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Biomedical subjects

A Luini

Publications and source records attributed to A Luini.

At least 91 records · Page 5Linked to original sources
PubMed1995

Evidence that the 50-kDa substrate of brefeldin A-dependent ADP-ribosylation binds GTP and is modulated by the G-protein beta gamma subunit complex.

Brefeldin A, a fungal metabolite that inhibits membrane transport, induces the mono(ADP-ribosyl)ation of two cytosolic proteins of 38 and 50 kDa as judged by SDS/PAGE. The 38-kDa substrate has been previously identified as glyceraldehyde-3-phosphate dehydrogenase (GAPDH). We report that the 50-kDa BFA-induced ADP-ribosylated substrate (BARS-50) has native forms of 170 and 130 kDa, as determined by gel filtration of rat brain cytosol, indicating that BARS-50 might exist as a multimeric complex. BARS-50 can bind GTP, as indicated by blot-overlay studies with [alpha-32P]GTP and by photoaffinity labeling with guanosine 5'-[gamma-32P] [beta,gamma-(4-azidoanilido)]triphosphate. Moreover, ADP-ribosylation of BARS-50 was completely inhibited by the beta gamma subunit complex of G proteins, while the ADP-ribosylation of GAPDH was unmodified, indicating that this effect was due to an interaction of the beta gamma complex with BARS-50, rather than with the ADP-ribosylating enzyme. Two-dimensional gel electrophoresis and immunoblot analysis shows that BARS-50 is a group of closely related proteins that appear to be different from all the known GTP-binding proteins.

Adenosine Diphosphate Ribose↗
PubMed1995

Local recurrences and distant metastases after conservative breast cancer treatments: partly independent events.

BACKGROUND: Local disease recurrences are a concern in conservative breast cancer surgery, and many studies have attempted to identify risk factors for these events. It is important to distinguish local recurrences linked to increased risk of distant spread from those due to inadequate local treatment. PURPOSE: We evaluated the incidence of local and distant recurrences according to demographic, biological, and pathologic variables in a large series of women who were conservatively and uniformly treated for breast cancer, with the aim of identifying women in whom local failure is predictive for distant metastases and who are therefore candidates for aggressive systemic treatment. METHODS: Medical records of 2233 women who had been hospitalized at the Milan Cancer Institute from 1970 to 1987 were analyzed. All women received quadrantectomy and axillary lymph node dissection followed by radiotherapy for the breast. Quadrantectomy is breast-conserving removal of most of the affected quadrant by a radial incision that includes part of the skin. The end points considered were local failures (including local recurrences and new ipsilateral carcinomas) and distant metastases. Statistical analysis employed the competing risks and multiple failures approaches. RESULTS: There were 119 local recurrences, 32 new ipsilateral carcinomas, and 414 distant metastases as first events. The timing of local failures and distant metastases differed: The yearly probability for local failures was approximately 1% up to the 10th year and for distant metastases was 5% in the 2nd year and decreased progressively until the 8th year. Young age was an important risk factor, with peritumoral lymphatic invasion also predictive for local and distant recurrences. Tumor size and axillary lymph node involvement were not related to local recurrence but were important predictors of distant metastases. Extensive intraductal component was only a risk factor for local recurrence. Early (< 2 years) local failure predicted for distant metastases compared with later failure. In local failure patients, the 5-year survival rate was 69% from failure. CONCLUSIONS: Local recurrences and distant metastases are partially independent events that occur at different times; several predicting factors also differ. However, women with local recurrences have increased risk of distant metastases. In particular, women 35 years old or younger at first diagnosis who had initial peritumoral lymphatic invasion and local recurrence within 2 years are at high risk for distant spread. For recurrence in cases with an extensive intraductal component or where initial local surgery was possibly inadequate, women are at lower risk.

Adult↗
PubMed1995

Breast conservation is a safe method in patients with small cancer of the breast. Long-term results of three randomised trials on 1,973 patients.

Breast conservation has become well-established in the treatment of early mammary carcinoma. However, a standardised treatment modality has not emerged. We have analysed the data from 1,973 patients treated in three consecutive randomised trials by four different radiosurgical procedures: Halsted mastectomy, quadrantectomy plus radiotherapy, lumpectomy plus radiotherapy, and quadrantectomy without radiotherapy, to compare the outcomes of these procedures in terms of local recurrence rate and overall survival. Eligibility criteria were similar in the three trials, and comparability between the four subgroups was excellent. Median follow-up for all patients was 82 months. The annual rates of local recurrence varied markedly according to the treatment. Patients treated with Halsted mastectomy and quadrantectomy plus radiotherapy had low annual rates of local recurrence (0.20 and 0.46, respectively) while both lumpectomy plus radiotherapy and quadrantectomy without radiotherapy had significantly higher rates (2.45 and 3.28, respectively). Patients under 45 years of age had a much higher incidence of local recurrences, while in women over 55 years local recurrences were much less frequent. Overall survival curves were identical in the four groups of patients, so that the three breast conserving radiosurgical procedures had the same survival rates as Halsted mastectomy. However, local recurrence rates were markedly influenced by the treatment method, patient age and specific histological features.

Adult↗
PubMed1995

Essential role of caldesmon in the actin filament reorganization induced by glucocorticoids.

Glucocorticoids induce the remodeling of the actin cytoskeleton and the formation of numerous stress fibers in a protein synthesis-dependent fashion in a variety of cell types (Castellino, F., J. Heuser, S. Marchetti, B. Bruno, and A. Luini. 1992. Proc. Natl. Acad. Sci. USA. 89:3775-3779). These cells can thus be used as models to investigate the mechanisms controlling the organization of actin filaments. Caldesmon is an almost ubiquitous actin- and calmodulin-binding protein that synergizes with tropomyosin to stabilize microfilaments in vitro (Matsumura, F., and Yamashiro, S. 1993. Current Opin. Cell Biol. 5:70-76). We now report that glucocorticoids (but not other steroids) enhanced the levels of caldesmon (both protein and mRNA) and induced the reorganization of microfilaments with similar time courses and potencies in A549 cells. A caldesmon antisense oligodeoxynucleotide targeted to the most abundant caldesmon isoform in A549 cells dramatically inhibited glucocorticoid-induced caldesmon synthesis and actin reorganization with similar potencies. Several control oligonucleotides were inactive. These results demonstrate that caldesmon has a crucial role in vivo in the organization of the actin cytoskeleton and suggest that hormone-induced changes in caldesmon levels mediate microfilament remodeling.

Actins↗
PubMed1995

Conservation surgery after primary chemotherapy in large carcinomas of the breast.

OBJECTIVE: The authors evaluated the utility of preoperative chemotherapy in patients with large size breast carcinoma, with a view to rendering a conservative surgical approach possible or easier. SUMMARY BACKGROUND DATA: Two hundred twenty-six of 227 patients with breast cancer involving a tumor larger than 3 cm at greatest dimension were candidates for mastectomy. They were treated with various primary preoperative chemotherapies and evaluated for surgery. METHODS: After administering various chemotherapeutic regimens, the authors reevaluated the patients' conditions clinically and radiologically to plan definitive surgical treatment. If the tumor diameter was sufficiently reduced, quadrantectomy was planned; otherwise, mastectomy was performed. Complete axillary lymph node dissection was done in all cases. RESULTS: In 90% of the cases, the size reduction was sufficient to justify breast conservation; in 10%, tumor size did not decrease enough or increased, thus mastectomy was performed. In 11.8% of the cases, the tumor was no longer identifiable at surgical inspection, and in 3.5% no tumor was found on microscopic examination. Axillary lymph nodes were free of metastases in 39% of cases. Twelve local recurrences occurred among the 203 patients treated with breast conservation (5.9%) and five among the 23 patients treated with mastectomy (21.7%). CONCLUSIONS: Primary chemotherapy can expand the indication for breast conservation to large tumors; careful attention, however, must be paid to surgical technique. The position of the tumor should be marked with tattoo points on the skin before chemotherapy. The macroscopic extent of the tumor regression must be evaluated carefully, and multiple frozen section biopsies may be needed. The margins of the resected breast should be evaluated microscopically. All microcalcifications present before treatment must be resected. The skin incision and mammary resection must fulfill criteria of radicality as well as good cosmetic outcome.

Breast Neoplasms↗
PubMed1995

[Italian study on the chemoprevention of breast cancer with tamoxifen].

There is currently a large breast cancer chemoprevention trial in Italy. The trial is based on the use of the antioestrogen tamoxifen, which is one of the most successful and most studied anticancer drugs. There is a strong evidence that this drug can prevent the growing of controlateral cancer in women previously operated for breast cancer. The chemoprevention trial using tamoxifen includes healthy women, aged 35 to 70 and hysterectomised. The participants are taking either 20 mg/day of tamoxifen or placebo for 5 years, in double blind; then they are followed-up clinically and instrumentally every 6 months for the further 5 years. The main end-point of the study is to verify the reduction of incidence and mortality from breast cancer. It was decided to recruit only hysterectomised women on the consideration that, according to some studies, tamoxifen could give an additional risk of endometrial cancer: the Italian study was especially designed with the intention of avoiding this unjustified risk.

Adult↗
PubMed1994

Effect of menstrual phase on surgical treatment of breast cancer.

1175 premenopausal women whose date of last menstrual period was known were followed up for up to 20 years (average 8 years) after surgery for breast cancer. 525 patients were in the follicular phase and 650 in the luteal phase. We observed 192 unfavourable events among patients operated on during the follicular phase (36.6%) and 192 among patients operated on during the luteal phase (29.6%). The effect of phase was restricted to patients with positive axillary nodes. The 5-year relapse-free survival was 75.5% in 246 node-positive patients operated on during the luteal phase and 63.3% in 190 node-positive patients who had surgery during the follicular phase. The hazard ratio at Cox multivariate analysis was 1.329 for all patients (p = 0.006) and 1.431 for node-positive patients (p = 0.03). In our study, premenopausal patients with breast cancer and positive axillary nodes operated on during the luteal phase had a significantly better prognosis than patients operated on during the follicular phase. It may be that the processes of cell metastases, such as loss of adhesiveness, may be enhanced by high concentrations of unopposed oestrogens or by reduced activity of natural killer cells during the first half of the menstrual cycle.

Adult↗
PubMed1994

Analysis of protein kinase C requirement for exocytosis in permeabilized rat basophilic leukaemia RBL-2H3 cells: a GTP-binding protein(s) as a potential target for protein kinase C.

The role of protein kinase C in calcium-dependent exocytosis was investigated in permeabilized rat basophilic leukaemia cells. When protein kinase C was down-regulated by phorbol myristate acetate (1 microM for 3-6 h) or inhibited by pharmacological agents such as calphostin C (1 microM) or a protein kinase C-specific pseudo-substrate peptide inhibitor (100-200 microM), cells lost the ability to secrete in response to 10 microM free Ca2+. In contrast, a short treatment (15 min) with phorbol myristate acetate, which maximally activates protein kinase C, potentiated the effects of calcium. Biochemical analysis of protein kinase C-deprived cells indicated that loss of the Ca(2+)-induced secretory response correlated with disappearance of protein kinase C-alpha. In addition, at the concentrations effective for exocytosis, calcium caused translocation of protein kinase C-alpha to the membrane fraction and stimulated phospholipase C, suggesting that, in permeabilized cells, protein kinase C can be activated by calcium through generation of the phospholipase C metabolite diacylglycerol. The delta, epsilon and zeta Ca(2+)-independent protein kinase C isoenzymes were insensitive to phorbol myristate acetate-induced down-regulation and did not, as expected, translocate to the particulate fraction in response to calcium. Interestingly, secretory competence was restored in cells depleted of protein kinase C or in which protein kinase C itself was inhibited by non-hydrolysable GTP analogues, but not by GTP, suggesting that protein kinase C might regulate the ability of a G protein(s) directly controlling the exocytotic machinery to be activated by endogenous GTP.

Amino Acid Sequence↗
PubMed1994

Immunodetection of bone marrow micrometastases in breast carcinoma patients and its correlation with primary tumour prognostic features.

Methods such as immunohistochemistry that have enhanced the detection of carcinoma cells in bone marrow aspirates appear to be useful in identifying patients with aggressive tumours. To detect epithelial cells in bone marrow aspirates from breast carcinoma patients, we used a pool of five different monoclonal antibodies (MAbs), which recognise 100% of breast carcinomas, together with the alkaline phosphatase method on cytospun cells obtained from sternum and iliac crest. Primary tumours were also analysed for the expression of the c-erbB-1 and c-erbB-2 oncogene products, and of two differentiation-related markers and laminin receptors. Immunoreactive cells were detected in the bone marrow of 62 of the 197 patients tested (31%) without any correlation with clinical parameters such as tumour size or lymph node metastasis, whereas a significant (P < 0.01) correlation was found with enhanced monomeric laminin receptor expression in the primary tumour. In fact, this receptor was expressed in respectively 63% and 38% of primary tumours from patients with and without immunoreactive cells in the bone marrow aspirates. Thus, the presence of immunoreactive cells in bone marrow correlates with the expression in the primary tumour of a marker of the metastatic potential of the tumour, the 67 kDa laminin receptor.

Age Factors↗
PubMed1993

Receptor and protein kinase C-mediated regulation of ARF binding to the Golgi complex.

The formation of constitutive transport vesicles involves the association of non-clathrin coat proteins to transport organelles. Here we report that IgE receptors and protein kinase C (PKC) regulate the GTP-dependent binding of the two coat proteins ADP-ribosylation factor (ARF) and beta-COP to Golgi membranes in rat basophilic leukaemia cells. Activation of IgE receptors and PKC prevented the ARF and beta-COP dissociation from Golgi membranes that occurs in permeabilized cells in the absence of GTP and potentiated the association-promoting effects of GTP and the G protein activator fluoroaluminate. In contrast, PKC downregulation and PKC inhibition abolished the activity of GTP and fluoroaluminae in promoting ARF binding to the Golgi complex. Studies of ARF binding to isolated Golgi membranes gave similar results. These findings suggest that coat assembly on Golgi membranes, and thus possibly constitutive secretory traffic, is modulated by membrane receptors and second messengers.

ADP-Ribosylation Factors↗
PubMed1993

Radiotherapy after breast-preserving surgery in women with localized cancer of the breast.

BACKGROUND AND METHODS: Conservative surgery and radiotherapy have become well-established treatments for breast cancer, and many trials in progress are attempting to define the most acceptable type of procedure. Between 1987 and 1989 we randomly assigned 567 women with small breast cancers (< 2.5 cm in diameter) to quadrantectomy followed by radiotherapy or to quadrantectomy without radiotherapy. All patients underwent total axillary dissection. The median follow-up period was 39 months (range, 28 to 54). RESULTS: The incidence of local recurrence was 8.8 percent among the patients treated with quadrantectomy without radiotherapy, as compared with 0.3 percent among those treated with postsurgical radiotherapy (P = 0.001). However, there was a substantial effect of age: patients more than 55 years old who did not receive radiotherapy had a low rate of local recurrence (3.8 percent). The four-year overall survival was similar in the two treatment groups. CONCLUSIONS: Administering radiotherapy after quadrantectomy reduces the risk of local recurrence in women with small cancers of the breast, but radiotherapy may not be necessary in elderly women.

Breast Neoplasms↗
PubMed1993

Tetanus toxin inhibits depolarization-induced [3H]serotonin release from rat brain cortex synaptosomes.

The effects of tetanus toxin on depolarization-induced [3H]serotonin release from superfused rat brain cortex synaptosomes was investigated. Two hours' preincubation of the synaptosomes with tetanus toxin resulted in a concentration-dependent decrease of K(+)-stimulated release, with an IC50 of about 30 nM (4.5 micrograms/ml); this inhibitory effect was blocked by a previous incubation of the tetanus toxin with antitoxin serum. Tetanus toxin had no effect on reserpine-induced release, a model of Ca(2+)-independent release. These results indicate that tetanus toxin is able to alter the exocytotic machinery of serotoninergic terminals, in agreement with results obtained with other neurotransmitters. They also indicate that serotoninergic terminals possess the receptor for tetanus toxin. These findings are in line with in vivo observations suggesting a role for serotoninergic system in tetanus intoxication.

Animals↗
PubMed1993

Covalent modification of synapsin I by a tetanus toxin-activated transglutaminase.

The synapsins are neuronal phosphoproteins that bind to small synaptic vesicles and to actin filaments and are believed to play a regulatory role in neurotransmitter release. Here we show that synapsin I is covalently modified with remarkable affinity and selectivity by the enzyme transglutaminase. Transglutaminase catalyzes the formation of covalent bonds between protein glutamine residues and primary amines and has been found recently to be potently activated by tetanus toxin, a dichain clostridial protein that selectively blocks neurotransmitter secretion. We also report the presence of two species of immunoreactive transglutaminases in nerve endings, one cytosolic and one located on synaptic vesicles; they are potently activated by tetanus toxin and, when activated, covalently modify synaptic vesicle-bound synapsin I. These results suggest a role for transglutaminase in the control of neurotransmitter secretion and provide evidence for synapsin I being a molecular target of tetanus toxin.

Animals↗
PubMed1993

Receptor-mediated regulation of constitutive secretion.

The traditional distinction between regulated and constitutive secretion may have contributed to the general belief that the latter is insensitive to extracellular modulatory signals. However, it now appears that signalling from membrane receptors can in fact modulate constitutive membrane traffic. In this article we discuss the molecular mechanisms, as well as the functional significance, of this modulation.

Journal Article↗
PubMed1993

The transglutaminase hypothesis for the action of tetanus toxin.

Tetanus toxin potently and almost irreversibly inhibits the release of neurotransmitters from nerve terminals. The toxin binds to and activates transglutaminase, a Ca(2+)-dependent enzyme that can form stable crosslinks between substrate proteins. Transglutaminase is present in nerve terminals and recognizes synapsin I, an abundant synaptic vesicle phosphoprotein involved in neurotransmission, as an excellent substrate. The neuroparalytic action of tetanus toxin might be due, at least in part, to the stimulation of synaptic transglutaminase and the consequent crosslinking of synapsin I.

Animals↗
PubMed1993

Central small size breast cancer: how to overcome the problem of nipple and areola involvement.

For centrally located small tumours we have sought, with the aid of a plastic surgeon, to achieve the same radicality as in the other quadrants, while achieving a good cosmetic result. We considered 37 patients with small centrally located breast carcinoma, in whom we performed a new surgical technique. From analysis of this series it emerged that a high percentage (54.1%) had nipple and areolar involvement, suggesting their removal; it is no problem to sacrifice these when a good cosmetic result can be achieved by plastic remodelling.

Adult↗