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Biomedical subjects

L Vergani

Publications and source records attributed to L Vergani.

At least 55 records · Page 3Linked to original sources
PubMed1988

Native chromatin and damage induced by nuclease.

Differential scanning calorimetry, gel electrophoresis and polarized light scattering of chromatin prepared by different methods have been carried out at low and high ionic strength, before and after shearing. These noninvasive studies, when compared to the ones similarly conducted in the corresponding native nuclei, conclusively point to the artefactual nature of chromatin prepared by limited nuclease digestion, which has no resemblence with the in situ chromatin-DNA structure being instead preserved by lysis of native nuclei and by subsequent sedimentation and suspension of the viscous chromatin mass. Native nucleofilaments appear longer than 200 nucleosomes and yield, from thermodynamic and optical standpoints, a tight quaternary structure maintained even at 0.01 M.

Animals↗
PubMed1988

Nuclear architecture, intranuclear DNA distribution, and nuclease digestion.

G0, G1, and mammalian cells and nuclei were shortly digested with either micrococcal nuclease or DNAse I, both before and after mild fixation, either before (G0) or after (G1) partial hepatectomy. Cells were Feulgen stained and examined by high resolution light microscopy. In metabolically active G1 nuclei, intranuclear DNA appears organized at least in two distinct domains, whereby the highly dispersed one is large enough to be detected at the resolution of the light microscope and appears preferentially attacked by limited DNAse I digestion. The action of the enzyme is readily apparent only in the nuclei that are first digested and then fixed. Spectroscopic characterization of the same nuclei reveals that the fixation causes a sizeable removal of proteins, mostly in the soluble chromatin subfraction. Results are discussed in terms of two control levels for gene expression and for higher order DNA structure.

Animals↗
PubMed1988

Comparison of the performances of an automated arrhythmia detector working on original and virtual ECG tracings.

Two approaches can be taken to improve the performance of an automatic arrhythmia detector: perfecting the detection algorithms or improving the quality of the investigated traces by preprocessing the original traces. This paper reports on the results of a data preprocessing approach. Preprocessing consists in constructing new traces, which we call virtual. They are mathematically obtained from the original traces and referred to the dominant cardiac electric axis. The classifications obtained with an arrhythmia detector using both virtual and original traces are presented and discussed. By comparing the performance indices obtained under the two different conditions, it can be seen that a diagnosis based on the virtual traces is as acceptable as one based on the original traces. This result should be judged as favorable, since the algorithm was not adjusted or calibrated to the virtual traces, while those who developed it had certainly calibrated the parameters to the original traces.

Algorithms↗
PubMed1987

Structure of a protein catalyzing the formation of 11 cis-retinal in the visual cycle of invertebrate eyes.

A pigment made up of a protein able to bind retinal as well as retinol is described. The molecule consists of a dimer with a molecular weight of 50,000 which binds one molecule of retinal. The binding site for retinal is a Schiff base buried in the interior of the protein. Retinol is probably bound to the protein in the same site as for retinal, although not covalently, as suggested by the absorbance spectra. The protein, extracted from honeybee retina, is involved in visual pigment metabolism, and its structure may elucidate the mechanism of the stereospecific photoisomerization of all trans-retinal to 11-cis-retinal.

Amino Acids↗
PubMed1987

Clinical varieties of carnitine and carnitine palmitoyltransferase deficiency.

Several clinical entities are associated with disorders of fatty acid oxidation or transfer across the inner mitochondrial membrane. Over 40 cases of the primary carnitine deficiency syndrome have been reported to date and various subtypes have been characterized. This represents a large clinical spectrum. The deficiency of carnitine in muscle is at the basis of a syndrome characterized by muscle weakness and lipid storage myopathy. The systemic form of carnitine deficiency is more generalized and includes recurrent episodes of hepatic encephalopathy as well as lipid storage in muscle, liver and heart. In one subtype, hypoglycemia upon fasting and cardiomyopathy are found. There are also several causes of secondary carnitine deficiency states which are either acquired or associated with inborn errors of metabolism (organic acidurias, defects of acyl-CoA dehydrogenases). Clinically, Carnitine palmitoyltransferase (CPT) deficiency is a rather homogeneous syndrome presenting with recurrent episodes of myoglobinuria provoked by fasting or prolonged exercise. The only exception is an infantile variety associated with severe hypoglycemia and hepatic CPT deficiency. Using malonyl-CoA, a specific inhibitor of CPT-I, we had suggestions in five adult patients with myoglobinuria that CPT-II is lacking in muscle, liver and platelets while CPT-I is above the control level. The enzyme abnormality seems partial and limited to CPT-II or to its binding to the inner mitochondrial membrane.

Acyltransferases↗
PubMed1986

Effect of light and calcium on cyclic GMP synthesis in rod outer segments of toad retina.

The rod outer segments of toad retina contain a guanylate cyclase activity of about 3 +/- 1 nmol of cGMP formed/min per mg protein. In darkness this value is largely independent of the Ca2+ concentration, although it is enhanced by light upon lowering the Ca2+ concentration from 10(-5) to 10(-8) M. The activating effect of light on cyclase at low Ca2+ concentrations is enlarged upon increasing the light intensity. With a flash of light bleaching 7 X 10(-2) percent of rhodopsin, cyclase activity increased by a factor of 30 when Ca2+ levels dropped from 10(-5) to 10(-8) M. In view of recent observations that shortly after a flash of light the calcium activity inside the photoreceptor cell decreases, it seems likely that Ca2+ plays a regulatory role on cGMP metabolism in visual excitation.

Animals↗
PubMed1986

Remarks and experiments on the construction of respiratory waveforms from electrocardiographic tracings.

We report on some observations and preliminary experiments on the deduction of respiratory waveforms from electrocardiographic traces by interpolating the values of angles related to a cardiac electrical axis. The experiments concern comparing the trends obtained from different definitions of the cardiac electrical axis: respiratory waveforms deducted by considering the electrical axis of either the QRS complex or the T wave, and those deducted in the presence of cardiac rhythm disorders, noise, and drifts. The most significant result was obtained when, starting from an ECG trace, we were able to plot curves that were very close to the respiration curve obtained from a belt impedance meter. This result indicates that the objective can be attained. Other results concern specific cases and the constraints to be observed. Among those, arrhythmia, missing beats, pauses, noise, and drifts superimposed on the original ECG traces.

Arrhythmias, Cardiac↗
PubMed1986

Childhood encephalomyopathy with cytochrome c oxidase deficiency, ataxia, muscle wasting, and mental impairment.

The son of third cousins was normal until age 2 when he had difficulty walking. At age 8 there was limb weakness, ataxia, loss of tendon reflexes, dislalia, and he was mildly retarded. During fasting, urinary organic acid excretion was abnormally high. Cytochrome c oxidase activity in muscle was 7% of the normal mean. The enzyme in platelets was 16% of controls with a decreased cytochrome aa3 peak. These data suggest an autosomal recessive transmission of this variant of cytochrome c oxidase deficiency.

Ataxia↗
PubMed1985

Familial neuromuscular disease with tubular aggregates.

We have studied four members of a family in which five individuals of both sexes in three generations have mild weakness and muscle aching. Serum creatine kinase (CK) and/or aldolase were mildly to moderately elevated. Tubular aggregates were present in all patients in all fiber types. Type 1 fiber predominance and type 2 hypotrophy or atrophy was noted in three biopsies. Fiber splitting was prominent in two cases. Electron microscopic studies confirm that the tubular aggregates originate from muscle sarcoplasmic reticulum (SR). The presence of T tubules making contacts with some tubules inside the collection of tubular aggregates is suggestive of their derivation from terminal cisternae.

Adolescent↗
PubMed1985

Virtual leads for the ambulatory ECG monitoring: remarks on the persistency of their direction.

We attempt to improve the performances of the algorithms devoted to the computer-based detection of arrhythmias by improving the quality of the tracings they have in input. This aim is pursued by building virtual tracings mathematically derived from the original ones. In this paper we describe the persistency in the time domain of the direction of some virtual leads. Such a persistency will tell us how often in a subject we must recalculate the virtual lead. They have been defined starting from the original tracings of the two leads belonging to the BIH/MIT Arrhythmia Database. We considered the width of the time window just more than the cycle duration: i.e., a severe experimental condition. We found there is no persistency and we have to recalculate continuously the direction of the virtual lead. The set consisting of only two original leads and the short window may have had a major influence on our results. About the specific contribution that the virtual leads take to the improving of the tracings quality, we have several examples where, in respect to the original tracings, the virtual tracings show a positive increase of the differences between normal and abnormal beats.

Ambulatory Care↗
PubMed1981

Fatal lipid storage with abnormal mitochondria in an infant.

Biochemical, electron microscopic observations in muscle and liver of an infant dying at 20 months of age of a mitochondrial myopathy are described. Biochemical analysis of tissues revealed low levels of free, esterified and total carnitine and marked decrease of succinic-dehydrogenase activity while cytochrome c-oxidase was normal. Ultrastructural data showed a megaconial myopathy.

Brain Diseases, Metabolic↗
PubMed1981

Carnitine deficiency induced during hemodialysis and hyperlipidemia: effect of replacement therapy.

Plasma carnitine levels were studied in 14 uremic patients before, during, and after hemodialysis. The predialysis plasma carnitine levels were normal but fell during dialysis (half-life of 3.6 h). Plasma carnitine levels rose quickly in the first 6 h after dialysis, after which time the rise was more gradual. Muscle carnitine was significantly reduced in the dialyzed patients (p less than 0.005) compared with controls. In four patients lipid droplets were observed in muscle. Ten patients on maintenance hemodialysis exhibited plasma hyperlipidemia and low muscle carnitine. These individuals were given DL-carnitine (50 mg/kg body weight) intravenously after each dialysis. At the end of a 2-month carnitine treatment, plasma triglyceride levels were found to be reduced (p less than 0.001) and muscle carnitine content significantly increased (p less than 0.005). These findings suggest that carnitine may be useful in treatment of hypertriglyceridemia and muscle carnitine deficiency states induced during maintenance hemodialysis.

Adult↗
PubMed1981

Carnitine palmityl transferase deficiency: clinical variability, carrier detection, and autosomal-recessive inheritance.

A 21-year-old man had recurrent myoglobinuria; his 28-year-old sister had symptoms of fatigability. During prolonged fasting, serum free fatty acid rose in both siblings, but only the sister produced ketone bodies and had elevated creatine phosphokinase activity. Carnitine palmityl transferase (CPT) activity was less than 30% of normal in muscle and platelets. Liver biopsy disclosed a low level of the enzyme in the brother. The parents had intermediate levels of the enzyme in platelets. CPT deficiency seems to have an autosomal-recessive pattern of inheritance and a variable phenotypic expression.

Acyltransferases↗
PubMed1980

Plasma and urine carnitine levels during development.

Plasma and urine free carnitine concentration during human development was evaluated. A positive correlation was found between plasma level and body weight in premature neonates weighting between 1.15 and 1.80 kg. In full terms newborns, the free carnitine concentration (mean +/- S.E., 31.2 +/- 2.5 nmoles/ml) is similar to that of premature babies with 33 to 36 wk of gestational age (37.5 +/- 3.1 nmoles/ml) but significantly lower than that of premature babies aged 30 to 33 wk of gestation (43.0 +/- 5.6 nmoles/ml). In the first 2 wk of life, free carnitine level showed a good correlation with age in the full-term newborns. Adult levels are reached by the end of the first 6 months. no sex related difference was observed in any of the different groups during growth. Urinary excretion of free carnitine per day is significantly lower in infants 0 to 3 years old (mean +/- S.E., 15.5 +/- 1.8 mumoles/24 hr) and in children 3 to 10 years old (115.3 +/- 11.4 mumoles/24 hr) than in subjects ranging in age from 22 to 70 years (216 +/- 20.6 mumoles/24 hr). We found no difference between day- and nighttime urinary excretion in newborns and infants.

Adolescent↗
PubMed1978

Carnitine deficiency: acute postpartum crisis.

A 16-year-old girl, previously in good health, developed progressive generalized muscle weakness following her first parturition. The neck and proximal limb muscles were especially weak and painful. Carnitine (4-trimethylamino-3-hydroxybutyrate) was markedly decreased in muscle, plasma, and urine. Dietary carnitine supplementation, 2.0 gm daily, was followed by clinical improvement and decreased lipid droplets in muscle biopsy. Together with previously reported cases, 2 fatal, the patient's illness emphasizes the risk of pregnancy in women with carnitine deficiency.

Adolescent↗
PubMedDate not supplied

Liver fatty acid-binding protein in two cases of human lipid storage.

FABPs in the various tissues play an important role in the intracellular fatty acid transport and metabolism. Reye's syndrome (RS) and multisystemic lipid storage (MLS) are human disorders characterized by a disturbance of lipid metabolism of unknown etiology. We investigated for the first time L-FABP in these two conditions. Affinity purified antibodies against chicken L-FABP were raised in rabbits, and found to cross-react specifically with partially purified human L-FABP. L-FABP content in liver samples of two patients with RS and MLS was investigated by immuno-histochemistry, SDS-PAGE and ELISA. L-FABP immuno-histochemistry showed increased reactivity in the liver of RS patient and normal reactivity in MLS liver. L-FABP increase in RS liver was confirmed by densitometry of SDS-PAGE and ELISA method. By these two methods the increase amounted to 180% and 199% (p less than 0.02), respectively, as compared to controls. A possible role of L-FABP in the pathogenesis of RS is discussed.

Adolescent↗