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Biomedical subjects

F Merante

Publications and source records attributed to F Merante.

34 records · Page 2Linked to original sources
PubMed1994

Maternally inherited hypertrophic cardiomyopathy due to a novel T-to-C transition at nucleotide 9997 in the mitochondrial tRNA(glycine) gene.

We report a unique heteroplasmic T-to-C transition at nucleotide 9997 in the mitochondrial tRNA(glycine) gene in a multiplex family who manifested nonobstructive cardiomyopathy. The degree of mtDNA heteroplasmy generally correlated with the severity of the symptoms. This T-to-C transition disrupts hydrogen bonding in the region adjacent to the acceptor stem of the tRNA molecule. The thymine residue at position 9997 is highly conserved in mammals, as well as in various vertebrates and invertebrates. A PCR diagnostic test for the presence of the 9997 T-to-C transition revealed that the base change was always present in high proportion in affected family members, not present in unaffected family members, and never present in control subjects from various ethnic groups (25 groups sampled, 42 individuals), thus ruling out the possibility that this change represents a polymorphic variant in the general population. The degree of heteroplasmy in lymphoblast cultures also correlated with the level of enzyme activity present for cytochrome c oxidase (complex IV) and succinate cytochrome c oxidoreductase (complexes II and III). The absence of previously reported mtDNA mutations associated with hypertrophic cardiomyopathy was verified by both PCR diagnostic procedures and sequence analysis. All mitochondrial tRNA genes, as well as genes encoding ATPase subunits 6 and 8, were sequenced and found not to possess base changes consistent with the clinical profile. More detailed biochemical and molecular biological investigations are discussed.

Adenosine Triphosphatases↗
PubMed1993

Mitochondrial encephalomyopathy, lactic acidosis, stroke-like episodes (MELAS): clinical, radiological, pathological, and genetic observations.

We reviewed 10 patients (5 males, 5 females) with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes. The age of symptom onset ranged from 3 months to 12 years. All had lactic acidosis, multiple stroke-like events with secondary neurological deficits, radiological changes of progressive brain infarction, and muscle biopsy showing ragged-red fibers. In patients with earlier onset of symptoms (< 2 yr), involvement tended to be more diffuse, with failure to thrive and early onset of delayed development. Patients whose symptoms appeared later tended to have focal neurological deficits with migraine-like headache, and a rate of cognitive regression reflecting the rapidity of disease progression. Radiological changes included multiple areas of infarction with initial predilection for parietal occipital areas, progressing to generalized atrophy. Pathological findings in muscle biopsies included type 1 fiber predominance, ragged-red fibers, increased intermyofibrillar lipid deposition, and abnormal mitochondria. Four patients showed mitochondrial DNA tRNA mutation at position 3,243. No difference was noted in clinical, radiological, or pathological findings in patients with and without this mutation, suggesting that multiple sites of point mutation may give rise to mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes.

Base Sequence↗
PubMed1993

Circadian blood pressure changes in patients with chronic renal insufficiency: a prospective study.

Circadian blood pressure (BP) rhythm was prospectively studied by ambulatory 24-h monitoring in normotensive (n = 27) and hypertensive (n = 41) patients with stable progression of chronic renal insufficiency, and in matched control groups (healthy subjects: n = 28 and patients with essential hypertension: n = 47) without renal disease. The follow-up period lasted 24 months. The renal patients showed a disturbance in the 24-h profile of BP, with significantly blunted nocturnal pressure reduction as compared with the respective control groups (p < 0.01 and p < 0.001, respectively). In addition to the rearrangement of circadian rhythm, the normotensive and hypertensive renal patients displayed a wider distribution of systolic and diastolic BP values and a greater nocturnal variability. Among the normotensive and hypertensive patients with chronic renal insufficiency, a significant correlation was found between the decline in creatinine clearance over the 24-month period and the average nighttime diastolic BP (r = 0.526; p < 0.01 and r = 0.613; p = 0.001, respectively) and nocturnal diastolic fall (r = 0.612; p < 0.001 and r = 0.496; p < 0.01, respectively). These data offer support for the view that renal normotensive patients are exposed to a relative hypertension at nighttime and that renal hypertensive subjects can be underestimated in their hypertensive status if the measurement of BP is confined to daytime. In both groups, nocturnal BP overload can accelerate the progression rate of renal insufficiency.

Adult↗
PubMed1993

A biochemically distinct form of cytochrome oxidase (COX) deficiency in the Saguenay-Lac-Saint-Jean region of Quebec.

We report the results of biochemical and molecular investigations on a group of patients from the Saguenay-Lac-Saint-Jean region of Quebec who have an unusual form of cytochrome oxidase deficiency and Leigh disease. This group can be distinguished from the classical presentation of cytochrome oxidase deficiency with Leigh disease, by the severity of the biochemical defect in different tissues. The activity in skin fibroblasts, amniocytes, and skeletal muscle of cytochrome oxidase is 50% of normal, while in kidney and heart it is close to normal values. Brain and liver, on the other hand, have very low activities. The defect in activity appears to result from a failure of assembly of the cytochrome oxidase complex in liver, but levels of mRNA for both mitochondrially encoded and nuclear-encoded subunits in liver and skin fibroblasts were found to be the same as those in controls. The cDNA sequence of the liver-specific cytochrome oxidase subunits VIa and VIIa were determined in samples from patient liver and skin fibroblasts and showed normal coding sequence.

Acidosis, Lactic↗
PubMed1990

The isolation of biologically active mating pheromone, a-factor, from the yeast, Saccharomyces cerevisiae.

Haploid cell-types of baker's yeast, Saccharomyces cerevisiae, secrete pheromones which are essential for conjugation. Recently a putative structure for the elusive a-factor pheromone has been reported. In this report we present a procedure to obtain a-factor from batch cultures of cells using hydrophobic Amberlite XAD-2 resin in the growth medium with subsequent differential washings of the resin with organic solvents. We have determined the biological activity of the a-factor preparation by verifying that there is an increase in transcription of the a-factor receptor gene, STE3, by Northern analysis of STE3 mRNA before and after exposure of the appropriate cell type to a-factor. Furthermore, a beta-galactosidase assay of the putative receptor gene fused to the lacZ gene, coding for beta-galactosidase (STE3-lacZ), was done to quantify the biological activity of the a-factor.

Amino Acid Sequence↗
PubMed1990

Simultaneous isolation of total cellular RNA and DNA from tissue culture cells using phenol and lithium chloride.

A rapid procedure for the isolation of intact total cellular RNA from cultured cells is described. This method combines the simultaneous disruption of cells and extraction of nucleic acids in a single step with the use of phenol and a buffer containing 100 mM LiCl. Total cellular RNA can be isolated in approximately 2 hours. The yield and quality of the RNA is comparable to the more widely employed methods requiring extensive preparatory steps such as extraction using guanidinium thiocyanate and subsequent CsCl gradient centrifugation. The RNA isolated using our procedure contains transcripts up to 10 kb in length and is suitable for Northern analysis. This procedure also yields high-molecular-weight DNA, which is a suitable substrate for restriction endonucleases.

Adrenal Gland Neoplasms↗
PubMed1984

Laryngeal cancer: long-term follow-up of respiratory functions after laryngectomy.

Pulmonary function of 31 heavy smokers with laryngeal cancer was evaluated before and during the 1st year after total (n = 21) and conservative (n = 10) laryngectomy. 2 of them died because of recurrences, 1 for bronchopulmonary complications. Long-lasting hoarseness was the only presenting symptom in all patients. Preoperative lung function data and mucociliary clearance were consistent with a coexisting chronic obstructive lung disease in most subjects and was probably due to smoking. No differences were observed comparing pre- and postoperative data in the 10 conservative laryngectomy patients. On the contrary, the total-laryngectomy patients showed a progressive impairment of bronchial obstruction and bacteriological infection of the trachea during the 1st year after the operation. An impressive increase in mucociliary clearance rates has been observed 2 months after total laryngectomy during the postoperative hypersecretory phase. the obtained data allow us to hypothesize that when clinical conditions of laryngectomized patients in whom local or distant recurrences have been excluded deteriorate, this is related to a progressive bronchial obstruction at any level of the bronchial tree due to descending bacterial infection of the airways. To our knowledge this is the only work demonstrating that total laryngectomized patients need a complete pre- and postoperative evaluation of lung function, airway dynamics, mucociliary function and tracheal bacteriology for long-term prognosis and treatment.

Aged↗
PubMed1981

[Bronchial mucociliary function. A new diagnostic technic].

To study mucociliary clearance of central airways we used a recently described method consisting of the inhalation of 99mTc labeled autologous spherocytes aerosol. In 3 of 8 normal non smoking subjects, an abnormally low rate of m.c.c. was observed. The m.c.c. rate was also very low in 2 of 6 patients with bronchial cr. who never smoked. These observations provide considerable evidence that those non smoking subjects presenting with low mucociliary clearance may be regarded as "high risk subjects" for broncho-pulmonary diseases. The good central deposition pattern of the inhaled spherocytes may provide, in very ill patients, a non-invasive visualization of the central airways.

Adult↗