Biomedical subjects

M L Rossi

Publications and source records attributed to M L Rossi.

At least 91 records · Page 5Linked to original sources

PubMed1990

Investigation of the expression of epidermal growth factor receptor and blood group A antigen in 110 human gliomas.

The presence of epidermal growth factor receptor (EGF-R) and blood group A antigen was studied immunohistochemically in a series of 110 malignant gliomas using monoclonal antibodies. Fifty-seven percent of the tumours strongly expressed EGF-R on the malignant cells. Although blood group A antigen is present on EGF-R of A431 cells (a cell line derived from a human epidermoid carcinoma), in gliomas it was found only on vascular endothelial cells of tumours from blood group A patients. The results suggest that the EGF-R present in gliomas differs from that in A431 cells in the type or amount of the carbohydrate chains. This is in contrast to previous reports which have suggested that A antigen is present on EGF-R in gliomas. This has relevance in the choice of monoclonal antibodies used to study the EGF-R, as those directed against the A antigen component of the A431 cell EGF-R will not recognize EGF-R elsewhere and may cause normal blood group A antigen to be mistaken for EGF-R.

ABO Blood-Group System↗

PubMed1990

[Inhibition and efferent facilitation of sensory activity in the isolated labyrinth of the frog].

The functioning modalities of the efferent system were analysed in the isolated frog labyrinth. The efferent synapses of the posterior canal were activated via an axon reflex by antidromic electrical shocks (10-200 Hz) applied for increasing times (250 ms-10 s) to the anterior-horizontal nerves. Either decrease (inhibition) or increase (facilitation) in the resting discharge rate were observed in the majority of the units examined. Inhibition and facilitation, however, are peculiar to any given unit since inhibition does not reverse to facilitation or vice-versa. This fact as well as the long response latency (not less than 10 ms) and the linear dependence of both effects on the stimulation frequency suggest that inhibition and facilitation are due to the repetitive activation of two different types of efferent fibres synapsing on the hair cells. The drastic modifications in the afferent synaptic discharge produced by full activation of the efferent system indicate that the static properties (response asymmetry) as well as the dynamic properties (response adaptation) of the mechanically driven afferent response can be substantially controlled by the central nervous system at the receptor level.

Action Potentials↗

PubMed1990

Haemangioblastoma: histological and immunohistological study of an enigmatic cerebellar tumour.

Paraffin-embedded blocks of 36 cerebellar haemangioblastomas were reacted with a panel of antibodies including glial fibrillary acidic protein, vimentin, epithelial membrane antigen, cytokeratin, Factor VIII, a neuroendocrine marker and with Ulex europaeus. agglutinin The main histological features, apart from the characteristic large abnormal vessels, were a prominent reticulin network, a cystic architecture and cellular and nuclear polymorphism. Two cell types were identified: endothelial and stromal. Twenty tumours were positive for glial fibrillary acidic protein because of included or reactive astrocytes as well as positive stromal cells. Vimentin was positive in all tumours with a diffuse distribution and a somatic pattern; blood vessels, stromal cells and reactive astrocytes were strongly positive. Factor VIII and Ulex europaeus agglutinin reactivity were present in a similar pattern of staining in endothelium and in five cases there were stromal cells that were positive with the latter. We were not able to ascertain the histogenesis of the stromal cell, which remains enigmatic.

Adolescent↗

PubMed1990

Mononuclear cell infiltrate, HLA-Dr expression and proliferation in 37 acoustic schwannomas.

Frozen sections from 37 schwannomas of the VIII nerve were reacted with a panel of monoclonal antibodies to macrophage, lymphocyte, HLA-Dr invariant chain and nuclear proliferation antigens. A moderate number of macrophages was demonstrated in 96% of tumours. CD8- and CD4-lymphocytes were detected in slightly smaller numbers in up to 87% and 23% of tumours respectively. B-lymphocytes were present in only 2/32 cases and NK-cells were absent from all 16 cases tested. HLA-Dr antigen was expressed by macrophages in most cases and by tumour cells in 13/24 tumours. These findings may represent evidence for a degree of cellular immune response. Occasional cells featuring nuclear proliferation were detected in 15/27 cases.

Cell Nucleus↗

PubMed1989

Glioblastoma multiforme of the cerebellum in an elderly man. A case report.

Glioblastoma multiforme of the cerebellum is rare and comprises a small fraction of all glioblastomas. Eight-five cases have been reported in the literature to date. A 75 year old man is reported with a left cerebellar glioblastoma multiforme. The pathogenesis, course, treatment and prognosis are reviewed.

Aged↗

PubMed1989

Medulloblastoma. An immunohistological study of 50 cases.

Fifty paraffin-embedded medulloblastomas (31 in children and 19 in adults) were reacted with a panel of ten antibodies to glial, neuronal, mesodermal and epithelial antigens. The tumours were divided according to their histological features into three groups: classic, desmoplastic and highly vascular. Reactivity for glial fibrillary acidic protein was observed in 20 cases. Forty tumours reacted with PGP9.5 (neuronal marker) in clusters of poorly differentiated cells, cell cords and some scattered cells. Cells forming rosettes were mostly negative except for slight central reactivity. Eight of the 40 tumours contained neurofilaments. In scattered cells somatic reactivity for vimentin was found in 14 tumours. Ten cases showed positivity for S-100 with a nuclear and perinuclear pattern. No difference in reactivity in relation with age was observed. Desmoplastic medulloblastomas showed less reactivity for glial and neural markers. It was concluded that medulloblastoma shows degrees of differentiation as evidenced by the expression of various proteins. Differentiation occurs along two lines: glial and/or neuronal. Most tumours also contain a component of poorly differentiated cells which may differentiate into one of these two lines or act as primarily stem cells.

Adolescent↗

PubMed1989

The mononuclear cell infiltrate compared with survival in high-grade astrocytomas.

Frozen samples from 92 malignant astrocytomas were stained with a panel of monoclonal antibodies directed against macrophages and lymphocytes. A follow-up to death was available on 68 cases which form the basis of this study. Large numbers of macrophages were found in all cases; T lymphocytes, mostly of the CD8 phenotype were also seen in moderate numbers in 70% of cases. CD4-positive cells were present in small numbers in 32% and B cells were seen in only 8% of cases. Analysis of the survival showed no demonstrable correlation between the numbers of macrophages or CD4 lymphocytes and survival. The survival curves for parenchymal CD8 infiltration diverged after 9 months suggesting increased survival for those patients without such an infiltration but the difference failed to reach statistical significance (P = 0.37). No correlation between lymphocytic cuffing and survival was seen after studying all paraffin-embedded material. We conclude that there is no significant statistical correlation between survival and the various types of mononuclear cell infiltrating malignant astrocytomas.

Antibodies, Monoclonal↗

PubMed1989

Pelizaeus-Merzbacher disease with thiamine deficiency or Leigh disease with extensive involvement of white matter? Case report.

We report on a case of a 30-month-old child who presented with a clinical syndrome compatible with leucodystrophy and in whom neuropathological features of both Pelizaeus-Merzbacher disease and subacute necrotizing encephalopathy were shown. The significance of the neuropathological findings is discussed in the light of a possible coexistence of both diseases which has not previously been reported.

Brain↗

PubMed1989

Static and dynamic properties of synaptic transmission at the cyto-neural junction of frog labyrinth posterior canal.

The properties of synaptic transmission have been studied at the cyto-neural junction of the frog labyrinth posterior canal by examining excitatory postsynaptic potential (EPSP) activity recorded intraaxonally from the afferent nerve after abolishing spike firing by tetrodotoxin. The waveform, amplitude, and rate of occurrence of the EPSPs have been evaluated by means of a procedure of fluctuation analysis devised to continuously monitor these parameters, at rest as well as during stimulation of the semicircular canal by sinusoidal rotation at 0.1 Hz, with peak accelerations ranging from 8 to 87 deg.s-2. Responses to excitatory and inhibitory accelerations were quantified in terms of maximum and minimum EPSP rates, respectively, as well as total numbers of EPSPs occurring during the excitatory and inhibitory half cycles. Excitatory responses were systematically larger than inhibitory ones (asymmetry). Excitatory responses were linearly related either to peak acceleration or to its logarithm, and the same occurred for inhibitory responses. In all units examined, the asymmetry of the response yielded nonlinear two-sided input-output intensity functions. Silencing of EPSPs during inhibition (rectification) was never observed. Comparison of activity during the first cycle of rotation with the average response over several cycles indicated that variable degrees of adaptation (up to 48%) characterize the excitatory response, whereas no consistent adaptation was observed in the inhibitory response. All fibers appeared to give responses nearly in phase with angular velocity, at 0.1 Hz, although the peak rates generally anticipated by a few degrees the peak angular velocity. From the data presented it appears that asymmetry, adaptation, and at least part of the phase lead in afferent nerve response are of presynaptic origin, whereas rectification and possible further phase lead arise at the encoder. To confirm these conclusions a simultaneous though limited study of spike firing and EPSP activity has been attempted in a few fibers.

Action Potentials↗

PubMed1989

Intrasellar gangliocytoma containing gastrin and growth hormone-releasing hormone associated with a growth hormone-secreting pituitary adenoma.

A 74-year-old acromegalic found to have an intrasellar gangliocytocytoma and GH-secreting pituitary adenoma is described. The gangliocytoma contained immunoreactive gastrin and, to a lesser extent, GHRH, and the adenoma immunostained for GH. Gastrin has not been previously reported in hypothalamic gangliocytomas. Since this peptide has been demonstrated in normal hypothalamus and pituitary, and provokes GH release when administered intraventricularly, it may have caused GHRH release from the gangliocytoma by a local paracrine action and led to adenoma formation and acromegaly.

Adenoma↗

PubMed1989

Choroid plexus papillomas: an immunohistological study of 16 cases.

Eleven benign and five malignant choroid plexus papillomas in children and adults were studied immunohistologically with a panel of antibodies against glial fibrillary acidic protein, S-100 protein, vimentin, desmin, epithelial membrane antigen and two different cytokeratins (LP34 and CAM 5.2). Glial fibrillary acidic protein was focally present in epithelial tumour cells, in cells within solid areas and in clusters of cells within the stroma. S-100 protein was diffusely present in tumour cells with focal accentuation. Vimentin was present in all cases, the epithelial tumour cells demonstrating strong and diffuse positivity with perinuclear accentuation; malignant tumours, however, showed stronger positivity than benign ones. Desmin was negative in all tumours. Epithelial membrane antigen and cytokeratin (LP34) were demonstrated in four of five malignant tumours but were absent in the benign ones; CAM 5.2 reacted with four of five malignant tumours and also reacted with eight of the 11 benign ones. The significance of these findings is discussed in respect of the ontogeny of these tumours.

Adolescent↗

PubMed1989

[High extracellular concentrations of potassium and rubidium modulate the synaptic transmission in the frog labyrinth].

High extracellular K or Rb levels (20 mM) produce an increase in the resting EPSP and spike frequencies recorded intra cellularly from single fibres of the posterior nerve in the isolated frog labyrinth. The afferent discharge facilitation proved to be inversely related to the fibre's initial resting activity. The K effect is systematically larger than the Rb effect. High sensitive and scarcely sensitive units may be identified with respect to K and Rb action. The present findings suggest that, according to previous models of hair cell functioning, the K and Rb effects are mediated by a raise in intracellular Ca concentration which sustains an increased transmitter release at the cyto-neural junction.

Action Potentials↗

PubMed1988

High perilymphatic potassium and rubidium levels modulate the sensory resting discharge in the isolated frog labyrinth.

The effects of high perilymphatic K+ and Rb+ concentrations (20 mM) on the posterior canal resting discharge have been examined in the isolated frog labyrinth. Both K+ and Rb+ produced an increase in spike frequency which is sustained by a parallel increase in the excitatory postsynaptic potential (EPSP) emission rate. High K+ and Rb+ levels reduce the size of the afferent spike, broaden its time course but do not induce repetitive activity at the axon level. The K+ and Rb+ facilitation proved to be inversely related to the fibre's initial resting activity. The facilitation produced by increased K+ was usually larger than that in Rb+ solution. High sensitive and low sensitive units with similar low resting discharge were detected in relation to their response either to K+ or Rb+. The effects of both ions can be explained on the basis of their interactions with the presynaptic hair cell currents.

Action Potentials↗

PubMed1988

Histologic characterization of 41 ependymomas with the help of a personal computer.

Fourty-one ependymomas were histologically analyzed in relation to patient age and sex and tumor location. A discriminant analysis model using Bayes' formula and a personal computer were employed. Ependymomas situated in the posterior fossa had a higher incidence in children. Ependymoblastomas were all situated above the tentorium and occurred only in young children. We identified three tumor groups on the basis of common histologic characteristics: benign ependymomas, anaplastic ependymomas, and ependymoblastomas. The main features useful for the grouping were the degree of differentiation and anaplasia. Ependymomas from the cauda equina showed histologic characteristics that allowed them to be differentiated from other benign ependymomas. In each group the particular histologic characteristics, age, and location were significant in terms of diagnosis and prognosis. This method of analysis may help to more precisely define ependymomas and may provide pathologists and clinicians with a quantifiable diagnostic tool that may be of help in establishing the appropriate treatment.

Adolescent↗

PubMed1988

The effect of barium and some channel blockers on sensory discharge of the frog labyrinth posterior canal recorded at rest and during rotation.

The effect on the afferent synaptic transmission of Ba2+, Sr2+, tetraethylammonium (TEA) and 4-aminopyridine (4-AP) has been investigated in the isolated frog labyrinth by intracellularly recording the posterior canal resting and evoked receptor discharge. BaCl2 (0.3 mM) or SrCl2 (1.8 mM) substitution for normal external CaCl2 restored the afferent activity without affecting the membrane potential of the sensory fibres. On further increasing Ba2+ concentration (0.5-5 mM) a dose-dependent increase in the EPSP and spike discharges was observed in all the units examined. Ba2+ (1.8-4 mM) removed the depression of the sensory activity operated by CoCl2 (3 mM), while its facilitatory effect was completely antagonized by raising Ca2+ concentration (up to 10 mM). TEA (20 mM) elicited a clear-cut increase in the EPSP and spike discharges which, however, was less consistent than that produced by Ba2+ (1 mM). The increment in spike frequency produced by TEA and Ba2+ proved to be inversely related to the initial resting firing level of the different units. The 4-AP (4-20 mM) effect resulted in a decrease of the sensory activity, which was fully restored by TEA or Ba2+. In normal saline a linear relationship was found between the mean unit resting discharge and the respective excitatory peak response during sinusoidal rotation (0.1-0.3 Hz). This result suggest that the mechanical response is mainly determined by the unit resting level. Consistent evoked responses were obtained under TEA and Ba2+ treatment which proved to depend linearly on the new mean resting discharge of the different units. Conversely, a reduced evoked response was invariably observed in all the fibres tested in the presence of 4-AP. The present results suggest that Ba2+ and Sr2+ may substitute for Ca2+ in the transmitter release process at the cyto-neural junction, the ability of Ba2+ being even larger than that of Sr2+ and Ca2+ itself. The effects of TEA and 4-AP are discussed in the light of their possible interaction with the presynaptic K+-currents recently described in hair cells.

4-Aminopyridine↗

PubMed1988

Pituitary metastasis from malignant bronchial carcinoid.

Metastases from a carcinoid tumor to the pituitary gland have, to our knowledge, not been described. We present a 49-year-old woman diagnosed as having a primary carcinoid tumor arising in the submucosa of a large bronchus who 8 years later presented with multiple metastases including one to the pituitary gland, which was in partial failure of pituitary function. This case illustrates than when confronted with a pituitary tumor resembling an adenoma but negative for pituitary hormones, the possibility of a metastasis from a carcinoid tumor should be considered.

Adenoma↗

PubMed1988

Mononuclear cell infiltrate and HLA-DR expression in low grade astrocytomas. An immunohistological study of 23 cases.

Frozen samples from 23 low grade (grade I and II) astrocytomas were studied by means of a panel of monoclonal antibodies to macrophages, lymphocytes (and their subsets) and HLA-DR antigens. Macrophages were present in low to moderate numbers in 38%-86% of cases, the variance in figures depending on the antibody used. T lymphocytes, the majority of CD8 phenotype, were detected in low numbers in 78% of tumours. B lymphocytes were scanty in 22% (5/22) and totally absent in the remaining cases. HLA-DR antigen was expressed by tumour cells in 35% (6/17) of cases. These findings indicate that in some low grade astrocytomas there is a mononuclear cell infiltrate with macrophages and secondarily CD8+ lymphocytes playing the major role. The significance of these findings remains speculative at present.

Adolescent↗

PubMed1988

Ependymoblastoma: a histological, immunohistological and ultrastructural study of five cases.

Five ependymoblastomas were studied by means of routine histological techniques, immunohistology and electron microscopy. The tumours were characterized histologically by medium sized, poorly differentiated cells with round or oval nuclei frequently in mitosis and by ependymoblastic rosettes. Reactions for cytokeratin and neurofilament were negative and tubular material positive for glial fibrillary acidic protein was scanty. All five tumors demonstrated positivity for vimentin and S-100 protein. Electron microscopy showed poorly differentiated cells with high nucleo-cytoplasmic ratio and scanty cytoplasmic organelles. Sparse rosettes were present and the cells were united by junctional complexes. Frequent rudimentary or incomplete cilia, a few basal bodies and a few short intercellular glial-like filaments were seen. Features differentiating ependymomas and anaplastic ependymomas from ependymoblastomas are discussed and the need for a definite category separating ependymoblastomas from the former tumours is emphasized.

Adolescent↗