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Biomedical subjects

L Martini

Publications and source records attributed to L Martini.

At least 307 records · Page 17Linked to original sources
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

The brain: a vulnerable target.

This article addresses the description of several endocrine-related functions of the brain. It has emerged that steroids and growth factors may influence brain functions, and that brain cells may metabolize sex steroids. The crosstalk between different types of brain cells (neurons, astrocytes, the LHRH (luteinizing hormone-releasing hormone) producing GT1 cell line, etc.) has been described. Of relevance is that brain enzymes may convert sex steroids into compounds able to bind the GABAa receptor, creating a link between brain steroids and one neurotransmitter system. The data presented also provide the first demonstration that glial-neuronal interactions may intervene, in conjunction with neuronal-neuronal communications, in the control of the secretion of hypothalamic hormones. The detailed discussion of all these mechanisms has provided a long list of possible targets during the aging process. Fortunately, the demonstration that stem cells may be rescued in the "adult" CNS by the proper manipulations with growth factors opens new hope and directions for future interventions.

Animals↗
PubMedDate not supplied

Effects of steroid hormones on gene expression of glial markers in the central and peripheral nervous system: variations induced by aging.

The present article summarizes our data regarding: (a) the effect of sex steroids on the expression of a specific astrocytic marker in glial cell cultures (GFAP); (b) the effects of aging on two markers of the peripheral myelin (glycoprotein Po and the myelin basic protein, MBP); (c) the possible modification of the damaging effects of aging on these two markers by the in vivo administration of progesterone and its derivatives; and, finally, (d) the effect of progesterone derivatives on the gene expression of Po in cultures of rat Schwann cells. The data obtained have indicated that progesterone and its 5 alpha-reduced metabolites may play an important role in the control of gene expression of GFAP and Po, respectively, in type 1 astrocytes and Schwann cells. It has also been found that the gene expression of Po and MBP is dramatically decreased in the myelin of the sciatic nerve of aged male rats and that the aged-linked decrease of the gene expression of Po is partially reversible with steroid treatment.

Aging↗
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

The action of steroid hormones on peripheral myelin proteins: a possible new tool for the rebuilding of myelin?

The present paper summarizes recent results we have obtained while studying the effect of sex steroids on the gene expression of two peripheral myelin proteins, the glycoprotein Po (Po) and the peripheral myelin protein 22 (PMP22). In particular, we have analyzed the effect of progesterone (P), testosterone (T) and their 5alpha- and 3alpha-5alpha-reduced derivatives [respectively, dihydrotestosterone (DHTT) and 5alpha-androstan-3alpha, 17beta-diol (3alpha-diol) for T, and dihydroprogesterone (DHP) and tetrahydroprogesterone (THP) for P]. The data obtained, utilizing different in vivo and in vitro experimental models, have indicated that: a) DHP is able to enhance the low messenger levels of Po present in the sciatic nerve of aged male rats; b) P, DHP and THP treatments stimulate the gene expression of Po in the sciatic nerve of adult male rats or in cultures of rat Schwann cells, while only THP is effective on PMP22; c) P and DHP are also able to increase the low messenger levels of Po present in transected sciatic nerve; d) the removal of circulating androgens by castration is able to decrease the mRNA levels of Po in the sciatic nerve, a phenomenon which is counteracted by the consequent treatment with DHT; e) the stimulatory effect of DHT on the gene expression of Po is also evident in cultures of rat Schwann cells, but in this case the effect seems to be due to the interaction of this steroid with the progesterone receptor; f) in cultures of Schwann cells PMP22 mRNA levels are stimulated only by 3alpha-diol treatment. Taken together, these observations showing the positive effects of sex steroid hormones on the gene expressions of Po and PMP22, suggest that a treatment with these molecules or their synthetic agonists may be useful in cases in which the rebuilding of myelin is necessary.

Animals↗
PubMedDate not supplied

Estrogen, progesterone receptors and proliferating activity evaluated by immunocytochemistry in breast cancer.

The correlation of the most important prognostic indicators was evaluated in 75 breast cancer cases. Estrogen-progesterone receptors and proliferating activity were analyzed by immunocytochemical methods (ER-ICA, PR-ICA, Ki-67). Both steroid receptors were inversely correlated with the proliferating activity (ER-ICA vs Ki-67, p less than 0.003; PR-ICA vs. Ki-67, p less than 0.0001). No correlation was found between steroid receptors or cell kinetics and tumor size or lymph node status. These findings confirm the relevance of biochemical and kinetic parameters as independent markers in breast cancer and suggest a routine use of the simple immunocytochemical methods in assessing the biological behavior of tumors.

Adult↗
PubMedDate not supplied

Adoptive immunotherapy of advanced solid tumors: an eight year clinical experience.

BACKGROUND: Adoptive immunotherapy (AI) of cancer, based upon the injection of in vitro manipulated autologous lymphocytes is still in an experimental phase. Our group started different clinical trials of AI in early 1990, and, at present, some specific targets for this approach seem to have been identified. PATIENTS AND METHODS: 296 patients with solid tumors (melanoma, kidney carcinoma, non-small-cell lung cancer, mesothelioma, neoplastic pleural effusion, and liver cancer) were treated with either locoregional or systemic adoptive immunotherapy (AI) using both LAK and TIL cells in combination with s.c. rIL-2. RESULTS: The surgery/AI combination resulted in good clinical results, characterized by enhanced survival and long lasting disease free periods in a significant number of patients. CONCLUSIONS: AI seems to be efficacious in the treatment of melanoma, lung and hepatic cancers. Further studies will expand the application of the treatment to other malignancies.

Clinical Trials as Topic↗
PubMedDate not supplied

In vivo study on critical defects using the sheep model.

Bone grafting procedures are widely used to repair large defects successfully in humans, but new surgical therapies can be designed to improve allograft integration. The objective of this study was to investigate the best surgical procedure to study bone graft integration in a large animal model. An osteoperiosteal defect of 3 cm in the tibia or in the metatarsal was made in 15 adult crossbreed sheep to investigate osteo-integration of a homologous bone graft in an intercalary critical defect. DCP plates, alone or in association with Scotchcast or external fixator were used as fixation devices. The Scotchcast as was applied after surgery and left for 2 months to avoid torsion stress of the limb during the stand up movement. Metatarsal defect fixed with 7-hole DCP plate and protected with Scotchcast was the best surgical approach to avoid early or late implant failures, and provided good radiographic results after 4 months.

Animals↗
PubMedDate not supplied

Rhythms in the ovulatory cycle. 3rd: Cortisol and dehydroepiandrosterone sulphate (DHEA-S).

The circadian profiles of cortisol and dehydroepiandrosterone sulphate (DHEA-S) were analyzed in a homogeneous group of 15 young normally cycling women, at 4 times of the menstrual cycle: early follicular (EF), late follicular (LF), early luteal (EL) and late luteal (LL) stages. The circatrigintan variations of the same hormones were also evaluated. Population-mean cosinor analysis allowed the demonstration of a highly significant circadian periodicity for both variables in any of the 4 stages of the menstrual cycle; on the other hand, the same computation failed to demonstrate a significant circatrigintan periodicity. In each of the stages considered, the circadian acrophase of DHEA-S was delayed in comparison to that of cortisol, being located in the early afternoon hours. The demonstration of a clear-cut circadian oscillation in serum DHEA-S prompts studies on possible chrono-abnormalities of the steroid production in women with hyperandrogenic diseases.

Adult↗
PubMedDate not supplied

Rhythms in the ovulatory cycle. 2nd: LH, FSH, estradiol and progesterone.

The circadian profiles of LH, FSH, estradiol and progesterone were compared in a homogeneous group of 15 young normally cycling women, at 4 well characterized times of the menstrual cycle: early follicular (EF), late follicular (LF), early luteal (EL) and late luteal (LL) stages. The circatrigintan profiles of the same hormones were also evaluated. Population-mean cosinor analysis failed to demonstrate a circadian periodicity of LH in any of the 4 stages of the menstrual cycle; a circadian rhythm for FSH was present only in the 2 luteal phases (EL, LL); the same type of rhythmicity was present for estradiol only in the late luteal stage; on the contrary, a highly significant circadian rhythm of progesterone was present in each of the 4 menstrual stages considered (EF, LF, EL and LL). Population-mean cosinor analysis showed a highly significant circatrigintan periodicity of LH and FSH with the acrophases respectively between -109 degrees and -181 degrees and between -74 degrees and -125 degrees. Circatrigintan rhythmicity was also present for estradiol (acrophases between -161 degrees and -245 degrees) and progesterone (acrophases between -246 degrees and -296 degrees).

Adult↗
PubMedDate not supplied

Rhythms in the ovulatory cycle. 1st: Prolactin. Chronobiological Research Group on Synthetic Peptides in Medicine.

Circadian and circatrigintan profiles of prolactin (PRL) in young normally cycling women at 4 well characterized times of the ovulatory cycle have been compared. Circadian patterns of PRL (collected at 2-h intervals for 24h at each phase selected) change during the 4 phases, being higher in the luteal phase. In a consistent percentage of individuals, serum PRL rises notably during the night; in one half of the subjects a peak is located also in the afternoon or early evening. The statistically significant circatrigintan rhythm of PRL shows the acrophase approximately in the mid-luteal phase.

Adult↗
PubMedDate not supplied

[A case of tuberous sclerosis: anatomo-pathologic description].

The authors describe the simultaneous presence of renal and pulmonary hamartomas occurring in a young man affected by tuberous sclerosis. The clinical diagnosis was based on the characteristic symptoms of epilepsy, adenoma sebaceum and mental retardation. These symptoms began at the age of four and were mostly characterized by epilepsy and adenoma sebaceum. The mental retardation was slight. The anatomopathological findings at death refer the presence of encephalic, renal and pulmonary lesions; the later are very rare.

Adult↗
PubMedDate not supplied

Progress in chronophysiology of peptide hormones with emphasis on clinical application of analogues.

It is now established that peptide hormones are among the most versatile substances involved in intercellular communications. By substitution of one or more natural aminoacids, numerous peptide analogues have been synthesized with increased duration of action and potency with respect to endogenous hormones. Most of these effects are programmable as a function of dose and timing of administration. Not surprisingly, the chronobiological use of hormone-related peptides may represent a valuable tool providing new approaches to diagnosis and therapy of different disease states. One pertinent example of the applicability of peptide analogues refers to a new short chain ACTH analogue (ACTH 1-17; Synchrodyn) that has been proved useful to reset or preset the rhythmic ordering of a number of functions and to provide, furthermore, information about specific pathogenetic mechanisms and/or subtle alterations of the adrenal function. A large body of evidence indicates that the same concepts apply to most actions of the gonadotropin-releasing hormone (LH-RH) related analogues. The efficacy of the so-called low-dose pulsatile LH-RH therapy in the management of hypogonadotropic hypogonadism and of some forms of infertility seems now established. The use of potent analogues is providing new approaches to the heretofore unsuccessful therapies in a number of disease conditions. In this light, chronoendocrinology and biotechnology have to be mutually supporting. Novel clinical applications are expected from the emerging use of portable instrumentation designed to record endogenous data and/or to deliver drugs according to a temporal program.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Alsactide: ACTH-agonist for use in microdoses in brain-adrenal and other feedsidewards.

An increasing number of ACTH-related peptides have been isolated and/or chemically synthesized. In addition to the multiplicity of molecules, there is experimental evidence for multiple target cells and multiple receptors, and hence for different biological activities. The heptadecapeptide analogue alsactide (ACTH 1-17: Synchrodyn) has a C-terminal amide group (butylamide) and the substitution of beta-alanine for serine in position 1 and of lysine for arginine in position 17. These modifications account for enhanced biological activity and uniquely demonstrated chronopharmacological properties. In adult healthy men, the tailoring of dosage and timing of peptide administration was successful in a selective and transient stimulation of glucocorticoid secretion, without a change in the plasma concentrations of aldosterone and testosterone. The dose of 10 micrograms alsactide injected subcutaneously at awakening is proposed for clinical application with the aim of enhancing cortisol secretion in diurnally active subjects. It is noteworthy that injection of even much higher doses for several days at this particular circadian stage did not elicit detectable antibodies to the peptide in more than 200 patients. Restoring or reinforcing the circadian ordering of bioperiodicities correlated with the adrenocortical cycle can thus be achieved as a result of a time-specified therapy with an ACTH-agonist analogue. The results of studies in experimental animals and of preliminary trials in human beings have emphasized the value of alsactide as the first chronizer-peptide in clinical medicine. Its use in the dosage here proposed is expected to be beneficial for preventing deterioration of the circadian system in the elderly, for enhancing psycho-physical performances, and for gaining compliance with regard to chronic disease as well as tolerance to a number of potentially damaging xenobiotics.

Adrenal Glands↗
PubMedDate not supplied

[A severe form of external otitis: necrosing diabetic otitis].

Otitis externa are of usual observation in inter-tropical regions. Pseudomonas aeruginosa is responsible generally. But, when immunodeficiency is associated or on diabetic diathesis, such an otitis externa can be extremely dangerous: extensive osteitis of the base of the skull, paralysis of the last pairs of cervical nerves rapidly creeping, built a clinical identity called malignant external otitis, leading to death in 50% of the cases.

Cranial Nerve Diseases↗