 in epithelial tissues, untreated and chemotherapeutically pretreated human malignancies, and identification of various agents capable of reversing resistance in vitro generated enthusiasm for clinical studies throughout the world. The authors provide an overview of the current status of clinical investigations of MDR1 reversing agents in hematologic and solid malignancies. Methods. The authors performed an extensive literature search and selected more than 70 articles concerning the potential clinical relevance of P‐glycoprotein/MDR1 modulating agents. Information abstracted included type of reverting agent and chemotherapeutic regimen, number of patients, tumor type, histologic proof of P‐glycoprotein expression, and objective response rates. Results. Proof of the involvement of MDR1 in clinical drug resistance has been slow to accumulate, primarily because of difficulties in adapting assays of MDR1 expression and in planning appropriate trials. Pilot studies have shown that verapamil, cyclosporine, and other chemosensitizers may reverse resistance in a subset of patients, but significant (cardiovascular) side effects are common. For leukemias, lymphomas, and multiple myeloma, response rates of 60–80% may be achieved with the potential for cure, whereas in solid tumors, only a few patients appear to benefit. Conclusions. Because of predominantly negative results and unanswered fundamental questions regarding the biology of P‐glycoprotein, additional clinical trials with less toxic modulators or their combination are appropriate to delineate optimal strategies for MDR1 reversal and to define the spectrum of responsive tumors. Additional attention also must be given to the coexistence of other resistance mechanisms that may offer separate opportunities for modulation.

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Muscle metabolism and red cell ATP/ADP concentration during bicycle ergometer in patients with AMPD-deficiency

Cited by 10 publications

References 14 publications

Effects of Oral Ribose on Muscle Metabolism during Bicycle Ergometer in AMPD-Deficient Patients

Effects of Oral Ribose on Muscle Metabolism during Bicycle Ergometer in AMPD-Deficient Patients

Ergometer exercise in myoadenylate deaminase deficient patients

Clinical trials of agents that reverse multidrug resistance. A literature review

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