Biomedical subjects
Publications and source records attributed to J E Carroll.
A child with the Dyggve-Melchior-Clausen syndrome associated with elevated pipecolic acid levels in plasma and urine is described. Other studies of peroxisomal function, including phytanic acid, very long-chain fatty acids, and plasmalogen synthesis, were normal. This disorder may represent an incompletely characterized defect in peroxisomal metabolism.
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In the developing nation of Kuwait, we undertook a case-control study of 43 consecutively born, asphyxiated, term infants. The asphyxia incidence of 9.4/1000 was only slightly higher than that in more developed countries. Severe morbidity occurred in 1.1/1000, and mortality in 1.1/1000. We found significant associations between asphyxia and primiparity, maternal hypertension, consanguinity, increased length of labour, and instrumental deliveries. Maternal age, socio-economic class, maternal illnesses other than diabetes, and breech delivery did not seem to play a role. The fact that the chosen method of delivery failed for a number of the asphyxiated patients, necessitating emergency Caesarian section, suggests that obstetric factors may need closer analysis.
Using bicycle ergometry with computerized respiratory gas exchange measurements, we compared exercise capacities in patients with various neuromuscular diseases to those in normal controls. As expected, male and female patients had significantly reduced maximum work capacities (kilopond-meters per minute per kilogram of body weight) and maximal oxygen consumptions. The oxygen cost of exercise was normal in the majority of patients, although some appeared to have abnormally high oxygen consumptions during exercise. Breathing patterns during exercise, particularly in regard to onset of hyperventilation, were similar in patients and controls.
A 38-hr fast was used as a provocative test in patients suspected of having defects in muscle substrate utilization. In five controls and nine patients, exercise capacity and respiratory exchange ratio were determined before and at the end of the fast. Blood was collected at intervals during the fast from ten controls and nine patients for creatine kinase (CK), free fatty acids, (FFA) beta-hydroxybutyrate, acetoacetate, free and total carnitine, glucose, and alanine. Two patients with myophosphorylase deficiency had increased exercise capacity, and a marked fall in CK, and one had a lesser fall in blood glucose than normal at the end of the fast. Two patients with known lipid myopathies (carnitine deficiency and carnitine palmityl transferase deficiency) had decreased exercise capacity and apparent increased dependence on carbohydrate metabolism during the fast. Carnitine concentrations became even more abnormal in the patient with carnitine deficiency during fasting. Several patients with less well-defined defects were also significantly different from the controls in several respects, indicating that the fast might be useful for finding new defects.
The response to a standardized exercise test was investigated in 12 volunteers and 13 patients with aches, cramps, and pains. In men, creatine kinase (CK) levels peaked (up to 1600 mU per milliliter) between 10 and 20 hours after exercise. High levels of blood lactate during exercise were related to the intensity of work and to high levels of CK after exercise. The patients could be divided into several groups: (1) those with no change in blood metabolites (psychogenic); (2) those with a disproportionate rise in CK (metabolic myopathies); (3) those with a disproportionate rise of lactate (mitochondrial abnormalities); and (4) in one patient with exercise-related pains, subnormal elevation of fatty acid levels. The correlation of changes in blood lactate, CK, and fatty acids may be useful, whereas an isolated measurement, even if outside the normal range, is often meaningless.
The effect of 2 hours of exercise on the serum creatine kinase (CK) level was investigated in 11 men and 9 women. The mean increase of CK 24 hours after exercise was significantly greater in men. The relative lack of CK elevation in women may: (1) indicate that female muscle is less susceptible to damage by adverse factors; and (2) explain discrepancies in previous reports.
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An infant was born with marked rigidity, a paucity of spontaneous movements, and increased serum creatine phosphokinase activity. Electromyogram was normal. A muscle biopsy, taken at the age of 7 weeks, contained numerous fibers composed of three concentric zones, warranting the designation "trilaminar fibers." Electronmicroscopy showed the innermost zone contained a densely packed collection of mitochondria, glycogen, electron opaque material, and single filaments. The middle zone consisted of myofibrils with Z-band smearing. The outer zone resembled a sarcoplasmic mass. Extrajunctional acetylcholine receptor (AChR) was present in the trilaminar fibers between the middle and outer zones. The increased muscle tone and extrajunctional AChR suggest and altered neural influence, but the markedly increased creatine phosphokinase activity is more characteristic of muscle damage. Precise definition of the nature of the defect awaits further study.
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We present 19 patients from 12 families with mild (Becker) X-linked recessive dystrophy and compare them with previously described cases. Features in common in the majority of patients include onset after the age of 7 years, walking beyond the age of 20 to 30 years, mild hypertrophy of the calves, mild joint contractures, and high arched feet. Pshychometric tests, EEGs, and ECGs were usually normal. Muscle biopsy specimens showed a combination of features, some more characteristic of severe (Duchenne) X-linked dystrophy and others more commonly seen in limb girdle dystrophy. Although there was some variation in the severity between different families, within any one kindred, the clinical picture was quite similar.
We report a 4 1/2-month-old female infant with subacute onset of hypotonia. Symmetrical weakness, association with a viral illness, high CSF protein level, diminished nerve conduction velocities, and a prompt recovery were compatible with the diagnosis of Guillain-Barré syndrome. The possibility that this disorder may occur in young infants with weakness should be considered.
In order to examine muscle ischemia, muscle blood flow in the rat hindlimb was decreased by vessel ligation. Amino acid uptake, studied with [14C]alpha-aminoisobutyric acid, was decreased in ischemic Type I (soleus) muscle. Glucose uptake, studied with [14C]deoxyglucose, was increased in Type I muscle. These changes were temporally associated with histologic changes of ischemia in soleus muscle. Denervation, atrophy, and hypertrophy also produced uptake changes with these techniques, and although more prominent in soleus, the changes were also seen in Type II muscle.
Patients with myotonic dystrophy often develop respiratory failure caused by alveolar hypoventilation. Abnormalities in the ventilatory response to hypoxia and hypercapnia may explain this phenomenon. Accordingly, hypoxic and hypercapnic responses were measured in seven patients with myotonic dystrophy who had only mild respiratory muscle weakness. Hypoxic response was significantly reduced, while hypercapnic response was affected more irregularly. It is possible that the high incidence of respiratory failure in such patients is related to decreased hypoxic ventilatory response, occurring because of an underlying neurogenic deficit.
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