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Biomedical subjects

G Martino

Publications and source records attributed to G Martino.

At least 19 recordsLinked to original sources
PubMed1996

Identification of peptides specific for cerebrospinal fluid antibodies in multiple sclerosis by using phage libraries.

The study of the origin and pathogenetic relevance of the oligoclonal antibodies present in the cerebrospinal fluid (CSF) of multiple sclerosis (MS) patients has been hampered by a lack of specific ligands. We recently reported a general strategy, based on phage-displayed random peptide libraries, to identify ligands for disease-specific antibodies even in the absence of any information on the nature of the pathologic antigen. With this procedure, we identified several peptides specifically recognized by antibodies present in the CSF of MS patients. Using these peptides as reagents, we demonstrated that they mimic different natural epitopes and react with antibodies enriched in the CSF of MS patients. Antibodies recognizing the selected peptides are commonly found with equal frequency in the sera of MS patients and of normal individuals. In contrast, the repertoire of CSF antibodies appears to be individual-specific and is probably the result of a nonspecific immunodysregulation rather than a stereotyped response to a single antigen/agent.

Adult↗
PubMed1996

Improved conditions for the analysis of large variable number of tandemly repeated (VNTR) unit polymorphisms.

Large variable number of tandemly repeated (VNTR) unit polymorphisms were identified by amplification of genomic DNA with appropriate primers, followed by agarose gel electrophoresis and ethidium bromide staining. However, when genomic DNA was extracted using paramagnetic beads, we found that the efficiency of polymerase chain reaction amplification of VNTR's was affected by the purity of the solid phase-eluted DNA. Here we report that VNTR's located in the human interleukin-1 receptor antagonist and interleukin-4 genes are clearly and reliably amplified only when more stringent conditions are used in order to obtain purer DNA eluates from DNA-bead complexes. In addition, polyacrylamide gel electrophoresis followed by silver staining is superior to ethidium bromide staining of agarose gels in visualizing the different allelic bands of heterozygous carriers.

DNA↗
PubMed1996

Autosomal dominant cerebellar ataxia type I: multimodal electrophysiological study and comparison between SCA1 and SCA2 patients.

A multimodal electrophysiological study was performed on 41 patients from 24 families with autosomal dominant cerebellar ataxia type I (ADCA I). Upper- and lower-limb motor evoked potentials (MEPs) to transcranial magnetic stimulation, median and tibial nerve somatosensory evoked potentials (Mn and Tn-SSEPs), orthodromic sensory (SCV) and motor conduction (MCV) velocity along median and tibial nerve, brainstem auditory evoked potentials (BAEPs), and visual evoked potentials (VEPs) were examined. Molecular analysis showed 2 SCA1 families and 2 families linked to the SCA2 locus. A sural nerve biopsy was performed in 5 patients. Brainstem damage of the auditory pathway was observed in 79% of patients examined. VEP abnormalities possibly of central origin were found in 52% of patients. MEP and SSEP abnormalities were differently distributed along the pathways examined: the longer the pathway, the higher the occurrence and severity of impairment. Peripheral dying-back neuropathy (confirmed by nerve bioptic data) was a frequent finding (56%). A progressive degenerative process involving first the longest tracts of the central motor and central and peripheral branches of somatosensory pathways is hypothesized in ADCA I. MEP abnormalities were more frequent in SCA1, and the sensory-motor neuropathy was more severe in SCA2.

Adolescent↗
PubMed1996

The insulin-dependent diabetes mellitus-associated ICA 105 autoantigen in stiff-man syndrome patients.

The pathogenetic role of anti-glutamic acid decarboxylase (GAD) antibodies found in up to 60% of patients with stiff-man syndrome (SMS) is still controversial. GAD, in fact, is also one of the major target antigen of insulin-dependent diabetes mellitus (IDDM), a disease affecting one third of anti-GAD antibody-positive patients with SMS. To better define the role of autoimmunity in SMS we looked for molecular and immunological evidence of an autoimmune recognition of a second IDDM-associated autoantigen, the pancreatic 37/40 kDa IDDM-autoantigen, whose gene called ICA 105 has been recently cloned. By Northern blot analysis we found that tissue distribution of human ICA 105 is restricted to pancreas and brain and within the central nervous system (CNS) its distribution is similar to GAD. We also measured anti-ICA 105 antibodies in 11 SMS patients and 56 control patients with other neurological diseases (OND). Anti-ICA 105 antibodies were found in 4/11 (36%) patients with SMS (a frequency similar to that of anti-GAD-antibodies in our SMS population) but in only 2/56 (3%) patients with OND (P < 0.001). Anti-ICA 105 and anti-GAD antibodies were associated in 3/4 (75%) patients with SMS but in none of the 2 anti-ICA 105 antibody-positive OND patients. Among anti-ICA 105 antibody-positive patients with SMS, only 1 suffered also from IDDM. In contrast, the only 2 anti-ICA 105 antibody-positive with OND had IDDM. Our results indicate that ICA 105 represents another putative neuroendocrine autoantigen in SMS. The presence of circulating anti-GAD and/or anti-ICA 105 antibodies might help the diagnosis of SMS. The absence, however, of antibodies recognising specific CNS autoantigens (e.g. GAD, ICA 105) does not rule out SMS.

Adult↗
PubMed1996

An immunovirological study of central nervous system involvement during HIV-1 infection of chimpanzees.

Chimpanzees infected with human immunodeficiency virus type 1 (HIV-1) are used to model acquired immunodeficiency syndrome (AIDS). Since the central nervous system (CNS) is involved in AIDS, we performed an immunovirological study in 18 chimpanzees inoculated up to 87 months prior to the study (mean, 45 months) with HIV-1 and 8 uninfected controls. Serum and cerebrospinal fluid (CSF) IgG and albumin levels of infected chimpanzees never exceeded those of controls. The CSF/serum albumin ratio was elevated in 1 of 18 infected chimpanzees compared to controls; however, all animals had an elevated ratio indicating a more open blood-brain barrier relative to humans. The intrathecal IgG production index was elevated in only 1 of 18 infected chimpanzees compared to controls. Identical serum and CSF IgG bands were found by isoelectric focusing in 2 of 8 controls and in 1 of 18 infected chimpanzees. None of these bands reacted with recombinant HIV-1 p24gag or gp 120env. HIV-1 was isolated from the peripheral blood of 4 of 18 infected chimpanzees but never from the paired CSF samples. Anti-HIV-1 antibody was detected by a enzyme-linked immunosorbent assay in 18 of 18 paired serum and CSF samples and by Western blot in 18 of 18 serum and 13 of 18 CSF samples from infected chimpanzees without a difference in pattern. Polymerase chain reaction analysis on brain tissue of one animal was negative for HIV-1 sequences. Our results demonstrate that, unlike human infection, chimpanzees inoculated with HIV-1 show no evidence of isolatable virus in the CSF and no evidence of intrathecal anti-HIV-1 antibody synthesis up to several years after experimental infection. The lack of CNS involvement may contribute to the delay or suppression of clinical disease in infected chimpanzees.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Clinical and radiologic correlates of a novel T lymphocyte gamma-interferon-activated Ca2+ influx in patients with relapsing-remitting multiple sclerosis.

T lymphocytes are the main cellular mediators in MS pathogenesis, and their activity is modulated by a complex cytokine network in which gamma-interferon (gamma-IFN) is considered essential. We have recently identified a new transplasmalemma Ca2+ influx activated by gamma-IFN in T lymphocytes (mainly CD4+) from patients with MS that makes T cells more susceptible to proliferation. To define the possible role of this Ca2+ influx as a marker of disease activity, we correlated its appearance with clinical and MRI findings in a cross-sectional study of 67 patients with relapsing-remitting MS (RR-MS). We also conducted a short-term longitudinal evaluation (every 15 days over a 5- to 7-month period) in three of the RR-MS patients. Sixty-five percent of all clinically active RR-MS patients showed the gamma-IFN-activated Ca2+ influx. However, positivity was higher in the first week (78%) after the onset of a clinical exacerbation than the second (57%) and third (44%) weeks. The influx was also detected in 45% of clinically stable RR-MS patients, 30% of RR-MS patients with a "benign" course of the disease, 14% of the other active autoimmune or neurologic disease patients, and 9% of healthy subjects (RR-MS versus control subjects, p < 0.001). Brain-MRI gadolinium-enhancing lesions were more frequently found in influx-positive (72%) than in influx-negative (47%) patients (p < 0.005). In the longitudinal study, we recorded five intracellular Ca2+ ([Ca2+]i) elevations and three clinical attacks (one per patient). A peak increase of [Ca2+]i due to the gamma-IFN-activated Ca2+ influx always preceded the clinical attacks from 4 to 45 days and coincided to MRI evidence of inflammation. [Ca2+]i had returned to baseline levels by the time of the onset of two clinical attacks. This finding may account for the lack of detection of the gamma-IFN-activated Ca2+ influx in some RR-MS patients during the first week after clinical onset. The strong association between the influx and clinical and MRI evidence of disease activity supports its role in the early phases of cellular immune activation leading to demyelination in MS. The detection of [Ca2+]i elevations due to the gamma-IFN-activated Ca2+ influx may represent a valuable prognostic marker of disease activity and may be useful to monitor immunologic studies of MS patients in future clinical trials.

Adolescent↗
PubMed1995

Talents and disorders: relationships among handedness, sex, and college major.

One-hundred and nine consistent left- and right-handers participated in an experiment investigating the role of Handedness, Sex, and College Major in predicting spatial talents, verbal problems, immune disorders, allergies, and myopia. Left-handers had poor verbal ability. Males in spatial majors (requiring extensive math) had high spatial ability and poor verbal ability. Left-handed males in spatial majors had high spatial ability, poor verbal ability, an elevated incidence of asthma, and a marginally higher incidence of myopia. No trade-off between spatial and verbal ability was found. Results provide qualified support for Geschwind and Galaburda's (1987) hypothesis of the "Pathology of Superiority."

Adolescent↗
PubMed1995

Interferon-gamma induces T lymphocyte proliferation in multiple sclerosis via a Ca(2+)-dependent mechanism.

The intracellular mechanisms underlying T lymphocyte activation leading to demyelination in multiple sclerosis (MS) have not yet been clarified. We have recently reported that interferon (IFN)-gamma activates a novel trans-plasmalemma Ca2+ influx on T lymphocytes (mainly CD4+) from patients with MS which induces intracellular Ca2+ ([Ca2+]i) elevation. Since Ca2+ is an essential second messenger in regulating transcription of T lymphocyte activation genes, we have evaluated how [Ca2+]i elevation due to the activity of this particular influx affects T lymphocyte proliferative behaviour in 12 influx-positive relapsing-remitting MS (RR-MS) patients. Fourteen influx-negative RR-MS patients and 14 healthy donors were used as controls. In lymphocytes from healthy controls, a significant correlation (r = 0.62; P < 0.001) was found between [Ca2+]i levels and proliferation rate after phytohemagglutinin (PHA) stimulation. Sustained proliferation was induced in T lymphocytes by > or = 10 micrograms/ml of PHA, a dose leading to a [Ca2+]i increase of at least 45% over basal level. Similar [Ca2+]i elevations were obtained when > or = 10 micrograms/ml of PHA were used on cells from RR-MS patients. However, T lymphocytes from RR-MS patients, but not from healthy donors, proliferated also in response to 1 micrograms/ml of PHA, indicating a state of preactivation. Moreover, 1 microgram/ml of PHA used in combination with suboptimal doses of IFN-gamma (5 UI/ml) doubled the proliferation rate of influx-positive MS cells, but not influx-negative MS cells or cells from healthy donors compared to the values obtained using PHA alone (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Does hemispheric dominance influence brain lesion distribution in multiple sclerosis?

To evaluate whether hemispheric lesion distribution in multiple sclerosis is related to the uneven interhemispheric localisation of cerebral function, a 10 item self administered questionnaire evaluating hand preference and supratentorial brain MRI was obtained in 23 patients with clinically definite multiple sclerosis. The mean degree of hand preference was +74 (range -86 to +100). The median lesion volumes were 7275 (range 1045-22,440) mm3 for the left hemisphere and 5385 (range 1010-19,490) mm3 for the right hemisphere. The degree of hand preference correlated with the index of interhemispheric lesion distribution (P = 0.02). The data suggest that local events, possibly related to specialisation of hemispheric function, might be responsible for the increased vulnerability of the dominant hemisphere to the pathological process of multiple sclerosis.

Adolescent↗
PubMed1995

Low molecular weight peptide from calf's liver mitochondrial DNA: structure and effect on DNA as a template.

A peptide fraction from the mitochondrial DNA of calf's liver was isolated using Drouin's method (1). This peptide fraction, which was extracted at pH 9.5 from an extensively purified mitochondrial DNA (2), has been shown to exert an in vitro regulatory role on the transcription and duplication activity of DNA (3). The same fraction also binds with mitochondrial DNA with a high affinity constant and stabilizes DNA from calf's thymus against thermal denaturation. The peptides from mitochondrial DNA have been subfractionated by fingerprinting-like techniques and one of them has been sequenced.

Amino Acid Sequence↗
PubMed1994

Gamma interferon activates a previously undescribed Ca2+ influx in T lymphocytes from patients with multiple sclerosis.

Multiple sclerosis (MS) is an immune-mediated demyelinating disease of the central nervous system. The etiology of the disease is still unknown. Activated T lymphocytes are considered essential in mediating the inflammatory process leading to demyelination in MS. They operate through a complex network of cytokines among which gamma interferon (gamma-IFN) plays a key role. Here we report that exposure to gamma-IFN of T lymphocytes from patients with MS activates, by a protein kinase C-mediated pathway, a previously undescribed gamma-IFN-activated Ca2+ influx, functionally coupled to the gamma-IFN receptor. The influx mainly expressed by CD4+ T lymphocytes, was found in 12 of 15 (80%) patients with clinically active MS and in 14 of 30 (46%) patients with stable MS. The influx was found in only 3 of 24 (12%) control patients and in none of the 15 healthy subjects studied. Our results document the appearance in MS lymphocytes of a gamma-IFN-activated, protein kinase C-dependent, Ca2+ influx that might be due to the expression of a new cation-specific plasmalemma channel. This finding suggests that at least part of gamma-IFN's contribution to the pathogenesis of MS is exerted through a Ca(2+)-dependent regulation of T lymphocyte activity.

Adult↗
PubMed1994

Short-term brain 'plasticity' in humans: transient finger representation changes in sensory cortex somatotopy following ischemic anesthesia.

Transient rearrangements of finger representation in primary somatosensory cortex induced by an anesthetic block of the sensory information from adjacent fingers have been shown invasively in animals. Such a phenomenon has been now replicated in seven healthy human volunteers. Somatosensory Evoked Fields (SEFs) have been recorded during separate electrical stimulation of the 1st, 3rd, or 5th finger. Recordings were obtained in control conditions (stage A), following complete ischemic anesthesia of the 4 non-stimulated fingers (stage B), and after regaining sensation (stage C). SEFs were recorded using a 28-channel DC-SQUID magnetometer; a single position of the sensor was enough to identify the source of N20m, P30m and following components using the Equivalent Current Dipole (ECD) model. The amount of afferent input during stages A through C was monitored with surface electrodes placed on the nerve at wrist and elbow. No variation of the nerve compound potential was observed during stages A through C. In stage A, the localizing algorithm was able to discriminate the individual finger representation in accordance with the somatotopic organisation of the sensory homunculus. It was observed that the ECDs responsible for the cortical responses from the unanesthetized finger were significantly changing following a relatively brief period of sensory deprivation from the adjacent fingers. Such changes of the ECDs with respect to the control conditions were characterized by an increase in strength and deepening for the middle finger, and by a shift on the coronal plane for the thumb and the little finger (medial for the former, lateral for the latter). Such changes became progressively evident in stage B, but were persisting in stage C.

Action Potentials↗
PubMed1994

Intracellular Ca2+ stores of T lymphocytes: changes induced by in vitro and in vivo activation.

Intracellular Ca2+ stores were investigated in resting and activated splenic T lymphocytes from Lewis rats. Activation was obtained either in vitro (spleen cells isolated from "naive" rats exposed to concanavalin A for 24 h) or in vivo (spleen cells from rats with fully developed symptoms of experimental allergic encephalomyelitis). In both experimental conditions several changes of Ca2+ homeostasis were observed with respect to resting lymphocytes: (1) a threefold increase of the total intracellular calcium (from 1.15 to 3.5 mmol/l); (2) a moderate increase of the pool sensitive to inositol 1,4,5-trisphosphate (IP3), investigated both in intact T lymphocytes (fura-2 and 45Ca(2+)-release techniques in cells challenged with phytohemagglutinin) and in T lymphocytes permeabilized with beta-escin (45Ca2+ release induced by saturating concentrations of IP3); and (3) the appearance of a pool released by the endoplasmic reticulum (ER) Ca2+ ATPase inhibitor thapsigargin (Tg), but insensitive to IP3, which, therefore, appears to be localized in areas of the ER devoid of the cognate receptor. The latter two findings were paralleled in activated lymphocytes by an increase of expression of ER markers, involved (calreticulin; Ca2+ ATPase) or not (protein disulfide isomerase) in the regulation of Ca2+ homeostasis. In contrast, calnexin (another ER marker) and the receptor for IP3 were increased to only a moderate extent. Finally, an enlargement of non-ER Ca2+ pools was observed in the cells pretreated with Tg in which 45Ca2+ release was induced by the Ca2+ ionophore ionomycin. Our results document structural and functional changes of intracellular Ca2+ stores which might play an important regulatory role in activated T lymphocytes.

Animals↗
PubMed1994

Analysis of interhemispheric asymmetries of somatosensory evoked magnetic fields to right and left median nerve stimulation.

This paper represents the first neuromagnetic systematic investigation of the asymmetries between the sources activated in the right and left hemispheres after electric median nerve stimulation. We focused our attention on the location and strength of the equivalent sources activated in the primary somatosensory cortex contralateral to the stimulated nerve in the 50 msec post-stimulus epoch. The spatial coordinates of the equivalent sources did not differ statistically significantly in the two hemispheres. Minor individual asymmetries are shown to be related to the interhemispheric differences in the position of the central sulcus as revealed by MRI investigation. The equivalent sources were significantly stronger in the left hemisphere. When comparing the location of the generators across individuals, we show that interhemispheric differences fluctuate less than absolute values. A quantitative evaluation of these findings is also given. Based on these results, a normative data set has been established, to be used as a baseline in following up changes of interhemispheric asymmetries due to hemispheric lesions and subsequent cortical reorganization.

Adult↗
PubMed1994

Absence of central nervous system pathology in severe combined immunodeficiency mice intraperitoneally injected with peripheral blood lymphocytes from multiple sclerosis patients.

In order to reproduce some of the pathological features of multiple sclerosis (MS) we transplanted peripheral blood lymphocytes (PBLs) from seven patients with MS into the peritoneal cavity of 28 severe combined immunodeficiency (MS-SCID) mice. Seven SCID mice were also transplanted with PBLs from two healthy subjects (hu-SCID). Animals were sacrificed between 2 and 8 weeks after transplantation (a.t.). Polymerase chain reaction (PCR) using primers able to amplify the HLA-DQ alpha region showed presence of human cells in neural tissues of MS-SCID mice. Immunocytochemical analysis revealed the scattered appearance of human lymphocytes (mostly CD45RO+ T cells) in the meningeal space and choroid plexuses of MS-SCID brains. However, human lymphocytes were similarly found in brains of hu-SCID mice. Both groups of mice never showed signs or symptoms of neurological impairment. Our results indicate that the simple transplantation of lymphocytes from MS patients into SCID mice is not likely to produce an MS-like pathology.

Animals↗
PubMed1994

Detection of anti-acetylcholine receptor antibody by an ELISA using human receptor from a rhabdomyosarcoma cell line.

A simple and reliable enzyme-linked immunosorbent assay (ELISA) has been developed for the measurement of anti-acetylcholine receptor (AChR) antibodies. The test utilizes a membrane-bound AChR obtained from a human rhabdomyosarcoma cell line (TE671) as antigen and employs an affinity-purified rabbit anti-human immunoglobulin G alkaline phosphatase-conjugated antibody as labelled antibody. To assess the sensitivity and the specificity of our assay we tested serum samples from 13 anti-AChR antibody-positive myasthenia gravis (MG) patients known to contain between 2 and 120 nmol/l of anti-AChR antibody, three anti-AChR antibody-negative MG patients, and 70 control subjects including patients with other neurological and autoimmune diseases. A panel of six different anti-AChR monoclonal antibodies and membranes from a AChR-negative rat adrenal pheochromocytoma cell line (PC 12) were also used in competitive studies. The test showed to be specific and able to detect as low as 2.0 nmol/l of anti-AChR antibodies. Moreover, we found a good correspondence between anti-AChR antibody levels measured in the serum samples tested by our assay and levels measured by the routinely adopted radioimmuno assay (RIA) using human-AChR (r = 0.96). Cross-reaction phenomena were observed only using serum samples containing high-titer anti-DNA antibodies. The proposed ELISA, circumventing the limitation of the commonly used RIA (radioactivity and amputated legs as source of human antigen), can be considered as an useful screening test for the diagnosis of myasthenia gravis.

Antibodies, Monoclonal↗