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Biomedical subjects

A Orsi

Publications and source records attributed to A Orsi.

At least 19 recordsLinked to original sources
PubMed2006

Epstein-Barr virus-associated post-transplant lymphoproliferative disease with central nervous system involvement after unrelated allogeneic hematopoietic stem cell transplantation.

Post-transplant lymphoproliferative disorders (PTLD) represent an heterogeneous group of abnormal lymphoid proliferation related to Epstein-Barr virus (EBV) reactivation that arise early after allogeneic hematopoietic stem cell transplant (HSCT). PLTD with central nervous system (CNS) involvement has been reported in few cases. We describe the case of a 31-year-old-man who developed an EBV-related PTLD with CNS involvement 2 months after an allogeneic unrelated HSCT for acute myeloid leukemia in first complete remission who was successfully treated with rituximab, cidofovir and intrathecal infusion of methotrexate and methylprednisolone.

Acute Disease↗
PubMed2006

Neurocutaneous syndrome with mental delay, autism, blockage in intracellular vescicular trafficking and melanosome defects.

We evaluated a 11-year-old male patient with mental delay, autism and brownish and whitish skin spots. The former resembled those of neurofibromatosis, the latter those of tuberous sclerosis. The patient received a complete clinical work-up to exclude neurofibromatosis, tuberous sclerosis, or any other known neurocutaneous disease, with biochemistry, chromosome analysis and analysis of skin specimens. Being all the other tests not significant, two main ultrastructural defects were observed. The first was a blockage in intracellular vescicular trafficking with sparing of the mitochondria; the second an aberrant presence of melanosomes in vacuoles of several cell lines and abnormal transfer of these organelles to keratinocytes. This patient presented with a unique clinical picture distinct from neurofibromatosis or tuberous sclerosis or any other known neurocutaneous disease. The ultrastructural abnormalities suggested a defect in cell trafficking involving several cell lines and compartments.

Autistic Disorder↗
PubMed2001

Role of individual disulfide bonds in the structural maturation of a low molecular weight glutenin subunit.

Gliadins and glutenins are the major storage proteins that accumulate in wheat endosperm cells during seed development. Although gliadins are mainly monomeric, glutenins consist of very large disulfide-linked polymers made up of high molecular weight and low molecular weight subunits. These polymers are among the largest protein molecules known in nature and are the most important determinants of the viscoelastic properties of gluten. As a first step toward the elucidation of the folding and assembly pathways that lead to glutenin polymer formation, we have exploited an in vitro system composed of wheat germ extract and bean microsomes to examine the role of disulfide bonds in the structural maturation of a low molecular weight glutenin subunit. When conditions allowing the formation of disulfide bonds were established, the in vitro synthesized low molecular weight glutenin subunit was recovered in monomeric form containing intrachain disulfide bonds. Conversely, synthesis under conditions that did not favor the formation of disulfide bonds led to the production of large aggregates from which the polypeptides could not be rescued by the post-translational generation of a more oxidizing environment. These results indicate that disulfide bond formation is essential for the conformational maturation of the low molecular weight glutenin subunit and suggest that early folding steps may play an important role in this process, allowing the timely pairing of critical cysteine residues. To determine which cysteines were important to maintain the protein in monomeric form, we prepared a set of mutants containing selected cysteine to serine substitutions. Our results show that two conserved cysteine residues form a critical disulfide bond that is essential in preventing the exposure of adhesive domains and the consequent formation of aberrant aggregates.

Base Sequence↗
PubMed2001

Additional case of Marden-Walker syndrome: support for the autosomal-recessive inheritance adn refinement of phenotype in a surviving patient.

In this report, we present a 14-year-old girl, born to consanguineous parents, who presented with severe mental retardation, hypotonia, short stature, and congenital joint contractures. The craniofacial features were scaphocephaly, thin/long and immobile face, marked hypoplasia of the midface, temporal narrowness, blepharophimosis, palpebral ptosis, and strabismus. The combination of such a distinctive craniofacial appearance and psychomotor retardation allows us to recognize a new case of the Marden-Walker syndrome. Our patient represents one of the rare cases in which consanguineous mating supports the autosomal-recessive pattern of inheritance of this condition. Furthermore, through refining the phenotype of a surviving patient, this report may contribute to a better recognition of this disorder in older affected children.

Adolescent↗
PubMed2001

Simvastatin-associated memory loss.

The statins are widely used to treat dyslipidemias. They are generally associated with mild adverse effects, but rarely, more serious reactions may occur. A 51-year-old man experienced delayed-onset, progressive memory loss while receiving simvastatin for hypercholesterolemia. His therapy was switched to pravastatin, and memory loss resolved gradually over the next month, with no recurrence of the adverse effect.

Anticholesteremic Agents↗
PubMed2000

Continuous exposure to high concentrations of nitric oxide leads to persistent inhibition of oxygen consumption by J774 cells as well as extraction of oxygen by the extracellular medium.

Nitric oxide (NO) plays a key role in many physiological and pathophysiological events, including the control of cell respiration. Both reversible and irreversible inhibition of mitochondrial respiration have been reported following the generation of NO by cells. We have exposed the murine macrophage cell line J774 to high concentrations of NO, such as are generated in some pathological conditions, and determined their effect on oxygen consumption. We observed a persistent inhibition of respiration which was due to a redox-dependent, progressive inhibition of complex I activity. No other enzyme of the respiratory chain was inhibited in this way. At the same time, we detected a paradoxical removal of oxygen by the extracellular medium. This removal was due to a chemical interaction between dissolved oxygen and NO-related species released from cells exposed to NO. A similar removal of oxygen by the cell supernatant also occurred following activation of cells with cytokines and bacterial products. Thus, the amounts of NO generated during pathological conditions may contribute to tissue hypoxia both by inhibiting cell respiration and by promoting removal of oxygen from the extracellular medium.

Animals↗
PubMed2000

Oxidative stress and S-nitrosylation of proteins in cells.

The effect of prolonged exposure to nitric oxide on enzymes involved in cell metabolism was investigated in T lymphocyte-derived Jurkat and L929 fibroblast human cell lines using a constant concentration of nitric oxide (1.5 microM) released by the nitric oxide donor DETA-NO (0.5 mM). Nitric oxide inhibited immediately the respiration of the cells acting reversibly at complex IV. With time, the inhibition became progressively persistent, i.e. not reversed by trapping of nitric oxide with oxyhaemoglobin, and was preceded by a decrease in the concentration of the intracellular reduced glutathione. This persistent effect of nitric oxide on respiration was due to inhibition of complex I activity which could be reversed by addition of reduced glutathione or by cold light, suggesting that it was due to S-nitrosylation of thiols necessary for the activity of the enzyme. The activity of other enzymes also known to be susceptible to inhibition by S-nitrosylation, i.e. glyceraldehyde-3-phosphate dehydrogenase and glutathione reductase, was progressively decreased by exposure to nitric oxide with a similar time course to that observed for the inhibition of complex I. Furthermore, inhibition of these enzymes only occurred when the concentrations of reduced glutathione had previously fallen and could be prevented by increasing the intracellular concentrations of reduced glutathione. Our results suggest that S-nitrosylation of different enzymes by nitric oxide may occur only if the reducing potential of the cells is impaired.

Cell Line↗
PubMed2000

Strongyloides stercoralis: ultrastructural study of newly hatched larvae within human duodenal mucosa.

AIM: To investigate the ultrastructural features of the newly hatched larvae of Strongyloides stercoralis in human duodenal mucosa. METHODS: Duodenal biopsies from an AIDS patient were studied by transmission electron microscopy to investigate morphology, location, and host-worm relations of newly hatched larvae. RESULTS: Newly hatched larvae were found in the Lieberkuhn crypts within the tunnels formed by migration of parthenogenic females. Delimiting enterocytes were compressed. Release of larvae into the gut lumen was also documented. It was shown that both a thin and a thick membrane surrounded the eggs and larvae, as a tegument derived respectively from parasite and host. Segmentary spike-like waves, caused by contractures of worm body musculature, were observed on the surface of newly hatched larvae, and their intestinal lumen was closed and empty, with no budding microvilli. Immaturity of the cuticle and some degree immaturity of amphidial neurones were found, but there was no evidence of either immaturity or signs of damage to other structures. CONCLUSIONS: Newly hatched larvae of S stercoralis appear to be a non-feeding immature stage capable of active movement through the epithelium, causing mechanical damage. The tegument resulting from the thin and the thick membrane may protect the parasite and reduce any disadvantage caused by immaturity.

AIDS-Related Opportunistic Infections↗
PubMed1998

Persistent damage to Enterocytozoon bieneusi, with persistent symptomatic relief, after combined furazolidone and albendazole in AIDS patients.

AIM: To investigate morphological changes in Enterocytozoon bieneusi and the duration of symptomatic relief after combination treatment with furazolidone and albendazole in AIDS patients. METHODS: Four severely immunocompromised AIDS patients with symptomatic E bieneusi infection of the gut received an 18 day course of combined furazolidone and albendazole (500 + 800 mg daily). All patients were monitored for parasite shedding in stool by light microscopy at the end of treatment and monthly during follow up. At the end of treatment, duodenal biopsy specimens obtained from three patients were studied by transmission electron microscopy by two pathologists blind to the patients' treatment or clinical outcome. Duodenal biopsy specimens obtained from one of the patients two months after completion of treatment were also studied electronmicroscopically. RESULTS: All patients had long lasting symptomatic relief, with a major decrease--or transient absence--of spore shedding in stools from completion of treatment. After treatment, changes in faecal spores were persistently found by light microscopy in all cases, and there was evidence of both a substantial decrease in the parasite load and ultrastructural damage in the parasite in all biopsy specimens. The treatment was well tolerated, and no patient had clinical or parasitological relapse during follow up (up to 15 months). CONCLUSIONS: The long lasting symptomatic relief observed in all four treated patients correlated with the persistent decrease in parasite load both in tissue and in stool, and with the morphological changes observed in the life cycle of the protozoan. These data suggest that combined treatment with furazolidone and albendazole is active against E bieneusi and may result in lasting remission even in severely immunocompromised patients.

AIDS-Related Opportunistic Infections↗
PubMed1998

Chronic cryptosporidiosis in patients with AIDS: stable remission and possible eradication after long-term, low dose azithromycin.

AIMS: To investigate the effectiveness of long term, low dose azithromycin treatment for chronic cryptosporidiosis in patients with AIDS. METHODS: Azithromycin was administered as initial daily treatment to 13 patients with AIDS: 6 patients received 500 mg for 30 to 40 days (mean 35); 3 patients received 1000 mg for 21 to 50 days (mean 37); and 4 patients received 1500 mg for 20 days. Nine of the 13 patients were also given low dose maintenance treatment with different schedules of azithromycin for 30 to 360 days (mean 129). Patients were monitored, during and after treatment, for parasite shedding in stool and for daily stool frequency and body weight. All but one patient had severe immunodeficiency. RESULTS: Long term, low dose maintenance treatment was associated with major clinical and parasitological benefits: there was probable eradication of infection in 2 patients, and 7 patients showed a complete response with persistent high decrease (5 patients) or clearance (2 patients) of parasite in stool. The drug was well tolerated, and there was no relapse either during treatment or during follow up (up to 21 months). These results were more impressive than those observed after the short term initial course of azithromycin, which was unable at any tested dose to achieve parasite clearance in stool (except in the patient with less advanced immunodeficiency) or to prevent relapse in 3 patients who discontinued treatment. Reversible side effects occurred with the 1500 mg daily dose. CONCLUSIONS: Long term, low dose azithromycin is well tolerated and may induce stable remission of chronic cryptosporidiosis in patients with AIDS. It may lead to probable eradication of the infection in some patients, even those with severe immunodeficiency.

AIDS-Related Opportunistic Infections↗
PubMed1997

Enterocytozoon bieneusi in AIDS: symptomatic relief and parasite changes after furazolidone.

AIMS: To investigate changes in morphology of the developmental stages of Enterocytozoon bieneusi and symptomatic relief observed in AIDS patients after treatment with furazolidone. METHODS: Six AIDS patients with symptomatic E bieneusi infection of the small intestine were treated with a course of furazolidone. All patients had a weekly monitoring of parasite shedding in stool by light microscopy during and after treatment. At the end of the treatment, duodenal biopsy specimens obtained from three patients were studied by transmission electron microscopy by two pathologists who were unaware of the patients' treatment. RESULTS: All patients showed both clinical and parasitological response with transient clearance or decrease of spore shedding in stool. After treatment, alterations in faecal spores were observed in all patients by light microscopy, and ultrastructural changes in E bieneusi at all stages of the life cycle were demonstrated in biopsy specimens of the three patients who underwent post-treatment endoscopy. CONCLUSIONS: The clinical benefit seen after treatment with furazolidone in six AIDS patients with E bieneusi intestinal infection may be due to damage to the developmental stages causing a partial inhibition to reproduction of the parasite.

AIDS-Related Opportunistic Infections↗
PubMed1996

Microflora persistence on duodenojejunal flat or normal mucosa in time after a meal in children.

A pathogenic role for high numbers of bacteria in the small intestine had been suggested previously by bacterial counts on luminal aspirates, but these investigations were flawed by the sampling device "contamination" in the mouth and the changing nature of fluent intestinal content. A procedure was developed to sterilize the Watson biopsy capsule with HCl in the upper portion of the duodenum. Bacteria were counted in the mucosal homogenate of the first (diagnostic) duodenojejunal biopsy in 80 untreated celiac children, and in 46 children with irritable bowel syndrome (IBS) in a four-cell, controlled, randomized investigation. Persistence of bacteria on the mucosa for 20 h after the last meal was investigated in 62 subjects, and for 26 h after the last meal in 64 subjects. Bacteria, mainly streptococci and staphylococci, persisted at a concentration of 10(6) per gram of mucosa 20 h after the last meal. The number of bacteria per gram of mucosa was 24 times higher in all 62 children of the 20-h fast groups than in all 64 children of the 26-h fast groups (p < 0.001). The bacteria count in celiac children was 39 times higher in the 20-h fast group than in the 26-h one. This difference was significantly higher than the 11 times difference that was found on the normal mucosa between the 20- and 26-h fast IBS groups (p < 0.001), which was still significant. The number of bacteria on duodenojejunal mucosa depends on nutrient absorption and persists longer than the intermeal interval in these subjects.

Adolescent↗
PubMed1996

Cause of oral ulcers in HIV-infected patients: a study of 19 cases.

OBJECTIVES: To study the cause and clinical aspects of oral ulcers in HIV-infected patients. STUDY DESIGN: Forty-one consecutive HIV-positive patients with long-standing oral ulcers were examined; 19 were evaluated by biopsy. From these 19 cases, viral, bacterial, and fungal cultures and biopsies were taken in each patient. When indicated, special microbial stains were undertaken to identify bacteria or fungi. Ten cases without granulomatous bacterial fungal or lymphomatous features were available for in situ hybridization to detect viral DNA of herpes simplex virus 1 and 2, cytomegalovirus, varicella-zoster virus, and Epstein-Barr virus. RESULTS: Most of the oral ulcers occurred in patients with severe immunodepression. Median CD4 T-lymphocyte count was 60 cell/mm3 (range, 3 to 335). It was ascertained that nine (47%) patients had nonspecific aphthous-like ulcers, and ulcers caused by herpes group viruses were identified in six (31.5%) patients. One (5%) person was diagnosed with non-Hodgkin's lymphoma; and in one (5%) patient, multiple ulcers were an expression of lues maligna. Two ulcers (10.5%) in the palate harbored mycotic granulomatous foci (cryptococcosis, histoplasmosis). In this population, almost all of these ulcers were found to be large, persistent, and painful. CONCLUSIONS: Nontumefactive oral ulcers in HIV-positive patients may be a source of diagnostic difficulties because of the diverse array of underlying pathologic entities and multiplicity of etiologic agents. Biopsy should always be performed on long-standing ulcers because either infection or a neoplastic process may be extant. In the absence of infection or neoplasm, such lesions are then designated as ulcers not otherwise specified.

AIDS-Related Opportunistic Infections↗
PubMed1995

Amplification of 18 dystrophin gene exons in DMD/BMD patients: simultaneous resolution by capillary electrophoresis in sieving liquid polymers.

Duchenne (DMD) and Becker (BMD) muscular dystrophies are the two most common myopathies described so far. In the late 80s, Chamberlain et al. and Beggs et al. proposed two PCR assays allowing detection of over 98% DMD/BMD deletions. Since each of them is based on specific co-amplification of 9 dystrophin gene exons, a method attempting simultaneous analysis of DMD/BMD should offer unambiguous resolution and identification of 18 DNA fragments ranging in size from approximately 100 to 500 bp. We have developed a novel capillary electrophoresis method that allows simultaneous analysis of the two PCR sets with full diagnostic value. It consists of (a) an ultrastable inner capillary coating based on a novel acrylamide monomer (N-acryloyl amino ethoxy ethanol); (b) a very low viscosity (barely 70 mPa) sieving polymer solution, formed by short-chain (average mol wt of 230,000, 55,000 Mn) polyacrylamides; (c) substitution of four fragments in the classical multiplex reaction (181 and 535 bp in the Beggs, 416 and 459 bp in the Chamberlain) with four new fragments of different lengths (170, 313, 154 and 88 bp, respectively). These new conditions allow resolution and unambiguous identification of all 18 PCR-amplified fragments in a single electrophoretic run. The set of 18 fragments comprises the following: 88, 113, 139, 154, 170, 196, 202, 238, 268, 271, 313, 331, 357, 360, 388, 410, 506 and 547 bp.

Acrylic Resins↗
PubMed1994

Capillary zone electrophoresis in polymer networks of polymerase chain reaction-amplified oligonucleotides: the case of congenital adrenal hyperplasia.

The use of capillary zone electrophoresis (CZE) in polymer networks for the analysis of an 8 bp (base pair) deletion in congenital adrenal hyperplasia was investigated. Separations were performed in Tris-borate-EDTA buffer (pH 8.3) containing 6% liquid linear polyacrylamide as a sieving dynamic matrix and 10 microM ethidium bromide for improving DNA fragment separation. Easy analysis and detection of the 127 and 135 bp amplified fragments was accomplished. The capillary column can be used for > 50 analyses before degradation and loss of resolution. The results are comparable to those obtained by gel-slab zone electrophoresis in a 12%T, 4%C polyacrylamide matrix. The sensitivity, by simple UV absorption at 254 nm, is similar to that obtained in gel slabs by dye intercalation staining.

Adrenal Hyperplasia, Congenital↗