Biomedical subjects

J Montoya

Publications and source records attributed to J Montoya.

At least 37 records · Page 2Linked to original sources

PubMed2000

Human mtDNA haplogroups associated with high or reduced spermatozoa motility.

A variety of mtDNA mutations responsible for human diseases have been associated with molecular defects in the OXPHOS system. It has been proposed that mtDNA genetic alterations can also be responsible for sperm dysfunction. In addition, it was suggested that if sperm dysfunction is the main phenotypic consequence, these mutations could be fixed as stable mtDNA variants, because mtDNA is maternally inherited. To test this possibility, we have performed an extensive analysis of the distribution of mtDNA haplogroups in white men having fertility problems. We have found that asthenozoospermia, but not oligozoospermia, is associated with mtDNA haplogroups in whites. Thus, haplogroups H and T are significantly more abundant in nonasthenozoospermic and asthenozoospermic populations, respectively, and show significant differences in their OXPHOS performance.

Base Sequence↗

PubMed2000

Oxygen consumption measurement in lymphocytes for the diagnosis of pediatric patients with oxidative phosphorylation diseases.

OBJECTIVES: To evaluate the results of oxygen consumption measurement in lymphocytes for the diagnosis and treatment monitoring of pediatric patients with oxidative phosphorylation diseases. DESIGN AND METHODS: Twenty-four children with an oxidative phosphorylation disease were studied. Results were compared with those of 87 healthy children. Oxygen consumption measurements in digitonine-permeabilized lymphocytes incubated with pyruvate plus malate and succinate were performed in a Clark-type oxygen electrode. RESULTS: A total of 58% of patients showed a decreased oxygen consumption in lymphocytes incubated with pyruvate. In 4 patients, this analysis was the unique initial biochemical test, which revealed an impaired mitochondrial energy metabolism. Significant differences were observed in lymphocytes incubated with pyruvate between patients and reference values (p<0.00005), and in lymphocytes incubated with pyruvate before and after treatment (p<0.05). CONCLUSIONS: This test is useful for diagnosing oxidative phosphorylation diseases in patients who did not have other biochemical alterations, although false-negative results can be found. It is not useful for treatment monitoring.

Adolescent↗

PubMed2000

Direct and highly species-specific detection of pork meat and fat in meat products by PCR amplification of mitochondrial DNA.

Highly species-specific primers for pork D-loop mtDNA have been designed. Use of these and restrictive PCR amplification conditions has improved a reliable and rapid method for detecting a PCR-amplified 531 bp band from pork. It has been proved useful for detecting both pork meat and fat in meat mixtures, including those dry-cured and heated by cooking. Absence of response in PCR-amplified samples or mixtures from bovine, ovine, chicken, and human was also demonstrated. Furthermore, wild boar and pork samples can be also easily distinguished by a simple AvaII restriction analysis.

Animals↗

PubMed2000

Meningitis caused by Pseudallescheria boydii treated with voriconazole.

Meningitis caused by Pseudallescheria boydii is an uncommon infection of the CNS that usually has a poor prognosis and a difficult treatment. We describe a case of chronic meningitis caused by P. boydii in an immunocompetent host that was successfully treated with voriconazole, a new antifungal agent.

Adult↗

PubMed2000

[Evaluation of the tuberculin reaction in health occupation students] .

A cross-sectional study was done at the University of Antioquia, MedellIn, Colombia, to evaluate the response to a tuberculin skin test among students in undergraduate health programs (medicine, odontology, nursing, and bacteriology) as compared to undergraduate students in nonhealth programs. The study included students from the beginning, middle, and end of the university's academic programs. The sample of 490 students included 273 from health programs and 217 from nonhealth programs. Participants were randomly selected using lists provided by the university registrar, for the second semester of 1998. The presence of a BCG vaccination scar was determined, and all the participants were also questioned about TB-related risk factors. Tuberculin skin test reactivity was evaluated by the size of induration 72 hours after intradermal injection of two tuberculin units of purified protein derivative RT 23. There were no differences in tuberculin reactivity between students from the health programs and from the nonhealth programs, irrespective of the academic level. However, there was a significantly higher proportion of positive skin tests among students with a BCG scar. These results suggest that undergraduate health students do not have extensive contact with TB patients or with clinical samples from such patients. Nevertheless, the results do not rule out TB as an occupational risk for health personnel.

Adult↗

PubMed2000

A MELAS phenotype and a paternal inherited inversion of chromosome 10 in a female patient.

A MELAS phenotype and a paternal inherited inversion of chromosome 10 in a female patient: We describe a patient suffering from encephalomyopathy with overlapping symptoms, including MELAS and Kearn-Sayre syndrome features. Mutations in tRNA LEU (UUR) were not found in mtDNA of blood cells, suggesting a different genetic defect. Cytogenetic studies revealed a paternal inherited pericentric inversion of chromosome 10 (p13;q22) pat. Although the presence of the same inversion in the father and in the apparently asymptomatic sister does rather suggest that the concurrence of the mitochondrial disease in the patient was due to chance, some alternative explanations to associate both events might be proposed.

Adult↗

PubMed1999

An improved one-pot procedure for the preparation of [11C-carbonyl]-WAY100635.

A simple one-pot procedure for the preparation of [11C-carbonyl]-WAY100635, a potent 5HT1A receptor antagonist, was developed. The procedure involves the trapping of 11CO2 in a tetrahydrofuran (THF) solution of cyclohexylmagnesium chloride, elimination of excess Grignard reagents with anhydrous HCl, reaction with SOCl2, and the reaction of the resulting acid chloride with WAY100634 (2 mg) and triethylamine (20 microL) in THF. The total synthesis time is 45 min. Starting from 1326 +/- 173 mCi of 11CO2, the average amount of [11C-carbonyl]-WAY100635 (n = 40) at end-of-synthesis (EOS) was 30 +/- 13 mCi (2.3% radiochemical yield), or 148 +/- 61 mCi (11%) at end-of-bombardment (EOB). The radiochemical purity was >99%, and the specific activity was 3.6 +/- 1.9 Ci/micromol (EOS, n = 40), or 21.3 +/- 9.8 Ci/micromol at EOB. This method is reliable and flexible for routine clinical studies.

Carbon Dioxide↗

PubMed1999

Clinical resistance patterns and responses to two sequential protease inhibitor regimens in saquinavir and reverse transcriptase inhibitor-experienced persons.

The efficacy of sequential protease inhibitor therapy was studied in 16 human immunodeficiency virus (HIV) 1-infected persons in whom saquinavir with multiple nucleoside reverse transcriptase (RT) inhibitors (NRTI) had failed. Nelfinavir plus two NRTIs (new or continued) resulted in minimal (0.59 log RNA copies/mL) and transient (8 weeks) suppression of plasma HIV RNA levels. Rapid failure was surprisingly associated with baseline presence of protease gene mutation L90M (P=.04) in the absence of D30N and with RT mutations D67N (P<.01), K70R/S (P=.02), and K219Q/W/R/E (P<.01). Ten patients were subsequently switched to indinavir plus nevirapine and 2 NRTIs, resulting in a median 1.62 log reduction in plasma HIV RNA, with 3 patients maintaining 400 copies/mL for 24 weeks. These results suggest that nelfinavir may have limited utility after saquinavir failure, particularly without potent concomitant therapy. Combining an NRTI with a new protease inhibitor for rescue may improve response.

Adult↗

PubMed1999

Direct regulation of mitochondrial RNA synthesis by thyroid hormone.

We have analyzed the influence of in vivo treatment and in vitro addition of thyroid hormone on in organello mitochondrial DNA (mtDNA) transcription and, in parallel, on the in organello footprinting patterns at the mtDNA regions involved in the regulation of transcription. We found that thyroid hormone modulates mitochondrial RNA levels and the mRNA/rRNA ratio by influencing the transcriptional rate. In addition, we found conspicuous differences between the mtDNA dimethyl sulfate footprinting patterns of mitochondria derived from euthyroid and hypothyroid rats at the transcription initiation sites but not at the mitochondrial transcription termination factor (mTERF) binding region. Furthermore, direct addition of thyroid hormone to the incubation medium of mitochondria isolated from hypothyroid rats restored the mRNA/rRNA ratio found in euthyroid rats as well as the mtDNA footprinting patterns at the transcription initiation area. Therefore, we conclude that the regulatory effect of thyroid hormone on mitochondrial transcription is partially exerted by a direct influence of the hormone on the mitochondrial transcription machinery. Particularly, the influence on the mRNA/rRNA ratio is achieved by selective modulation of the alternative H-strand transcription initiation sites and does not require the previous activation of nuclear genes. These results provide the first functional demonstration that regulatory signals, such as thyroid hormone, that modify the expression of nuclear genes can also act as primary signals for the transcriptional apparatus of mitochondria.

Animals↗

PubMed1998

Reduced mitochondrial DNA transcription in senescent rat heart.

We studied the effect of senescence on mitochondrial DNA (mtDNA) transcription with an in organello system using intact isolated rat heart mitochondria. A comparison of the electrophoretic patterns of mtDNA transcription products in young, adult and senescent rats showed an age-related reduction in newly-synthesized mitochondrial RNAs that reflects a decrease in the synthesis rate. These results correlate with the enzyme activities of the oxidative phosphorylation complexes I and IV, that are partially encoded by the mitochondrial genome. In addition, an age-related increase in the protein carbonyl content of the mitochondrial membranes was observed in senescent mitochondria suggesting an accumulation of mitochondrial oxidative damage. This reduction in the mtDNA transcriptional rate in the heart of senescent animals suggests that this could be one of the molecular bases underlying senescence of the myocardium.

Aging↗

PubMed1998

Multiple endocrine involvement in two pediatric patients with Kearns-Sayre syndrome.

We present 2 cases of progressively severe Kearns-Sayre syndrome (KSS) with multisystemic affectation and atypical endocrine and cutaneous features, a 16-year-old patient (case 1) and a 5-year-old patient (case 2). Endocrine studies showed high glucose and glycohemoglobin concentrations with normal pancreatic reserve and low values of ACTH, cortisol, LH and FSH in case 1. Normal ACTH values with low concentrations of cortisol and PTH were observed in case 2. Southern blot analysis and PCR amplification revealed the presence of a deletion of approximately 6.7 kb in the mitochondrial DNA of both patients. Endocrinological studies suggest that adrenal insufficiency may be an additional feature of KSS that worsens the clinical evolution of the patients. In spite of a normal pancreatic reserve, insulin therapy should be considered in patients with diabetes mellitus of mitochondrial origin.

Adolescent↗

PubMed1998

Familial multiple symmetric lipomatosis associated with the A8344G mutation of mitochondrial DNA.

We describe familial multiple symmetric lipomatosis in a pedigree harboring the 8344 mutation in the tRNA(Lys) gene of mitochondrial DNA (mtDNA). The proband showed neuromuscular involvement but lacked the typical manifestations of myoclonic epilepsy and ragged-red fibers disease. The distribution of the mutation was unusual because the proportion of mutated genomes was higher in blood and lipomas than in muscle tissue.

Adult↗

PubMed1998

[Mitochondrial respiratory chain deficiency may present as multiple sclerosis].

Defects of the mitochondrial respiratory chain are associated with a great variety of clinical disorders. In addition to the well recognized syndromes, a significant number of patients present non-specific encephalopathic disorders. In consequence these types of mitochondrial disorder are very difficult to diagnose on clinical features alone. In this paper, we describe the clinical and the magnetic resonance findings of 2 patients with a neurological syndrome indistinguishable from multiple sclerosis (Poser). Muscle biochemistry revealed defect of complex IV of the respiratory chain. We think that these patients have a mitochondrial encephalomyopathy. We suggest that in patients presenting as atypical multiple sclerosis it could be necessary investigating mitocondrial encephalopathy.

Adult↗

PubMed1998

Correlation of sperm motility with mitochondrial enzymatic activities.

Until now, little attention has been paid to the contribution of mitochondrial dysfunction to germinal tissue disorders. The target of this study was to investigate the relationship between sperm motility and mitochondrial respiratory chain enzyme activities. The results obtained showed that semen samples of control individuals (n = 33) have substantially higher activities of complexes I, II, and IV compared with those of asthenozoospermic subjects (n = 86). Moreover, a direct and positive correlation was found in the whole population studied between spermatozoa motility and all the mitochondrial respiratory complex activities assayed (I, II, I+III, II+III, and IV). The ratio of these enzymes to citrate synthase (a reliable enzymatic marker of mitochondrial volume) activities did not correlate with sperm motility. This suggests that motility depends largely on the mitochondrial volume within the sperm midpiece. These observations could be of physiopathological relevance because they suggest that factors affecting the mitochondrial energy production could be then responsible for particular cases of idiopathic asthenozoospermia.

Citrate (si)-Synthase↗

PubMed1998

[Human mitochondrial genetic system].

The mitochondria are subcellular organelles devoted to energy production in form of ATP that contain their own genetic system. Mitochondrial DNA codify a small, but extremely important, number of polypeptides of the respiratory chain. The other mitochondrial proteins are encoded in the nucleus. Therefore, mitochondrial biogenesis require the coordinated expression of nuclear and mitochondrial genetic systems. The gene arrangement in mitochondrial DNA is extremely compact with the tRNA genes interspersed with the rRNA and protein-coding genes. This organization has its precise counterpart in the mode of expression and distinctive structural features of the RNAs. Both mitochondrial DNA strands are transcribed as a whole in the form of three polycistronic molecules that are later cut by specific enzymes that recognize the 5' and 3' end of the tRNA sequences, to produced the mature rRNA, mRNA and tRNA. The mitochondrial coded mRNAs are translated into proteins by a mitochondrial specific protein-synthesizing machinery. The genetics of the mitochondrial DNA differs from that of the nuclear DNA in several features. In particular, the mitochondrial genome is inherited from the mother that transmit their mitochondrial DNA to all her offsprings. Another characteristic of this genome is its tendency to mutate more frequently than the nuclear DNA. This provides a powerful tool for studying the evolution of man.

DNA, Mitochondrial↗

PubMed1998

[Studies of pathogenicity and characterization of molecular phenotype caused by mutations in human mitochondrial DNA].

Mitochondrial DNA evolves and accumulates mutations more rapidly than nuclear DNA. These nucleotide variation may produce neutral polymorphisms or affect to functional conserved positions being very deleterious. On the other hand the relation between the type of mutation (genotype) and the observed clinical symptoms (phenotype) is nowadays practically unknown. Therefore it is very important to demonstrate clearly that the new described mutations are pathogenic and understanding the molecular mechanisms responsible for the energetic metabolism dysfunction produced by these mutations at cellular level. In the last years several procedures have been developed, including in situ hybridization, single-fiber PCR and the use of patient myoblast, fibroblast and lymphoblast cell culture lines. Specially relevant is the cybrid technology that allow repopulate a cell line depleted of mtDNA with mitochondria obtained from patient fibroblasts, producing transmitochondrial cell lines. The use of these methodology in the last few years has been very important to understand the pathogenic mechanism of some of the classical mutations associated to mitochondrial pathology.

Bone Neoplasms↗

PubMed1998

[Acute presentation of leukodystrophy due to mitochondrial cytopathology and multiple deletions of mitochondrial DNA].

INTRODUCTION: Deletions of mitochondrial DNA (mtDNA) are a known cause of various mitochondrial cytopathies, which are sporadic and usually not due to maternal transmission. The multiple deletions are usually transmitted on a Mendelian pattern, and are frequently of autosomal dominant character. Leukodystrophy may be part of the picture, or even the form of presentation, of some mitochondrial cytopathies. Thus, in a case of leukoencephaly of unknown origin, mitochondrial cytopathy should be considered in the differential diagnosis. CLINICAL CASE: We present the case of a boy with no previous clinical abnormalities who, at the age of 13, suddenly fell to the floor with an encephalopathy which required aggressive treatment, needing mechanical ventilation and prolonged sedation. Following partial recovery spastic-dystonic quadriplegia remained. Neuroimaging showed advanced leukodystrophy with small hemorrhages in the white matter, which later disappeared. After rejecting other aetiologies, mitochondrial cytopathies in muscle were studied. A partial defect of the I and IV complexes of the respiratory chain and two deletions of mtDNA were shown. CONCLUSIONS: This case is another example of the variable clinical presentation of mitochondrial cytopathies and yet another argument for their inclusion in the diagnosis of leukodystrophy of unknown origin.

Acute Disease↗

PubMed1997

Regulation of mitochondrial transcription by mitochondrial transcription factor A.

In order to test the hypothesis that mitochondrial transcription factor A (mtTFA) regulates mitochondrial transcription in vivo, mtTFA was overexpressed in HeLa cells and imported into isolated rat liver mitochondria. Five hours after transfection with an eukaryotic expression vector, mitochondrial transcripts for cytochrome-c-oxidase subunit I and 12 S rRNA were increased over controls. In the presence of rat liver mitochondria, the 29 kDa mtTFA, generated by in vitro translation, was processed to a 24 kDa protein which was protected from protease digestion. This demonstrates that mtTFA was imported into the matrix. Incorporation of 32P-UTP into mitochondrial transcripts was stimulated following import of mTFA. We conclude that the intracellular and intramitochondrial concentration of mtTFA, respectively, indeed regulates mitochondrial transcription.

Animals↗