Biomedical subjects
A Riccio
Publications and source records attributed to A Riccio.
Multiple levels of control of insulin-like growth factor gene expression.
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Mono- and bi-allelic expression of insulin-like growth factor II gene in human muscle tumors.
Insulin-like growth factor II (IGF-II) is a mitogen for many cell types and an important modulator of muscle growth and differentiation. IGF-II gene is prevalently expressed during prenatal development and its gene activity is regulated by genomic imprinting, in that the allele inherited from the father is active and the allele inherited from the mother is inactive in most normal tissues. IGF-II expression is activated in several types of human neoplasms and an alteration of IGF-II imprinting has been described in Beckwith-Wiedemann syndrome and Wilms' tumor. Here we show that monoallelic expression of IGF-II gene is conserved in normal adult muscle tissue whereas two or more copies of active IGF-II alleles, arising by either relaxation of imprinting or duplication of the active allele, are found in 9 out of 11 (82%) rhabdomyosarcomas retaining heterozygosity at 11p15, regardless of the histological subtype. Since IGF-II has been indicated as an autocrine growth factor for rhabdomyosarcoma cells, these findings strongly suggest that acquisition of a double dosage of active IGF-II gene is an important step for the initiation or progression of rhabdomyosarcoma tumorigenesis. Among different types of muscle tumors, relaxation of imprinting seems to arise prevalently in rhabdomyosarcomas, since we have detected only one case of partial reactivation of the maternal IGF-II allele out of 7 leiomyosarcomas tested.
Regulation of nitrogen metabolism is altered in a glnB mutant strain of Rhizobium leguminosarum.
We isolated a Rhizobium leguminosarum mutant strain altered in the glnB gene. This event, which has never been described in the Rhizobiaceae, is rare in comparison to mutants isolated in the contiguous gene, glnA. The glnB mutation removes the glnBA promoter but in vivo does not prevent glnA expression from its own promoter, which is not nitrogen regulated. The glnB mutant strain does not grow on nitrate as a sole nitrogen source and it is Nod+, Fix+. Two -24/-12 promoters, for the glnII and glnBA genes, are constitutively expressed in the glnB mutant, while two -35/-10-like promoters for glnA and ntrBC are unaffected. We propose that the glnB gene product, the PII protein, plays a negative role in the ability of NtrC to activate transcription from its target promoters and a positive role in the mechanism of nitrate utilization.
Spinal dural arteriovenous fistulas: an underestimated cause of myelopathy.
13 patients with spinal dural arteriovenous fistulas (DAVF) diagnosed in our Institution have been the object of this study. The necessity to include the disease in the differential diagnosis with other pathologies affecting the lower thoracic cord, particularly in middle-aged and old males, is emphasized. Involvement of the spinal cord was always demonstrable on magnetic resonance studies, but pathologic vessels suggesting the possibility of DAVF were seldom recognizable. Myelography still remains an important complementary method. Spinal angiography is essential, taking into account that the fistula can be located far from the spinal cord. The therapy consisting in embolization in 7 cases and embolization associated with surgery in 6 cases led to improvement or stabilization of the disease in all cases. Our cases are discussed in comparison with the literature.
Improvement of basal hepatic glucose production and fasting hyperglycemia of type I diabetic patients treated with human recombinant ultralente insulin.
OBJECTIVE: To test whether a suppertime injection of human ultralente insulin in patients with type I diabetes would result in a larger inhibition of basal hepatic glucose production (HGP) and improvement in fasting and mean daily plasma glucose levels. RESEARCH DESIGN AND METHODS: We studied 16 type I diabetic patients (41 +/- 4 years of age; body mass index [BMI] = 23.3 +/- 0.3 kg/m2; diabetes duration > 3 years) with a crossover protocol of therapy with an intermediate and ultralente insulin. All patients were already treated with three injections per day of regular insulin in addition to intermediate-acting (NPH) insulin at suppertime. After a 14-day run-in period, patients were randomly assigned to treatment with equivalent doses (10.8 +/- 0.8 U, at 1900) of intermediate (Humulin I) or ultralente (Humulin U) insulin. After 1 month of treatment, patients were crossed over. No change of the insulin dosage was performed during the study period. Basal HGP was measured by D-(6,6-2H2)-glucose infusion. Plasma glucose concentration was measured in the fasting state and monitored during the day. RESULTS: Before starting the study period, fasting plasma glucose was 13.4 +/- 1.1 mM and plasma free-insulin was 48.0 +/- 4.8 pM. Daily plasma glucose concentration averaged 10.3 +/- 0.3 mM and the area under the curve (AUC) was 1.41 +/- 0.05 mol/14 h. NPH insulin, given at suppertime for a month, did not induce significant changes in fasting plasma insulin (40.2 +/- 4.8 pM), glucose concentration (14.0 +/- 0.9 mM) or HGP (20.2 +/- 2.2 mumol.kg-1.min-1). Accordingly, no change occurred in the average daily plasma glucose (10.3 +/- 0.3 mM) or AUC (1.41 +/- 0.9 mol/14 h). Glycated hemoglobin also was not affected (8.2 +/- 0.4 vs. 8.2 +/- 0.3%). On the contrary, a 4-week treatment with ultralente insulin, also given at suppertime, was associated with a decline in the basal HGP (16.0 +/- 1.3 mumol.kg-1.min-1), fasting (11.3 +/- 0.9 mM) and average daily (9.4 +/- 0.3 mM) plasma glucose concentrations, and AUC (1.29 +/- 0.07 mol/14 h) of plasma glucose level (all P < 0.05). Glycated hemoglobin was reduced (7.9 +/- 0.4%). In each condition, fasting plasma glucose concentration was correlated with the average daily plasma glucose level (basal = 0.78; intermediate = 0.89; ultralente = 0.62; all P < 0.05), which suggests that ultralente insulin likely induces the improvements of metabolic control through reducing fasting plasma glucose. CONCLUSIONS: Our results suggest that treating type I diabetic patients with ultralente insulin at suppertime provides a better modulation of basal HGP so that lower fasting plasma glucose levels are ensured. The reduction of fasting hyperglycemia is likely to affect positively daily plasma glucose control.
Antioxidant activity of all-trans-retinol in homogeneous solution and in phosphatidylcholine liposomes.
A kinetic quantification of the lipoperoxyl radical-scavenging activity of all-trans-retinol has been carried out in homogeneous solution, when radicals were produced from the oxidation of methyl linoleate in methanol, initiated by the lipid-soluble 2,2'-azobis (2,4-dimethylvaleronitrile) (AMVN) as well as in a soybean phosphatidylcholine membrane model, in which peroxidation was induced either by AMVN or the hydrophylic 2,2'-azobis(2-amidinopropane)hydrochloride (AAPH). The physical microenvironment contributes to the determination of antioxidant efficiency of all-trans-retinol. In homogeneous solution the kinetic constant kinh is 3.5 x 10(5) M-1 s-1 and appears of the same order of magnitude as the inhibition constant measured for alpha-tocopherol under the same experimental conditions. Nevertheless, despite its very high chemical reactivity toward lipoperoxyl radicals, the overall antioxidant efficiency of all-trans-retinol in this system appears quite limited, since the evaluated stoichiometric factor is 0.21. When the polyenoic chain of all-trans-retinol is incorporated into a phosphatidylcholine lipid bilayer, the antioxidant efficiency depends on the site of peroxyl-radical production. The highest lipoperoxyl radical-scavenging activity is measured when radicals are generated by AHVN inside the bilayer multilamellar liposomes. Under these conditions, the relative antioxidant efficiency is similar to that of alpha-tocopherol, and the stoichiometric factor is 3.1. When radicals are generated by AAPH in the aqueous phase of an unilamellar liposomal system, the antioxidant effectiveness of all-trans-retinol appears reduced and lower than that measured with equivalent amounts of alpha-tocopherol. Synergistic antioxidant effects between all-trans-retinol and alpha-tocopherol are observed when both antioxidants are simultaneously incorporated into unilamellar liposomes in which peroxidation is induced by AAPH. This suggests that all-trans-retinol may interact with tocopheroxyl radicals, thereby regenerating alpha-tocopherol. This interaction, which may be related to molecular features and to the relative location of the antioxidants in the bilayer, could provide an effective antioxidant system that may be of great importance in vivo.
Mechanism(s) of the blood glucose lowering action of benfluorex.
Benfluorex is a hypolipidaemic agent with biguanide-like properties. To evaluate its blood glucose lowering action, a single-blind study protocol was designed. Two groups of seven type II (non-insulin-dependent) diabetic patients matched for age (50 +/- 4 vs. 53 +/- 1 years), sex, body mass index (27.8 +/- 0.6 vs. 26.5 +/- 0.7 kg/m2), and duration of diabetes were studied before and after 1 month of treatment with benfluorex 150 mg tid (= tres in die = three times a day), PO (= per os = by mouth) or a placebo, respectively. All patients had previously been treated by diet alone. In all patients, parameters of glucose and lipid metabolism were obtained. Insulin sensitivity was assessed by means of a euglycaemic (5.1 +/- 0.1 mM) hyperinsulinaemic (516 +/- 28 pM) clamp performed in combination with [3(-3)H]glucose infusion and indirect calorimetry. In no case was there a significant change in body mass index (27.6 +/- 0.5 vs. 26.4 +/- 0.7 kg/m2). After 1 month of treatment, fasting plasma glucose (6.8 +/- 0.2 vs. 8.1 +/- 0.6 mM) and HbA1C (glycated haemoglobin; 6.5 +/- 0.2 vs. 8.0 +/- 0.7%) were lower in the benfluorex group than in the placebo-treated patients (both p < 0.05). No change was observed in hepatic glucose production (HGP) (13.5 +/- 1.4 vs. 13.9 +/- 1.1 mumol/min per kg), the basal rate of glucose, and lipid oxidation and non-oxidative glucose metabolism, or in plasma triglyceride and total cholesterol concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)
Hormonal pattern in women affected by rheumatoid arthritis.
Gonadal sex hormones may account for the sexual dimorphism in the immune response and for the greater incidence of autoimmune disease in females. We have previously reported the presence of progesterone (P) deficiency in female patients with thyroid and ovarian autoimmune disease. In this context, the hormonal profile in 9 women with rheumatoid arthritis (RA) and in 9 age-matched ealthy women, were evaluated to verify the presence of a steroid hormone secretion impairment in a systemic autoimmune disease, further supporting our hypothesis of P deficiency involvement. P and androgen plasma levels, in the luteal phase, were significantly lower (p < 0.05 and 0.005, respectively) in RA patients than in the control group, with a consequent decrease of the free androgen index. Moreover, despite normal cortisol values, corticosterone (B) plasma levels were significantly higher in the RA patients (p < 0.01 and 0.05 in follicular and luteal phase, respectively). Therefore, our present data confirm the androgen deficiency in patients with a systemic autoimmune disease, such as RA and support the immunomodulator effect of P. Finally, the higher B plasma levels in RA patients may suggest the presence of a slight impairment of the immune hypothalamic-pituitary-adrenal axis (HPAA), supporting its role in certain phases of RA pathogenesis. In conclusion, in addition to androgens, the immunomodulator role of P should also be taken into account in the pathogenesis of the systemic autoimmune disease.
Mechanisms of fasting hypoglycemia and concomitant insulin resistance in insulinoma patients.
To gain further insight into the pathogenesis of fasting hypoglycemia in patients with insulin-secreting adenoma of the pancreas, we studied seven patients affected by insulinoma (age, 42 +/- 7 years; body mass index [BMI], 27 +/- 2 kg/m2) and seven normal subjects. In insulinoma patients, hepatic glucose production (HGP) and glucose utilization (Rd) were evaluated by infusion of 3-3H-glucose at spontaneous fasting plasma glucose concentration, after restoration of euglycemia and during euglycemic insulin clamp (40 mU/m2/min). In insulinoma patients, fasting plasma glucose concentration (2.8 +/- 0.2 v 4.5 +/- 0.1 mmol/L; P < .001), HGP, and glucose Rd (7.8 +/- 1.1 v 12.0 +/- 0.3 mumol/kg/min; P < .01) were lower than in normal subjects, while plasma insulin level was higher (138 +/- 19 v 38 +/- 3 pmol/L; P < .001). In insulinoma patients after attainment of euglycemia (4.7 +/- 0.2 mmol/L) by exogenous glucose infusion, insulin level increased slightly (174 +/- 18 pmol/L; P < .01) and glucose Rd was similar to that of normal individuals (12.8 +/- 0.6 v 12.0 +/- 0.3 mumol/kg/min). During the clamp studies, glucose Rd was lower in insulinoma patients (18.7 +/- 1.2 v 33.8 +/- 3.1 mumol/kg/min; P < .01) despite higher plasma insulin concentration (612 +/- 48 v 420 +/- 12 pmol/L). Therefore, glucose Rd/I x 100 ratio (where I is plasma insulin concentration) was much lower in insulinoma patients (3.1 +/- 0.9 v 8.0 +/- 0.7; P < .01), suggesting a marked degree of insulin resistance.(ABSTRACT TRUNCATED AT 250 WORDS)
The ntrBC genes of Rhizobium leguminosarum are part of a complex operon subject to negative regulation.
We report here that ntrB and ntrC genes of Rhizobium leguminosarum biovar phaseoli are cotranscribed with an open reading frame (called ORF1) of unknown function. The promoter region of the ORF1-ntrB-ntrC operon was mapped immediately upstream of ORF1 and two in vivo transcription initiation sites were identified, both preceded by -35/-10 promoter consensus sequences. Some major aspects differentiate R. leguminosarum from the enteric nitrogen regulatory system: the ntrBC genes are cotranscribed with ORF1 which is homologous to an ORF located upstream of ntrBC of R. capsulatus and to the ORF1 located upstream of the fis gene of Escherichia coli; ntrBC are not transcribed from a -24/-12 promoter and are only autogenously repressed. Moreover, the intracellular concentration of the NtrC protein increases when the bacterium is grown on ammonium salts, while under the same conditions the promoter of one of its target genes, glnII, is 12 times less active.
[A case of Reiter syndrome in HIV infection].
The onset of Acquired Immunodeficiency Syndrome (AIDS) is often characterized by a variety of symptoms, with the involvement of several tissues and organs. In the present case a polyarthritic syndrome was the symptomatology at the onset. Clinical onset. A 26 year old man, drug abuser, anti HIV positive, with a CD4/CD8 ratio = 0.8, was observed in January 1990. He presented polyarthritic involvement of the ankles and right knee, conjunctivitis and successfully keratodermia. The diagnosis of Reiter syndrome was made on the basis of the clinical features and laboratory findings (Chlamydia in his urethral secretion). The patient did not denote any symptom of immunodeficiency, except small lymphonodal painless swelling in axillary and latero-cervical region. A significant clinical improvement was obtained with chlortetracycline at a dosage of 100 mg daily and 6 methylprednisolone 12 mg daily. Comment. This experience suggests the importance and the usefulness of the anti HIV test in patients affected by a reactive arthritis, as the Reiter's syndrome, since the progressive diffusion of the HIV infection.
The lack of correlation between the positivity of anti-platelet antibodies and the presence of thrombocytopenia in course of HIV infection.
The presence of anti-platelet autoantibodies has been reported in many cases of HIV infection, but there is no accordance about their pathogenic role in the onset of thrombocytopenia in the patients studied. In the present study surface anti-platelet antibodies (PAIgG) and serum anti-platelet antibodies (sPAIgG) were assayed in a group of 135 HIV-infected patients (109 men, 26 women), in different clinical stages by using an immunofluorescence test (PSIFT). In order to investigate the possible correlation of the positivity of these autoantibodies and the onset of thrombocytopenia, some of these patients were controlled in a follow-up study, with two successful controls: 10 months (II control: 89 patients) and 20 months (III control: 59 patients) after the first time. In the I control PAIgG were positive in 68 subjects (50.4%) and sPAIgG in 34 (25.2%); both PAIgG and sPAIgG were present in 23 patients (17%). 56 patients did not present anti-plt antibodies (41.5%). No significantly different distribution of these autoantibodies in each stage of disease was observed. The mean value of platelet count resulted in the normal range both in the anti-plt antibody positive and in the anti-plt antibody negative patients, but the value found in the anti-plt antibody positive patients was significantly lower than the one found in the anti-plt antibody negative group (p < 0.01). This difference was more marked between the group with PAIgG and anti-plt antibody negative patients than between the group with sPAIgG and the anti-plt antibody negative patients (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
[Correlated study of visual evoked potentials-polyneuropathy in diabetic patients without retinopathy].
The functional study of visual pathways by means of pattern reversals VEPs (visual evoked potentials) was used as a noninvasive method in the study of diabetic patients, but the correlations between alterations in VEPs and the involvement of peripheral nervous system were not explored. Among 35 diabetic patients not suffering from retinopathy, we tested early deteriorations in visual pathways by means of pattern reversals VEPs and we considered similarities between these alterations, clinical metabolic parameters of the disease and clinical and paraclinical aspects of polyneuropathy (PNP). Four of these patients were insulin-dependent and 31 non-insulin-dependent, all with normal electroretinography and fluorangiography. Monitoring control of diabetes was performed by measuring hemoglobin HbA1. The control group was composed of 35 healthy subjects with normal neurologic and ophthalmologic examinations and normal visual acuity. In all subjects we tested four peripheral nerve conduction velocities (PNCV) (sensory and motor conduction of median nerve, motor conduction of peroneal nerve, anthidromic sensory conduction of sural nerve) diabetic patients were distributed in two groups according to the presence (group A, 15 patients) or absence (group B, 20 patients) of polyneuropathy. Pattern reversals PEVs were recorded after mono and binocular stimulation; screen was 25 x 18 cm with black and white check board pattern, check size 1.1 cm. Subject-to-stimulus distance was 1 m, corresponded to a visual angle of 38 degrees. Active electrode were located in Oz, O1 and O2, reference electrode in Fz.(ABSTRACT TRUNCATED AT 250 WORDS)
[Mechanisms of hypoglycemic action of benfluorex].
UNLABELLED: Benfluorex is a hypolipidemic agent with biguanide-like properties. Its action on glucose metabolism was evaluated in 6 NIDDM patients previously treated with diet alone. Before and after 1 month of benfluorex therapy (450 mg/day p.o.), an euglycemic (100 mg/dl) insulin (40 mU/m2/min) clamp was performed along with 3-3H-glucose infusion and indirect calorimetry. Benfluorex did not affect body weight, while it reduced fasting plasma glucose (144 +/- 16 vs 119 +/- 8 mg/dl; P < 0.05), glycosylated hemoglobin (6.8 +/- 0.8 vs 6.4 +/- 0.4 percent) and fructosamine (2.9 +/- 0.6 vs 2.4 +/- 0.2 mmol/l; P < 0.05). Both triglycerides (2.3 +/- 0.6 vs 1.9 +/- 0.5 mmol/l) and total cholesterol (5.7 +/- 0.7 vs 5.2 +/- 0.6 mmol/l) declined. No changes occurred in plasma fatty acid, insulin, and C-peptide. Basal hepatic glucose production did not change and it was completely suppressed during the clamp studies both before and after benfluorex. Basal oxidation rates of carbohydrates and lipids did not change significantly. During the insulin clamp study, insulin-mediated glucose disposal increased after benfluorex (5.7 +/- 0.3 vs 4.8 +/- 0.2 mg/kg/min; P < 0.01). Lipid oxidation was equally suppressed before and after therapy with benfluorex. Glucose oxidation was not enhanced after benfluorex while non-oxidative glucose metabolism was significantly improved (2.2 +/- 0.7 vs 3.4 +/- 0.4 mg/kg/min; P < 0.05). CONCLUSION: short-term benfluorex administration a) improves glucose and lipid control, b) improves insulin action by enhancing non-oxidative glucose metabolism, c) does not affect basal insulin secretion. The long-term effect of benfluorex treatment remains to be evaluated.
Activation of the Rhizobium leguminosarum glnII gene by NtrC is dependent on upstream DNA sequences.
The cloning and sequence determination is reported of the DNA region of Rhizobium leguminosarum coding for glutamine synthetase II (GSII). An open reading frame (ORF) encoding 326 amino acids was defined as the glnII gene on the basis of its similarity to other glnII genes and the ability of a DNA fragment carrying this ORF to complement the glutamine auxotrophy of a Klebsiella pneumoniae glnA mutant. We find that the glnII gene in R. leguminosarum is transcribed as a monocistronic unit from a single promoter, which shows structural features characteristic of rpoN (ntrA)-dependent promoters. In K. pneumoniae, such promoters require the ntrC and rpoN (ntrA) gene products for transcription. The intracellular level of glnII mRNA changes when R. leguminosarum is grown on different nitrogen sources, as expected for regulation by the nitrogen regulatory system. Promoter deletion analysis has shown that an extensive upstream DNA sequence (316 bp) is essential for in vivo activation of the glnII promoter in different biovars of R. leguminosarum. This DNA region requires a wild-type ntrC gene for activity and includes two conserved putative NtrC-binding site sequences. The results conclusively show that transcription from the R. leguminosarum glnII promoter is fully dependent on positive control by NtrC protein and on an upstream activator sequence (UAS).
The amino acid sequence of the single hemoglobin of the high-antarctic fish Bathydraco marri Norman.
1. Bathydraco marri Norman is a cold-adapted Antarctic teleost (Family: Bathydraconidae), living preferably at depths between 400 and 1200 m. 2. The blood of this species contains a single hemoglobin, in which oxygen binding is pH-regulated (Bohr and Root effects). 3. The complete amino acid sequence of the alpha and beta chains of the hemoglobin of B. marri has been elucidated.
Phenotype of a Rhizobium leguminosarum ntrC mutant.
A Tn5 insertion mutant, strain CFN2012, of Rhizobium leguminosarum biovar phaseoli devoid of glutamine synthetase II (GSII) activity was analysed. It was shown to contain Tn5 within an 11-kb BamHI DNA fragment, which was isolated (pSM261) from the wild-type strain and, when introduced into strain CFN2012, was shown to complement the absence of GSII activity. The DNA sequence of the corresponding region from the wild-type allele revealed the presence of an ntrC regulatory gene, and restriction analysis indicated that the mutant allele carried the Tn5 insertion within it. Further analysis of strain CFN2012 indicated that this mutant has reduced levels of the PII regulatory protein and that, in contrast to ntrC mutants of other Rhizobiaceae, it grows on nitrate as the sole nitrogen source.