Search PubMed⌕ Search

Biomedical subjects

R Bianchi

Publications and source records attributed to R Bianchi.

At least 253 records · Page 14Linked to original sources
PubMed1985

Morpho-quantitative analysis of nuclear inclusions in periaqueductal grey matter neurons in the cat.

The morpho-quantitative analysis carried out in the neuronal population of the periaqueductal grey matter of the cat has shown that nuclear inclusions are mainly of the filamentous type and that they are distributed predominantly in the external region, i.e. in the part of the periaqueductal grey matter situated furthest from the cerebral aqueduct, where 30% of the cells contain nuclear inclusions. In the internal region, i.e. in the part nearest the subependymal zone, only 2% of the neurons have nuclear inclusions. The glia in the internal region is more abundant and surrounds each nerve cell body while in the external zone of the periaqueductal grey matter it is scanty and does not delimit the neuronal soma. This difference suggests that there may be a relationship between the incidence of nuclear inclusions and the neuron/glia ratio.

Animals↗
PubMed1984

High-performance liquid chromatographic separation of iodoamino acids for tracer turnover studies of thyroid hormones in vivo.

A reversed-phase high-performance liquid chromatographic technique was developed to separate radioiodinated thyroxine (T4), 3,5,3'-triiodothyronine (T3), 3,3',5'-triiodothyronine (rT3) and two diiodothyronines (3,3'-T2 and 3',5'-T2), in extracts from either serum or urine. Chromatography was performed with 10-micron C18 silica gel, packed in a glass column (3 X 300 mm); the mobile phase was methanol-water (55:45) adjusted to pH 3 with H3PO4, at a flow-rate of 1.2 ml/min and a pressure of 2800 p.s.i. The results demonstrate the ability of the system to yield a clear-cut separation of the iodothyronines involved in in vivo turnover studies, i.e., T4, T3, rT3, and the two T2 compounds together.

Chromatography, High Pressure Liquid↗
PubMed1984

Cytoarchitecture of the periaqueductal gray matter in the cat: a quantitative Nissl study.

We studied the periaqueductal gray matter (PAG) in cresyl-violet-stained serial sections from 5 cats applying quantitative determinations. No significant variations were observed in the cytological aspects in the various sites examined (lateral, ventral and dorsal regions, and external and internal portions). The neuronal density was constant in the different regions, but showed a gradual and significant increase in the most external regions of the PAG. Our findings do not, therefore, confirm the existence in the PAG of subnuclei with a specific cytoarchitecture; this does not, however, rule out the possibility that there are specific regions for connections, histochemical properties or functions.

Animals↗
PubMed1984

A new case of familial partial generalized resistance to thyroid hormones: study of 3,5,3'-triiodothyronine (T3) binding to lymphocyte and skin fibroblast nuclei and in vivo conversion of thyroxine to T3.

A clinically euthyroid 30-yr-old man with high serum levels of both total (T4, 14.5 micrograms/dl; T3, 272 ng/dl) and free (FT4, 33 pg/ml; FT3, 9.7 pg/ml) thyroid hormones and inappropriately normal TSH levels, both basally and after TRH stimulation, is described. Peripheral indices of thyroid hormone action and the patient's clinical status were not modified by the prolonged administration of supraphysiological doses of both T4 (up to 900 micrograms/day) and T3 (up to 80 micrograms/day), which decreased but did not completely abolish the TSH response to TRH. However, the TSH response to TRH was normally blunted by dexamethasone administration, which also reduced serum T4 and T3 levels to normal. T3 binding to nuclei of mononuclear leukocytes and cultured skin fibroblasts was normal. The overall pattern demonstrates that the patient was affected by partial peripheral resistance to thyroid hormone action. Study of the patient's family revealed the same hormone pattern in the patient's father, suggesting an autosomal dominant mode of inheritance. An in vivo study performed after the iv injection of tracer doses of [125I]T4 and [131I]T3, demonstrated increased production rates (PR) of both T4 [PR, 113.0 micrograms/day X m2; normal subjects, 55.4 +/- 12.3 (mean +/- SD); n = 13] and T3 (PR, 41.1 micrograms/day X m2; normal subjects, 16.3 +/- 2.7). In vivo conversion of T4 to T3 was also evaluated in the patient; a nearly normal T4 to T3 conversion factor was found (0.3108 vs. 0.2576 +/- 0.0422 in normal subjects). In four hyperthyroid patients, the T4 to T3 conversion factors were similar (0.2932 +/- 0.0600), while the PRs of T4 and T3 were increased (PR of T4, 308.6 +/- 85.6; PR of T3, 110.3 +/- 35.0 micrograms/day X m2) compared to those in the normal subjects.

Adult↗
PubMed1984

Comparison of plasma and urinary methods for the direct measurement of the thyroxine to 3,5,3' - triiodothyronine conversion rate in man.

A further development of a new method recently proposed for the direct measurement of the conversion ratio (CR) of T4 to T3 in man is presented. [125I]T4 and [131I]T3 are injected simultaneously, and Sephadex chromatography is performed on urine samples to determine [125I]T3 formed in vivo, while plasma samples are used to measure the injected tracers. CR is calculated with the assumption that urinary [125I]T3 closely reflects [125I]T3 appearing in plasma after the injection of precursor [125I]T4. Four normal subjects and six patients with various thyroid disorders were studied using this method. The experimental data were also analyzed by our previous method based on plasma sampling only and by two recently described methods based on urinary measurements. These comparisons were made in an attempt to ascertain whether there is any systematic difference between the conversion values derived from plasma data and those derived from urinary data. Using plasma data alone, the CR was 28.6 +/- 3.4% (mean +/- SEM) in a group of four normal subjects, 37%, in two untreated hypothyroid patients, 40.2% in one hypothyroid subject receiving T4 treatment, 30.9% in one hyperthyroid patient, 24.9% in one patient with selective hyperthyroxinemia due to amiodarone treatment, and 10.7% in one normal subject after iopanoic acid administration. These values were in excellent agreement with those obtained by the modified procedure described here, in which both urinary and plasma measurements are used. Of the methods using urinary data alone, however, one gave similar results, while the other systematically overestimated the CR, possibly due to delayed excretion of labeled T4 metabolites into the urine. We conclude that 1) the analytical procedure to separate the labeled tracers and metabolites in urine or plasma is critical for the accurate estimation of CR; 2) when an adequate separation procedure is available, plasma and urinary methods for measuring CR yield comparable results; and 3) the plasma method should be used when, in addition to CR, other kinetic (distribution and turnover) parameters of T4 and T3 metabolism are to be estimated.

Adult↗
PubMed1984

Ultrastructural features of the synapses of the periaqueductal gray matter (PAG) of the cat.

The periaqueductal gray matter (PAG) of cat has a very complex cytoarchitecture. Given the considerable functional role of connection and modulation of this region, we investigated the ultrastructure of the synapses completing the analysis with morphoquantitative evaluations of some characteristics of the synaptic boutons. The quantitative data revealed that the somatic synapses are scarce, 93% are of the symmetrical type and the pleomorphic vesicles are predominant. The synapses of the neuropil appear more numerous and complex; only 50% are of the symmetrical type. The vesicular contents are of the pleomorphic type as in the somatic synapses. A significant difference was found between the dimensions of the somatic vesicles and those of the neuropil, which may indicate the presence of two distinct populations of vesicles. These findings may be correlated with the variety of substances (neuro-transmitters, neuropeptides etc.) shown to be in the PAG.

Animals↗
PubMed1983

Short intrinsic circuit in the periaqueductal gray matter of the cat.

In heavily impregnated Golgi material of cat periaqueductal gray matter (PAG), we were able to follow the course of early axon collaterals to their endings on the soma of neighboring neurons. A short intrinsic circuit is therefore created. Combined Golgi and electron microscope observation give evidence of the inhibitory action of this circuit.

Animals↗
PubMed1983

Systemic adoptive immunotherapy of a highly immunogenic murine lymphoma growing in the brain.

Systemic adoptive immunotherapy with specifically immune lymphocytes was successfully performed in immunodepressed mice challenged intracerebrally with L5178Y/DTIC lymphoma cells, a tumor subline rendered highly immunogenic through in vivo exposure to 5-(3,3-dimethyl-1-triazenyl)-IH-imidazole-4-carboxamide (DTIC). The systemic immunotherapy relied on the infusion of the in vitro-generated primary cytotoxic T-lymphocytes (CTL), the anti-tumor activity of which was evaluated by measuring tumor-cell proliferation in the brain in terms of radiolabel uptake and by recording survival times of recipient leukemic mice. The protection afforded by CTL appeared to be specific and was largely conditioned by dose and time of CTL administration. The levels of protection correlated well with the in vitro killing of L5178Y/DTIC tumor cells.

Animals↗
PubMed1983

MIR: a versatile program for the statistical analysis of enzyme kinetic data.

We have developed a package program for the estimation of Michaelis-Menten parameters for enzymes that conform to different kinetic mechanisms. Data from different experimental schemes can be fitted with appropriate weighing factors to any of 6 mathematical models, corresponding to 5 kinetic mechanisms: ordered bi-bi, Theorell-Chance, rapid equilibrium random bi-bi, rapid equilibrium ordered bi-bi and ping pong bi-bi. The program also performs a significance test to discriminate between different candidate models. To illustrate the performance of the program, real data from kinetic experiments with glucose 6-phosphate from Leuconostoc mesenteroides have been fitted to different mathematical models, and the results are discussed. The program can be easily implemented for the fitting of kinetic data to any other model.

Computers↗
PubMed1983

Peripheral metabolism of thyroid hormones in man. I. Direct measurement of the conversion rate of thyroxine to 3,5,3'-triiodothyronine (T3) and determination of the peripheral and thyroidal production of T3.

We describe here a new method for the direct measurement of the conversion rate of T4 to T3 in man. The metabolic study was performed in 23 subjects: 13 healthy controls, 7 T4-treated hypothyroids, and 3 sick euthyroid patients. The experimental protocol involved the simultaneous iv bolus injection of [125I]T4 and [131I]T3, and the use of Sephadex G-25 column chromatography to determine the plasma concentrations of [125I]T4, [131I]T3, and [125I]T3 newly formed through 5'-monodeiodination of labeled T4 in the peripheral tissues. The T4 and T3 kinetic parameters were determined by noncompartmental analysis. The conversion rate of T4 to T3 was computed by a method based on the precursor-product relationship, using the [131I]T3 disappearance curve for correcting the concentrations of newly formed [125I]T3 (convolution method). The conversion rate of T4 to T3 was 0.2541 +/- 0.0125 (mean +/- SEM) in the control group and was significantly reduced (0.1283 +/- 0.0204; P less than 0.001) in the sick euthyroid patients, while it was slightly, though not significantly, increased in the T4-treated patients (0.2932 +/- 0.0220). A close agreement was found between the values for the conversion rate obtained by the convolution approach and those derived from the ratio between the serum concentrations of [125I]T3 and [125I]T4 at equilibrium. The conversion rates obtained by the convolution approach were also in good agreement with the values estimated from the molar ratio between the turnover rates of T3 and T4. In the control group, 72.0 +/- 3.6% of the circulating T3 was produced by 5'-monodeiodination of T4 in the peripheral tissues, and 28.0 +/- 3.6% of the circulating T3 derived from direct thyroidal secretion. The sick euthyroid patients showed a significantly smaller proportion of circulating T3 deriving from peripheral conversion of T4 (52.5 +/- 3.9%; P less than 0.025).

Adult↗
PubMed1983

The ultrastructure of the periaqueductal gray matter of the cat.

The neurons of the periaqueductal gray matter (PAG) in cat are generally spindle shaped, small and medium size cells. They have a very high nucleo-cytoplasmic ratio, frequent complex nuclear inclusions and very few axo-somatic contacts. The larger neurons have spine-like extrusions. The neuropil is very extensive, made up mainly by small unmyelinated axons and small dendrites. Also the synaptic boutons are very numerous, and sometimes have particular modalities of contact and arrangement (axo-axonic and dendro-dendritic synapses, 'boutons en passant', and glomerulus-like structures). No significant differences have been observed in the dimensions and shape of the vesicles present in the axo-somatic synapses compared with those present in the neuropil synapses. In both cases pleomorphic vesicles predominate. The particular complexity and abundance of the synaptic contacts in the neuropil suggests that the neuropil is the main site where the afferent inputs to the PAG are modulated and integrated.

Animals↗
PubMed1983

Drug-induced immunogenic changes of murine leukemia cells: dissociation of onset of resistance and emergence of novel immunogenicity.

n vivo exposure of tumor-bearing mice to the antineoplastic agent 5-(3,3-dimethyl-1-triazenyl)-1H-imidazole-4-carboxamide (DTIC) results in increased immunogenicity of tumor cells, an event often referred to as "chemical xenogenization" (CX). To verify the hypothesis of DTIC-induced somatic mutation(s) as the major mechanism underlying CX, studies were performed to dissociate CX from the onset of drug resistance, which was invoked in the past as an event leading to selection of preexisting immunogenic clones. Therefore, experiments were done with a DTIC-susceptible tumor line treated with DTIC and quinacrine dihydrochloride (Q), an antimutagenic compound, according to selected experimental schedules. At different transplant generations, the CX and the onset of drug resistance were evaluated. The results show that a) Q does not prevent the onset of DTIC resistance, b) DTIC-resistant clones arising after treatment with DTIC plus Q are not immunogenic, and c) CX is selectively antagonized by Q. The present data confirm that DTIC-induced immunogenicity is not the result of a selection mechanism mediated by the drug and give further support to the hypothesis that the molecular mechanism of CX may be related to somatic mutation(s).

Animals↗
PubMed1983

Immunobiological aspects of the nude mouse model relative to human cancer chemosensitivity tests.

The nude mouse model (NMM) has been proposed for testing chemosensitivity of human cancer cells with encouraging results. However, nude mice cannot be considered as unreactive "test tube" recipients of allogeneic or xenogeneic tissues, since a variety of immunological functions are fully represented in these hosts. In general, graft resistance against tumour cells can be classified as: (a) elicitable responses (ER), thymus-dependent, evoked by tumour-associated antigens; (b) natural resistance (NR), T-independent, not requiring previous exposure to transplantation antigens. Graft resistance may therefore play a substantial role even in the absence of a functional T-cell system. This has been demonstrated in irradiated euthymic mice capable of rejecting Hh-incompatible lymphomas, and in nude mice, where NR-type responses are particularly efficient, either in vitro or in vivo. It is reasonable to assume that these responses could interfere with tumour responsiveness to the chemotherapeutic effects of drugs. In fact, marked synergistic effects have been observed in conventional hosts combining chemotherapy with limited ER, or with Hh-type NR present in lethally irradiated mice. Similar combined effects could occur in nude mice bearing NR-susceptible human tumours in the course of chemosensitivity assays. These considerations have led to the search for privileged sites associated with low levels of NR; previous results show that these responses appear to be substantially absent in the brains of conventional mice and extremely low in the same organ of congenitally athymic hosts. It follows that the brain of the nude mouse appears to be a suitable site for human tumour cell growth, unaffected by or minimally subjected to NR.

Animals↗