Biomedical subjects
Publications and source records attributed to C Benelli.
We identified a new Y243S mutation in the X-linked E1 alpha-PDH gene in a patient with pyruvate dehydrogenase complex (PDHc) deficiency. The activity in cultured fibroblasts was very low even in the presence of high thiamine pyrophosphate (TPP) concentrations, indicating that the defect could be due to decreased affinity of PDHc for TPP.
The biochemical properties of an in vivo hormonally regulated low Km cAMP phosphodiesterase (PDE) activity associated with a liver Golgi-endosomal (GE) fraction have been characterized. DEAE-Sephacel chromatography of a GE fraction solubilized by a lysosomal extract resulted in the sequential elution of three peaks of activity (numbered I, II, and III), while ion-exchange HPLC resolved five peaks of activity (numbered 1, 2, 3, 4, and 5). Based on the sensitivity of the eluted activity to cGMP and selected phosphodiesterase inhibitors, two phosphodiesterase isoforms were resolved: a cGMP-stimulated and EHNA-inhibited PDE2, eluted in DEAE-Sephacel peak I and HPLC peak 2 and a cGMP-, a cilostamide-, and ICI 118233-inhibited PDE3, eluted in DEAE-Sephacel peak III and HPLC peaks 3, 4, and 5. GE fractions isolated after acute treatments with insulin, tetraiodoglucagon, and growth hormone displayed an increase in phosphodiesterase activity relative to saline-injected controls, as did GE fractions from genetically obese and hyperinsulinemic rats relative to lean littermates. In all experimental rats, an increase in PDE3 activity associated with DEAE-Sephacel peak III and HPLC peaks 4 and 5 was observed relative to control animals. Furthermore, in genetically obese Zucker rats, an increase in the sensitivity of PDE activity to cilostamide and in the amount of PDE activity immunoprecipitated by an antibody to adipose tissue PDE3 was observed relative to lean littermates. These results extend earlier studies on isolated hepatocytes and show that liver PDE3 is the main if not sole PDE isoform activated by insulin, glucagon, and growth hormone in vivo.
The gene SURF1 encodes a factor involved in the biogenesis of cytochrome c oxidase, the last complex in the respiratory chain. Mutations of the SURF1 gene result in Leigh syndrome and severe cytochrome c oxidase deficiency. Analysis of seven unrelated patients with cytochrome c oxidase deficiency and typical Leigh syndrome revealed different SURF1 mutations in four of them. Only these four cases had associated demyelinating neuropathy. Three mutations were novel splicing-site mutations that lead to the excision of exon 6. Two different novel heterozygous mutations were found at the same guanine residue at the donor splice site of intron 6; one was a deletion, whereas the other was a transition [588+1G>A]. The third novel splicing-site mutation was a homozygous [516-2_516-1delAG] in intron 5. One patient only had a homozygous polymorphism in the middle of the intron 8 [835+25C>T]. Western blot analysis showed that Surf1 protein was absent in all four patients harboring mutations. Our studies confirm that the SURF1 gene is an important nuclear gene involved in the cytochrome c oxidase deficiency. We also show that Surf1 protein is not implicated in the assembly of other respiratory chain complexes or the pyruvate dehydrogenase complex.
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Growth retardation occurs frequently in renal transplanted children (RTx) and can be improved by growth hormone (GH) treatment. This study retrospectively examines the insulin-like growth factor-1 (IGF-1) and IGF binding protein (IGFBP) profile of ten growth-retarded children previously given renal allografts, after 1 year of GH treatment period. Ten prepubertal patients (nine boys and one girl) were investigated. They had a mean chronological age (CA) of 11.4 +/- 1.1 years and a mean bone age (BA) of 7.3 +/- 0.9 years. Mean height was -3.9 +/- 0.4 SD units below the mean for CA. The mean body mass index (BMI) was 16.9 +/- 0.6 and the mean inulin clearance was 36.5 +/- 4.9 ml/min/1.73 m2. Recombinant hGH was given at 4 IU/m2/day. Plasma GH, total and free IGF-1, IGFBP-2 and -3 were measured by specific radioimmunoassay (RIA). IGFBPs were characterized by SDS PAGE techniques and ligand and immunoblot analyses. Mean velocity was markedly increased (P < 0.01) after 1 year of GH therapy, expressed as SD score for BA. The range of growth response was wide. The total and free plasma IGF-1 increased (P < 0.01) by about 100% (mean values after GH therapy: 95.9 +/- 2.1 nM and 165 +/- 29 pM, respectively). Plasma IGFBP-3 concentrations increased by about 40% (mean value: 148 +/- 18 pM, P < 0.01), with a concomitant increase in both intact IGFBP-3 and its 30-kDa proteolytic fragment. There was no change in plasma IGFBP-2 concentration. Both mean values of inulin clearance and BMI were unchanged during the treatment. In view of the IGF-1/IGFBP concentration changes, there should have been an even better growth response to GH therapy in these patients. This strongly suggests IGF-1 insensitivity, probably as a result of corticosteroid therapy.
Hyperinsulinism and hyperammonemia syndrome has been reported as a cause of moderately severe hyperinsulinism with diffuse involvement of the pancreas. The disorder is caused by gain of function mutations in the GLUD1 gene, resulting in a decreased inhibitory effect of guanosine triphosphate on the glutamate dehydrogenase (GDH) enzyme. Twelve unrelated patients (six males, six females) with hyperinsulinism and hyperammonemia syndrome have been investigated. The phenotypes were clinically heterogeneous, with neonatal and infancy-onset hypoglycemia and variable responsiveness to medical (diazoxide) and dietary (leucine-restricted diet) treatment. Hyperammonemia (90-200 micromol/L, normal <50 micromol/L) was constant and not influenced by oral protein, by protein- and leucine-restricted diet, or by sodium benzoate or N-carbamylglutamate administration. The patients had mean basal GDH activity (18.3 +/- 0.9 nmol/min/mg protein) not different from controls (17.9 +/- 1.8 nmol/min/mg protein) in cultured lymphoblasts. The sensitivity of GDH activity to inhibition by guanosine triphosphate was reduced in all patient lymphoblast cultures (IC(50), or concentrations required for 50% inhibition of GDH activity, ranging from 140 to 580 nM, compared with control IC(50) value of 83 +/- 1.0 nmol/L). The allosteric effect of ADP was within the normal range. The activating effect of leucine on GDH activity varied among the patients, with a significant decrease of sensitivity that was correlated with the negative clinical response to a leucine-restricted diet in plasma glucose levels in four patients. Molecular studies were performed in 11 patients. Heterozygous mutations were localized in the antenna region (four patients in exon 11, two patients in exon 12) as well as in the guanosine triphosphate binding site (two patients in exon 6, two patients in exon 7) of the GLUD1 gene. No mutation has been found in one patient after sequencing the exons 5-13 of the gene.
The synthesis and structural characterisation of a series of cobalt and nickel cages are reported. Eight of these structures contain a [M10(mu3-OH)6(eta2, mu3-xhp),(eta2, mu2-O2CR)6]2+ core (where M = Co or Ni; xhp = 6-chloro- or 6-methyl-2-pyridonate: R = Me, Ph, CHMe2, CH2Cl, CHPh2 or CMe3), where the ten metal atoms describe a centred-tricapped-trigonal prism (ttp). The cage contains six hydroxide ligands around the central metal, and the exterior is coated with pyridonate and carboxylate ligands. For four of the cages additional metal centres are found attached to the upper and/or lower triangular faces of the trigonal prism, generating dodeca- and undecanuclear cages. Three further cages are reported that contain a metal core based on an incomplete centred-tetraicosahedron. These cages involve trimethylacetate as a ligand in company with either 6-methyl-2-pyridonate or 6-chloro-2-pyridonate. Comparison of these latter structures with the trigonal prisms reveal that they can be described as a pentacapped-trigonal prism missing one edge. Magnetic studies of three of the nickel cages with trigonal prismatic cores show spin ground states of S = 8, 4 and 2 for Ni12, Ni11 and Ni10 cages, respectively.
Dermoscopy improves sensitivity in the diagnosis of melanoma. We have developed a new diagnostic dermoscopic method which evaluates only seven dermoscopic features or criteria. We called the method Seven features for melanoma (7FFM). To present and to evaluate the reproducibility of our dermoscopic diagnostic method (7FFM) we held eight dermoscopic courses from 10/4/96 to 04/03/98 in various Italian cities. In fact the reliability of a diagnostic test or method mainly depends on the level of agreement in the interpretation of results among different observers. Only methods with good agreement can be used in clinical practice for the diagnosis of melanoma. Many dermatologists (207) attended one of the eight dermoscopic courses: each course was one-day in length and at the end of the course the participants evaluated a set of 25 dermoscopic slides using our dermoscopic method. Percentages of concordance and K values for a kappa statistical analysis to evaluate inter-rater reliability have been calculated. The method showed a mean percentage of concordance of 85.7%, median 88%, a mean K value of 0.699, median 0.684. These data point to a good agreement level. Our method shows good reproducibility after a short training program.
We have previously reported a genetic study of a neonatal lactic acidosis linked to a pyruvate dehydrogenase complex deficiency due to the absence of the protein X subunit. This rare autosomal recessive disorder is associated with specific deletions in this polypeptide which is encoded by the HsPDX1 gene, located on chromosome 11p1.3. The pathology of the patient was considered to arise from a large homozygous deletion (78del85) found at the 5' end of the HsPDX1 coding sequence. Her heterozygous mother underwent prenatal diagnosis during a subsequent pregnancy. Chorionic villus samples were used for three independent studies: (1) normal levels of the protein X component of the PDH complex were detected by immunoblotting; (2) RT-PCR analysis showed no deletion at the 5' end of the cDNA but the presence of a distinct heterozygous deletion (965del59) at its 3' end inherited from the father; (3) haplotype analysis revealed the presence of the father's mutated allele and the mother's normal allele. It was concluded that the fetus was heterozygous for this separate 3' deletion, so, it was likely to be not affected. This study permitted us to characterize more precisely the genetic abnormalities of the HsPDX1 cDNA occurring in each family's member.
The ability of Ca2+/phospholipid-dependent protein kinase (protein kinase C, PKC) to stimulate cAMP phosphodiesterase (PDE) activity in a liver Golgi-endosomal (GE) fraction was examined in vivo and in a cell-free system. Injection into rats of 4 beta-phorbol 12-myristate 13-acetate, a known activator of PKC, caused a rapid and marked increase in PKC activity (+325% at 10 min) in the GE fraction, along with an increase in the abundance of the PKC alpha-isoform as seen on Western immunoblots. Concurrently, 4 beta-phorbol 12-myristate 13-acetate treatment caused a time-dependent increase in cAMP PDE activity in the GE fraction (96% at 30 min). Addition of the catalytic subunit of protein kinase A (PKA) to GE fractions from control and 4 beta-phorbol 12-myristate 13-acetate-treated rats led to a comparable increase (130-150%) in PDE activity, suggesting that PKA is probably not involved in the in-vivo effect of 4 beta-phorbol 12-myristate 13-acetate. In contrast, addition of purified PKC increased (twofold) PDE activity in GE fractions from control rats but affected only slightly the activity in GE fractions from 4 beta-phorbol 12-myristate 13-acetate-treated rats. About 50% of the Triton-X-100-solubilized cAMP PDE activity in the GE fraction was immunoprecipitated with an anti-PDE3 antibody. On DEAE-Sephacel chromatography, three peaks of PDE were sequentially eluted: one early peak, which was stimulated by cGMP and inhibited by erythro-9 (2-hydroxy-3-nonyl) adenine (EHNA); a selective inhibitor of type 2 PDEs; and two retarded peaks of activity, which were potently inhibited by cGMP and cilostamide, an inhibitor of type 3 PDEs. Further characterization of peak I by HPLC resolved a major peak which was activated (threefold) by 5 microM cGMP and inhibited (87%) by 25 microM EHNA, and a minor peak which was insensitive to EHNA and cilostamide. 4 beta-Phorbol 12-myristate 13-acetate treatment caused a selective increase (2.5-fold) in the activity associated with DEAE-Sephacel peak I, without changing the K(m) value. These results suggest that PKC selectively activates a PDE2, cGMP-stimulated isoform in the GE fraction.
The clinical diagnosis of melanoma has a mean sensitivity of 67%, dermoscopy or dermatoscopy is a non invasive technique which improves this sensitivity. Our purpose was to create a simple dermoscopic method for the diagnosis of melanoma useful in daily office practice. For this reason a training set of 218 cutaneous pigmented lesions was used and scored for 16 dermoscopic features: for each feature sensitivity, specificity and statistical significance were evaluated. The results were used to create a simple dermoscopic diagnostic method of only seven dermoscopic features (7FFM). The method was used to evaluate a test set of 713 pigmented skin lesions consecutively observed. The diagnostic dermoscopic method developed gave a sensitivity of 94.6%, a specificity of 85.5% and an efficiency of 87.6%. Our method improves the sensitivity in the diagnosis of melanoma and can be used for the screening of pigmented skin lesions.
Dermoscopy is an useful technique for the diagnosis of melanoma. All the diagnostic dermoscopic methods developed until now have been tested on dermoscopic slides and the real improvement given by this technique to the clinical diagnosis based upon ABCDE criteria is still unknown. For this reason, we decided to undertake a prospective study to compare the clinical diagnosis made with ABCDE criteria, to the dermoscopic diagnosis, made with the method 7FFM, developed by us. A total of 401 lesions were evaluated clinically and dermoscopically. On the basis of the number of the clinical criteria considered sufficient to diagnose a melanoma, various clinical scores, ranging from 1 to 5, can be obtained; data about the sensitivity of the clinical diagnosis of melanoma suggest that the most often used score is score 3. Our method 7FFM presents a sensitivity and a specificity better than those obtained with score 3: 80% versus 66.6% and 89.1% versus 79.3%. Besides this, we have evaluated if the sensitivity of our method 7FFM in the diagnosis of melanoma can be improved with the adjunct of the clinical criteria or of the clinical scores. The best values of sensitivity 93.3% and predictive value negative 97.3% have been obtained with score 2 plus 7FFM. Our results confirm that our method can be used in the screening of pigmented skin lesions in daily office practice and that an improvement in sensitivity without an excessive sacrifice of specificity can be obtained with the adjunct of the clinical score 2.
The tissue-specific expression of the mitochondrial pyruvate dehydrogenase complex (PDHc) has been studied in an animal model of obesity with hyperinsulinemia, the obese (fa/fa) Zucker rat. Liver and heart were obtained from 4 and 8 week-old obese rats and age-matched lean animals, and in each tissue the following parameters were analyzed: (1) total activity of the mitochondrial PDHc; (2) abundance of the mitochondrial PDHc subunits on Western blots; and (3) abundance of the E1alpha and E1beta subunit mRNAs on Northern blots and semi-quantitative RT-PCR. Regardless of age, obese rats showed an increase in liver total PDHc activity and a coordinate increase in liver E1alpha and E1beta PDHc subunit abundance. At 4 weeks, obese rats also showed an increase in liver PDH E1alpha mRNA level, but regardless of age E1beta mRNA level was unchanged. In contrast, neither total PDHc activity nor the concentration of its protein subunits were increased in heart of obese rats. Thus, obese Zucker rats display a liver-specific early increase in PDHc which results from a selective up-regulation of the E1alpha gene expression.
The pyruvate dehydrogenase complex (PDHc) is a multienzyme complex consisting of three catalytic and two regulatory enzymes, as well as a less well defined subunit called protein X. PDHc deficiency is a common cause of congenital lactic acidosis. Most patients with PDH deficiency have a mutation in the alpha chain of the PDH E1 enzyme. Very few patients have been described in whom the basic defect of a PDH deficiency is situated in the X protein. We studied a boy with severe lactic acidosis and developmental delay in whom a deficiency of PDH activity led to further investigations. Immunochemical analysis with anti-PDHc antibodies demonstrated an absence of the X component. This report is the fourth family in which an abnormal protein X has been found. In cases with PDH deficiency where no mutation of the PDHE1 alpha gene is found, further investigations by means of immunoblotting with specific antibodies against the different subunits should be performed.
This double-blind randomized study was designed to compare the efficacy and safety of calcipotriol ointment (50 microg/g) with betamethasone dipropionate (64 mg/g) and salicylic acid (0.03 g/g) ointment in the treatment of nail bed psoriasis. Fifty-eight patients applied the given drug to the affected nails twice a day for 3-5 months, depending on clinical response. Efficacy was assessed monthly on the basis of nail thickness, measured in millimetres. Photographs of the treated nails were taken at baseline, and after 3 and 5 months. Tolerability was assessed at 3 and 5 months. In patients with fingernail psoriasis, after 3 months of treatment subungual hyperkeratosis was reduced from 2.3 +/- 0.1 mm (mean +/- SEM) to 1.5 +/- 0.1 mm (-26.5%) in the calcipotriol group and from 2.3 +/- 0.1 mm to 1.6 +/- 0.1 mm (-30.4%) in the betamethasone dipropionate and salicylic acid group [not significant (NS) between treatments, analysis of variance (ANOVA)]. After 5 months, responders showed a 49.2% reduction in hyperkeratosis in the calcipotriol group (from 2.8 +/- 0.1 mm to 1.4 +/- 0.2 mm) and 51.7% (from 2.1 +/- 0.1 mm to 1.0 +/- 0.1 mm) in the betamethasone dipropionate and salicylic acid group (P < 0.001 from baseline, NS between treatments, ANOVA). In patients with toenail psoriasis, after 3 months of treatment there was an overall reduction in hyperkeratosis from 2.6 +/- 0.1 mm to 2.1 +/- 0.1 mm (-20.1%) in the calcipotriol group and from 3.0 +/- 0.1 mm to 2.3 +/- 0.1 mm (-22. 9%) in the betamethasone dipropionate and salicylic acid group (P < 0.001 from baseline, NS between treatments, ANOVA). By the end of the fifth month there was a 40.7% reduction in hyperkeratosis in the calcipotriol group (from 2.1 +/- 0.1 mm to 1.2 +/- 0.1 mm) and 51.9% in the betamethasone dipropionate and salicylic acid group (from 2.7 +/- 0.1 mm to 1.3 +/- 0.1 mm; P < 0.0001 from baseline, NS between treatments, ANOVA). The results of the study show that calcipotriol is as effective as a combination of a topical steroid with salicylic acid in the treatment of nail psoriasis and represents a safe alternative in the topical treatment of nail psoriasis.
BACKGROUND: Psoriasis is present all over the world and its prevalence varies in the different populations and different geographical areas. For example, Northern European countries seem to have rates of incidence which are greater than those known for Southern Europe. However, today there is still a lack of adequate data to allow comparisons at an international level. METHODS: In Italy in 1994 the AISP (Interdisciplinary Association for the Study of Psoriasis) co-ordinated the recording of monthly case histories and clinical results relating to psoriasis in patients observed in dermatology centres homogeneously distributed throughout Italy. The results were extrapolated from the overall case series. RESULTS: A sample of nearly 8000 cases was collected, most presenting psoriasis vulgaris. This pathology, prevalent in males, first appears at an age somewhere between the teens and twenties. Numerous factors may be involved, and onset is mainly attributed to stress, viral or bacterial infections and pharmacological therapy. Over 90% of cases lost between 1 and 7 working days in the course of the year. Local anti-psoriasis treatment in monotherapy was administered more frequently than systemic therapy or combined therapy. CONCLUSIONS: The results of this first Italian epidemiological study confirm that psoriasis is homogeneously distributed throughout the country. About 50% of patients avail themselves of specialist cures, even several times in the course of the year, and use a wide range of therapies which may be more or less demanding. The internal socio-economic cost of the disease is evident, particularly in terms of working days lost and/or medical expenses.
We report studies of four patients with pyruvate dehydrogenase complex (PDH) deficiency caused by mutations in the E1 alpha subunit. Two unrelated male patients presented with Leigh syndrome and a R263G missense mutation in exon 8. This mutation has previously been described in males with the same phenotype. The two other patients had different novel mutations: (1) an 8-bp deletion at the C-terminus (exon 11) was found in one allele of a young girl suffering from microcephaly and (2) a C88S missense mutation (exon 3) in a boy who only presented with motor neuropathy. These mutations were not found in the mothers of any of the four cases. Immunoblot analysis revealed decreased immunoreactivity for the E1 alpha and E1 beta subunits in three out of the four patients. These findings confirm that: (1) PDH deficiencies are genetically heterogeneous, (2) the R263G mutation is more frequent in male cases than are other mutations and this amino acid is a hot spot for gene mutations, (3) the last eight amino acids may be important for the conformation of the tetrameric E1-PDH enzyme, and (4) the amino acids at positions 88, 263 and 382-387 are essential for the linking of the alpha subunit with the beta subunit and for the activity of the holoenzyme.
We have identified and sequenced a cDNA that encodes an apparent human orthologue of a yeast protein-X component (ScPDX1) of pyruvate dehydrogenase multienzyme complexes. The new human cDNA that has been referred to as "HsPDX1" cDNA was cloned by use of the "database cloning" strategy and had a 1,506-bp open reading frame. The amino acid sequence of the protein encoded by the cDNA was 20% identical with that encoded by the yeast PDX1 gene and 40% identical with that encoded by the lipoate acetyltransferase component of the pyruvate dehydrogenase and included a lipoyl-bearing domain that is conserved in some dehydrogenase enzyme complexes. Northern blot analysis demonstrated that the major HsPDX1 mRNA was 2.5 kb in length and was expressed mainly in human skeletal and cardiac muscles but was also present, at low levels, in other tissues. FISH analysis performed with a P1-derived artificial chromosome (PAC)-containing HsPDX1 gene sublocalized the gene to 11p1.3. Molecular investigation of PDX1 deficiency in four patients with neonatal lactic acidemias revealed mutations 78del85 and 965del59 in a homozygous state, and one other patient had no PDX1 mRNA expression.