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Biomedical subjects

E Bonilla

Publications and source records attributed to E Bonilla.

At least 235 records · Page 13Linked to original sources
PubMed1978

Studies of fragmented sarcoplasmic reticulum from human skeletal muscle.

Sarcoplasmic reticulum (SR) vesicles were isolated from muscle biopsies of 4 normal volunteers, a patient with McArdle disease (before and during contracture), and a patient with normokalemic periodic paralysis. Fractions were analyzed for purity by electron microscopy and biochemical analysis of specific marker enzymes. Adenosine triphosphate (ATP)-dependent calcium ion uptake was measured kinetically by the absorbence changes of murexide, a metallochromic indicator of ionized Ca++ concentrations, in the absence of oxalate or other calcium-complexing anions. In these experiments, time resolution of the Ca++ transport rate was limited by the manual mixing of reagents, which occurred in 1 to 3 seconds. In 1 case the "true" initial velocity of Ca++ uptake was measured by rapid mixing of ATP in a stopped-flow apparatus and by following the change in absorbence of murexide in a storage oscilloscope. In SR from normal human muscle the ATP-dependent Ca++ uptake was 3.5 nmoles per second per milligram of protein for the first 5 seconds after ATP mixing. Fast kinetic experiments showed that Ca++ uptake proceeded linearly for the first 500 msec at a rate of 9 nmoles per second per milligram of protein (at 25 degrees C) and then progressively declined to reach steady-state levels in 40 to 50 seconds. No abnormality of Ca++ transport was found in SR vesicles from the patient with McArdle disease and the patient with normokalemic periodic paralysis.

Adenosine Triphosphatases↗
PubMed1978

Duchenne dystrophy: focal alterations in the distribution of concanavalin A binding sites at the muscle cell surface.

In 6 patients with Duchenne dystrophy, electron microscopical studies of concanavalin A (Con A) binding sites using the peroxidase labeling technique revealed a population of muscle fibers in which the reaction at the cell surface was irregular and patchy in areas larger than 0.5 mu. In 5 control subjects, such focal alterations were not observed and the reaction appeared continuous and regular. The findings indicate focal abnormalities at the muscle cell surface of Con A receptors in Duchenne dystrophy.

Adult↗
PubMed1978

Alteration in erythrocyte membrane structure in Duchenne muscular dystrophy.

Freeze-fracture studies of erythrocytes from patients with Duchenne muscular dystrophy revealed depletion of particles on both fracture faces of the plasma membrane. This study indicates that the structure of the erythrocyte plasma membrane is abnormal in Duchenne dystrophy and supports the concept that a generalized membrane abnormality is present in this disease.

Adolescent↗
PubMed1978

Flameless atomic absorption spectrophotometric determination of manganese in rat brain and other tissues.

I describe a method for determining manganese in biological tissues by flameless atomic absorption spectrophotometry, It is simple to perform and does not require prior extraction with solvents. Small tissue samples are dried for 48 h at 110 degrees C and dissolved in concentrated nitric acid; the clear acid solution is introduced into the furnace and the sequential drying (120 degrees C, 20 s), charring (800 degrees C, 70 s), and atomization (2400 degrees C, 8 s) are automatically performed. The technique of standard additions was used ot overcome matrix effect. The detection limit is 0.86 X 10(-11) g of Mn. The CV is 4.7%. Only sodium and potassium interfere at 500-fold concentrations, and their interferences were overcome by using the Deuterium Arc Background Corrector.

Animals↗
PubMed1977

Duchenne dystrophy: alteration in muscle plasma membrane structure.

Freeze fracture studies of skeletal muscle from eight patients with Duchenne dystrophy showed nonuniform distribution and depletion of particles on both protoplasmic and extracellular faces of the muscle plasma membrane. The findings support the view that the muscle surface membrane is abnormal in this disorder and indicate that alterations are present in the internal molecular architecture of the membrane.

Child↗
PubMed1977

Isolation and characterization of muscle membranes using surface-specific labels.

Membranes were purified from rat muscle by a differential centrifugation method that avoids the use of salt extraction or incubations at elevated temperature. Three populations of membrane-limited vesicles were defined having average densities of 1.112 (fraction I), 1.141 (fraction II), and 1.158 (fraction III) g/ml in a continuous sucrose gradient. Lactoperoxidase-catalyzed iodination of intact muscle prior to isolation of membranes resulted in highest specific activity in fraction I, although all fractions could be equally labeled after isolation. 125I-Labeled wheat germ agglutinin incubated at low concentration with intact muscle preferentially labeled fraction I. Parallel studies on previously isolated fractions indicated that fraction I also contained the highest concentration of potential receptors for wheat germ agglutinin. In experiments on whole muscle, concanavalin A bound predominantly to sarcolemma with slight variable binding to T-tubular and nuclear membrane but no binding to sarcoplasmic reticulum or mitochondria. Parallel binding studies with isolated membrane fragments indicated heavy binding of concanavalin A by membranes in fraction I with scattered binding in fractions II and III. Na+K+Mg2+ ATPase was specifically enriched in fraction I but was also present in fraction II in a proportion similar to 125I labeling. Ca2+ ATPase was most active in fraction II but present in significant levels in fraction I. It is concluded from these and other data that fraction I contains predominantly sarcolemma membrane, while T-tubular membrane may represent a significant component of fraction II. Ca2+ ATPase activity in fraction I is intrinsic to the sarcolemma.

Adenosine Triphosphatases↗
PubMed1976

Neuromuscular disorder associated with a defect in mitochondrial energy supply.

A limb muscle biopsy specimen from a patient with a slowly progressive congenital neuromuscular disorder disclosed, by electron microscopy, widespread mitochondrial crystalline inclusions. Biochemical studies of isolated mitochondria showed decreased respiratory rate and respiratory control with both nicotine adenine dinucleotide and flavor-protein-linked substrates. Mitochondrial adenosine triphosphatase (ATPase) activity, both basal and magnesium (Mg++) or 2,4-dinitrophenol- (DNP) stimulated, was greatly reduced in contrast to normal. The rate and extent of mitochondrial calcium accumulation was normal. These findings are consistent with a defect of the respiratory chain-linked energy transfer at a level common to all three energy coupling sites of the respiratory chain. The defect in ATPase activity may be secondary to replacement of functional mitochondrial inner membrane by crystalline inclusions.

Adenosine Triphosphatases↗
PubMed1976

Luft's disease. Further biochemical and ultrastructural studies of skeletal muscle in the second case.

In the second known case of non-thyroidal hypermetabolism (Luft's disease), there were large areas of mitochondrial aggregates in all fibers. Many mitochondria were abnormally large and contained packed cristae. In isolated mitochondrial fractions, studies of oxidative phosphorylation showed defective respiratory control and normal phosphorylation capacity ("loose coupling"). Spectra and content of cytochromes were normal. Basal ATPase activity was seven times greater than normal and poorly stimulated by 2,4-dinitrophenol. The rate of energy-dependent calcium uptake by isolated mitochondria was normal, but the amount of calcium accumulated was much decreased. Calcium could not be retained and was spontaneously released into the medium within 30 seconds. "Recycling" of calcium between mitochondria and cytosol may take place in vivo and result in sustained stimulation of respiration and loose coupling.

Adult↗
PubMed1976

Core formation in the muscles of rats intoxicated with triethyltin sulfate.

Young adult Osbourne-Mendel rats intoxicated for up to 23 days with triethyltin sulfate (TET) at a dose of 20 mg/liter of drinking water given ad libitum, developed core-like structures in type 1 extrafusal fibers of the soleus muscles. Frozen sections revealed an absence of oxidative enzyme activity (NADH-tetrazolium reductase) and diminished or absent myosin ATPase (pH 9.4) in the core regions. The main electron microscopic features within the cores were loss of mitochondria and streaming of the Z-disks. The histochemical and electron microscopic similarities and differences between the TET-induced cores, other core models, and those reported in some human neuromuscular disorders are discussed. The present experiments do not clarify whether the cores are produced from a direct effect of TET upon skeletal muscle or upon the neural component of the motor unit.

Animals↗
PubMed1975

A disorder of muscle lipid metabolism and myoglobinuria. Absence of carnitine palmityl transferase.

Two brothers, 29 and 33 years of age, had recurrent myoglobinuria, renal failure and azotemia, but were otherwise normal, without apparent muscle weakness or exercise intolerance. Ischemic exercise resulted in normal lactate production. Muscle glycogen content and activities of phosphorylase and phosphofructokinase were normal. Plasma triglycerides were elevated (500 mg per deciliter) on a regular diet and rose during fasting. During a 72-hour fast, serum creatine phosphokinase rose more than 10 times, and myoglobin was detected in urine. Plasma ketone production was minimal during fasting, but prompt ketonemia ( a normal response) occurred after ingestion of medium-chain triglycerides. Carnitine palmityl transferase activity was virtually absent in crude muscle extracts and mitochondrial fractions. Lack of this enzyme impairs long-chain fatty acid utilization, reflected in increased content of plasma free fatty acids and plasma triglycerides. Depletion of ATP because of this metabolic block in muscle may account for the attacks of myoglobinuria.

Acute Kidney Injury↗