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Biomedical subjects

R Parini

Publications and source records attributed to R Parini.

At least 19 recordsLinked to original sources
PubMed2001

Lectin analyses of glycoprotein hormones in patients with congenital disorders of glycosylation.

OBJECTIVE: The congenital disorders of glycosylation (CDGs) are progressive multisystemic disorders characterized by a heterogeneous deficiency of the carbohydrate moieties in various structural and circulating glycoproteins, representing a natural model for glycoprotein hormone studies. Here, we studied the carbohydrate moiety of circulating glycoprotein hormones in four patients with a clinical suspicion of CDGs. METHODS: The diagnosis of CDG-I was confirmed in two out of the four cases by transferrin isoelectrofocusing (IEF) and/or carbohydrate-deficient transferrin (CDT) test. The carbohydrate moiety of serum endocrine-related glycoproteins was investigated by means of Ricin (immunopurified thyrotropin (TSH)) and Concanavalin A (Con-A) (TSH, follicle-stimulating hormone, alpha-subunit and thyroglobulin) lectin affinity chromatography measurement. RESULTS: CDT concentrations were very high in the two patients with CDG-I and moderately enhanced in the remaining two. In the two CDG-I patients, Ricin analysis of immunopurified TSH showed a severe impairment of lectin binding, both before and after neuroaminidase treatment, indicating a nearly complete lack of terminal sialic acid and galactose residues. In these two cases, Con-A analysis showed a significant prevalence of firmly bound isoforms with poorly processed carbohydrate chains. In the remaining two cases with unknown CDG classification, TSH binding pattern to Ricin was modestly affected and Con-A analysis showed the prevalence of weakly bound glycoprotein isoforms. CONCLUSIONS: The results of Ricin analyses in all four patients were consistent with the CDT test and/or serum transferrin IEF. The severe alteration of TSH binding pattern to Ricin seems to be characteristic of CDG-I. Nevertheless, TSH biological properties are not severely altered, as normal thyroid function was found in both cases.

Carbohydrate Metabolism, Inborn Errors↗
PubMed2000

Novel mutations in lysosomal neuraminidase identify functional domains and determine clinical severity in sialidosis.

Lysosomal neuraminidase is the key enzyme for the intralysosomal catabolism of sialylated glycoconjugates and is deficient in two neurodegenerative lysosomal disorders, sialidosis and galactosialidosis. Here we report the identification of eight novel mutations in the neuraminidase gene of 11 sialidosis patients with various degrees of disease penetrance. Comparison of the primary structure of human neuraminidase with the primary and tertiary structures of bacterial sialidases indicated that most of the single amino acid substitutions occurred in functional motifs or conserved residues. On the basis of the subcellular distribution and residual catalytic activity of the mutant neuraminidases we assigned the mutant proteins to three groups: (i) catalytically inactive and not lysosomal; (ii) catalytically inactive, but localized in lysosome; and (iii) catalytically active and lysosomal. In general, there was a close correlation between the residual activity of the mutant enzymes and the clinical severity of disease. Patients with the severe infantile type II disease had mutations from group I, whereas patients with a mild form of type I disease had at least one mutation from group III. Mutations from the second group were mainly found in juvenile type II patients with intermediate clinical severity. Overall, our findings explain the clinical heterogeneity observed in sialidosis and may help in the assignment of existing or new allelic combinations to specific phenotypes.

Adolescent↗
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

Structure of the SLC7A7 gene and mutational analysis of patients affected by lysinuric protein intolerance.

Lysinuric protein intolerance (LPI) is a rare autosomal recessive defect of cationic amino acid transport caused by mutations in the SLC7A7 gene. We report the genomic structure of the gene and the results of the mutational analysis in Italian, Tunisian, and Japanese patients. The SLC7A7 gene consists of 10 exons; sequences of all of the exon-intron boundaries are reported here. All of the mutant alleles were characterized and eight novel mutations were detected, including two missense mutations, 242A-->C (M1L) and 1399C-->A (S386R); a nonsense mutation 967G-->A (W242X); two splice mutations IVS3 +1G-->A and IVS6 +1G-->T; a single-base insertion, 786insT; and two 4-bp deletions, 455delCTCT and 1425delTTCT. In addition, a previously reported mutation, 1625insATCA, was found in one patient. It is noteworthy that 242A-->C causes the change of Met1 to Leu, a rare mutational event previously found in a few inherited conditions. We failed to establish a genotype/phenotype correlation. In fact, both intrafamilial and interfamilial phenotypic variability were observed in homozygotes for the same mutation. The DNA-based tests are now easily accessible for molecular diagnosis, genetic counseling, and prenatal diagnosis of LPI.

Amino Acid Metabolism, Inborn Errors↗
PubMed2000

Maternal chromosome 7 hetero/isodisomy in Silver-Russell syndrome and PEG1 biallelic expression.

Silver-Russell syndrome (SRS) is characterized by a severe intrauterine and postnatal growth retardation, relative macrocephaly associated with 'mild' facial anomalies. The diagnostic importance of skeletal asymmetry remains controversial. The aetiology of the syndrome is heterogeneous. Maternal uniparental disomy of chromosome 7 (mUPD7) has been reported in approximately 7% of patients, but two carriers of chromosomal abnormalities involving the band 17q25 have also been described. We investigated a clinically selected sample of 20 SRS patients for the presence of mUPD7 using polymorphic microsatellite markers spanning the whole chromosome. Maternal UPD7 was found in only one patient corresponding to an incidence of 5%. The allelic distribution in this patient was consistent with heterodisomy. Segregation analysis of chromosome 14 and 16 showed a biparental contribution in all the 20 patients. Blood RNA from the mUPD7 patient and a normal donor were evaluated for the expression of Paternally Expressed Gene (PEG1), an imprinted gene on chromosome 7q32. Biallelic expression of the gene in adult blood tissues was found in both samples. Our results confirm the causal role of mUPD7 in a minority of SRS patients.

Abnormalities, Multiple↗
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↗
PubMed1999

Medium-chain triglyceride loading test in carnitine-acylcarnitine translocase deficiency: insights on treatment.

The results of a medium-chain triglyceride loading test in a patient with severe carnitine-acylcarnitine translocase deficiency clearly demonstrated impaired in vivo utilization of medium-chain triglycerides. The loading test was performed at the ages of 7 and 36 months. The diet was adjusted accordingly. The clinical course has been favourable and the child is now in very good condition at age 4 years. We conclude that the utilization of medium-chain triglycerides is only partial in carnitine-acylcarnitine translocase deficiency and cannot reasonably be considered an optimal source of energy for these patients. Careful adjustment of dietetic treatment may help to improve prognosis.

3-Hydroxybutyric Acid↗
PubMed1997

Spherophakia associated with molybdenum cofactor deficiency.

Molybdenum cofactor deficiency is an autosomal recessive disorder characterized by lack of activity of the enzymes sulfite oxidase, aldehyde oxidase, and xanthine dehydrogenase or oxidase. The clinical manifestations are indistinguishable from those of isolated sulfite oxidase deficiency: craniofacial alterations, intractable neonatal convulsions, very severe mental retardation, lens dislocation, and death in the first decade of life. Lens dislocation is found in nearly all patients after neonatal age. In the present case it developed late (at the age of 8 years) and was preceded by bilateral spherophakia. We hypothesize that an abnormal relaxation of the zonular fibers is the cause of spherophakia in this disease; this causes lens dislocation eventually, after days, months, or years.

Child↗
PubMed1990

Determination of argininosuccinate lyase and arginase activities with an amino acid analyzer.

The measurement of argininosuccinate lyase (ASase) and arginase, both in liver and erythrocytes, was developed by using a commercial amino acid analyzer. The method is based upon the use of two different substrates, argininosuccinate and arginine for ASase and arginase, respectively, and the measurement of only one final metabolite: ornithine. The use of ornithine as a marker of biological activity of ASase is related to the fact that in the urea cycle, the specific activity of arginase is much higher than that of ASase; thus, during in vitro determinations, arginine, which is the product of ASase, is rapidly converted to ornithine. The sensitivity of the methods is very high since we were able to detect both activities using very diluted rat liver homogenates (0.10 mg protein/ml) or few microliters of human blood. In rat liver the Vmax for ASase and arginase were respectively 0.54 and 140 mumol/h/mg protein; the apparent Km values 1.25 and 13.5 mM. In human erythrocytes the Vmax for the same enzymes were 7.2 and 170 nmol/h/mg Hb and the apparent Km values were 0.66 and 9.5 mM. In 10 healthy volunteers the specific activity of ASase and arginase determined in blood were respectively 8.60 +/- 0.46 and 124.1 +/- 14.5 nmol/h/mg Hb. The results obtained from 2 patients suffering from argininosuccinic aciduria were also reported. In these latter cases while ASase was not detectable in blood, arginase activity was at the lowest end of the confidence limits determined in healthy volunteers.

Amino Acids↗
PubMed1985

Clinical pharmacology of netilmicin in preterm and term newborn infants.

Sixty-four neonates, with gestational age ranging from 27 1/2 to 40 weeks, postnatal age from 1 to 15 days, and birth weight from 800 to 3400 gm, were given netilmicin 2.5 mg/kg intramuscularly two or three times per day according to postnatal age, for 5 to 14 days. Serum concentrations were measured before and 1 hour after a dose at least twice during treatment. The serum washout profile of the drug was observed in 22 neonates after discontinuation of therapy. Renal function was studied in 37 infants by measuring serum creatinine concentrations and in 27 by urinary excretion of N-acetyl-glucosaminidase during and up to 15 days after therapy. Behavioral and impedance audiometry, and in infants failing those, auditory brainstem evoked response tests, were performed between 6 and 12 months of age. In 23.5% of the neonates, trough serum levels were greater than 3 micrograms/ml. The serum washout followed a multiexponential decay, accounting for distributional, rapid (initial), and slow (tissue) elimination phases. Linear regression analysis performed between each kinetic parameter and gestational age or birth weight showed that initial elimination half-life, steady-state volume of distribution, and total body clearance were significantly correlated with both variables. Netilmicin did not cause detectable renal or auditory damage.

Acetylglucosaminidase↗
PubMed1983

Monitoring of amikacin in the neonate.

The purpose of this study was to analyze the role of gestational and postnatal age and of clinical conditions [e.g., respiratory distress syndrome (RDS)] on serum concentrations of amikacin in neonates treated according to commonly recommended dose schedules. Thirty-nine neonates (28.5-42 weeks of gestational age) were treated with the aminoglycoside at a mean dose of 7.2 mg/kg every 12 h for an average period of 6.5 days, and serum levels were monitored throughout treatment. Both gestational and postnatal age influenced amikacin levels. During the first days of life the presence of RDS was found to be strongly associated with amikacin accumulation. Neonates with retarded intrauterine growth according to their gestational age tended to have lower amikacin trough levels in the first days of life. No correlation was found between amikacin serum levels and hematocrit. Peak concentrations of the drug did not correlate with vital or clinical data, probably because of the variability in drug absorption from the intramuscular injection site. These data are discussed in light of the development of renal function and changes in body fluid compartments occurring in the preterm and term neonates during the first weeks of life.

Age Factors↗