PubMed Health⌕ Search

Biomedical subjects

D Segura

Publications and source records attributed to D Segura.

15 recordsLinked to original sources
PubMed1998

Myophosphorylase deficiency associated with a defect in complex I of the mitochondrial respiratory chain.

We studied a 21-year-old patient with clinical, biochemical and histochemical evidence of myophosphorylase deficiency and unusual repetitive episodes of pigmenturia. His muscle biopsy also revealed morphological signs of mitochondrial proliferation and a defect of complex I of the respiratory chain. His mother had exercise intolerance without myoglobinuria and no histochemical evidence of myophosphorylase deficiency. In muscle, the mother showed some ragged-red fibers, normal respiratory chain levels and a significant residual phosphorylase activity. Molecular genetic analysis revealed that the proband was homozygous for the mutation commonly found in McArdle's disease. The mother, father, and the five siblings were all heterozygous for the same mutation. Mitochondrial DNA analysis of the proband's muscle failed to demonstrate known mutations associated with his clinical pattern. Moreover, we sequenced his tRNA(Leu(UUR)) gene, a hot spot for mutations, showing no abnormality.

Adult↗
PubMed1998

Mutational inactivation of a gene homologous to Escherichia coli ptsP affects poly-beta-hydroxybutyrate accumulation and nitrogen fixation in Azotobacter vinelandii.

Strain DS988, an Azotobacter vinelandii mutant with a reduced capacity to accumulate poly-beta-hydroxybutyrate, was isolated after mini-Tn5 mutagenesis of the UW136 strain. Cloning and nucleotide sequencing of the affected locus revealed a gene homologous to Escherichia coli ptsP which encodes enzyme INtr, a homologue of enzyme I of the phosphoenol pyruvate-sugar phosphotransferase system with an N-terminal domain similar to the N-terminal domain of some NifA proteins. Strain DS988 was unable to grow diazotrophically with 10 mM glucose as a carbon source. Diazotrophic growth on alternative carbon sources such as gluconate was only slightly affected. Glucose uptake, as well as glucose kinase and glucose-6-phosphate-dehydrogenase activities that lead to the synthesis of gluconate-6-phosphate, were not affected by the ptsP mutation. The inability of DS988 to grow diazotrophically in 10 mM glucose was overcome by supplying ammonium or other sources of fixed nitrogen. Acetylene reduction activity but not transcription of the nitrogenase structural gene nifH was shown to be impaired in strain DS988 when it was incubated in 10 mM glucose. The diazotrophic growth defect of DS988 was restored either by increasing the glucose concentration to above 20 mM or by lowering the oxygen concentration. These data suggest that a mutation in ptsP leads to a failure in poly-beta-hydroxybutyrate metabolism and in the respiratory protection of nitrogenase under carbon-limiting conditions.

Amino Acid Sequence↗
PubMed1997

Association of genetically proven deficiencies of myophosphorylase and AMP deaminase: a second case of 'double trouble'.

We studied a 25-year-old man with paresis of the limbs and neck, scapular atrophy, facial weakness, exercise intolerance and frequent episodes of myoglobinuria. Muscle histochemistry and biochemistry revealed a combined defect of myophosphorylase and AMP deaminase. Molecular genetic analysis showed that the patient was homozygous for the two most common mutations associated with myophosphorylase and AMP deaminase deficiencies. This is the second documented case of genetic 'double trouble', which should be looked for in patients with unusual severe phenotypes.

AMP Deaminase↗
PubMed1996

Antiinflammatory activity of extracts from Aloe vera gel.

We studied the effects of aqueous, chloroform, and ethanol extracts of Aloe vera gel on carrageenan-induced edema in the rat paw, and neutrophil migration into the peritoneal cavity stimulated by carrageenan. We also studied the capacity of the aqueous extract to inhibit cyclooxygenase activity. The aqueous and chloroform extracts decreased the edema induced in the hind-paw and the number of neutrophils migrating into the peritoneal cavity, whereas the ethanol extract only decreased the number of neutrophils. The antiinflammatory agents indomethacin and dexamethasone also decreased carrageenan-induced edema and neutrophil migration. The aqueous extract inhibited prostaglandin E2 production from [14C]arachidonic acid. The chemical tests performed in the aqueous extract for anthraglycosides, reductor sugars and cardiotonic glycosides were positive. In the ethanol extract, the chemical tests performed for saponins, carbohydrates naftoquinones, sterols, triterpenoids and anthraquinones were also positive. In the chloroform extract, the chemical tests performed for sterols type delta 5, and anthraquinones were positive. These results demonstrated that the extracts of Aloe vera gel have antiinflammatory activity and suggested its inhibitory action on the arachidonic acid pathway via cyclooxygenase.

Aloe↗
PubMed1995

Clinical heterogeneity in two pedigrees with the 3243 bp tRNA(Leu(UUR)) mutation of mitochondrial DNA.

We studied two pedigrees with a mutation at the nucleotide 3243 of mitochondrial DNA (mtDNA). The proband from the first pedigree had clinically defined MELAS plus maternally transmitted insulin-dependent diabetes mellitus (IDDM). The propositus of the other pedigree had exercise intolerance, lactic acidosis and ragged-red fibers (RRF). In the first pedigree, both the mother and the sister's proband harbored the point mutation in their muscle. The mother had 40% of mutant mitochondrial genomes and the sister 70%. In the second pedigree, the mutation was present in both muscle and blood from the proband as well as in blood from all other members studied. Proportion of mutant mtDNA was 90% in muscle and ranged from 40% to 90% in blood.

Adult↗
PubMed1995

[Congenital myopathy with cores and nemaline rods in one family].

We present a mother and 2 children with congenital myopathy whose clinical signs were facial paresis in all three, and mild involvement of the lower extremities in the mother and one son. All three presented skeletal abnormalities, hypertelorism, arched palate, retraction of the Achilles tendon or short neck. Symptoms were not progressive and muscle biopsies showed central cores and nemaline rods in the mother and only nemaline rods in the 2 sons. The mother also suffered carpal tunnel syndrome, as had other members of the family as the result of autosomal dominant inheritance.

Adolescent↗
PubMed1995

[Adult onset mitochondrial myopathy without ophthalmoplegia. Four cases attributable to complex III and IV deficits in the respiratory chain].

Four adults with proximal myopathy of mitochondrial origin but no ocular involvement are presented. Biochemical analysis showed combined complex III and IV deficits in the respiratory chain in all cases, suggesting an apparent correlation between clinical phenotype and biochemical findings. Mitochondrial DNA analysis of muscle from 1 patient failed to detect either large-scale deletion or point mutations at position 3243 of tRNA(Leu(UUR)) or at 8344 of tRNA(Lys). The tissue specificity of the disease and the absence of family history suggest that a mutation in a nuclear DNA gene encoding a specific subunit of muscle could underlie this disease.

Adult↗
PubMed1993

Muscle carnitine deficiency and lipid storage myopathy in patients with mitochondrial myopathy.

Abnormal carnitine distribution in muscle was found in 22 of 77 patients (29%), with mitochondrial myopathy. Furthermore, total (TC) and free (FC) carnitine levels in muscle were lower in patients than in controls (P < 0.01). Muscle long-chain acylcarnitines (LCAC) were significantly increased in these patients (P < 0.01). Muscle carnitine deficiency was found in 31.5% of patients with lipid storage myopathy (LSM) and in 25.6% of patients with ragged-red fibers (RRF). Therefore, carnitine deficiency can be found in patients with mitochondrial myopathy even in the absence of LSM. Muscle levels of TC and FC were lower in patients with respiratory chain defects than in those with normal respiratory chain (P < 0.01). In contrast, LCAC levels were significantly increased (P < 0.05). Carnitine levels did not differ significantly, among patients with different respiratory-chain defects. Consequently, these patients, owing to their biochemical block, reduce progressively the muscle carnitine pool and subsequent LCAC rise, due to long-chain fatty acid (LCFA) accumulation.

Adolescent↗
PubMed1991

[Complex I (NADH coenzyme-Q-reductase) deficiency, MELAS syndrome and hypertrophic cardiomyopathy].

A 24-year-old male had a deficiency of the complex I (NADH coenzyme-Q-reductase) of the mitochondrial respiratory chain, which clinically presented as a mitochondrial encephalomyopathy, with lactic acidosis and stroke-like episodes (MELAS syndrome). The encephalopathic episodes were preceded by migraine and were characterized by focal deficit signs, motor partial seizures and hypodense areas in the CT scan. An echocardiographic diagnosis of hypertrophic cardiomyopathy without intracavitary thrombi was made. It is suggested that hypertrophic cardiomyopathy is caused by the mitochondrial abnormalities that have been reported in the myocardium, and that migraine and cerebral infarctions are associated with abnormalities in the mitochondria from the endothelium and smooth muscle fibres of the cerebral small arteries and arterioles.

Acidosis, Lactic↗
PubMed1984

Sequential morphological and functional changes in kaolin-induced hydrocephalus.

An experimental model of kaolin-induced hydrocephalus in the dog was studied in order to evaluate the progress of ventricular dilatation and the communications between the ventricular system and the subarachnoid space. Skull and spine radiological studies were obtained after metrizamide intraventricular injection, and the baseline ventricular pressure and cerebral pulse pressure amplitude were measured in anesthetized animals. Intracranial compliance and resistance to drainage of cerebrospinal fluid were calculated by means of bolus injection test. Light and scanning electron microscope studies were done at different developmental stages of hydrocephalus. With these experimental parameters, two successive phases were seen: an initial acute hypertensive hydrocephalus (H1) with high resistance, low compliance, severe ependymal damage, and subependymal edema; and a late chronic normotensive hydrocephalus (H2) with little resistance increase, normal compliance, epithelial regeneration, and subependymal gliosis. Both the H1 and H2 stages showed an increase in the cerebral pulse pressure amplitude.

Animals↗
PubMedDate not supplied

[Comparative study between propofol and thiopental for anesthesia induction in surgery of short duration].

To compare anesthetic characteristics of thiopental and propofol in short duration surgical interventions, we have studied 40 patients undergoing gynecologic and proctologic surgery. Patients were randomly assigned to two groups receiving 2.5 mg/kg of propofol or 5 mg/kg of thiopental. In both groups, arterial hypotension of comparable intensity occurred. Heart rate was significantly higher in thiopental anesthesia. Postanesthesia recovery was significantly more rapid with propofol. Some of these results can be influenced by the different immediate premedication (atropine and diazepam in thiopental group) and duration of anesthesia.

Adult↗
PubMedDate not supplied

[Synthesis, function, and evolutionary origin of secondary metabolites produced by micro-organisms].

The microbial secondary metabolites are compounds with a wide range of chemical structures, produced mainly by actinomycetales and some fungi, usually in the late growth phase. Although a high proportion of this metabolites are antibiotics, there are also examples with pigment, herbicide and surfactant properties. Its function has been correlated to bacterial pathogenicity and cellular differentiation, however, properties dealing with chelation, hormonal and antitumor activities as well as nutritional reserve have been also reported. As in other examples of cellular compounds, the secondary metabolites are produced from low molecular weight precursors. For this purpose, specific biosynthetic pathways are utilized and regulated by processes which generally affect either the activity or the synthesis of the enzymes involved in it. Considering the secondary metabolites apparently are dispensable compounds, there are difficulties to explain their existence from an evolutionary point of view. Explanations to their existence have gone from laboratory artifacts to those conferring them an adaptative value in the past. It seems that they were maintained due to selective advantages to the producer microorganisms and probably, their sometimes complex biosynthetic pathways, have emerged from primary metabolites and evolved later independently by random mutation, amplification and genetic transfer.

Adaptation, Physiological↗
PubMedDate not supplied

[Comparative study of intravenous anesthesia with propofol in continuous perfusion and neuroleptanalgesia in traumatology surgery].

OBJECTIVE. To study propofol as the single agent for both anesthetic induction and maintenance with respect to quality of anesthesia, hemodynamic effects, quality of recovery and analgesic requirements in comparison with neuroleptoanesthesia as the technique of reference. PATIENTS AND METHODS. We selected 2 homogeneous groups of 15 ASA I-III patients undergoing traumatological surgery. Patients were premedicated with bromazepam 3 mg p.o. and droperidol 0.03 mg/kg prior to induction. Induction was achieved with propofol 1.5-2.5 mg/kg in group I (GI) and with sodium thiopental 4-5 mg/kg in group II (GII). Maintenance was by continuous infusion of propofol 6-12 mg/kg in GI and with droperidol 0.15 microgram/kg/h and 50% N2O/O2 in GII. Both groups received fentanyl 4 micrograms/kg/h. Neither analgesia nor curarization were antagonized pharmacologically. Variables recorded were time and quality of anesthetic induction, mean duration of anesthesia, anesthetic education time, time until orientation and time of residual analgesia. Hemodynamic parameters were recorded for both groups at baseline, after induction, at intubation, at 2 and 5 min after intubation, at the start of surgical incision, 30 min after start of incision, and at the end of surgery. Results for the two groups were compared, as were results at the various moments of measurement within groups.

Adult↗