M H Brooke

University of Alberta, Edmonton, Alberta, Canada

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Publications (77)482.19 Total impact

  • R Majumdar, D Gowda, M H Brooke
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    ABSTRACT: Recent studies have shown that mild hypothermia (32-35 degrees C) confers striking protection against ischemic muscle and neuronal injuries, although the mechanisms are unknown. We previously demonstrated that the release of prostaglandin E2 (PGE2) from metabolically stressed muscles was dependent on calcium and was abolished at or below 35 degrees C. In this study, we examined the temperature response of the release of arachidonic acid (AA) and its cyclooxygenase metabolites, PGE2 and prostaglandin F2 alpha (PGF2 alpha) from rat skeletal muscle in the presence of calcium ionophore A23187, an agent that directly elevates intracellular calcium. Calcium ionophore markedly stimulated the release of AA, PGE2 and PGF2 alpha at 37 degrees C, as expected. Reducing the temperature to 35 degrees C and below sharply decreased PGE2 and PGF2 alpha release but not AA release. The activity of phospholipase A2 stimulated by calcium ionophore was unaffected when temperature of incubation was lowered from 37 to 32 degrees C. The results suggest that reducing temperature from 37 degrees C to 35 degrees C or below inhibits the conversion from free arachidonate to PGs in calcium ionophore-stimulated muscle.
    Prostaglandins Leukotrienes and Essential Fatty Acids 09/1995; 53(2):117-22. · 2.73 Impact Factor
  • R Majumdar, J T Nguyen, M H Brooke
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    ABSTRACT: Calcium influx plays a critical role in the activation of the arachidonic cascade in muscle damage. We examined the effects of L-type calcium channel antagonists on the release of prostaglandin E2 (PGE2), a bioactive metabolite of arachidonic acid metabolism, from skeletal muscle. The basal release of PGE2 was not affected by calcium channel inhibitors, such as nifedipine and verapamil. The release of PGE2 induced by dinitrophenol, an uncoupler of oxidative phosphorylation, was abolished by nifedipine and verapamil at 50 and 150 microM, respectively. It was not necessary to include the calcium channel blockers in the medium before or at the time of dinitrophenol stimulation to produce the effect on PGE2 release. The release of PGE2 was prevented for as long as calcium channel blockers were present in the medium after the dinitrophenol stress.
    Biochemical Pharmacology 08/1994; 48(2):371-4. · 4.58 Impact Factor
  • V A Cwik, R Majumdar, M H Brooke
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    ABSTRACT: An in vitro model of muscle damage was used to investigate the protective effect of mild hypothermia in muscle injury. Rat epitrochlearis muscles were dissected in their entirety and suspended in Krebs-Ringer solution and DNP, a mitochondrial uncoupler, was added. PGE2 and lactate release and the contractile response to stimulation were measured and compared to untreated controls. Experiments were done at 37, 35, 33 and 27 degrees C. At 37 degrees C, DNP stimulated muscle releases large amounts of PGE2 and lactate and is unable to contract. As the temperature is reduced, there is progressive preservation of contractile force, although high lactate levels at the lowest temperatures indicate that the metabolic stress is still present. In contrast, DNP stimulated PGE2 release is completely inhibited at or below 35 degrees C and may be related to a similar protective phenomenon seen in experimental ischemic neuronal death.
    The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques 06/1994; 21(2):120-4. · 1.33 Impact Factor
  • R Majumdar, V A Cwik, M H Brooke
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    ABSTRACT: In spite of recent progress, treatment of muscle disease based on specific gene therapy is not yet available. An alternative approach is to develop treatment which affords non-specific protection against general factors involved in cell damage. This approach is used effectively to prevent neuronal damage in experimental brain ischemia in animals and has been proposed for human trials. The most effective intervention is the use of mild (35 degrees C) hypothermia. An in vitro model to study muscle cell damage employs the rat epitrochlearis muscle exposed to low concentrations of 2:4-dinitrophenol, an uncoupler of oxidative phosphorylation. The efflux of prostaglandin E2 (PGE2) from the muscle is used as an indicator of muscle damage. We now show that there are two types of PGE2 release. "Basal" efflux gradually declines with decreasing temperatures and is not affected by removal of calcium from the medium. The efflux of PGE2 in response to metabolic stress is dependent on the presence of calcium and is abolished by mild hypothermia of 35 degrees C. The latter effect suggests that cell death is muscle and neurons have features in common and that muscle may be a useful tissue in which to investigate this phenomenon further.
    Neuromuscular Disorders 01/1994; 4(5-6):483-8. · 3.46 Impact Factor
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    ABSTRACT: The efflux of hypoxanthine and uric acid from skeletal muscle has been noted to follow exercise and metabolic stress both in vivo and in vitro. Since the action of xanthine oxidase and hypoxanthine generates free radicals with potential damaging effect on the muscle membranes, an in vitro model was used to study the relationship of metabolic stress, oxypurine release and muscle contraction. When rat epitrochlearis muscle was exposed to the mitochondrial uncoupler dinitrophenol at 37 degrees C, lactate release was pronounced and hypoxanthine and uric acid appeared in the incubating medium. The twitch tension, in response to supramaximal stimulation, was reduced to less than 5% of the initial value. When the same experiment was repeated at 27 degrees C, hypoxanthine and uric acid formation was inhibited, although lactate release indicated that metabolic stress was still present. Twitch tension was relatively preserved (57% of the initial value). The lower temperature did not alter the decrease in ATP and phosphocreatine levels in the muscle which is produced by dinitrophenol. There was an inverse relationship between oxypurine release and twitch tension in individual muscles (r = 0.80, P < 0.01 for hypoxanthine and r = 0.95, P < 0.0002 for uric acid). Xanthine dehydrogenase/xanthine oxidase was detected in muscle and between 16 and 22% of the activity was in the oxidase form.
    Acta Physiologica Scandinavica 11/1993; 149(3):249-55. · 2.55 Impact Factor
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    ABSTRACT: Prednisone improves strength and function in patients with Duchenne dystrophy. Although the mechanism of this effect is uncertain, prior studies suggested that the benefit might result from immunosuppressive effects on T lymphocytes invading muscle. A recent randomized, double-blind, controlled trial of prednisone and azathioprine demonstrated that azathioprine had no effect in Duchenne dystrophy, raising questions about the role of immunosuppression in mediating clinical improvement. The goal of this current study was to compare the effects of prednisone and azathioprine on mononuclear infiltrates from biopsies performed at the end of the controlled clinical trial (reported separately in the article by Griggs et al on page 520). We studied 14 patients from the prednisone group (0.75 mg/kg/d), 10 from the combination therapy group (prednisone 0.3 mg/kg/d and azathioprine 2.5 mg/kg/d), and 13 from the azathioprine group (2.5 mg/kg/d), and used monoclonal antibodies for cell typing. There were no significant differences between the groups for total T cells, T-cell subsets, B cells, natural killer cells, total mononuclear cells, necrotic muscle fibers, or fibers focally invaded by mononuclear cells. These data indicate that azathioprine decreases mononuclear subsets infiltrating muscle to a similar degree as does prednisone, although azathioprine-treated patients do not show a clinical improvement. This implies that immunosuppressive actions on cellular infiltrates in muscle are probably not the primary mechanism of prednisone-induced clinical improvement.
    Neurology 04/1993; 43(3 Pt 1):532-6. · 8.30 Impact Factor
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    ABSTRACT: Prednisone has been shown to improve strength in Duchenne dystrophy. Azathioprine often benefits corticosteroid-responsive diseases and can reduce the dose of prednisone needed. The present study reports a randomized, controlled trial of prednisone and azathioprine designed to assess the longer-term effects of prednisone and to determine whether azathioprine alone, or in combination with prednisone, improves strength. Ninety-nine boys (aged five to 15 years) with Duchenne dystrophy were randomized to one of three groups: (I) placebo; (II) prednisone 0.3 mg/kg/d; or (III) prednisone 0.75 mg/kg/d. After 6 months, azathioprine 2 to 2.5 mg/kg/d was added in groups I and II and placebo added in group III. The study showed that the beneficial effect of prednisone (0.75 mg/kg/d) is maintained for at least 18 months and is associated with a 36% increase in muscle mass. There was weight gain, growth retardation, and other side effects. Azathioprine did not have a beneficial effect. This study suggests that prednisone's beneficial effect is not due to immunosuppression.
    Neurology 04/1993; 43(3 Pt 1):520-7. · 8.30 Impact Factor
  • G J Pestronk, K K Kaiser, M H Brooke
    Muscle & Nerve 03/1992; 15(2):258. · 2.31 Impact Factor
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    ABSTRACT: Two successive, 6-month, randomized, double-blind, controlled trials of prednisone showed that 0.75 mg/kg/d was the optimal dose to improve strength in boys with Duchenne muscular dystrophy (DMD). We attempted to maintain 93 boys on that dose for an additional 2 years. During the 3 years of observation, the decline in average muscle strength scores of all boys taking prednisone was 0.072 units/yr, as compared with an expected decline of 0.341 units/yr from natural history controls. The occurrence of side effects in some boys prevented maintenance of the full dose, which may have lessened the response. At the time of last visit, dosages ranged from 0.15 mg/kg to 0.75 mg/kg. In addition to maintaining their strength, several of the boys actually improved their performance in lifting kilogram weights and in some timed function tests. Treatment of DMD with prednisone significantly slows the progression of weakness and loss of function for at least 3 years.
    Neurology 01/1992; 41(12):1874-7. · 8.30 Impact Factor
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    ABSTRACT: We previously reported the results of a randomized, double-blind 6-month trial of prednisone therapy in which 102 boys aged 5 to 15 years with Duchenne muscular dystrophy received daily doses of 1.5 and 0.75 mg/kg per day and were compared with those receiving placebo. The strength and function in both prednisone-treated groups improved equally and were significantly better than in the placebo group. To compare alternate-day and daily dosing of prednisone with respect to benefits and adverse side effects, the placebo group was started on alternate-day prednisone therapy, and the treatment group regimens were changed to equivalent doses of alternate-day prednisone without breaking the double-blind nature. At the end of 6 months, the group that was changed from daily to alternate-day therapy had declined in strength back to levels observed 12 months previously, at the start of daily therapy. The group in which alternate-day therapy was started showed a significant improvement in strength at 3 months, similar in magnitude to the response of boys treated with daily therapy. However, their strength declined significantly in the subsequent 3 months compared with boys who received daily therapy. The frequency of side effects was not significantly different for alternate-day therapy compared with daily therapy. We conclude that alternate-day prednisone therapy effectively increases strength but does not sustain the improvement to the same extent as daily therapy or mitigate side effects.
    JAMA Neurology 07/1991; 48(6):575-9. · 7.58 Impact Factor
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    ABSTRACT: A randomized, controlled trial of daily prednisone was conducted in 99 boys (aged 5 to 15 years) with Duchenne dystrophy to define the time course of improvement and the dose response to treatment. Prednisone at 0.3 mg/kg (n = 33), prednisone at 0.75 mg/kg (n = 34), and placebo (n = 32) were administered for 6 months. Patients were examined using manual muscle and myometry testing, timed functional testing, pulmonary function testing, and laboratory measurements at 10 days, 1 month, 2 months, 3 months, and 6 months of treatment. Boys treated with prednisone had stronger average muscle strength scores, than did boys treated with placebo as early as 10 days after starting therapy. At the 3-month visit, the boys in the group given 0.75 mg/kg of prednisone were significantly stronger than those in the group given 0.3 mg/kg of prednisone, indicating a dose response. At 6 months, significant side effects occurred in the group treated with 0.75 mg/kg of prednisone, including weight gain, cushingoid appearance, and excessive hari growth. Only weight gain was observed in the group taking prednisone at a dose of 0.3 mg/kg. Importantly, no side effects were evident at 10 days or 1 month of treatment, despite improvement in muscle strength and function. We conclude that prednisone produces a rapid increase in muscle strength in patients with Duchenne dystrophy and that this improvement is maximal at a prednisone dosage of 0.75 mg/kg or less.
    JAMA Neurology 05/1991; 48(4):383-8. · 7.58 Impact Factor
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    ABSTRACT: There is evidence that growth hormone may be related to the progression of weakness in Duchenne dystrophy. We conducted a 12-month controlled trial of mazindol, a putative growth hormone secretion inhibitor, in 83 boys with Duchenne dystrophy. Muscle strength, contractures, functional ability and pulmonary function were tested at baseline, and 6 and 12 months after treatment with mazindol (3 mg/d) or placebo. The study was designed to have a power of greater than 0.90 to detect a slowing to 25% of the expected rate of progression of weakness at P less than 0.05. Mazindol did not benefit strength at any point in the study. Side effects attributable to mazindol included decreased appetite (36%), dry mouth (10%), behavioral change (22%), and gastrointestinal symptoms (18%); mazindol dosage was reduced in 43% of patients. The effect of mazindol on GH secretion was estimated indirectly by comparing the postabsorptive IGF-I levels obtained following 3, 6, 9, and 12 months in the mazindol treated to those in the placebo groups. Although mazindol-treated patients gained less weight and height than placebo-treated patients, no significant effect on IGF-I levels was observed. Mazindol doses not slow the progression of weakness in Duchenne dystrophy.
    Muscle & Nerve 01/1991; 13(12):1169-73. · 2.31 Impact Factor
  • G M Fenichel, D O Cooper, M H Brooke
    Muscle & Nerve 02/1990; 13 Suppl:S1. · 2.31 Impact Factor
  • M H Brooke, R Miller
    Muscle & Nerve 02/1990; 13 Suppl:S35-7. · 2.31 Impact Factor
  • Michael H. Brooke
    Muscle & Nerve 02/1990; 13 Suppl:S38-9. · 2.31 Impact Factor
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    ABSTRACT: We performed a randomized, double-blind, controlled six-month trial of prednisone in 103 boys with Duchenne's muscular dystrophy (age, 5 to 15 years). The patients were assigned to one of three regimens: prednisone, 0.75 mg per kilogram of body weight per day (n = 33); prednisone, 1.5 mg per kilogram per day (n = 34); or placebo (n = 36). The groups were initially comparable in all measures of muscle function. Both prednisone groups had significant improvement of similar degree in the summary scores of muscle strength and function. Improvement began as early as one month and peaked by three months. At six months the high-dose prednisone group, as compared with the placebo group, had improvement in the time needed to rise from a supine to a standing position (3.4 vs. 6.2 seconds), to walk 9 m (7.0 vs. 9.7 seconds), and to climb four stairs (4.0 vs. 7.1 seconds), in lifting a weight (2.1 vs. 1.2 kg), and in forced vital capacity (1.7 vs. 1.5 liters) (P less than 0.001 for all comparisons). There was an increase in urinary creatinine excretion (261 vs. 190 mg per 24 hours), which suggested an increase in total muscle mass. However, the prednisone-treated patients who had required long-leg braces (n = 5) or wheelchairs (n = 11) continued to require them. The most frequent side effects were weight gain, cushingoid appearance, and excessive hair growth. We conclude from this six-month study that prednisone improves the strength and function of patients with Duchenne's muscular dystrophy. However, further research is required to identify the mechanisms responsible for these improvements and to determine whether prolonged treatment with corticosteroids may be warranted despite their side effects.
    New England Journal of Medicine 07/1989; 320(24):1592-7. · 54.42 Impact Factor
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    ABSTRACT: Two-hundred eighty-three boys with Duchenne dystrophy and 10 with Becker dystrophy have been followed for up to 10 years in a protocol that accurately measured their function, strength, contractures, and back curvature. Clinical heterogeneity is noted. Patients whose muscles were stronger were more likely to die from a cardiomyopathy. Weaker patients died from respiratory failure. A series of milestones is defined, which is of use in following the illness in an individual patient. This approach permits a scoring system that allows the severity of the disease to be defined in an individual boy. Evaluation of physical therapy and surgical intervention shows that night splints and scoliosis surgery are effective forms of treatment.
    Neurology 05/1989; 39(4):475-81. · 8.30 Impact Factor
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    ABSTRACT: Because testosterone has an anabolic effect in myotonic dystrophy, we conducted a 12-month, randomized, double-blind therapeutic trial of testosterone enanthate (3 mg/kg/wk) in 40 men with myotonic dystrophy. We evaluated strength by manual muscle tests, quantitative myometry, pulmonary function, and quantitative functional assessment. A sustained, significant elevation of testosterone levels was produced but there was no effect on any measurement of muscle strength. Muscle mass as estimated by creatinine excretion and lean body mass (40K method) increased significantly. We conclude that testosterone does not improve strength in myotonic dystrophy despite increasing muscle mass.
    Neurology 03/1989; 39(2 Pt 1):219-22. · 8.30 Impact Factor
  • M H Brooke
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    ABSTRACT: The results of the various studies and an analysis of the methodology are presented in TABLE 1. As can be seen, there was no "perfect" study. In five of the studies enough information was presented with regard to the measurements and the behavior of control patients that a statistical analysis could be performed. Three of the studies showed a transient, statistically significant effect in at least some muscles. The two studies that demonstrated no such effect both used TRH in very small doses. It therefore seems reasonable to conclude that the effect of TRH in ALS is a definite, acute, and transient response. The cause of this response, however, has not been documented, and whether it is associated with an effect of the drug on the disease process remains to be seen.
    Annals of the New York Academy of Sciences 02/1989; 553:422-30. · 4.38 Impact Factor
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    ABSTRACT: A double-blind controlled trial of penicillamine and vitamin E against placebo was conducted in 106 boys with Duchenne muscular dystrophy. Nine dropped out of the study after being randomized. Patients were evaluated using an established protocol that measures muscle strength, joint contractures, functional grade, and pulmonary function. The trial lasted for 18 months. The power of the study to detect a 75% slowing of the disease was 0.95 at a P less than 0.05. No therapeutic effect was observed in the patients taking penicillamine and vitamin E as compared with those taking placebo.
    Muscle & Nerve 12/1988; 11(11):1164-8. · 2.31 Impact Factor

Publication Stats

3k Citations
482.19 Total Impact Points

Institutions

  • 1990–1995
    • University of Alberta
      • • Division of Neurology
      • • Department of Medicine
      Edmonton, Alberta, Canada
  • 1991
    • University of Rochester
      • Department of Neurology
      Rochester, NY, United States
  • 1978–1991
    • Washington University in St. Louis
      • • Department of Neurosurgery
      • • Department of Neurology
      • • Division of Urologic Surgery
      San Luis, Missouri, United States
    • University of Colorado at Boulder
      • Department of Molecular, Cellular, and Developmental Biology (MCDB)
      Boulder, Colorado, United States
  • 1989
    • University of Washington Seattle
      • Department of Neurology
      Seattle, WA, United States
  • 1976
    • University of Colorado Hospital
      Denver, Colorado, United States