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M Bianchi

Publications and source records attributed to M Bianchi.

At least 55 records · Page 3Linked to original sources
PubMed2001

Binding of phosphatase-1 delta to the retinoblastoma protein pRb involves domains that include substrate recognition residues and a pRB binding motif.

Protein Ser/Thr phosphatase-1 (PP1) controls the retinoblastoma protein (pRb) function, including its dephosphorylation at mitotic exit. Since PP1delta was found to coimmunoprecipitate with pRb from mitotic and early G1 cells, we further investigated the PP1delta-pRb association using GST-full length and GST-deletion mutants of delta. GST-delta pulled-down pRb from G2, mitotic and G1 HeLa cells, thus confirming the coimmunoprecipitation results. Among the delta deletion mutants tested, pRb was pulled down by mutant 159-295, which reproduces the C-terminal domain of delta without the C-terminus, whereas the C-terminus alone did not pull-down pRb. Further fragmentation of the 159-295 mutant indicated that pRb was pulled down by fragment 195-260, which includes several residues involved in substrate binding, and by fragment 159-212, which contains the putative pRb-binding motif LxSxE. Altogether the results supported the hypothesis that PP1delta may contribute to the dephosphorylation of pRb at mitotic exit and that the PP1delta-pRb interaction may be at multiple sites.

Binding Sites↗
PubMed2001

Genotype-phenotype correlation for thiopurine S-methyltransferase in healthy Italian subjects.

OBJECTIVE: The aim of the present study was to estimate the concordance rate between erythrocyte thiopurine methyltransferase (TPMT) activity and genotype at the TPMT locus in an Italian population sample. METHODS: The TPMT phenotype and genotype were determined in an unrelated population of 103 Italian healthy blood donors. Erythrocyte TPMT activity was measured with a radiochemical assay using 12.5 microM S-adenosyl-L-(methyl-14C)-methionine and 4 mM 6-mercaptopurine. The genotyping assay was based on restriction fragment length polymorphism polymerase chain reaction (RFLP-PCR) and allele-specific oligonucleotide polymerase chain reaction (ASO-PCR) methods. RESULTS: All subjects had detectable TPMT activity. The activity of TPMT varied 2.8-fold between the 5th and 95th percentile. This variation was neither age (P = 0.63) nor gender (P = 0.44) regulated and the frequency distribution of TPMT activity is compatible with a polymorphic distribution. The presence of the four most common defective alleles, i.e. TPMT*2, TPMT*3A, TPMT*3B and TPMT*3C, was examined through the entire phenotyped population. Ninety-two subjects did not carry any of the tested mutations. Eleven individuals were heterozygous for one of the mutant alleles and had a TPMT activity lower than 30 pmol/min/mg. Eight subjects were TPMT*1/TPMT*3A, two TPMT*1/TPMT*3C and one was TPMT*1/TPMT*2. The TPMT*3B allele was not detected in the samples analysed. CONCLUSION: There was a concordance of 97% between genotype and phenotype. All the heterozygotes had an intermediate phenotype. However, the wide variation range in TPMT activity detected in the wild-type homozygotes indicates that other genetic or epigenetic factors influence the TPMT phenotype.

Adult↗
PubMed2001

Ontogenic expression of anterior pituitary GABA(B) receptor subunits.

gamma-Aminobutyric acid (GABA) is involved in the neuroendocrine control of hypophyseal secretion, acting both in the central nervous system and directly at the pituitary. We have characterized the properties of anterior pituitary GABA(B) receptors. In this work the ontogeny of rat anterior pituitary GABA(B) receptors and the pattern of subunit expression in rats of both sexes were determined. Western blot analysis showed a temporal decrease in GABA(B) subunits GABA(B(1a)) and GABA(B(1b)) expression in female anterior pituitary membranes from day 4 to adulthood, with GABA(B(1a)) being significantly more abundant than GABA(B(1b)) at early stages of development; the GABA(B(2)) subunit was barely detectable. In the male, GABA(B(1a)) followed a similar pattern and appeared to be significantly less abundant than in 4- and 12-day-old females; GABA(B(1b)) and GABA(B(2)) expression in the male was barely detectable. Scatchard plot analysis showed a temporal decrease in binding sites in female anterior pituitary membranes, in agreement with the western blot results. The number of binding sites was significantly higher in female than in male 4-day-old membranes. Dissociation constant values were similar for both sexes at all ages studied. This study reports for the first time the ontogeny of anterior pituitary GABA(B) receptors, showing a particular developmental pattern of subunit expression and a clear sexual dimorphism.

Animals↗
PubMed2001

Role of Rusa deer Cervus timorensis russa in the cycle of the cattle tick Boophilus microplus in New Caledonia.

Two field experiments were conducted to evaluate the efficiency of Rusa deer in the development of the cattle tick Boaphilus microplus in comparison with that of steers in the same pastures and under the same conditions of infestation. No difference was noted between a mixed steer/deer herd and a pure steer or pure deer herd in the infestation pattern of each host, suggesting that attachment to the alternative host is mechanical and not affected by the simultaneous presence of the primary host on the pasture. Deer are capable of producing engorged viable females, with weight and reproductive performances similar to or even better than females fed on steers. For moderate levels (1 million larvae per hectare) and high levels (32 million larvae per hectare) of pasture infestation, tick burdens on steers were not very different (e.g. average 1,911 and 2,681 ticks per m2 skin, respectively, on day 24). This may be because of saturation of steer skin sites at the moderate larval dose. Deer harboured 2.7-33 times fewer ticks than steers and produce no engorged females at the moderate larval level and 32 times fewer engorged females than steers at the high larval level. Infestation of deer was dose-dependent with averages of 12 and 399 ticks per m2 skin on day 25 at the moderate and high larval levels, respectively. At a high infestation level of the environment, Rusa deer may contribute, but to a limited extent, to infestation of pastures and, consequently, of cattle. However, their role in sustaining a viable tick population requires further investigation.

Animals↗
PubMed2001

GABA(B) receptors in anterior pituitary cells. Mechanism of action coupled to endocrine effects.

The activation of pituitary GABA(B) receptors by the specific agonist baclofen inhibits pituitary hormone secretion in vitro. Here we studied the mechanism of action of GABA(B) receptors in rat adenohypophysis. Anterior pituitary cells were obtained by trypsinization and were either plated for hormonal studies and cAMP determination or incubated in FURA 2AM for calcium measurements. Baclofen (BACL: 1 x 10(-5) M) significantly inhibited basal and thyrotropic releasing hormone (TRH)-stimulated (1 x 10(-7) M) PRL secretion in anterior pituitary cells from proestrous rats. In the presence of pertussis toxin (PTX: 150 ng/ml, 20 h), which leads to the uncoupling of the G(i/o)-protein from the receptor, both effects of BACL were abolished while the effect of dopamine (DA: 1 x 10(-8) M), used as an inhibitory control, was reduced from 70 to 25%. PTX also reversed BACL-induced inhibition of gonadotropin-releasing hormone (GnRH)-elicited luteinizing hormone (LH) secretion in anterior pituitary cells from 15-day-old female rats. In addition, though working in a pituitary mixed cell population, in which only some cell types possess GABA(B) receptors, BACL (1 x 10(-5) M) attenuated the forskolin-induced (0.5 microM) increase in cAMP. This effect was prevented by co-incubation with the antagonist 2 hydroxysaclofen and by preincubation with PTX. BACL (5 x 10(-5) M) and DA (5 x 10(-7) M) inhibited basal intracellular calcium concentrations ([Ca(2+)](i)) in pituitary cells and the effect of the latter was significantly stronger. The effect of BACL on [Ca(2+)](i) was abolished after preincubation with PTX. In the presence of the potassium channel blocking agents barium (200 microM and 1 mM) and tetraethylammonium (10 mM), BACL was still able to inhibit [Ca(2+)](i). Blockade of voltage-sensitive calcium channels (VSCC) with either verapamil (5 x 10(-6) M) or nifedipine (1 x 10(-6) M) completely abolished the effect of BACL on [Ca(2+)](i). In the presence of 12.5 mM potassium concentration baclofen significantly inhibited [Ca(2+)](i). In conclusion, our results describe the negative coupling of adenohypophyseal GABA(B) receptors to VSCC through PTX-sensitive G-proteins. These characteristics suggest a resemblance of these receptors to the typical presynaptic GABA(B) sites described in the central nervous system.

Animals↗
PubMed2001

In vivo anti-inflammatory effect of statins is mediated by nonsterol mevalonate products.

This study set out to clarify whether the inhibition of sterol or nonsterol derivatives arising from mevalonate biotransformation plays a major role in the in vivo anti-inflammatory action of statins. Hepatic synthesis of all these derivatives was inhibited in mice by administered statins, whereas squalestatin inhibited only sterol derivatives. Using a short-term treatment schedule, we found that statins reduced the hepatic activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase without affecting blood cholesterol. This treatment inhibited lipopolysaccharide- and carrageenan-induced pouch leukocyte recruitment and the exudate production of interleukin-6, monocyte chemotactic protein-1, and RANTES. Coadministration of mevalonate reversed the effect of statin on leukocyte recruitment. The inhibition of sterol synthesis by squalestatin did not have any anti-inflammatory effect, indicating that the biosynthesis of nonsterol compounds arising from mevalonate is crucial for the in vivo regulation of cytokine and chemokine production by statins. Their inhibition by statins may account for the reported anti-inflammatory effects of these drugs and may provide a biochemical basis for the recently reported effects of statins in the prevention of cardiovascular disease and mortality.

Animals↗
PubMed2001

[Bilobed flap in the reconstruction of cheek defects].

The bilobed flap is a reliable means for the reconstruction of facial defects in one stage. This reconstruction technique has been applied on a 69-years-old man affected by carcinoma of the cheek, involving overhanging skin and underlying oral mucosa. Stensen's duct reconstruction was also performed with a vein graft and, 8 months later, deviation of the rima oris was corrected by inserting a goretex strip at the level of the upper lip elevator muscle. The present work considers the bilobed flap as a means for cheek defects reconstruction compared with other reconstruction techniques.

Aged↗
PubMed2000

Inhibition of IL-2-induced Jak-STAT signaling by glucocorticoids.

Glucocorticoids (GCs) are potent anti-inflammatory agents that block cytokine production. We investigated whether GCs also block cytokine signaling via the Janus kinase (Jak)-signal transducer and activator of transcription (STAT) pathway. Dexamethasone inhibited IL-2-induced DNA binding, tyrosine phosphorylation, and nuclear translocation of Stat5 in primary T cells. Inhibition of Stat5 correlated with inhibition of expression of IL-2-inducible genes and T cell proliferation. The mechanism of inhibition involved suppression of IL-2 receptor and Jak3 expression. Signaling by IL-4, IL-7, and IL-15, which use IL-2 receptor components, also was inhibited, indicating a block in T cell responses similar to that seen in immunodeficient patients lacking the IL-2 receptor gamma chain or Jak3. IL-2 signaling also was blocked in patients after treatment with GCs, suggesting that inhibition of cytokine signaling contributes to the clinical efficacy of these agents. These results identify inhibition of Jak-STAT signaling by IL-2 and related cytokines as a novel mechanism of GC action and suggest that inhibition of both cytokine production and signaling contribute to their therapeutic potency.

Biological Transport↗
PubMed2000

Selective inhibition of NF-kB activation and TNF-alpha production in macrophages by red blood cell-mediated delivery of dexamethasone.

Glucocorticoids are a widely used class of anti-inflammatory and immunosuppressive drugs, but their therapeutic use is limited by endocrine and metabolic side effects that they produce when given systemically. Since cells of the monocyte/macrophage lineage play an important role in the pathogenesis of several autoimmune and inflammatory diseases, a drug-delivery system which targets phagocytic cells was studied. We had previously demonstrated that dexamethasone, a potent glucocorticoid analogue, can be encapsulated in erythrocytes and selectively delivered to macrophages. In addition, lipopolysaccharide (LPS) stimulation of dexamethasone-targeted macrophages results in the suppression of TNF-alpha secretion. In this paper we demonstrate that the administration of dexamethasone to macrophages by means of opsonized red blood cells allows efficient interference with NF-kB activation. This NF-kB repression was in part mediated by induction of IkBalpha gene transcription and, as a consequence, by an increased rate of IkBalpha protein synthesis. Furthermore, NF-kB inactivation correlated with downmodulation of TNF-alpha mRNA expression, demonstrating that suppression of TNF-alpha production in dexamethasone-targeted cells occurs at the transcriptional level.

Capsules↗
PubMed2000

Diabetic Foot in the Elderly: Capillaroscopic Findings.

Microangiopathy is the most frequent complication of diabetes mellitus. It frequently precedes metabolic and biohumoral pathology. The diabetic foot is a particular aspect of the disease. Capillary videomicroscopy has proven to be a valuable technique for detecting early morpho-functional changes in the microcirculation in vivo. It is performed at the fingers' nailfold, at conjunctiva, and on the skin. This study aims to propose a qualitative assessment of microvascular complications in elderly patients with diabetes mellitus by toe nailfold capillary microscopy.

Journal Article↗
PubMed2000

Dehydroascorbic acid irreversibly inhibits hexokinase activity.

The oxidized form of vitamin C (dehydroascorbic acid, DHA) completely and irreversibly inactivates recombinant human hexokinase type I, in a pseudo-first order fashion. The inactivation reaction occurs without saturation, indicating that DHA does not form a reversible complex with hexokinase. Further characterization of this response revealed that the inactivation does not require oxygen and that dithiothreitol, while able to prevent the DHA-mediated loss of enzyme activity, failed to restore the activity of the DHA-inhibited enzyme. Inactivation was not associated with cleavage of the peptide chain or cross-linking. The decay in enzymatic activity was however both dependent on deprotonation of a residue with an alkaline pKa and associated with covalent binding of DHA to the protein. In addition, inactivation of hexokinase decreased or increased, respectively, in the presence of the substrates glucose or MgATP. Finally, amino acid analysis of the DHA-modified hexokinase revealed a decrease of cysteine residues. Taken together, the above results are consistent with the possibility that covalent binding of the reagent with a thiol group of cysteine is a critical event for the DHA-mediated loss of hexokinase activity.

Amino Acids↗
PubMed2000

The usefulness of blood culture in diagnosing HIV-related systemic mycoses: evaluation of a manual lysis centrifugation method.

The results of 5034 blood cultures, implementing a lysis-centrifugation method with saponin, are summarized in this paper. Three hundred and twenty-two blood samples (6.3%) obtained from a pool of human immunodeficiency virus (HIV)-positive patients yielded fungi. Cryptococcus neoformans was isolated in 199 samples (3.95%), Histoplasma capsulatum in 95 (1.89%). Candida parapsilosis in 12 (0.23%), C. albicans in 7 (0.13%), C. tropicalis in 2, C. krusei in 1, C. guillermondii in 1, and Prototheca wickerhamii in 4 (0.07%). Blood cultures were positive for C. neoformans in 76.23% of patients having a diagnosis of cryptococcosis and in 89.65% of those who had histoplasmosis. The blood culture was the first means of confirming the diagnosis in 23.8% of the patients with cryptococcosis and in 54% with histoplasmosis. In the four patients in whom P. wickerhamii was isolated, a diagnosis of disseminated protothecosis was not achieved by other findings. Catheter infections were responsible for the majority of recovered Candida spp.

AIDS-Related Opportunistic Infections↗
PubMed2000

The effects of tramadol and morphine on immune responses and pain after surgery in cancer patients.

UNLABELLED: There has been growing interest in determining the possible immune consequences of opioid administration for the management of postoperative pain. We studied the effects of morphine and tramadol on pain and immune function during the postoperative period in 30 patients undergoing abdominal surgery for uterine carcinoma. Phytohemoagglutinin-induced T lymphocyte proliferation and natural killer cell activity were evaluated immediately before and after surgery, and 2 h after the acute administration of either 10 mg of morphine IM or 100 mg tramadol IM for pain. In all patients, phytohemagglutinin-induced lymphoproliferation was significantly depressed by surgical stress. However, in the morphine-treated group, proliferative values remained lower than basal levels for 2 h after treatment, whereas in tramadol-administered patients proliferative values returned to basal levels. Natural killer cell activity was not significantly affected by surgery nor by morphine administration, whereas tramadol significantly enhanced the activity of natural killer cells. Both drugs produced a comparable reduction in postoperative pain. We conclude that, as previously observed in the experimental animal, tramadol and morphine, when administered in analgesic doses, induce different immune effects. IMPLICATIONS: Recent studies suggest that opioids can have an adverse impact on the immune system. Because surgical stress also induces immune dysfunction, the search for analgesic drugs devoid of immunosuppressive effects is of import. This study compared the effects on immune responses of morphine and of the atypical opioid analgesic, tramadol, given for postoperative pain to gynecological cancer patients. Tramadol and morphine showed comparable analgesic activity; however, tramadol, in contrast to morphine, induced an improvement of postoperative immunosuppression and, therefore, may be preferred to morphine for the treatment of postoperative pain.

Aged↗
PubMed2000

Risk factors for urinary incontinence in women.

OBJECTIVES: To review the epidemiological evidence on risk factors for urinary incontinence (UI) in women. METHODS: Using Medline and a manual search we identified the main papers published in English up to 1998. RESULTS: There is consistent evidence that the frequency of UI increases with age, but there is little information on the frequency of different types of UI in different age groups. With regard to other risk factors, there is a clinical consensus that vaginal delivery and, more in general, obstetric traumas are associated with UI, although epidemiological studies are not always consistent. Less defined is the role of race, menopausal status, history of gynecological surgery, body mass index, smoking, and coffee and alcohol consumption on the risk of UI. CONCLUSION: In the coming years, epidemiological research should focus particularly on the potential differences in the epidemiological characteristics of different types of UI in order to gain insight into the pathogenic mechanisms.

Adolescent↗
PubMed2000

The ubiquitin-dependent proteolytic system and other potential targets for the modulation of nuclear factor-kB (NF-kB).

Nuclear Factor-kB (NF-kB), is a transcription factor composed of dimeric complexes of p50 (NF-kB1) or p52 (NF-kB2) usually associated with members of the Rel family (p65, c-Rel, Rel B) which have potent transactivation domains. Different combinations of NF-kB/Rel proteins bind distinct kB sites to regulate the transcription of different genes. In resting cells NF-kB resides in the cytoplasm in inactive form, complexed to members of a family of inhibitory proteins referred to as IkB. The bound IkB masks the NF-kB nuclear localization signal and thereby inhibits its nuclear transport. NF-kB can be activated by a variety of signals relevant to pathophysiology including inflammatory cytokines and bacterial lipopolysaccharides (LPS) as well as oxidative and fluid mechanical stress. Upon activation by these stimuli, IkB is phosphorylated and subsequently degraded. Phosphorylation targets IkB for ubiquitination and degradation by the 26S proteasome thus leading to NF-kB nuclear translocation. The same proteolytic pathway is involved in the processing of the p105 and p100 precursors to generate mature p50 and p52 subunits, respectively. Once in the nucleus, NF-kB is able to regulate the expression of many genes involved in the immune and inflammatory responses (i.e. inflammatory cytokines and adhesion molecules). Thus, new approaches to modulating NF-kB activation, and as a consequence inflammatory or metastatic processes, may take advantage of the selectivity of the ubiquitination and ATP-dependent proteolytic processes leading to IkB turnover. This review will analyze the current strategies aimed at interfering with NF-kB activation and will consider the ubiquitination system as a new selective target for the development of new anti-inflammatory therapies.

Animals↗
PubMed2000

A large 6q deletion is a common cytogenetic alteration in fibroadenomas, pre-malignant lesions, and carcinomas of the breast.

To assess whether early breast lesions are the precursors of invasive carcinomas, three classes of breast lesions, namely benign tumors (including fibroadenomas), putative premalignant lesions (including cases of atypical hyperplasia), and invasive carcinomas, were compared at the cytogenetic and molecular cytogenetic levels. Genetic relatedness was clearly demonstrated by the sharing of several anomalies, among which 6q deletions outnumbered all of the other alterations detected. Indeed, deletions of the long arm of chromosome 6, most likely occurring in epithelial cells, were present in 83.9% of benign breast tumors, 64% of putative premalignant lesions, and 77.4% of analyzable carcinomas. Furthermore, the interval between 6q24 and qter appeared to be the common region of deletion in all three classes of breast lesions, whereas the minimal common region of deletion was 6q27-qter. Interestingly, the latter region was reported previously to be deleted in benign ovarian tumors and recently found to harbor a gene (SEN6) that is important for SV40-mediated immortalization of human cells.

Adolescent↗
PubMed2000

[Septic shock caused by perforation of sigmoid diverticulum into the Retzius space. A case report].

An uncommon complication of the sigmoid diverticulitis personally observed is described. A woman, 59 years old, presented a septic shock caused by perforated sigmoid diverticulum into the space of Retzius. The diagnosis was carried out by an X-ray of the abdomen that suspected the presence of air in the retroperitoneum and then by barium enema showing a perforation of the sigmoid colon. During laparotomy a perforation of sigmoid diverticulum in to the space of Retzius was observed. So the space of Retzius was opened and then pus and watery exudate containing bubbles of gas were found extended also to the retroperitoneum and the right abdomen wall. The patient was submitted to a sigmoid resection; bowel continuity was restored by circular stapled anastomosis and a temporary colostomy was made. Some drainages were placed into the space of Retzius, into the retroperitoneum and into the peritoneal cavity. Nevertheless the patient died because of the septic shock and the postoperative MOF.

Colostomy↗