Biomedical subjects

M L Rossi

Publications and source records attributed to M L Rossi.

At least 55 records · Page 3Linked to original sources

PubMed1996

Synaptophysin in spinal anterior horn in aging and ALS: an immunohistological study.

Aged-related spinal cord changes such as neuronal loss have been related to the degree of clinical severity of amyotrophic lateral sclerosis (ALS); morphological data on synapses are, however, wanting. Variations in synaptophysin (Sph) expression in aging and ALS were thus studied at the level of lower motor neurons in 40 controls with non-neurological diseases and 11 cases of ALS. Control sections of formalin fixed paraffin embedded cervical (C7/8), thoracic (T10) and lumbar spinal cord (L5) and C6, C7, C8 and L5 of ALS cases were stained with haematoxylin and eosin, luxol fast blue (LFB), and immunostained with a mouse monoclonal antibody against Sph. The neuropil of the anterior horn (AH) in all control cases demonstrated Sph positivity. A dot-like pattern of positivity of presynaptic terminals on soma of motor neurons and fine immunoreactivity along neuronal processes were observed. A significant reduction of Sph immunostaining was observed in the neuropil with increasing age and 3 different somatic patterns were seen: a- well preserved Sph reactivity around the soma and the proximal dendrites of histologically normal neurons; b- few chromatolytic neurons showing large numbers of dot-like presynaptic terminals around the cell body and in a "fused" pattern; c- intense, diffuse, and homogeneous reactivity of some neurons. Attenuation of Sph reactivity in the AH neuropil, to its complete loss, was observed in all ALS cases. In addition to patterns a-c, two additional microscopic findings were noted in ALS: d- chromatolytic neurons showing complete absence of Sph reactivity; e- absence of Sph reactivity around the soma and the proximal dendrites of histologically normal surviving neurons. Our findings demonstrate that there is a decrease in Sph immunostaining with aging, thus suggesting an alteration in dendritic networks of the AH with aging. Changes in the pattern of Sph immunoreactivity in cell bodies may represent synaptic plasticity and/or degeneration. Reinnervation may also be a possible mechanism as a response to neuronal loss in oldest control cases. Sph reactivity results may thus lend support to the presence of superimposed aging components in ALS cases which may give an insight into explaining the increasing severity of the disease which is encountered with advancing age.

Adult↗

PubMed1996

Techniques in facial identification: computer-aided facial reconstruction using a laser scanner and video superimposition.

A facial image was reconstructed from the skull, part of a complete skeleton found in woodland, of a male person who hanged himself from a tree. In addition, video superimposition was carried out with antemortem photographs of a person suspected of being the victim, and a good match was obtained. In a further case, a cheaper video-transparency superimposition was carried out, with identity later being confirmed on the basis of dental records. The techniques and the problems encountered are discussed. According to our experience, 3D computer reconstruction and video superimposition have a useful role in the process of identification, particularly in the early stages of an investigation and when other more definitive methods may not be available.

Adult↗

PubMed1996

Ascending paralysis due to myelitis in a newborn with congenital toxoplasmosis.

We present a female neonate in her second week of life with borderline microcephaly, microphthalmia and progressive ascending sensory and motor deficit leading to complete paralysis with respiratory failure and death at 27 days of age. Neurological imaging revealed, in addition to cerebral atrophy, marked hydrocephalus, ependymal basal ganglia calcification, leptomeningeal enhancement, and patchy myelitis throughout the entire spinal cord. CSF cytological examination revealed the presence of a mononuclear pleocytosis with Toxoplasma gondii trophozoites free in the CSF and within the cytoplasm of some macrophages, and a 100-fold raised protein content. To our knowledge, this is the first reported case of clinical acute spinal cord involvement in congenital toxoplasma infection, proven by the presence of toxoplasma trophozoite in the CSF.

Atrophy↗

PubMed1996

Effects of clofilium, a K channel blocker, on electrogenic K secretion and afferent discharge at the frog semicircular canal. A preliminary report.

Application of clofilium to the endolymphatic side of the isolated frog semicircular canal abolished the transepithelial potential and produced increased K and mannitol outfluxes from the lumen to the dark cells or the basolateral perilymph, with no apparent effect on active K secretion. These results suggest an increased permeability of the paracellular pathway. When applied to the perilymphatic side in the intact labyrinth, clofilium reduced the rates of quantal transmitter release (miniature EPSP frequency), an effect that might arise from a decrease in the transduction current intensity secondary to the reduced transepithelial electrochemical potential for K+. Moreover, afferent spike rates were almost completely abolished at rest as well as during mechanical stimulation. This effect together with a decreased mEPSP amplitude points to a further direct action of clofilium on the afferent postsynaptic terminal. These results suggest a multi-factorial effect of clofilium that would reduce the sensitivity of the vestibular function.

Animals↗

PubMed1996

Isolated hepatic mucormycosis in an immunocompetent child.

A case of isolated localized hepatic mucormycosis in an immunocompetent 3 1/2-yr-old girl with concomitant acute toxoplasmosis is described. Mucormycosis is rare in immunocompetent patients, and hepatic mucormycosis has so far been described only in the context of disseminated disease. The infection resolved spontaneously without surgical debridement and/or appropriate medical therapy with amphotericen B.

Amphotericin B↗

PubMed1995

The slow Ca(2+)-activated K+ current, IAHP, in the rat sympathetic neurone.

1. Adult and intact sympathetic neurones of the rat superior cervical ganglion maintained in vitro at 37 degrees C were analysed using the two-electrode voltage-clamp technique in order to investigate the slow component of the Ca(2+)-dependent K+ current, IAHP. 2. The relationship between the after-hyperpolarization (AHP) conductance, gAHP, and estimated Ca2+ influx resulting from short-duration calcium currents evoked at various voltages proved to be linear over a wide range of injected Ca2+ charge. An inflow of about 1.7 x 10(7) Ca2+ ions was required before significant activation of gAHP occurred. After priming, the gAHP sensitivity was about 0.3 nS pC-1 of Ca2+ inward charge. 3. IAHP was repeatedly measured at different membrane potentials; its amplitude decreased linearly with membrane hyperpolarization and was mostly abolished close to the K+ reversal potential, EK (-93 mV). The monoexponential decay rate of IAHP was a linear function of total Ca2+ entry and was not significantly altered by membrane potential in the -40 to -80 mV range. 4. Voltage-clamp tracings of IAHP could be modelled as a difference between two exponentials with tau on approximately 5 ms and tau off = 50-250 ms. 5. Sympathetic neurones discharged only once at the onset of a long-lasting depolarizing step. If IAHP was selectively blocked by apamin or D-tubocurarine treatments, accommodation was abolished and an unusual repetitive firing appeared. 6. Summation of IAHP was demonstrated under voltage-clamp conditions when the depolarizing steps were repeated sufficiently close to one another. Under current-clamp conditions the threshold depolarizing charge for action potential discharge significantly increased with progressive pulse numbers in the train, suggesting that an opposing conductance was accumulating with repetitive firing. This frequency-dependent spike firing ability was eliminated by pharmacological inhibition of the slow IAHP. 7. The IAHP was significantly activated by a single action potential; it was turned on cumulatively by Ca2+ load during successive action potential discharge and acted to further limit cell excitability.

Animals↗

PubMed1994

Quantal nature of synaptic transmission at the cytoneural junction in the frog labyrinth.

1. The mechanism of transmitter release at the cytoneural junction of the frog posterior canal was investigated by recording intracellularly subthreshold postsynaptic potentials (EPSPs), and performing a statistical analysis of time intervals and peak amplitudes. In single units EPSPs display highly variable size, so it is not clear whether they are generated by the release of single quanta of transmitter and whether large ones represent giant events, multiquantal events, or the random summation of independent unitary events. 2. In units with low resting EPSP rates, peak amplitudes and time intervals between EPSPs were measured directly. Peak amplitude histograms were continuous, unimodal and well fitted by log normal distributions. Time-interval histograms were well described by single exponentials. 3. At high EPSP rates (either at rest or during experimental treatments), where single events overlapped extensively, peak amplitude histograms were skewed markedly towards high values. Under these conditions, the EPSP waveform was estimated by autoregressive fit to the autocorrelation of the recorded signal. The fit was used to build a Wiener filter, for sharpening the original signal, before computing time-interval and peak amplitude histograms. This yielded consistent log normal peak amplitude distributions with no 'excess' skewness, similar to those obtained with low resting rates. 4. After sharpening by the Wiener filter, shoulders or small second peaks in amplitude distributions were observed only at the highest EPSP rates (> 300 s-1). The number of 'multiquantal' events was reduced by Wiener filtering, and was in general consistent with the expectation that more than one independent event occurred within the duration of the single event. This suggests that the events are uniquantal, random and independent, i.e. miniature EPSPs (mEPSPs). 5. In general, peak amplitude distributions obtained with modified external Ca2+ concentration ([Ca2+]o) and/or during mechanical stimulation or under efferent activation were not significantly altered with respect to those obtained in the same units at rest. Time-interval histograms were generally mono-exponential at rest as well as during mechanical or efferent stimulation, and irrespective of [Ca2+]o. Resting mEPSP rate was slightly increased by elevated [Ca2+]o and reduced by low [Ca2+]o. The increase in mEPSP rate produced by mechanical excitation was depressed by both high and low [Ca2+]o, whereas both conditions enhanced mechanical inhibition. Efferent inhibition was little affected. High [Ca2+]o hastened adaptation during efferent facilitation. Low [Ca2+]o reduced peak response during facilitation, but suppressed its warning. 6. In the presence of ATP a consistent though transient increase in resting mEPSP rate was observed in about 50% of units.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine Triphosphate↗

PubMed1994

Postmortem injuries by indoor pets.

Four cases of postmortem injuries caused by indoor pets (three by dogs and one by cats) are presented. A pattern which is associated with this phenomenon is described. The important common factors appear to be the presence of free-moving pets inside the house, social isolation of the deceased, and the victim having a predisposing condition causing sudden death.

Adult↗

PubMed1994

Congenital insensitivity to pain: a 20 year follow up.

The exact nosological status of "congenital insensitivity to pain" remains in doubt. Possible pathological correlates of this clinical syndrome include sensory neuropathy, central lesions at the level of the reticular formation or dorsal horn of the spinal cord, or a central indifference to, or asymbolia for, pain. The reassessment of two members of a kindred previously reported more than 20 years ago as having congenital insensitivity to pain indicated that they in fact had an inherited sensory and autonomic neuropathy. Prolonged follow up and morphometric analysis of sequential nerve biopsies may be necessary to definitively establish this diagnosis.

Adult↗

PubMed1993

Immunohistochemical localization of the inositol 1,4,5-trisphosphate receptor in the human nervous system.

A monoclonal antibody raised against the mouse cerebellar inositol trisphosphate receptor was used to study the immunohistochemical localization of this protein in the human central nervous system. As in the brain of rodents, strong immunoreactivity was found in dendrites, axon and cell bodies of Purkinje cells, as well as in nerve endings in the cerebellar and vestibular nuclei. Cerebellar efferent fibres were the only positive structures demonstrated in the brainstem and no immunostaining could be detected in the spinal cord or dorsal root ganglia. By contrast, numerous immunoreactive neurons were present in several telencephalic and diencephalic structures, including the brain cortex, hippocampus, basal ganglia, basal forebrain, amygdala and thalamus. Immunostaining of these brain neurons was weaker than that found in Purkinje cells and was evident in cell bodies and dendrites. Thus, the human brain contains a molecule cross-reacting with the mouse inositol trisphosphate receptor protein that is expressed in a pattern similar to that found in rodents. These findings can be of great importance for understanding the function of this protein in normal brain and its modifications in neuropathological disorders.

Aged↗

PubMed1993

Cerebral intraventricular haemorrhage in a young adult.

A case of a 26-year-old man who suffered a fatal intraventricular cerebral haemorrhage following an episode of trauma is described. The initial appearance at necropsy suggested a traumatic subarachnoid haemorrhage and initial investigation was directed towards the anterior neck structures and the vertebral arteries with negative results. Dissection of the fixed brain showed a massive intraventricular bleed with secondary involvement of the subarachnoid space and dissection into the cerebral parenchyma. No bleeding points or natural disease of the cerebral vessels could be identified. The practical aspects of diagnosis and the cautious approach necessary in interpreting subarachnoid bleeding is emphasised. The significance of intraventricular haemorrhage following trauma has become more apparent with the advent of computed tomographic scanning. The implications for this and similar cases are considered.

Adult↗

PubMed1993

A paraffin wax technique of Golgi-Cox impregnated CNS that permits the joint application of other histological and immunocytochemical techniques.

Our technique permits the application of other histological and immunohistological methods to sections of CNS already impregnated in a modified Golgi-Cox solution. This combined approach gives a more comprehensive picture of anatomical, cytological and antigenic relationships. Furthermore the technique is reproducible, sections are of known thickness and there is no problem with long term storage. Details of the technique are given and its application in neuroanatomy and neuropathology is discussed.

Brain↗

PubMed1993

[Quantal mediator release mechanism at the cyto-neural junction of the labyrinth in the frog].

The cytoneural junctions of the frog labyrinth posterior canal usually show different (m)EPSP resting rates (10-300/s). A statistical analysis of (m)EPSPs, recorded intracellularly from the posterior nerve, is carried out to investigate the basic mechanisms of transmitter release. In units with low resting rates (< 100/s) and during mechanical as well as efferent inhibitory stimulation, where a direct evaluation of the event parameters is possible, peak amplitude distributions are continuous, unimodal and fitted by lognormal functions, while time interval distributions between events are monoexponential. For higher resting rates, and systematically during mechanical excitation or activation of the facilitatory efferent system, single events extensively overlap. To reduce summation, a Wiener filter is built to sharp the original signal. The Wiener filter transfer function is calculated from the EPSP waveform estimated by the autoregressive fit to the autocorrelation of the original signal. This procedure yields peak size distributions well fitted by lognormal functions in all the situations tested. After filtering, time intervals are still monoexponential at rest as well as during the evoked release. Results suggest that only the rate of transmitter release, but not its basic mechanism, is altered during sustained synaptic activity. Furthermore, the Ca(2+)-free EGTA-solution slightly affects efferent inhibition and depresses facilitation. The high Ca(2+)-level enhances inhibition and depresses facilitation.

Action Potentials↗

PubMed1993

Amyotrophic lateral sclerosis brain banking: a proposal to standardize protocols and neuropathological diagnostic criteria.

Motorneurons which are primarily affected in ALS cannot be sampled during life. Morphological, biochemical, ultrastructural and molecular investigations can be only performed on post-mortem material. No animal model reproduce adequately ALS. All these features and the low ALS incidence and the absence of definite clusters stress the need for brain banking in Europe. We present the protocol which is followed in our centers. The clinical information is supplied by neurologists in order to provide clinical data necessary for an accurate interpretation of pathological features. Initial symptomathology, duration and type of ALS, cause of death and a simple disability scale shortly before death are included. CNS relevant samples stained with H-E, luxol fast blue, the Marchi impregnation technique and immunostained with ubiquitin, are used for diagnosis. Samples for Golgi impregnation and immunohistochemistry are also obtained and the remaining tissue is frozen. Classical criteria for pathological diagnosis include: neurogenic changes in muscles, loss of motorneurons and degeneration of corticospinal tracts. We propose new diagnostic criteria based only on CNS examination. Muscle tissue is not always available and other classical criteria could be absent in rapid evolution or early death cases. Our criteria includes: a) Major criteria: loss or degeneration (chromatolysis, basophilia or neuronophagia) of motorneurons in brainstem and/or spinal cord, degeneration of corticospinal tracts. b) Minor criteria: axonal spheroids, Bunina bodies, ubiquitin-immunoreactives bodies. Criteria necessary for the pathological diagnosis are discussed and the need to quantify neuronal loss in relation to age-matched controls is stressed.

Amyotrophic Lateral Sclerosis↗

PubMed1993

Changes in the myelinated axons of femoral nerve in amyotrophic lateral sclerosis.

Myelinated fibres in femoral nerves removed from amyotrophic lateral sclerosis (ALS) cases at post mortem were compared with age matched controls. A technique for processing whole transverse sections of the nerves for osmication and subsequent morphometric analysis is described. Although areas depleted in myelinated fibres were seen in the nerves from the ALS group, no statistically significant difference was shown due to wide variations in the controls. However, the ALS nerves showed a degree of disruption in the myelin which was not apparent in the controls. The most obvious effect was widespread "wrinkling" of the myelin in both large and small fibres from the ALS nerves. This phenomenon is the initial stage of a process which eventually results in uneven myelin thickness and nodal swellings and finally myelin ovoids and balls. We illustrate the steps in the progression of this degeneration with teased nerve studies and electron microscopy and propose that there are qualitative changes in the myelin of peripheral nerve in ALS. It seems likely that these are secondary effects resulting from axonal degeneration caused by deterioration and loss of anterior horn cells in the spinal cord.

Amyotrophic Lateral Sclerosis↗

PubMed1993

Clinico-pathological correlations in meningiomas: a DNA and immunohistochemical study.

We have studied 41 meningiomas classified histologically as benign, atypical or anaplastic. There were 26 females and 15 males and the mean age was 53 years. 36 tumours were supratentorial, 4 infratentorial and one spinal. Flow cytometry was performed on paraffin-embedded tissue using a selective staining technique for DNA. The ploidy index of DNA and percentage of cells in the S and G2/M phases were calculated. Results were correlated with clinical, histological and immunohistological data. 16/41 tumours were found to be diploid, 17/41 aneuploid and 8/41 could not be analysed. Significant correlations were found between aneuploid tumours and some qualitative features such as recurrence, pleomorphism, high cellular density, mitotic activity and brain and soft tissue infiltration. A high proliferative index appeared to be associated with clinical aggressiveness. No particular correlation between the expression of cytokeratin and epithelial membrane antigen markers and flow cytometry was found. Our results suggest that DNA flow cytometry in meningiomas may be of value in predicting the behaviour of these neoplasms and confirm that epithelial pattern in meningiomas is not linked to increased anaplasia or poor prognosis.

Adult↗

PubMed1992

Clinical and pathological study of two patients with progressive supranuclear palsy and Alzheimer's changes. Antigenic determinants that distinguish cortical and subcortical neurofibrillary tangles.

Two cases with classical clinical manifestations of progressive supranuclear palsy (PSP) showed severe progressive dementia as an additional clinical feature. Neuropathological study demonstrated typical features of PSP in the brainstem. Additionally, histological criteria of Alzheimer's disease (AD) were observed. A topographic and immunohistological study (with neurofilament subunit and Tau and Ubiquitin antibodies) of the distribution of neurofibrillary tangles (NFTs) was performed in order to compare the characteristics of NFTs from cortex and brainstem. NFTs from cortex were positive with all antibodies used and were predominantly distributed in cortical layers III and V and affected medium size neurons. Brainstem NFTs were positive only for neurofilament subunits and Tau. Cortical and brainstem NFTs showed immunohistological differences. Cortical NFTs in our two cases had a similar distribution as in control AD cases. On the basis of our observations we believe (1) that cortical tangles in our PSP cases are related to Alzheimer's disease and (2) that the cortical NFTs of PSP and AD are morphologically and immunohistologically distinct. Mechanisms concerned with the production of cortical and brainstem NFTs in PSP and AD are discussed.

Aged↗

PubMed1992

Epithelial differentiation in gliomas, meningiomas and choroid plexus papillomas.

The immunohistological findings using antibodies to different intermediate filaments (glial fibrillary acidic protein, vimentin and two types of cytokeratin) and epithelial membrane antigen are described in 89 gliomas, 19 meningiomas and 8 choroid plexus papillomas (CPPs) from adult patients. All the patients had total or subtotal surgical excision of their tumours with clinical follow up for between 3 and 7 years. The immunohistological results were correlated with the histological features and patient survival. Tumours other than low grade astrocytomas, oligodendrogliomas and anaplastic ependymomas expressed one or more epithelial markers. This immunohistological evidence of epithelial differentiation in the absence of histological epithelial features in gliomas confirms that the two are not necessarily correlated. It is concluded that the expression of epithelial markers in some intradural tumours may reflect aberrant differentiation related to the degree of anaplasia in poorly differentiated astrocytomas and glioblastomas. All the patients with anaplastic epithelial marker-positive gliomas died within 1 year, whereas only 68% of patients with marker-negative tumours died within the follow-up period. In ependymomas and meningiomas, the expression of epithelial markers may reflect their histogenesis, while in malignant CPPs such expression could denote either their aberrant differentiation or histogenetic derivation.

Adolescent↗