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Biomedical subjects

M Di Stefano

Publications and source records attributed to M Di Stefano.

At least 73 records · Page 4Linked to original sources
PubMed1997

In vitro effects of IL-12 and IL-2 on NK cells, cytokine release and clonogenic activity in myelodysplastic syndromes (MDS).

We evaluated the in vitro effects of IL-12, alone and in association with IL-2 on MDS bone marrow and peripheral blood cells. Thirty-six patients and 14 healthy subjects were studied. Natural killer-activity (NK-a) levels and lymphocyte immunophenotypes were determined in fresh bone marrow (BMMNC) and peripheral blood mononuclear cells (PBMNC), which then were resuspended in medium containing IL-2, IL-12 or IL-2 + IL-12 for 7 days. Re-evaluation of NK-a levels, lymphocyte immunophenotypes, clonogenic activity and cytokine release showed that, unlike IL-2, IL-12 did not significantly increase NK-a or CD3-/56+ cell levels in either bone marrow or peripheral blood; IL-2 + 12 led to a significant increase that fell between the values reached by each cytokine alone. IL-2 + 12 and, although to a lesser extent, also IL-12 alone induced the release of large amounts of gamma-IFN and alpha-TNF. In addition, the number of clusters particularly decreased in the samples treated with IL-2 + 12 and IL-12 alone. Clonogenic activity was not modified after stimulation with any of the treatment. These data suggest that IL-12 induces the release of inhibitory cytokines in normal as well as MDS cells and that it could be used in patients with elevated bone marrow blastosis.

Adult↗
PubMed1997

Interocular interactions in esotropia.

In cats the unilateral convergent strabismus surgically induced in the early postnatal life causes monocular spatial vision deficits and loss of binocular activation of the primary visual cortex. It is assumed that the asynchrony of inputs from the two eyes, by disrupting binocular convergence, leads to unbalanced binocular interactions that favour the non-deviated eye. The competitive advantage of this eye reduces both the excitatory drive to the cortex and the behavioural visual capabilities of the strabismic eye that exhibits the loss of the nasal portion of the visual field. Our experimental evidence indicate that the esotropic input, released by interocular influences by the chiasm section, recovers at least as much effectiveness to achieve orienting reactions in the previously neglected nasal field. In addition we found that the excitatory drive of the ipsilateral strabismic input, which is the one mostly impaired in esotropic animals, is fully preserved when the interocular interactions are impeded at birth and it is greatly improved in the esotropic cats with section of the optic chiasm performed in adulthood. All together these results suggest that functional impairment of the esotropic input prior of chiasmotomy does not reflect developmental changes of the visual afferents yet the active inhibition exerted by interocular mechanisms.

Animals↗
PubMed1997

The use of serum-free medium delays, but does not prevent, the cytotoxic effects of seminal plasma in lymphocyte cultures: implications for studies on HIV infection.

Evidence indicates that seminal plasma is cytotoxic when used in lymphocyte cultures. In fact, an amine oxidase which is normally present in Fetal Calf Serum (FCS) causes spermine oxidation and, finally, cytotoxic substances are released. This seminal quality might obviously hamper studies aiming to evaluate the role of semen in HIV sexual transmission, since lymphocytes are generally used as target or effector cells in virological or immunological studies on HIV. We evaluated the efficacy of FCS free-medium, heat inactivated seminal plasma and/or the washing-out of cultures after a three hour incubation period in preventing the cytotoxicity to lymphocytes. Results show that when cultures are carried out in the absence of FCS and/or after seminal plasma removal, cytotoxicity is not prevented, although delayed. This finding indicates that, along with still unrecognized additional factors, spermine oxidation is still an important factor for semen cytotoxicity, and this considerably hampers any immunological and virological study, requiring the use of lymphocytes, concerning seminal fluid.

Animals↗
PubMed1996

HIV type 1 V3 sequences and the development of dementia during AIDS.

The most frequent neurological complication of AIDS is a dementia-like syndrome. Power and collaborators (J Virol 1994; 68:4643-4649) have reported an association between the clinical signs of AIDS dementia and the amino acid composition of two positions (305 and 329) within the V3 region of HIV-1 strains amplified from brain tissue. Similarly, we analyzed position 305 in the V3 region of HIV-1 present in the brain or cerebrospinal fluid of 25 nondemented subjects at different clinical stages of HIV-1 infection. Our results are, however, at variance with the findings presented by Power and colleagues. Histidine, found to be common among sequences derived from demented patients, was also present in the majority (16 of 25) of nondemented patients analyzed by us. In the hands of Power and colleagues, sequences derived from nondemented patients contained proline at position 305. None of our patients had proline in this position. We also asked the question whether the presence of a specific amino acid at position 305 of the V3 loop is linked to an increased capacity of HIV-1 isolates to infect primary microglial cells, the major target cell for HIV-1 infection in the brain. Primary HIV-1 isolates derived from blood and cerebrospinal fluid of five patients, two asymptomatic and three AIDS patients, were used to infect microglia cell cultures. Infection was monitored by syncytium formation and by p24 antigen release in the culture supernatant. All but one of the paired blood/CSF isolates replicated in human brain cultures. Replication occurred independently from the amino acid present at position 305 of the V3 region of the viral envelope. Our results indicate that the majority of HIV-1 isolates, even derived during the asymptomatic stage, have the capacity to infect microglial cells. The relevance of viral envelope sequences in determining tropism for microglial cells and development of neurological symptoms remains an open question.

AIDS Dementia Complex↗
PubMed1996

Analysis of ENV V3 sequences from HIV-1-infected brain indicates restrained virus expression throughout the disease.

The isolation of human immunodeficiency virus type 1 (HIV-1) from the cerebrospinal fluid (CSF) of asymptomatic virus carriers suggests that the viral infection spreading to the brain occurs early during infection. The aim of the present study was to investigate whether HIV-1 infection of the brain parenchyma also occurs during the early phase of infection. We also wished to compare the degree of replication of the virus in the brain at different clinical stages associated with HIV-1 infection. With the use of polymerase chain reaction (PCR), the viral genomes present in seven of eight brain specimens obtained from two asymptomatic HIV-1 carriers and six AIDS patients were amplified. Thereafter, the number of viral copies present in each brain specimen was quantified, the third variable region (V3) of the gp 120 glycoprotein was sequenced and these results compared with the histopathological findings in the tissue. The HIV-1 DNA genome was amplified from seven of the eight brain tissues, including the specimens obtained from the two asymptomatic carriers. An increased number of viral copies in the brain was found in association with histopathological findings of HIV-1 encephalitis. The analysis of the V3 sequences, however, revealed the presence of a homogeneous virus population in the brain at every clinical stage of the disease. These results suggest that, although entry of the virus in the parenchyma may occur early during infection, HIV-1 replication in the brain is constrained until the terminal phase of AIDS encephalitis.

Adult↗
PubMed1996

Visual field defects in esotropic cats: a developmental consequence of the squint.

In nine adult cats with surgically induced esotropia (squint-angle ranging between 8 degrees and 32 degrees), the extent of binocular and monocular visual fields was behaviourally assessed by the food-perimetry method. Results indicate that: (1) The extention of both the nasal and the temporal hemifield of the esotropic eye is narrowed. (2) Field losses are largest in the cats with severe esotropia (> 15 degrees); yet the relationship between rate of impairment scored in each animal and individual angles of squint is not linear. (3) In the cats with severe esotropia, the visual field of the non-deviated eye is also narrowed. (4) We suggest that field deficits reflect a stop in the developmental expansion of the immature visual field as a consequence of ocular misalignment.

Animals↗
PubMed1996

Influence of pattern of clinical presentation and of gluten-free diet on bone mass and metabolism in adult coeliac disease.

Since no information is available on bone derangements in subclinical coeliac disease (CD), we evaluated bone mineral density (BMD, expressed as z score) at lumbar spine, by X-ray dual-photon absorptiometry, and serum indices of bone metabolism and remodeling in 14 subclinical or silent patients, 10 classical patients, and 15 healthy volunteers all on a gluten-containing diet. In the subclinical group, BMD at lumbar spine was significantly higher than in the classical group (-1.3 +/- 0.8, 73% vs. -2.6 +/- 0.6, 88%, respectively; p < 0.001), but significantly lower than in volunteers (+0.4 +/- 1.1, 104%; p < 0.001). Similar changes were observed in serum calcium, whereas, as regards parathyroid hormone, no significant difference was found between subclinical and classical patients. 25-vitamin D was significantly lower, and 1,25-vitamin D was significantly higher in subclinical and classical patients than in healthy volunteers. Indices of bone remodeling were higher in the subclinical and classical groups than in the volunteers, but lower in the subclinical than in classical patients. Eight subclinical and 8 classical patients were reexamined after a period of gluten-free diet (GFD), and in both groups BMD had significantly improved. Our results show that osteopenia is a frequent feature also in subclinical CD, although the extent of bone and mineral metabolism derangements is lower than in classical CD. GFD is able to normalize BMD in subclinical and to significantly improve it in classical patients.

Absorptiometry, Photon↗
PubMed1996

In vitro effects of IL-2 on NK-activity, clonogenic potential, blast cell proliferation and cytokine release of MDS bone marrow patients.

To evaluate the clinical usefulness of IL-2 in myelodysplastic syndromes (MDS) the in vitro effects of interleukin-2 (IL-2) on blast cell proliferation, clonogenic activity, cytokine release and cell mediated cytotoxicity were examined in 49 MDS patients. Morphological analyses of bone marrow (BM) cytospin preparations showed a significant decrease in the number of blast cells in MDS after incubation with IL-2. Incubation of bone marrow mononuclear cells (BMMNCs) with IL-2 induced a significant increase in the number of CFU-GM in comparison with untreated controls. gamma-IFN and GM-CSF, but not alpha-TNF were found to be released in significant amounts by the BMMNCs cultured with IL-2. No significant differences in the surface phenotypes of fresh lymphocytes were observed between the normal and MDS subjects. After incubation with IL-2, we observed a significant increase in the number of CD3-/CD56+ cells in both normal and MDS subjects. Peripheral blood (PB) and BM NK activity against K562 was significantly greater in MDS after stimulation with IL-2. These data suggest the clinical usefulness of IL-2 in a large subgroup of patients as it may reduce the percentage of blasts and increase clonogenic capacity and cell-mediated cytotoxicity.

Adult↗
PubMed1995

Recovery of the nasal field loss in esotropic cats after section of the optic chiasm.

It is assumed that in esotropic cats the behavioural suppression of the nasal field reflects inhibition of the input conveyed through the temporal retinal afferents of the strabismic eye. We hypothesized that inhibition underlying the field defect might be actively operated by interocular competitive mechanisms. If so, effectiveness of the strabismic eye input might be restored and loss of the corresponding visual field might be recovered by interrupting the direct interactions between the eyes with the section of the optic chiasm. Results obtained in eight esotropic split-chiasm cats confirm the hypothesis and suggest that suppressive mechanisms of binocular rivarly are involved in the behavioral loss of the esotropic nasal field.

Animals↗
PubMed1995

Alterations of exocrine pancreas in end-stage renal disease. Do they reflect a clinically relevant uremic pancreopathy?

Serum pancreatic enzyme behavior, exocrine function, and morphology of the pancreas were studied in 28 patients with end-stage renal disease undergoing regular hemodialysis, in order to better delineate and assess the clinical relevance of the pancreatic alterations that occur in these patients. Twenty-eight healthy subjects served as controls. Initial studies included serum amylase, isoamylase, and lipase assays; fecal chymotrypsin measurement; and abdominal ultrasonography. The amylase, lipase, and chymotrypsin determinations, as well as ultrasound examination, were repeated four years later. None of the patients had clinical evidence of pancreatic disease at entry into the study, but one had had previous attacks of pancreatitis and another developed mild acute pancreatitis one month after entry. Initial mean serum enzyme levels were significantly higher in patients than in controls (amylase, pancreatic isoamylase, and lipase, P < 0.001; salivary isoamylase P < 0.05). Serum amylase was raised in 16/28 patients; pancreatic isoamylase in 15/28, and lipase in 7/28; these elevations were generally mild. Mean fecal chymotrypsin was significantly lower (P < 0.001) in patients than in controls: abnormally low values were found in 9/28 patients. Amylase, lipase and chymotrypsin measurements repeated after four years showed no significant difference with respect to the first study. Ultrasonographic changes were rare and mild: one patient had a small cyst in the pancreas head, another, an increase in echogenicity of the gland not related to age; these findings were unchanged at repeat examination. The results demonstrate that the frequent elevations of serum pancreatic enzymes and the rare sonographic changes found in patients undergoing hemodialysis do not generally reflect a relevant pancreopathy. However, the finding of significantly decreased fecal chymotrypsin may indicate the presence of pancreatic dysfunction in end-stage renal disease.

Amylases↗
PubMed1995

Reverse transcriptase sequence of paired isolates of cerebrospinal fluid and blood from patients infected with human immunodeficiency virus type 1 during zidovudine treatment.

Human immunodeficiency virus type 1 (HIV-1) isolates obtained from the blood of patients undergoing treatment with 3'-azido-3'-deoxythymidine (zidovudine [AZT]) show a decreased sensitivity to the drug in vitro. The aim of the present study was to determine if HIV-1 variants resistant to AZT are present also in the brain compartment. We selected sequential HIV-1 isolates from the blood and the cerebrospinal fluid (CSF) of six patients with HIV-1 infection undergoing AZT therapy for a time varying between 1 and 3 years. The isolates were used to infect peripheral blood mononuclear cell cultures which were used to prepare viral DNA. The viral DNA was amplified by PCR and then directly sequenced. Analysis of the reverse transcriptase (RT) sequence of the isolates from the CSF during therapy demonstrated that CSF-resistant isolates are characterized by the same mutations documented in resistant isolates from the blood compartment. Isolates obtained from one patient (patient 3) showed the same two mutations (codons 70 and 215) in blood and CSF, whereas isolates obtained from an additional four patients presented a different pattern of mutations in the two compartments. We also analyzed the degree of amino acid homology between RT sequences from blood and CSF isolates in patients before and during AZT treatment. The percentages of amino acid variations were approximately equal when isolates from the same or different compartments were considered. Excluding the codons involved in AZT resistance, the time point of sampling did not affect RT variations during therapy significantly. In conclusion, our studies show that AZT-resistant HIV-1 can be found in the CSF of patients undergoing treatment. The mutations linked to AZT resistance in the CSF isolates are the same as those identified in AZT-resistant isolates from blood.

AIDS Dementia Complex↗
PubMed1995

P24 antigen detection, viral isolation, DNA-PCR and in vitro antibody production for the diagnosis of HIV-1 latent infection in heterosexual women at high risk for HIV-1 infection.

INTRODUCTION: The report of the existence of at-risk seronegative subjects, latently infected with HIV-1 and producing "in vitro" HIV-1 specific antibodies, prompted the authors to evaluate extensively twenty-five heterosexual HIV-1 seronegative women at high risk for HIV-1 infection. MATERIAL AND METHODS: The capability of peripheral blood mononuclear cells from such subjects to produce "in vitro" HIV-1 specific antibodies after pokeweed-mitogen stimulation, was studied. Silent HIV-1 infection was investigated by HIV-1 DNA PCR, viral isolation and serum p24 Ag detection at entry and after 6 and 12 months. RESULTS: Three seroconversions took place within 12 months, but no HIV-1 infections were found in the absence of detectable serum anti HIV-1 antibodies, even in subjects who apparently produced such antibodies in vitro. The antibodies produced in vitro by the seronegative women studied appeared of narrow specificity, reacting mainly with gp 160/120 envelope glycoproteins. CONCLUSIONS: A strong concordance was found between the serological status and the other markers for HIV-1 infection, suggesting that the phenomenon of HIV-1 "latent infection" is a very rare event, if it occurs at all. Seronegative women sexually exposed to the virus may produce in vitro anti HIV-1 antibodies of narrow specificity in the absence of other signs of infection and this phenomenon might be related to an anamnestic response to the virus.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Binocular interactions and visual acuity loss in esotropic cats.

Visual acuity was measured behaviorally in various groups of cats by using a two-choice discrimination procedure. Cats in group 1 were rendered strabismic soon after birth by sectioning the tendon of the lateral rectus muscle (unilateral esotropia); at adulthood, their visual acuity (VA) was evaluated, after which the optic chiasm was sectioned and VA reassessed. Cats in group 2 were not only tenotomized but also chiasmatomized neonatally, while cats in group 3 underwent a neonatal section of the optic chiasm only. VA was measured at adulthood in the two latter groups. Group 4 consisted of adult cats whose VA was evaluated before and after an optic chiasm section. Stimuli consisted of square-wave gratings of various spatial frequencies. Results showed that in normal cats, the average threshold values under monocular viewing were identical for each eye (4.76 cycles/degree); however, following optic chiasm section, monocular VA was reduced to 1.23 cycles/degree. VA in early optic chiasm section cats was lower than that of the normal cats but higher than that of late-lesioned animals (2.33 cycles/degree). In strabismic cats, mean VA was 1.25 cycles/degree for the deviated eye and 2.8 cycles/degree for the normal eye. Following the optic chiasm section at adulthood, VA was lower not only for the deviated eye (< 0.17 cycles/degree) but also for the normal eye (1.14 cycles/degree). Similar results were found when both the deviation and chiasmatomy were performed neonatally. The elimination of interocular interactions through chiasm transection failed to improve VA in the strabismic eye.

Animals↗
PubMed1995

[Synthetic salmon calcitonin suppositories for the short-term treatment of involutive osteoporosis].

Intramuscular and intranasal synthetic salmon calcitonin (sCT) has long been used in the treatment of involutional osteoporosis. A new suppository formulation was developed and many studies demonstrated that rectally administered sCT is efficacious and well tolerated. Thirty postmenopausal women, who had a bone mineral density at the lumbar spine below the mean of age-matched women, were enrolled in this study. Using an open balanced, randomized design, the patients were allocated to two groups of treatment: sCT suppositories at the dose of 100 UI/day or 200 UI every other day for six months. Treatment with sCT suppositories caused a statistically significant decrease of pain in both study groups. Bone mineral density at lumbar spine showed an increase in both study groups with significant difference respect the basal value for the patients treated with sCT on alternate day. Based on the results of this study, we can thus conclude that sCT in suppository formulation is effective in reducing pain sintomatology, bone loss and turnover in involutional osteoporosis.

Aged↗