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Biomedical subjects

A Poletti

Publications and source records attributed to A Poletti.

At least 127 records · Page 7Linked to original sources
PubMed1984

CEA and ABO(H) in upper urinary tract transitional tumors.

The expressivity of carcinoembryogenic antigen CEA and ABO(H) isoantigens is studied in a group of 40 pelvic and ureteral transitional cell carcinomas. CEA was not shown to be a tumor marker since it is not found in all tumors whereas it is demonstrated in a case of cystic pyelitis. Nevertheless, it seems to be associated with certain prognostic morphologic markers, i.e., grading and vascular invasion. The ABO(H) isoantigens do not seem to be correlated with the prognosis; many advanced-stage and grade tumors showed, in fact, positivity for these isoantigens in most neoplastic cells. Association of histological techniques and immunohistochemical studies does not seem as useful in predicting the course of upper urinary tract transitional tumors as in bladder tumors.

ABO Blood-Group System↗
PubMed1984

Dye-sensitized photo-oxidation of pig kidney Dopa decarboxylase.

The effects of irradiation of pig kidney Dopa decarboxylase by visible light absorbed by the intrinsic chromophore, pyridoxal-P, and by the externally added dyes, pyridoxal-P or proflavin, have been studied. In all cases inactivation was observed, even though to different extens, which seemed to be essentially correlated to tryptophanyl residues photodestruction. Kinetics of inactivation and oxidation of these amino acid residues revealed the presence of two distinct groups of tryptophan residues with different photooxidation rate constants. A different role for these classes of residues in the structure and function of Dopa decarboxylase has been suggested.

Amino Acids↗
PubMed1981

[Comparative photodynamic effect of methylene blue in solution and immobilized on Escherichia coli and Bacillus subtilis].

The photodynamic activity of Methylene Bleu (MB) in homogeneous aqueous solution and in heterogeneous phase was compared in order to experiment the disinfection of waters and waste waters using the photosensitation technique. Insolubilized MB was obtained by covalent bonding on a styrene - 2% Divinylbenzene copolymer. E. coli and B. subtilis were used as gram-positive and gram-negative test microorganism. In the present experimental condition high inactivation towards both microorganism was obtained without substantial difference between homogeneous and heterogeneous phases. Therefore the photooxidation with immobilized BM seem to exalte the potential advantage of this technique in water disinfection for the remarkable bactericidal activity associated with the oossibility of the reuse of the photosensitizer.

Bacillus subtilis↗
PubMedDate not supplied

The 5 alpha-reductase activity of the subcortical white matter, the cerebral cortex, and the hypothalamus of the rat and of the mouse: possible sex differences and effect of castration.

Previous studies have shown that the central nervous system is able to convert testosterone into 17-beta-hydroxy-5-alpha-androstan-3-one (DHT), by the action of the enzyme 5-alpha-reductase. The data here presented show that, in the brain of the rat and the mouse of both sexes, the 5-alpha-reductase activity is more concentrated in the subcortical white matter than in the hypothalamus and in the cerebral cortex. The enzymatic activity is apparently higher in the rat than in the mouse brain. The formation of DHT in the subcortical white matter, in the hypothalamus and in the cerebral cortex of both rats and mice does not show any sexual difference. Moreover, in the rat no effect of short- or long-term castration or neonatal castration or testosterone replacement could be observed on the formation of DHT in the three brain structures considered (even in the subcortical white matter, the cerebral tissue more active in converting testosterone into DHT). The present data support the view that the 5-alpha-reductase present in the brain is not under androgenic control.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMedDate not supplied

5 alpha-reductase isozymes in the central nervous system.

The enzyme 5 alpha-reductase (5 alpha-R) activates several delta 4-3keto steroids to more potent derivatives which may also acquire new biological actions. Testosterone gives rise to the most potent natural androgen dihydrotestosterone (DHT), and progesterone to dihydroprogesterone (DHP), a precursor of the endogenous anxiolytic/anesthetic steroid tetrahydroprogesterone (THP). Two isoforms of 5 alpha-R, with a limited degree of homology, different biochemical properties and distinct tissue distribution have been cloned: 5 alpha-R type 1 and type 2. In androgen-dependent structures DHT is almost exclusively formed by 5 alpha-R type 2; 5 alpha-R type 1 is widely distributed in the body, with the highest levels in the liver, and may be involved in steroid catabolism. In the brain, the roles of the two isozymes are still largely unknown. This brief review will summarize recent experimental data from our laboratory which try to assign possible functional roles to the process of 5 alpha-reduction, and to the two 5 alpha-R isoforms in the CNS.

Animals↗
PubMedDate not supplied

Effects and metabolism of steroid hormones in human neuroblastoma cells.

The development of the central nervous system is influenced by sex steroids and by their metabolites. However, little information on the possible effects of steroid hormones on neuroblastoma cells is available. Human neuroblastoma cell lines have been used as a model of human neuroblasts in vitro to study the metabolism of steroid hormones; in addition, the effects of steroids and steroid antagonists on neuroblastoma cell growth have also been investigated. The results obtained show that SH-SY5Y human neuroblastoma cells may actively metabolize testosterone and progesterone to their respective 5 alpha-reduced metabolites and that differentiation of neuroblastoma cells is paralleled by a significant increase in expression of the type-1 5 alpha-reductase and of the formation of steroid metabolites. All these data are suggestive of a potential role of steroid 5 alpha-reduced metabolites in the biology of neuroblastoma cells. Studies performed to analyze the role of steroid hormones on neuroblastoma cell proliferation show that progesterone at low doses may induce minor stimulation, and at higher doses, a toxic effect on the neuroblastoma cell line SK-N-SH is seen. Moreover, the antiprogestin 17 beta-hydroxy-11 beta-(4-dimethylamino-phenyl-1)-17-(prop-1-ynyl)estra-4,9-dien+ ++-3-one (RU486) decreases the proliferation of these cells in a dose-dependent manner. The effect of RU486 is not antagonized by either progesterone or dexamethasone, a result that seems to exclude the action of RU486 via classic intracellular steroid hormone receptors.

Cell Division↗
PubMedDate not supplied

Polyglutamine tract expansion of the androgen receptor in a motoneuronal model of spinal and bulbar muscular atrophy.

Spinobulbar muscular atrophy (SBMA) is a late-onset disorder characterized by progressive muscle loss, degeneration of motoneurons in the spinal cord and brainstem, and partial androgen insensitivity. SBMA is directly correlated with the expansion of CAG repeats encoding a polyglutamine tract (polyQ) of extended length. The identification of polyQ expansion in SBMA led to the discovery of an entire class of neurodegenerative disorders. In fact, at least eight different diseases, including Huntington's disease, share a common molecular mechanism involving an expansion of a polyQ tract within different proteins. The elongated polyQ tract causes a toxic gain of function in the mutant protein and is associated with the formation of intracellular aggregates, whose pathogenetic role has not been fully established yet. Our observations in a motoneuron cell line (NSC34), indicate that the expression of the androgen receptor (AR) carrying the elongated polyQ tract (AR-Q48) has a toxic effect in aggregate-independent manner. In fact, in basal condition, AR-Q48 shows a cytoplasmic diffuse distribution, yet it reduces the viability of transfected NSC34. In contrast, testosterone treatment, while inducing aggregation of the mutant AR, also increases cell viability. Aggregates in NSC34 are localized mainly in the perinuclear region and occasionally in the neuropil, whereas no nuclear aggregate has ever been found. Further observations of the minor subset of cells showing neuropil aggregates, reveal an alteration of the neurite morphology, suggesting a different role of the two types of cytoplasmic aggregates.

Humans↗
PubMedDate not supplied

Androgen-activating enzymes in the central nervous system.

In the rat brain, several steroids can be converted by specific enzymes to either more potent compounds or to derivatives showing new biological effects. One of the most studied enzyme is the 5alpha-reductase (5alpha-R), which acts on 3keto-delta4 steroids. In males, testosterone is the main substrate and gives rise to the most potent natural androgen dihydrotestosterone. In females, progesterone is reduced to dihydroprogesterone, a precursor of allopregnanolone, a natural anxiolytic/anesthetic steroid. Other substrates are some gluco- and minero-corticoids. Two isoforms of the 5alpha-R, with limited degree of homology, have been cloned: 5alpha-R type 1 and type 2. The 5alpha-R type 1 possesses low affinity for the various substrates and is widely distributed in the body, with the highest levels in the liver; in the brain, this isoform is expressed throughout life and does not appear to be controlled by androgens. 5Alpha-R type 1 in the rat brain is mainly concentrated in myelin membranes, where it might be involved in the catabolism of potentially neurotoxic steroids. The 5alpha-R type 2 shows high affinity for the various substrates, a peculiar pH optimum at acidic values and is localized in androgen-dependent structures. In the rat brain, the type 2 isoform is expressed at high levels only in the perinatal period and is controlled by androgens, at least in males. In adulthood, the type 2 gene appears to be specifically expressed in localised brain regions, like the hypothalamus and the hippocampus. The 5alpha-R type 2 is present in the GT1 cells, a model of LHRH-secreting neurons. These cells also contain the androgen receptor, which is probably involved in the central negative feedback effect exerted by androgens on the hypothalamic-pituitary-gonadal axis. The physiological significance of these and additional data will be discussed.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMedDate not supplied

Splenomegaly as the first manifestation of thyroid cancer metastases.

We report the case of a 65-year-old man who developed a symptomatic splenomegaly due to spleen metastasis from thyroid follicular carcinoma. In 1982, at the age of 53, the patient had undergone a thyroid lobectomy for a cold node, followed one year later by a second intervention for a microfollicular adenoma. He was subsequently administered thyroid suppressive therapy with no further follow-up. The diagnosis of spleen metastases from thyroid cancer was first suspected on the basis of history, high serum thyroglobulin (Tg) levels, and the presence of pulmonary 99Tc uptake. The patient underwent a splenectomy, during which vast infiltration involving the diaphragm, spleen, stomach, colon and pancreas, was found. Histological and immunohistochemical results showed that the spleen and diaphragm metastases derived from thyroid follicular carcinoma. Radioiodine uptake by the pulmonary metastases confirmed the thyroid source. Retrospective re-evaluation of the thyroid tissue removed in 1983 revealed a histological pattern consistent with follicular carcinoma, which could not be unequivocally attributed to the widely or minimally invasive form. To our knowledge this is the first report of splenomegaly as the first manifestation of thyroid cancer metastases. In this paper cases of splenomegaly due to metastatic spread are reviewed and the management of the present case is discussed.

Adenocarcinoma, Follicular↗
PubMedDate not supplied

Significance of S-100 protein immunostaining in the immunohistological analysis of normal and neoplastic lymphoid tissues--an appraisal.

S-100 protein is a heterogeneous fraction of dimeric polypeptides (alpha and beta subunits) that can exist in different combination forms within the various tissues. Concerning the S-100 protein immunodetection within lymphoid tissue, the heterogeneity of the S-100 antigen, the tissue quality (frozen or paraffin-embedded after treatment with different fixatives) and the treatment of the tissue with different immunostaining methods and antibodies of different nature, all make for inconsistent results obtained in the immunohistological studies reported in the literature. Most of the S-100-positive cells of the lymphoreticular system are dendritic cells involved in the immune response (interdigitating reticulum cells, Langerhans cells, and follicular dendritic reticulum cells), other S-100-positive cells belonging to the mononuclear/phagocytic system. S-100 protein immunostaining may be used as a helpful immunohistological diagnostic clue to certain malignancies of the immune system (follicular center cell lymphomas) on the basis of their specifically related dendritic cell microenvironment. In addition to monoclonal antibodies for the immunophenotypic characterization of dendritic cells and macrophages and to enzyme reactions, the combined use of anti-S-100 antibodies specific for each of the S-100 protein subunits, tested with sensitive procedures, would be a very useful tool in the attempt to classify the proliferative disorders of dendritic cells and macrophages.

Biomarkers, Tumor↗
PubMedDate not supplied

Enzyme and immunohistochemistry of follicular hyperplasia in AIDS-related lymphadenopathy.

We used a panel of monoclonal and polyclonal antibodies to analyze frozen and paraffin-embedded lymph node biopsy specimens from 25 intravenous drug abusers (IVDA) with acquired immunodeficiency syndrome (AIDS)-related lymphadenopathy histologically characterized by follicular hyperplasia. Our aim was to obtain diagnostic clues to this commonly occurring pattern. Double-labelling immunohistological studies were also performed on selected frozen sections and 13 plastic-embedded specimens were tested by a number of enzyme reactions. Consistent features in IVDA included abnormally high numbers of intrafollicular T-cells, positive for acid phosphatase and beta-glucuronidase, most of which had Leu-2a-positive phenotype; a marked reduction or loss of mantle zone B-cells (positive for surface IgD-IgM and alkaline phosphatase); and disarray of the network of follicular dendritic reticulum cells (DRCs), as revealed with DRC-1 and anti-S-100 protein antibodies or with reaction for 5'-nucleotidase. When present, distinctive intrafollicular clusters of Leu-2a-positive T-cells and mantle zone B-cells were nearly always associated with areas lacking DRCs in some patients. The intrafollicular hypervascularity invariably found in IVDA proved to be of a true capillary nature, as demonstrated by alkaline phosphatase, 5'-nucleotidase, and ATPase reactions. In control tissues, all showing absence of Leu-2a-positive intrafollicular T-cells, most of the above individual changes could be detected, although they were occasional, mild, and never associated within the same follicle. By contrast, combined immunohistological and enzyme histochemical findings in IVDA indicated that in most follicles such changes were marked and very often associated within the same follicle in each case.(ABSTRACT TRUNCATED AT 250 WORDS)

AIDS-Related Complex↗