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Biomedical subjects

G Biagini

Publications and source records attributed to G Biagini.

At least 199 records · Page 11Linked to original sources
PubMedDate not supplied

Age-related alterations in tanycytes of the mediobasal hypothalamus of the male rat.

By means of semiquantitative immunocytochemistry, possible age-related changes in dopamine and cyclic AMP-regulated phosphoprotein mr 32 (DARPP-32) and glial fibrillary acidic protein (GFAP) immunoreactivities (IR) were investigated in tanycytes of the arcuate nucleus. These two markers showed opposite changes during aging. DARPP-32 IR decreased by around 70%, whereas GFAP IR increased by around 300% in 24-month-old vs. 3-month-old rats. These changes were accompanied by a progressive loss in the number of tanycytes, measured by counting of their long processes in the arcuate nucleus. No significant age-related change was observed either in GFAP IR in astrocytic populations of the mediobasal hypothalamus or in tyrosine hydroxylase IR in dopaminergic neurons of the dorsal arcuate nucleus. These observations indicate that the tanycytic population of the arcuate nucleus undergoes important modifications during aging, which include cell loss, impairment in the intracellular signalling cascade linked to DARPP-32, and hypertrophy. These changes may be related to the alterations in the neuroendocrine systems known to occur during aging.

Aging↗
PubMedDate not supplied

Postnatal maternal separation during the stress hyporesponsive period enhances the adrenocortical response to novelty in adult rats by affecting feedback regulation in the CA1 hippocampal field.

The aim of the present experiment was to study the effects of early postnatal maternal separation on behavioural and adrenocortical responses to novelty in rats tested as adults. Sprague-Dawley rat pups were exposed to daily maternal separation (5 h/day) from postnatal day 2 to 6, during the stress hyporesponsive period. Since this procedure requires physical contact with the animals, a first control group of daily handled pups was introduced. A second control group, consisting of pups never handled or separated from the mother, was also considered. At postnatal day 45, the rats were tested in a two-compartment exploratory apparatus: the maternally separated and the non-handled rats, whose behavioural performance did not differ, showed higher emotional behaviour when compared with the handled rats (P < 0.05), suggesting that the handling procedure but not maternal separation improved the capacity to cope with novelty. Corticosterone plasma levels were found to be higher in the maternally separated rats than in the other two groups (P < 0.05), either at resting conditions or at 30 min after novelty exposure (P < 0.05). Levels of nuclear glucocorticoid receptor immunoreactivity in the CA1 hippocampal field were shown to be regulated by novelty exposure, as expected, in both the handled and the non-handled rats but not in the maternally separated rats. In conclusion, repeated maternal separation periods of 5 h/day during the first week of life produced long-lasting effects on the hippocampal regulation of the hypothalamic-pituitary-adrenocortical axis, which appear to be associated with increased responsiveness to stress stimuli in adulthood.

Adrenal Cortex↗
PubMedDate not supplied

VEGF is likely a key factor in the link between inflammation and angiogenesis in psoriasis: results of an immunohistochemical study.

Psoriasis is a chronic skin disease, characterized by epidermal hyperplasia, inflammation, angiogenesis and vascular remodelling. An immunohistochemical study on fifteen cryosections of psoriatic skin was performed using antibodies against VEGF, HIF1-alpha, CD34, Factor VIII, MMP-2, MMP-9, TIMP-1 and TIMP-2. Psoriatic skin showed a diffuse VEGF positive staining (13.15+/-6.6), while no expression was observed in normal epidermis. No or faint HIF-1alpha immunostaining was detected in healthy skin, while in psoriatic skin HIF-1alpha was diffusely expressed. A positive correlation between HIF-1alpha and VEGF was reported in psoriatic skin (r= 0.644; p=0.010). In psoriatic sections CD34 expression was significantly higher in respect to control skin (19.15+/-12.61 vs 3.0+/-0.23; p= 0.04), factor VIII immunostaining also demonstrated a significant increased development of the microvasculature in comparison with healthy skin (18.39+/-8.16 vs 7.4+/-0.20; p= 0.033). Total MMP-2 expression of healthy skin (30+/-2.26) was significantly lower in respect to the MMP-2 psoriatic skin (71.5+/-4.13; p= 0.0001) and a positive correlation was observed between VEGF and MMP-2 in psoriatic patients (r= 0.688; p= 0.046). In psoriatic skin MMP-9 expression was significantly increased in comparison to control skin (31+/-3.3 vs 8+/-6.1; p=0.007). All cases of psoriatic skin tissue showed that TIMP-2 and TIMP-1 expression statistically decreased in psoriatic skin (respectively 11+/-1.2 and 12+/-1.5) in comparison with healthy skin (respectively 15+/-3.2 and 53+/-3.8; p=0.0001). In conclusion, we observed that VEGF overexpression correlated with HIF-1alpha and MMP-2 expression, underlining the role of VEGF in psoriasis as a key factor in the link between inflammation and angiogenesis.

Adult↗
PubMedDate not supplied

Effect of Ca2+ on structure and fluidity of microvillus membranes of human placenta.

This investigation shows the effect of a Ca2+ addition on the structural and physiochemical properties of microvillus plasma membranes obtained from human placenta. Ca2+ addition induces an increase in microviscosity, as shown by the increase of order parameter and rotational correlation time of 5- and 16-doxylsterate derivatives and by the increase of fluorescence polarization of diphenylhexatriene. All the effects were obtained in a wide temperature range. The morphometric analysis of the ultrastructural images shows that the vesicle profiles of syncytiotrophoblast membranes decrease both area and form factor (FF) in the presence of Ca2+ with respect to the controls. The freeze-fracture results also show that Ca2+ induces an enhanced tendency to IMP clusterization. The Ca2+-induced changes were observed in both E and P faces. Our results underline the important role of Ca2+ in the cell membrane structure per se and in modulating interactions between cytoplasmic and extracellular microenvironments. The results of morphometric analysis of the ultrastructural images agree with biochemical data showing an increased stability induced by calcium on plasma membranes.

Calcium↗
PubMedDate not supplied

Effects of diabetes mellitus on structural and functional properties of erythrocyte membranes.

Diabetic patients present alterations in the activity of a number of enzymes of the plasma membrane. The aim of this study was to verify if the modifications of the enzymatic activities in diabetes mellitus are associated with structural alterations of the cellular membrane. By means of the freeze-fracturing technique, we studied the structure of erythrocyte membranes from 15 insulin-dependent diabetic patients (24-43 years) and 15 age-matched healthy subjects (26-47 years). The kinetic properties of the Na+/K(+)-ATPase of the same membranes were also investigated. The Na+/K(+)-ATPase of the erythrocyte plasma membrane shows an uncompetitive inhibition in the diabetic subjects. As for the freeze-fracturing results, the intramembrane particles of the erythrocyte membranes from diabetic patients appear more clustered with respect to those obtained from controls. The uncompetitive inhibition of the enzyme suggests the presence of conformational modifications of the protein. This hypothesis is supported by the freeze-fracture results which indicate that the integral protein constituents of the membrane in diabetes tend to aggregate. Modifications of the interactions between the enzymatic subunits and the membrane lipid environment might be at the basis of the Na+/K(+)-ATPase alteration in diabetes.

Adult↗
PubMedDate not supplied

Osteoblast behaviour in the presence of bisphosphonates: ultrastructural and biochemical in vitro studies.

OBJECTIVE: A positive balance in bone remodelling is an important goal of bone metabolism both in the presence of the osteoporotic processes characteristic of ageing and, especially, of prosthetic implants. The aim of the present work was to obtain new information about the initial steps of osteoblastic growth in an in vitro osteoblastic model in the presence of two bisphosphonates. METHODS: Experiments were performed with Alendronate and Neridronate, two molecules used in the therapy of osteoporosis. Since differentiating features into osteoblastic cells are known to parallel the presence in the cytoplasm of alkaline phosphatase and osteocalcin, we also carried out immunohistochemical typing. RESULTS: Good differentiation and osteoblastic activity were generally observed in the cells in contact with these compounds, except for 10(-4) Neridronate, where biochemical data clearly indicated its toxic effect on the cells. CONCLUSION: The detection of osteoblastic markers associated with an ultrastructural picture of correct organellar morphology in our cultures further supports the hypothesis of a metabolically positive action of these molecules on osteoblasts.

Alendronate↗
PubMedDate not supplied

bcl-2 protein expression in cervical intraepithelial neoplasia: no evidence of a prognostic significance in mild and moderate lesions.

BACKGROUND: The bcl-2 proto-oncogene codes for a protein which appears to block apoptosis. In our study, we examined bcl-2 protein expression in cervical squamous metaplasia, cervical intraepithelial neoplasia (CIN) and microinvasive squamous carcinoma with the aim of identifying a relationship between bcl-2 protein expression and neoplastic development and progression. MATERIALS AND METHODS: Cervical bioptic samples were obtained from 86 white women, selected consecutively from our Colposcopic Service from January 1993 to June 1994, because of abnormal pap- smear suspicious for cervical dysplasia and/or human papilloma virus (HPV) infection. Upon histologic evaluation, 41 women had CIN, 23 cervical condyloma, and 22 squamous metaplasia. Ten patients with microinvasive squamous carcinoma, matched for age and demographic characteristics, were selected from our series of invasive cervical carcinomas and immunohistochemically analyzed. The expression of primary tumor bcl-2 protein was immunohistochemically evaluated by antihuman bcl-2 monoclonal antibody (diluted 1:100, Dako, Copenhagen, Denmark) on formalin-fixed paraffin-embedded tissue. Positive staining was expressed as a percentage of positive cells per 1000 counted dysplastic cells for each case. RESULTS: Bcl-2 immunostaining was found in all the 22 squamous metaplasias, limited to the basal layer. Nineteen of the 41 CINs (46%) were bcl-2 immunoreactive, and 2 of the 10 microinvasive carcinomas (20%). By analysing CIN lesions, the bcl-2 protein showed a striking increase in the rate of positivity with increasing severity of CIN; the bcl-2 protein expression in CINs III was significantly higher than for CINs I, CINs II or microinvasive carcinomas (P = 0.03, P = 0.02, and P = 0.03 respectively). No relationship was observed between bcl-2 immunostaining and HPV infection. bcl-2 protein expression was not useful for predicting CIN I and II evolution, although the rate of persistence/progression was higher in bcl-2 positive dysplasias (7 of 9 cases, 78%) than in negative ones (13 of 21 cases, 62%) (p = 0.88). CONCLUSIONS: Based on these results, it seems possible that the increase in bcl-2 expression in higher grade of CINs implies an increasing protection against programmed cell death, but also the induction of genetic instability in dysplastic epithelial cells and a greater capacity to evolve into invasive carcinoma.

Adult↗
PubMedDate not supplied

[Bio-metabolic changes produced by 2 commercial fluoride-containing compounds on human keratinocytes].

BACKGROUND: Although fluoride has been used for decades either systemically or topically to prevent dental caries, the cellular and molecular mechanisms underlying its action are poorly understood. METHODS: An in vitro study of the human keratinocyte cell line NCTC 2544 was conducted in the presence of two different fluoride-containing commercial compounds (Zymafluor and Elmex) to investigate their toxicity threshold and the sequence of events involved in fluoride ion toxicity in this cell population. The toxicity threshold was determined by incubating cells with rising concentrations of Zymafluor and Elmex for 20 h. The study of the sequence of events involved in ion toxicity was performed through a time-effect study by exposing cells to 4 mM fluoride ions and testing them at 2, 6, and 20 h. Cell viability and ultrastructural parameters were assessed: degree of confluence, semiquantitative assessment of dead cells and debris in the supernatant, and morphology. RESULTS: Ultrastructural morphological analysis showed different cell behaviours with the two compounds; moreover, their toxic effect appeared to be both concentration- and time-dependent. CONCLUSIONS: These data underline the susceptibility of the intracellular communication system to fluoride and show that exceeding the therapeutic dose of fluoride involves substantial risk of toxicity.

Amines↗
PubMedDate not supplied

Platelet abnormalities in idiopathic myelofibrosis: functional, biochemical and immunomorphological correlations.

BACKGROUND: An extensive study of platelet function was performed on 18 consecutive patients affected by idiopathic myelofibrosis (IM). MATERIALS AND METHODS: Clinical hematological and morphofunctional parameters were studied in IM patients and control subjects. Platelet tests, ultrastructural data, immunocytochemical von Willebrand factor detection, freeze fracturing results and free cytosolic calcium level were evaluated. RESULTS: Bleeding time was frequently found to be prolonged, but it never reached levels which could give any cause for concern. Aggregation by ADP, collagen and epinephrine was always altered, sometimes profoundly; on the contrary, agglutination by ristocetin was almost always normal, albeit occasionally increased. Plasma beta-TG and PF4 levels were found to be elevated in 11 and 12 patients, respectively. This indicated an abnormal release from platelet alpha-granules. Depletion of alpha-granules was also confirmed by the intraplatelet von Willebrand factor (vWF) labelling with colloidal gold particles bound to polyclonal antibodies against human vWF. In fact: 1) the number of positive alpha-granules/microm2 and per single platelet was reduced; 2) the intensity of the immunocytochemical reaction for single positive alpha-granules and for each platelet was significantly reduced. Freeze-fracturing studies showed an increase in the number of intra-membrane particles (IMP) on the P face of the platelet membrane with respect to normal platelets preincubated with ADP. However, no differences in their distribution or diameter were observed. High concentrations of free cytosolic calcium were always found and Ca++ ATPase activity was increased. Conversely, Na+/K+ ATPase activity was always reduced. CONCLUSIONS: We can hypothesize that the platelet membrane is altered in IM, resulting in facilitated activation, even by subliminal stimuli, and that this continuous platelet activation ultimately leads to alpha-granule depletion.

Adenosine Diphosphate↗
PubMedDate not supplied

Microvascular changes in progressive systemic sclerosis: immunohistochemical and ultrastructural study.

Fifteen patients affected by Progressive Systemic Sclerosis have been studied. With immunofluorescence, specific antibodies against collagen type IV and laminin clearly outlined the microvessels, while endothelial cells showed a brilliant heavy fluorescence for vimentin antibodies. In the deep dermis, fibronectin proved to have increased. At electron microscopy, microvessels appeared with occluded lumina due to the presence of swollen endothelial cells. Endothelial cytoplasm was filled with intermediate filaments (vimentin type), generally condensed into peripherally located bundles or in perinuclear rings. The perivascular basal lamina was thickened and laminated. Although these changes do not demonstrate a specific pattern, representing a common step in several connective tissue disorders, the data tend to confirm a clear involvement of the microvasculature in Progressive Systemic Sclerosis.

Adult↗