Search PubMed⌕ Search

Biomedical subjects

G Manfredi

Publications and source records attributed to G Manfredi.

At least 37 records · Page 2Linked to original sources
PubMed1998

Alzheimer's disease: patterns of cognitive impairment at different levels of disease severity.

The aim of this study was to establish the presence and the consistency of different cognitive profiles in AD patients taking into consideration the severity of mental impairment. Therefore we stratified 679 neuropsychological observations on 119 probable AD patients followed longitudinally on the basis of overall degree of cognitive impairment. To compare performance on tests with different score ranges we transformed raw test scores into coefficients; to summarize our results in terms of language versus visuo-spatial performance we computed indices of prevalent impairment of performance (IPIP) by subtracting the coefficients for constructional praxis from coefficients for language-related tests. Finally, we converted these indices into z-scores for each level of mental decline to identify patients with generalized, language (L) or visuo-spatial (V) prevalent impairment. The latter, 30% of the sample, can be detected at all stages of dementia. There was a higher percentage of males among language impaired patients (P<0.05). Approximately half of patients with L/V prevalent impairment continued to show such a focality when followed longitudinally. The groups did not differ in the annual rate of cognitive decline.

Age of Onset↗
PubMed1998

Giant dystrophin deletion associated with congenital cataract and mild muscular dystrophy.

We report a patient with a large intragenic dystrophin deletion of exons 17-51 inclusive associated with congenital cataract and mild Becker muscular dystrophy. The cataract was similar to the congenital cataract described in the mdx mouse. The loss of 68% of the rod domain including hinge 2 and 3 regions did not adversely affect the correct localization of the dystrophin and the association with the dystrophin-associated glycoprotein complex. This observation may have implications for minigenes suitable for gene therapy.

Cataract↗
PubMed1997

Association of myopathy with large-scale mitochondrial DNA duplications and deletions: which is pathogenic?

We identified large-scale heteroplasmic mitochondrial DNA (mtDNA) rearrangements in a 50-year-old woman with an adult-onset progressive myopathy. The predominant mtDNA abnormality was a 21.2-kb duplicated molecule. In addition, a small population of the corresponding partially deleted 4.6-kb molecule was detected. Skeletal muscle histology revealed fibers that were negative for cytochrome c oxidase (COX) activity and had reduced mtDNA-encoded COX subunits. By single-fiber polymerase chain reaction analysis, COX-negative fibers contained a low number of wild-type or duplicated mtDNA molecules (ie, nondeleted). In situ hybridization demonstrated that the abnormal fibers contained increased amounts of mtDNA compared with normal fibers and that most of the genomes were deleted. We concluded that deleted mtDNA molecules were primarily responsible for the phenotype in this patient.

Base Sequence↗
PubMed1997

Serum osteocalcin and bone mineral density at various skeletal sites: a study performed with three different assays.

The purposes of this study were threefold: (1) to compare values obtained by three conventional radioimmunoassays for serum bone-gla-protein (BGP) in a population of normal women, (2) to study the relationship between serum BGP and bone mineral density (BMD) measured at four different skeletal sites (lumbar spine, proximal femur, proximal and ultradistal radius), and (3) to compare the results obtained by the three assays with conventional markers of bone turnover. Ninety-seven normal women (age range 25 to 75 years, mean +/- 1 SD = 54.3 +/- 10.9 years) were studied. Three independent assays were used to measure serum osteocalcin levels: a heterologous radioimmunoassay (RIA) (A) (Incstar Co., Stillwater, Minn.), a homologous RIA (B) (Nichols Institute, San Juan Capistrano, Calif.), and a two-site immunoradiometric assay (C) (Cis Biointernational, Gif-sur-Yvette, France). Mean +/- SD values of serum osteocalcin in the group as a whole were 4.05 +/- 1.37 microg/L by assay A, 6.03 +/- 2.90 microg/L by assay B, and 22.67 +/- 7.52 microg/L by assay C. Serum osteocalcin levels increased linearly with age; however, no correlation between serum BGP (whatever the assay used) and age was observed when only postmenopausal women were taken into account. When the effect of age was held constant by means of partial correlation analysis, only serum BGP levels measured by assays B and C were still inversely related with lumbar spine and ultradistal radius BMD; the latter assay was also weakly correlated with Ward's triangle BMD. After all the biochemical and clinical variables taken into consideration were introduced in a multiple regression equation, serum BGP still represented an important predictor of ultradistal radius and lumbar spine BMD only. Regarding relationships with other markers of bone turnover, the assay C in general showed the highest r values. In conclusion, our results indicate that commercially available BGP assays differ analytically and clinically; furthermore for the first time they show the existence of an inverse correlation between serum osteocalcin levels (which reflects bone turnover at the time of examination) and bone mass (which at a given time represents the balance of all previous metabolic events), after the influence of aging is excluded.

Adult↗
PubMed1997

Functional involvement of central nervous system in mitochondrial disorders.

Thirty-nine patients with mitochondrial diseases were studied with somatosensory and motor evoked potentials. Sixteen patients (41%) had clinical and 12 (31%) had neuroradiological evidence of central nervous system involvement. The overall incidence of electrophysiological abnormalities was 64%. Abnormal evoked potentials were also found in a significant percentage (33%) of patients with pure myopathic forms of mitochondrial diseases and in an asymptomatic carrier of MERRF mutation. Of the individual tests, somatosensory evoked potentials were abnormal in 49% of the patients and motor evoked potentials were abnormal in 46% of the patients. The outcome is that electrophysiological evidence of central nervous system involvement is present in a high percentage of patients with mitochondrial disorders, and that the threshold for central nervous system electrophysiological abnormalities is well below that for clinical and/or radiological manifestations.

Adolescent↗
PubMed1997

The fate of human sperm-derived mtDNA in somatic cells.

Inheritance of animal mtDNA is almost exclusively maternal, most likely because sperm-derived mitochondria are actively eliminated from the ovum, either at or soon after fertilization. How such elimination occurs is currently unknown. We asked whether similar behavior could be detected in somatic cells, by following the fate of mitochondria and mtDNAs after entry of human sperm into transformed cells containing mitochondria but lacking endogenous mtDNAs (rho0 cells). We found that a high proportion (10%-20%) of cells contained functioning sperm mitochondria soon after sperm entry. However, under selective conditions permitting only the survival of cells harboring functional mtDNAs, only approximately 1/10(5) cells containing sperm mitochondria survived and proliferated. These data imply that mitochondria in sperm can enter somatic cells relatively easily, but they also suggest that mechanisms exist to eliminate sperm-derived mtDNA from somatic cells, mechanisms perhaps similar to those presumed to operate in the fertilized oocyte.

Animals↗
PubMed1997

Functional and structural features of a tandem duplication of the human mtDNA promoter region.

An approximately 260-bp tandem duplication of the human mtDNA regulatory region has been identified in patients with mitochondrial disorders and in a specific Caucasian haplogroup. The functional significance of this mtDNA duplication was difficult to assess, because it was present at very low levels in human tissues. We have isolated several transmitochondrial cybrid lines harboring this mutation, one of which (clone CA17.1) was essentially homoplasmic for the duplication. Oxidative-phosphorylation function was not impaired in clone CA17.1, suggesting that this mtDNA alteration is not pathogenic. mtDNA copy number and steady-state levels of heavy- and light-strand transcripts were unaltered in clone CA 17.1. The steady-state levels of RNAs made from the two promoters (either from the heavy-strand or from the light-strand) were also similar, indicating that oppositely oriented promoters did not interfere with each other.

Base Sequence↗
PubMed1996

Efficient and specific amplification of identified partial duplications of human mitochondrial DNA by long PCR.

The use of PCR to identify mtDNAs containing a partial duplication (dup-mtDNA) in the presence of a heteroplasmic population of mtDNAs harboring the corresponding deletion (delta-mtDNA) leads to ambiguous results: when the primers anneal in the duplicated portion of the dup-mtDNA (which is also the non-deleted region of the delta-mtDNA) and point towards the abnormal breakpoint junction, both templates are amplified indiscriminately. We have developed two different 'long PCR' approaches to amplify dup-mtDNA even in the presence of delta-mtDNA and wild-type mtDNA (wt-mtDNA). Long PCR with two primers annealing in the non-duplicated region in dup-mtDNA (equivalent to the region missing in delta-mtDNA) and whose 3' ends pointed towards the duplicated area amplified both dup-mtDNA and coexisting wt-mtDNA. We observed, however, a preferential amplification of the wt-mtDNA over that of the longer dup-mtDNAs. This problem was partly overcome by modifying the PCR conditions (extension time, amplicon length, amount of template). In order to overcome the problem of co-amplification, we developed a novel PCR method to amplify specifically dup-mtDNAs. A forward primer annealing across the breakpoint junction was used in conjunction with a backward primer annealing in the non-duplicated region. For those duplication breakpoints flanked by direct repeats, we designed a 'breakpoint loop-out' primer whose sequence omitted the repeated region, in order to avoid the annealing of this primer to wt-mtDNA. This second approach was able to amplify specifically and efficiently the dup-mtDNA in all samples analyzed, irrespective of the size of the duplication or its proportion in the samples.

Base Sequence↗
PubMed1996

Partial block of glycolysis in late-onset phosphofructokinase deficiency myopathy.

A late-onset, myopathic variant of phosphofructokinase (PFK) deficiency has been previously described in two patients of Ashkenazic descent. We report here on a non-Ashkenazic woman with the onset, at the age of 48 years, of a progressive limb girdle myopathy that was not preceded by a history of exercise intolerance. Muscle biopsy findings at the age of 58 years showed deposition of amylopectin-like material in muscle fibers and the absence of histochemical PFK activity. Enzymatic PFK activity in vitro was only 4% of normal. Since the forearm ischemic exercise test induced a sub-normal production of serum lactate, the patient underwent phosphorus magnetic resonance spectroscopy (31P-MRS), a non-invasive method that allows in vivo assessment of the functional status of the glycolytic pathway and mitochondrial oxidative metabolism by measuring the high-energy phosphates and cytosolic pH. In vivo, 31P-MRS disclosed a residual glycolytic flux and a normal rate of ATP production both at rest and during exercise. These results suggest that, in some patients, muscle PFK deficiency may be partial in vivo, and more severe in vitro, possibly due to protein or mRNA instability rather than absence. The presence of these findings in a patient with the late-onset myopathic form is compatible with a distinct pathogenetic mechanism, relying on progressive polysaccharide accumulation, rather than on acute energetic shortage in muscle fibers.

Female↗
PubMed1995

A new mutation associated with MELAS is located in a mitochondrial DNA polypeptide-coding gene.

We report a patient with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) who harbored a novel missense mutation at mtDNA position 9957 in the gene specifying subunit III of cytochrome c oxidase (COX III). This T-->C transition converted Phe-251, a highly conserved amino acid in the C-terminus of the polypeptide, to Leu. The mutation, which was not present in 107 normal controls or in 57 patients with various mitochondrial diseases, was heteroplasmic in both muscle and blood of the proband and in blood from his asymptomatic mother. These results provide evidence that the MELAS clinical phenotype can be due not only to mutations in mtDNA-encoded tRNA genes, but in polypeptide-coding genes as well.

Amino Acid Sequence↗
PubMed1995

High levels of mitochondrial DNA with an unstable 260-bp duplication in a patient with a mitochondrial myopathy.

Other investigators reported the presence of low levels of a 260-bp heteroplasmic duplication of mitochondrial DNA in patients with mitochondrial DNA deletions and their asymptomatic mothers. In this study, we were not able to detect this polymorphism in 30 patients with mitochondrial DNA deletions, but the 260-bp duplication was detected in relatively high levels (32% in muscle) in a patient with a slowly progressive mitochondrial myopathy. The duplication was also present in cultured fibroblasts (10%) and in WBC (< 1%). Mitochondrial dysfunction in this patient was evidenced in muscle by the presence of ragged-red fibers and a partial decrease in cytochrome c oxidase activity. We also detected low levels of mitochondrial DNA harboring a triplication of the 260-bp region, indicating that this polymorphism is unstable. Taken together, our results suggest that an unstable 260-bp duplication, which includes important mitochondrial DNA cis-acting regulatory sequences, may be pathogenic per se, if present at high levels.

Base Sequence↗
PubMed1995

Segregation patterns of a novel mutation in the mitochondrial tRNA glutamic acid gene associated with myopathy and diabetes mellitus.

We have identified a novel mtDNA mutation in a 29-year-old man with myopathy and diabetes mellitus. This T-->C transition at mtDNA position 14709 alters an evolutionarily conserved nucleotide in the region specifying for the anticodon loop of the mitochondrial tRNA(Glu). The nt-14709 mutation was heteroplasmic but present at very high levels in the patient's muscle, white blood cells (WBCs), and hair follicles; lower proportions of mutated mtDNA were observed in WBCs and hair follicles of all examined maternal relatives. In the patient's muscle, abnormal fibers showed mitochondrial proliferation, severe focal defects in cytochrome c oxidase activity, and absence of cross-reacting material for mitochondrially synthesized polypeptides. These fibers had higher levels of mutated mtDNA than did surrounding "normal" fibers. Although the percentage of mutated mtDNA in WBCs from family members were distributed around the percentage observed in the mothers, the pattern was different in hair follicles, where the mutated population tended to increase in subsequent generations. PCR/RFLP analysis of single hairs showed that the intercellular variations in the percentage of mutated mtDNA differed among family members, with younger generations having a more homogeneous distribution of mutated mtDNA in different hair follicles. These results suggest that the intercellular distribution of the mutated and wild-type mtDNA populations may drift toward homogeneity in subsequent generations.

Adult↗
PubMed1994

Ophthalmoplegia, demyelinating neuropathy, leukoencephalopathy, myopathy, and gastrointestinal dysfunction with multiple deletions of mitochondrial DNA: a mitochondrial multisystem disorder in search of a name.

This article describes a 37-year-old woman with progressive external ophthalmoplegia, peripheral neuropathy, and chronic intractable diarrhea. Laboratory studies disclosed lactic acidosis, ragged red fibers lacking cytochrome c oxidase, high-normal muscular mitochondrial enzymes, demyelinating neuropathy, leukoencephalopathy and multiple mitochondrial DNA deletions. This is the fourth patient described with this clinical syndrome, which represents a separate entity among multisystemic mitochondrial disorders. The patient described here is the first with this syndrome to have multiple mitochondrial DNA deletions.

Adult↗
PubMed1994

Autosomal recessive hypermyelinating neuropathy.

We studied three patients from two kinships, affected by early onset hereditary motor and sensory neuropathy with probable autosomal recessive inheritance (HMSN type III). Morphological studies of sural nerve biopsies revealed an abnormal myelin proliferation. Two adult patients with long-term follow up, lost ability to walk at 28 and 22 years and showed severe involvement of the cranial nerves. Our observations suggest that "hypermyelination neuropathy" with early onset is a progressive disease with poor long-term prognosis. In one kinship the occurrence of the disease in two sibs of both sexes but not in parents, is consistent with an autosomal recessive inheritance. Familial cases of hypermyelination neuropathy have not been described in previous reports. Morphological aspects of this condition are compared with other forms of hypermyelination neuropathy.

Adult↗