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Biomedical subjects

R Gatti

Publications and source records attributed to R Gatti.

At least 55 records · Page 3Linked to original sources
PubMed2001

Cobalamin (Cbl) C/D deficiency: clinical, neurophysiological and neuroradiologic findings in 14 cases.

The early onset type of cobalamin (Cbl) C/D deficiency is characterised by feeding difficulties, failure to thrive, hypotonia, seizures, microcephaly and developmental delay. It has an unfavourable outcome, often with early death and significant neurological impairment in survivors. While clinical and biochemical features of Cbl C/D deficiency are well known, only a few isolated case reports are available concerning neurophysiological and neuroimaging findings. We carried out clinical, biochemical, neurophysiological and neuroradiologic investigations in 14 cases with early-onset of the Cbl CID defect. Mental retardation was identified in most of the cases. A variable degree of supratentorial white matter atrophy was detected in 11 cases by MR imaging and tetraventricular hydrocephalus was present in the remaining 3 patients. Waking EEG showed a clear prevalence of epileptiform abnormalities, possibly related to the high incidence of seizures in these cases. Increased latency of evoked responses and/or prolongation of central conduction time were the most significant neurophysiological abnormalities. The selective white matter involvement, shown both by neuroradiologic and neurophysiological studies, seems to be the most consistent finding of Cbl C/D deficiency and may be related to a reduced supply of methyl groups, possibly caused by the dysfunction in the methyl-transfer pathway.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed2001

Early-onset combined methylmalonic aciduria and homocystinuria: neuroradiologic findings.

BACKGROUND AND PURPOSE: Combined methylmalonic aciduria and homocystinuria (MMA-HC) is caused by impaired hepatic conversion of dietary cobalamin to methylcobalamin and adenosylcobalamin, resulting in decreased activity of methylmalonyl-CoA mutase and methionine synthase. Patients with the early-onset variety present within 12 months of age with severe neurologic, hematologic, and gastrointestinal abnormalities. We describe the neuroradiologic features of early-onset MMA-HC and discuss related pathophysiological mechanisms. METHODS: Twelve infants with hypotonia, failure to thrive, poor feeding, and hematologic abnormalities were diagnosed with MMA-HC on the basis of a typical plasmatic and urinary metabolic profile and enzyme activity in fibroblastic cultures. Complementation studies were performed in two cases, and yielded a CblC result. MR imaging was performed at presentation in four cases and later in the others. All patients showed prompt biochemical improvement with intramuscular hydroxocobalamin administration, and most had moderate neurologic improvement. RESULTS: Diffuse supratentorial white matter edema and dysmyelination was the typical MR picture at presentation, whereas white matter bulk loss characterized later stages of the disease. Nucleocapsular areas of gliosis were an additional finding in one case. One patient had tetraventricular hydrocephalus at presentation. CONCLUSION: White matter damage is probably caused by reduced methyl group availability and nonphysiological fatty acids toxicity, whereas focal gliosis results from homocysteine-induced toxicity to the endothelium. Hydrocephalus may result from diffuse intracranial extracerebral arterial stiffness, known as reduced arterial pulsation hydrocephalus. MR imaging features at presentation and at follow-up are nonspecific.

Brain↗
PubMed2000

Analysis and stability study of retinoids in pharmaceuticals by LC with fluorescence detection.

Liquid chromatographic (HPLC) methods with fluorescence detection at different wavelengths were developed for measurements of retinoic acids (13-cis and all-trans) in pharmaceutical dosage forms and components of 'retinoid solution' (all-trans retinoic acid, vitamin A palmitate and beta-carotene), a galenical of 'Di Bella therapy', using reversed phase columns under isocratic conditions. The stability of all-trans retinoic acid in cream and all-trans retinoic acid and vitamin A palmitate in 'retinoid solution' was investigated. Solid-phase extraction (SPE), using C18 sorbent was applied to the analysis of retinoic acids (9-cis, 13-cis and all-trans) in the 'retinoid solution' to obtain a practical and reliable sample clean-up. The results showed that these preparations (cream and solution) can be conveniently stored in the dark (t.a. or 2-8 degrees C): under these conditions about 86-87% of the all-trans retinoic acid initial concentration in both formulations and about 73-78% of vitamin A palmitate in the 'retinoid solution' remained after 90 days, while under sunlight exposure rapid degradation of the drugs was observed.

Chromatography, High Pressure Liquid↗
PubMed2000

Modifications in heme iron of free and vesicle bound cytochrome c by tert-butyl hydroperoxide: a magnetic circular dichroism and electron paramagnetic resonance investigation.

To characterize changes to the heme and the influence of membrane lipids in the reaction of cytochrome c with peroxides, we studied the reaction of cytochrome c with tert-butyl hydroperoxide (tert-BuOOH) by magnetic circular dichroism (MCD) and direct electron paramagnetic resonance (EPR) in the presence and absence of different liposomes. Direct low-temperature (11 degrees K) EPR analysis of the cytochrome c heme iron on exposure to tert-BuOOH shows a gradual (180 s) conversion of the low-spin form to a high-spin Fe(III) species of rhombic symmetry (g = 4.3), with disappearance of a prior peroxyl radical signal (g(o) = 2.014). The conversion to high spin precedes Soret band bleaching, observable by UV/Vis spectroscopy and by magnetic circular dichroism (MCD) at room temperature, that indicates loss of iron coordination by the porphyrin ring. The presence of cardiolipin-containing liposomes delayed formation of the peroxyl radical and conversion to high-spin iron, while dicetylphosphate (DCP) liposomes accelerated these changes. Correspondingly, bleaching of cytochrome c by tert-BuOOH at room temperature was accelerated by several negatively charged liposome preparations, and inhibited by mitochondrial-mimetic phosphatidylcholinephosphatidylethanolaminecardiolipin (PCPECL) liposomes. Concomitant with bleaching, spin-trapping measurements with 5,5-dimethyl-1-pyroline-N-oxide showed that while the relative production of peroxyl, alkoxyl, and alkyl radicals was unaffected by DCP liposomes, PCPECL liposomes decreased the spin-trapped alkoxyl radical signal by 50%. The EPR results show that the primary initial change on exposure of cytochrome c to tert-BuOOH is a change to a high-spin Fe(III) species, and together with MCD measurements show that unsaturated cardiolipin-containing lipid membranes influence the interaction of tert-BuOOH with cytochrome c heme iron, to alter radical production and decrease damage to the cytochrome.

Animals↗
PubMed2000

beta-galactosidase gene mutations affecting the lysosomal enzyme and the elastin-binding protein in GM1-gangliosidosis patients with cardiac involvement.

GM1-gangliosidosis is a lysosomal storage disorder caused by deficiency of acid beta-galactosidase (GLB1). We report five new beta-galactosidase gene mutations in nine Italian patients and one fetus, segregating in seven unrelated families. Six of the eight patients with the infantile, severe form of the disease presented cardiac involvement, a feature rarely associated with GM1-gangliosidosis. Molecular analysis of the patients' RNA and DNA identified two new RNA splicing defects, three new and three previously described amino acid substitutions. Interestingly, all patients with cardiac involvement were homozygous for one of these mutations: R59H, Y591C, Y591N, or IVS14-2A>G. In contrast, all other patients were compound heterozygous for one of the following mutations: R201H, R482H, G579D, IVS8+2T>C. Although we could not directly correlate the presence of cardiac abnormalities with specific genetic lesions, the mutations identified in patients with cardiomyopathy fell in the GLB1 cDNA region common to the lysosomal enzyme and the Hbeta-Gal-related protein, also known as the elastin binding protein (EBP). Consequently, both molecules are affected by the mutations, and they may contribute differently to the occurrence of specific clinical manifestations.

Amino Acid Sequence↗
PubMed2000

HPLC-fluorescence determination of equilin and equilenin in postmenopausal women's urine.

A high-performance liquid chromatographic (HPLC) method with fluorescence detection (lambda(ex) = 280 nm; lambda(em) = 410 and 312 nm) in combination with a post-column on-line photochemical derivatization is described for the determination of equilin and equilenin in urine from normal postmenopausal women after therapy with conjugated oestrogens. The column effluents were subjected on-line to UV irradiation (254 nm) and the photo-induced modifications were useful for the identification of the analytes. The conjugated (sulphate and glucuronide) forms were analysed after enzymatic or chemical hydrolysis and extracted with chloroform. Solid-phase extraction using strong anion-exchange sorbent was applied to the analysis of unconjugated oestrogen fraction to obtain a practical and reliable sample clean-up. The HPLC separations were achieved using ODS columns with a mobile phase consisting of 0.05 M triethylamine phosphate buffer (pH 4.0)-acetonitrile (64:36, v/v) at a flow rate of 1.0 mL/min. The method was accurate and reproducible; for the equilin and equilenin separation isocratic conditions were satisfactory, allowing a sensitive detection in urine samples with a detection limit of about 50 fmol for equilin (lambda(ex) = 280 nm; lambda(em) = 312 nm, after photoderivatization) and 10 fmol for equilenin (lambda(ex) = 280 nm; lambda(em) = 410 nm).

Chromatography, High Pressure Liquid↗
PubMed2000

Identification of a novel recombinant allele in three unrelated Italian Gaucher patients: implications for prognosis and genetic counseling.

Gaucher disease (GD) results from deleterious mutations in the glucocerebrosidase gene. The relatively high frequency of some of these, especially at cDNA nucleotide 1226G (N370S) and at cDNA nucleotide 1448C (L444P), has led to the development of rapid screening techniques that can sometimes be misleading. In this report, we describe a novel rearrangement between the glucocerebrosidase gene and its pseudogene, identified as a consequence of a discrepancy between the genotype, homozygous for the common 1226G mutation, of an Italian patient with type 1 Gaucher disease, and the absence of the 1226G allele in her daughter. Additional investigations went on to reveal a novel recombinant allele beginning in intron 6 and extending through the rest of the coding sequence. Italian GD patients found homozygous for a specific mutation or with one or both alleles still unknown were further investigated and the novel recombinant allele was identified in an adult type 1 patient previously genotyped 1226G/1226G and in a young patient with an unknown genotype. The detection of this allele in three unrelated GD patients originating from the same geographic area in central Italy suggested a founder effect. This study emphasizes the implications of an accurate genotyping for the prognostic value of glucocerebrosidase genotype and reliable genetic counseling.

Adult↗
PubMed2000

Molecular defects in the alpha-N-acetylglucosaminidase gene in Italian Sanfilippo type B patients.

Sanfilippo syndrome type B (mucopolysaccharidosis IIIB) is a rare autosomal recessive disorder characterized by the inability to degrade heparan sulfate because of a deficiency of the lysosomal enzyme alpha-N-acetylglucosaminidase (NAGLU). We performed mutation screening in a group of 20 patients, identyifing 28 mutations, 14 of which were novel (L35F, 204delC, 221insGCGCG, G82D, W156C, 507delC, IVS3+1G-->A, E336X, V501G, R520W, S534Y, W649C, 1953insGCCA, 2185delAGA). Four of these mutations were found in homozygosity and only one was seen in two different patients, showing the remarkable molecular heterogeneity of the disease. Mutation IVS3+1G-->A produces aberrant RNA splicing: it represents a base substitution from G to A of the invariant GT dinucleotides at the splicing donor site of intron 3 resulting in the skipping of exon 3 and both exons 2 and 3. Transient transfection of COS cells, by DNA mutagenized with NAGLU mutations, produced enzymatic molecules without activity, demonstrating the deleterious nature of the defects. Metabolic labeling of transfected mutants suggested a normal synthesis of the involved polypeptide for missense alterations, whereas increased protein or mRNA instability was shown for nonsense and most of the frameshift mutations.

Acetylglucosaminidase↗
PubMed2000

Secretin increases the paracellular permeability of CAPAN-1 pancreatic duct cells.

The effects of secretin, the physiological secretagogue for pancreatic ducts, were studied in CAPAN-1 pancreatic duct carcinoma cells. When grown to confluence on plastic dishes, CAPAN-1 cells form domes and exhibit marked increases in culture content of Na+ and urea distribution space (UDS). This parameter is measured as an index of both intracellular and dome compartments under the conditions adopted. Both Na increase and dome formation are inhibited by long term incubation with phorbols, DIDS, DPC, EIPA, H2DIDS, and brefeldin. Short term treatment with secretin or 8-Br-cAMP/teophylline causes dome collapse and a marked decrease in UDS and culture content of Na. Secretin-induced sodium decrease is not abolished by ion channel inhibitors, suggesting that diffusion routes other than ion channels are involved in hormone effects. This hypothesis is also in agreement with data obtained on CAPAN-1 cells cultured on permeable inserts, where no change in Na content or UDS is detected upon secretin treatment. Confluent monolayers exhibit a high transepithelial resistance (Rms) which is markedly and reversibly decreased by secretin. The hormone also decreases the transepithelial voltage (Vms) and raises the monolayer permeability to mannitol. It is concluded that secretin enhances the paracellular permeability of pancreatic duct cells. This effect of secretin, unknown thus far, may be involved in the mechanism of pancreatic secretion in vivo.

Cell Membrane Permeability↗
PubMed2000

Fluorescent in situ hybridisation on tissue sections: a quantitative approach with confocal laser scanning microscopy.

The use of fluorescent detection methods in association with digital microscopy technologies is an innovative approach for tissue localisation of messenger RNA. The success of such methods relies on the tissue preservation, local availability of the probe and on the existence of high resolution tridimensional analysis systems. Cryostatic sections, mild denaturation, short oligonucleotide probes (20mer) and confocal laser scanning microscopy allow the fulfillment of all these conditions avoiding photobleaching and tissue autofluorescence. In this paper, we describe in detail a method for in situ hybridisation set up with digoxigenin-coupled oligonucleotide complementary to beta-actin mRNA as a probe and an anti-hapten fluorescent antibody as second step for detecting specific hybridisation. Fluorescence was analysed by means of a confocal laser scanning microscope (CLSM) that provides images with low out-of-focus blurring also with relatively low numerical aperture (NA) objectives. We propose also an easy method to perform semi-quantitative thresholding analysis which allows to discriminate between background and specific signal.

Humans↗
PubMed1999

Mutations in the glucose-6-phosphate transporter (G6PT) gene in patients with glycogen storage diseases type 1b and 1c.

Glycogen storage diseases type 1 (GSD 1) are a group of autosomal recessive disorders characterized by impairment of terminal steps of glycogenolysis and gluconeogenesis. Mutations of the glucose-6-phosphatase gene are responsible for the most frequent form of GSD 1, the subtype 1a, while mutations of the glucose-6-phosphate transporter gene (G6PT) have recently been shown to cause the non 1a forms of GSD, namely the 1b and 1c subtypes. Here, we report on the analysis by single-stranded conformation polymorphism (SSCP) and/or DNA sequencing of the exons of the G6PT in 14 patients diagnosed either as affected by the GSD 1b or 1c subtypes. Mutations in the G6PT gene were found in all patients. Four of the detected mutations were novel mutations, while the others were previously described. Our results confirm that the GSD 1b and 1c forms are due to mutations in the same gene, i.e. the G6PT gene. We also show that the same kind of mutation can be associated or not with evident clinical complications such as neutrophil impairment. Since no correlation between the type and position of the mutation and the severity of the disease was found, other unknown factors may cause the expression of symptoms, such as neutropenia, which dramatically influence the severity of the disease.

Antiporters↗