The GM130 and GRASP65 Golgi proteins cycle through and define a subdomain of the intermediate compartment

Integrating the pleomorphic membranes of the intermediate compartment (IC) into the array of Golgi cisternae is a crucial step in membrane transport, but it is poorly understood. To gain insight into this step, we investigated the dynamics by which cis-Golgi matrix proteins such as GM130 and GRASP65 associate with, and incorporate, incoming IC elements. We found that GM130 and GRASP65 cycle via membranous tubules between the Golgi complex and a constellation of mobile structures that we call late IC stations. These stations are intermediate between the IC and the cis-Golgi in terms of composition, and they receive cargo from earlier IC elements and deliver it to the Golgi complex. Late IC elements are transient in nature and sensitive to fixatives; they are seen in only a fraction of fixed cells, whereas they are always visible in living cells. Finally, late IC stations undergo homotypic fusion and establish tubular connections between themselves and the Golgi. Overall, these features indicate that late IC stations mediate the transition between IC elements and the cis-Golgi face.

A preliminary report of intraoperative radiotherapy (IORT) in limited-stage breast cancers that are conservatively treated

Local recurrences after breast conserving surgery occur mostly in the quadrant harbouring the primary carcinoma. The main objective of postoperative radiotherapy should be the sterilisation of residual cancer cells in the operative area, while irradiation of the whole breast may be avoided. We have developed a new technique of intra-operative radiotherapy (IORT) of a breast quadrant after the removal of the primary carcinoma. A mobile linear accelerator (linac) with a robotic arm is utilised delivering electron beams able to produce energies from 3 to 9 MeV. Through a perspex applicator, the radiation is delivered directly to the mammary gland and to spare the skin from the radiation, the skin margins are stretched out of the radiation field. To protect the thoracic wall, an aluminium-lead disc is placed between the gland and the pectoralis muscle. Different dose levels were tested from 10 to 21 Gy without important side-effects. We estimated that a single fraction of 21 Gy is equivalent to 60 Gy delivered in 30 fractions at 2 Gy/fraction. Seventeen patients received a dose of IORT of 10 to 15 Gy as an anticipated boost to external radiotherapy, while 86 patients received a dose of 17-19-21 Gy intra-operatively as their whole treatment. The follow-up time of the 101 patients varied from 1 to 17 months (mean follow-up time was 8 months). The IORT treatment was very well accepted by all of our patients, either due to the rapidity of the radiation course in cases where IORT was given as the whole treatment or to the shortening of the subsequent external radiotherapy in cases where IORT was given as an anticipated boost. We believe that single dose IORT after breast resection for small mammary carcinomas may be an excellent alternative to the traditional postoperative radiotherapy. However, a longer follow-up is needed for a better evaluation of the possible late side-effects.

Histologic detection and clinical implications of micrometastases in axillary sentinel lymph nodes for patients with breast carcinoma

BACKGROUND

Sentinel lymph node (SLN) biopsy is used increasingly in patients with clinically lymph node negative, early-stage breast carcinoma, because it can spare axillary dissection when the sentinel lymph nodes are negative. The question arises, however, whether complete axillary lymph node dissection (ALND) also is necessary in patients with only micrometastases (< or = 2 mm in greatest dimension) in axillary SLNs. The authors carried out the current study to ascertain the risk of non-SLN axillary metastases in such patients and to assess the detection rate of SLN micrometastases in relation to the sectioning interval and the number of sections examined.

METHODS

The authors examined 109 patients with micrometastatic SLNs from a series of 634 patients with carcinoma of the breast who underwent SLN biopsy and complete ALND as part of the surgical treatment for their disease. The SLNs were sectioned completely at 50-microm intervals, and the sections were examined intraoperatively.

RESULTS

The overall frequency of metastases in axillary non-SLNs was 21.8%. The frequency was correlated significantly with the size of the SLN micrometastatic focus (P = 0.02): 36.4% of patients with foci > 1 mm had metastases in axillary lymph nodes--a percentage approaching 44.7% of patients with macrometastatic SLNs--whereas only 15.6% of patients with micrometastases < or = 1 mm had other involved axillary lymph nodes.

CONCLUSIONS

Outside of clinical trials, patients with T1 and small T2 breast carcinoma and micrometastatic SLNs should undergo complete ALND for adequate staging. However, patients with SLN micrometastases up to 1 mm in greatest dimension have a significantly lower risk of additional axillary metastases, raising the question of whether ALND may be avoided in this subgroup of patients.

Radiotherapy after breast-conserving surgery in small breast carcinoma: long-term results of a randomized trial

BACKGROUND

Breast-conserving surgery followed by radiotherapy is a widely accepted form of treatment in patients with breast cancer of limited extent. Many attempts have been made to identify subgroups of patients who might avoid radiotherapy.

PATIENTS AND METHODS

Between 1987 and 1989, 579 women with carcinoma of the breast were randomly assigned to quadrantectomy, axillary dissection and radiotherapy (299) and to quadrantectomy with axillary dissection without radiotherapy (280). Eligible patients were women with a breast carcinoma less than 2.5 cm in maximum diameter up to 70 years of age. Primary endpoints were intra-breast tumour reappearance (IBTR) and all-cause mortality.

RESULTS

The number of IBTRs was significantly higher in patients treated with surgery alone (59 cases out of 273; 10-year crude cumulative incidence of 23.5%) than in patients treated with surgery plus radiotherapy (16 cases out of 294; 10-year crude cumulative incidence of 5.8%). The difference in IBTR frequency between the two treatments appeared to be particularly high in women up to 45 years of age, tending to decrease with increasing age up to no apparent difference in women older than 65 years. Overall survival curves for the two groups, did not differ significantly (P = 0.326). However, a limited survival advantage was evident after radiotherapy for node-positive women.

CONCLUSIONS

After breast-conserving surgery radiotherapy appears indicated in all patients up to 55 years of age, in patients with positive axillary nodes, and in patients with extensive intraductal component at histology. The data suggest that radiotherapy may be avoided in patients older than 65, and may be optional in women aged 56-65 years with negative nodes.

Timing of breast cancer surgery in relation to the menstrual cycle: an update of developments

It is well-established that hormones have multiple effects on breast cancer. Some, but not all studies indicate that the phase of the menstrual cycle (and hence hormonal status) at the time of breast surgery may influence survival. In this paper we review the literature in this area, explore how it is possible that such an association may occur, and note that randomised studies which unambiguously determined the phase of the cycle at the time of the operation are lacking. We go on to describe an ongoing self-randomised trial designed to address this problem and present preliminary results which show that only about 75% of the women ovulated during the cycle in which the operation took place, and that the established prognostic factor Ki-67 varied with the phase of the cycle in women who ovulated. It is too early to assess the significance of this finding.

[Current concept of structure and function of the Golgi apparatus. On the 100-anniversary of the discovery by Camillo Golgi]

The paper is a brief review of the current data on the structure and function of the Golgi apparatus since its discovery till the recent investigations, including the works published in 1997. Apart from reviewing the electron microscopy level of the structure of the Golgi apparatus, the data are considered on its molecular and supramolecular organization. The paper analyses critically the proposed mechanisms of the intracellular transport of proteins and their processing and modifications in the Golgi apparatus both in terms of the vesicular theory and in a model based on the gradual maturation of the cis-cistern and its transformation to the trans-cistern (i.e. its propagation from one pole to the other, a so-called "progression"). Experimental data are described, which disagree with the current models of the intracellular transport. Based on the literature and authors' own data, a modified model of the intracellular transport is proposed. This model eliminates, to a degree, the contradictions present in the models discussed above.

The lysosomal protease cathepsin D is efficiently sorted to and secreted from regulated secretory compartments in the rat basophilic/mast cell line RBL

Basophils and mast cells contain a peculiar class of inflammatory granules that discharge their content upon antigen-mediated crosslinking of IgE-membrane receptors. The pathways for granule biogenesis and exocytosis in these cells are still largely obscure. In this study we employed the rat basophilic leukemia (RBL)/mast cell line to verify the hypothesis that inflammatory granules share common bioactive molecules and functional properties with lysosomes. We demonstrate that inflammatory granules, as identified by the monoclonal 5G10 antibody (which recognises an integral membrane protein) or by Toluidine Blue staining, have an intralumenal acidic pH, possess lysosomal enzymes and are accessible by fluid-phase and membrane endocytosis markers. In addition, we studied the targeting, subcellular localisation and regulated secretion of the lysosomal aspartic protease cathepsin D (CD) as affected by IgE receptor stimulation in order to obtain information on the pathways for granule biogenesis and exocytosis. Stimulation with DNP-BSA of specific IgE-primed RBL cells led to a prompt release of processed forms of CD, along with other mature lysosomal hydrolases. This release could be prevented by addition of EGTA, indicating that it was dependent on extracellular calcium influx. Antigen stimulation also induced exocytosis of immature CD forms accumulated by ammonium chloride, suggesting the existence of an intermediate station in the pathway for granule biogenesis still sensitive to regulated exocytosis. The targeting of molecules to secretory granules may occur via either a mannose-6-phosphate-dependent or mannose-6-phosphate-independent pathway. We conclude that endosomes and lysosomes in basophils/mast cells can act as regulated secretory granules or actually identify with them.

Visualizing membrane traffic in vivo by combined video fluorescence and 3D electron microscopy

In studies of dynamic cellular processes, it would be ideal to be able to combine the capability of in vivo fluorescence video microscopy with the power of resolution of electron microscopy (EM). This article describes an approach based on the association of these two techniques, by which an individual intracellular structure can be monitored in vivo, typically through the use of markers fused with green-fluorescent protein, and then analysed by EM and three-dimensional reconstruction methods, resulting in a 'snapshot' of its fine structure at any chosen time in its life cycle. The potential of this approach is discussed in relation to various aspects of cell biology and especially to the question of the morpho-functional organization of the intracellular membrane trafficking pathways.

Use of technetium-99m-labeled colloid albumin for preoperative and intraoperative localization of nonpalpable breast lesions

BACKGROUND

Management of clinically occult breast lesions is still a major point of debate. Several techniques (eg, skin projection, guidewire localization) have been proposed, but all of them have technical limitations.

STUDY DESIGN

The aim of this study was to assess the efficacy of a new method to locate occult breast lesions using technetium-99m (99mTc)-labeled colloid particles of human serum albumin (radioguided occult lesion localization). We studied 647 consecutive patients (mean age 51.3 years; range 25 to 77 years) with nonpalpable breast lesions detected mammographically or by ultrasonography. Within 24 hours before operation, 3.7 MBq (0.1 mCi) of 99mTc-labeled colloid was injected directly into the center of the lesion using stereotactic mammographic guidance (when only microcalcifications were present) or ultrasonographic guidance (for opacities). Excision biopsy was performed with a gamma-detecting probe. After excision, the area was checked for residual radioactivity and the specimen was radiographed to verify complete removal of the lesion. The material was then sent for pathologic examination. The absorbed dose to the inoculated area and the external irradiation to staff were also determined.

RESULTS

In all 647 patients, the "hot spot" was located easily and quickly. X-ray and scintigraphy of the specimen verified the presence and centricity of the lesion in all patients but three (99.5%). Pathologic examination revealed 340 cancer lesions (52.6%). Of these patients, 339 (99.7%) were treated by breast-conserving operations and one (0.3%) received a modified radical mastectomy. No major surgical or postoperative complications were encountered. No recurrences were documented during follow-up. The absorbed dose to the breast and other tissue was negligible (0.03 +/- 0.02 mGy/MBq), as was the dose to the surgeon's hands (7.5 +/- 5.0 microSv/h). The latter dose represents 0.015% and 0.002% of the recommended limits of the European Community for the general population and for exposed workers, respectively.

CONCLUSIONS

Radioguided occult lesion localization seems to offer a simple and reliable method to locate occult breast lesions with a gamma-detecting probe, allowing complete removal of the lesion in 99.5% of patients. Because of the small quantity of radioactivity, the procedure is safe for both patients and medical staff.

Regulation of protein sorting at the TGN by plasma membrane receptor activation

We show that in the rat basophilic leukemia cell line RBL, the physiological stimulation of the IgE receptor or direct activation of PKC leads to the missorting of proteins to the plasma membrane, diverting them from their normal intracellular destination. This is demonstrated for two classes of proteins that are normally targeted to the secretory lysosomes via completely different mechanisms, i.e. proteoglycans and the aspartic protease cathepsin D. In the latter case, normal processing of the enzyme is also affected, leading to secretion of the immature form of cathepsin. The present study shows how completely different sorting mechanisms, such as those for delivering proteoglycans and cathepsin D to secretory lysosomes, might share common regulatory signals and are similarly affected when the levels of these signals are perturbed. Finally, protein kinase C appears to be a major player in the signal transduction pathways, leading to proteoglycan and cathepsin D missorting.

Radioguided sentinel node biopsy to avoid axillary dissection in breast cancer

BACKGROUND

Sentinel node (SN) biopsy may predict axillary status in breast cancer. We retrospectively analyzed more than 500 SN cases, to suggest more precise indications for the technique.

METHODS

99mTc-labeled colloid was injected close to the tumor; lymphoscintigraphy was then performed to reveal the SN. The next day, during surgery, the SN was removed by using a gamma probe. Complete axillary dissection followed, except in later cases recruited to a randomized trial. The SN was examined intraoperatively by conventional frozen section, in later cases by sampling the entire node and using immunocytochemistry.

RESULTS

In the first series, the SN was identified in 98.7% of cases; in 6.7%, the SN was negative but other axillary nodes were positive; in 32.1%, the SN was negative by intraoperative frozen section but metastatic by definitive histology, prompting introduction of the exhaustive method. In the randomized trial, the SN was identified in all cases so far, the false-negative rate is approximately 6.5%, and in 15 cases, internal mammary chain nodes were biopsied.

CONCLUSIONS

SN biopsy can reliably assess axillary status in selected patients. The problems are the SN detection rate, false negatives, and the intraoperative examination, which can miss 30% of SN metastases. Our exhaustive method overcomes the latter problem, but it is time consuming.

CtBP/BARS induces fission of Golgi membranes by acylating lysophosphatidic acid

Membrane fission is essential in intracellular transport. Acyl-coenzyme As (acyl-CoAs) are important in lipid remodelling and are required for fission of COPI-coated vesicles. Here we show that CtBP/BARS, a protein that functions in the dynamics of Golgi tubules, is an essential component of the fission machinery operating at Golgi tubular networks, including Golgi compartments involved in protein transport and sorting. CtBP/BARS-induced fission was preceded by the formation of constricted sites in Golgi tubules, whose extreme curvature is likely to involve local changes in the membrane lipid composition. We find that CtBP/BARS uses acyl-CoA to selectively catalyse the acylation of lysophosphatidic acid to phosphatidic acid both in pure lipidic systems and in Golgi membranes, and that this reaction is essential for fission. Our results indicate a key role for lipid metabolic pathways in membrane fission.

PDMP blocks the BFA-induced ADP-ribosylation of BARS-50 in isolated Golgi membranes

We reported that an inhibitor of sphingolipid biosynthesis, D, L-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP), blocks brefeldin A (BFA)-induced retrograde membrane transport from the Golgi complex to the endoplasmic reticulum (ER) (Kok et al., 1998, J. Cell Biol. 142, 25-38). We now show that PDMP partially blocks the BFA-induced ADP-ribosylation of the cytosolic protein BARS-50. Moreover, PDMP does not interfere with the BFA-induced inhibition of the binding of ADP-ribosylation factor (ARF) and the coatomer component beta-coat protein to Golgi membranes. These results are consistent with a role of ADP-ribosylation in the action of BFA and with the involvement of BARS-50 in the regulation of membrane trafficking.

Radiation protection in radioguided surgery of breast cancer

The protocols for sentinel lymph node biopsy and radioguided occult lesion localization could potentially be of great value in the management of breast cancer patients. Both involve the injection of a 99Tcm-labelled radiopharmaceutical close to or into the lesion, localization of the sentinel lymph node or occult lesion by scintigraphy, and surgical removal with the aid of a hand-held gamma-ray detector. We present dosimetric data on patients and hospital personnel involved in these procedures. For evaluation of radiation protection, we measured the absorbed dose and air kerma rate. Activity levels in excised tissues and surgical instruments were also determined. For patients, the mean absorbed dose to the abdomen was 0.45 mGy, which is low compared to doses received from other diagnostic examinations. For surgeons after 100 operations, the mean absorbed dose to the hands was 0.45 mGy and the mean effective dose 0.09 mSv. Absorbed doses to all hospital personnel involved in the procedures were very low compared to recommended annual limits stipulated by the International Commission on Radiological Protection. We conclude that these procedures, performed according to protocols laid down by the European Institute of Oncology, Milan, are safe from the point of view of radiological protection and that only routine precautions are necessary.

Importance of the level of axillary involvement in relation to traditional variables in the prognosis of breast cancer

Survival in breast cancer correlates with the presence of metastatic lymph nodes, so that removal and pathological examination of the axillary nodes provides the most important prognostic information and basis for planning subsequent therapy. However as the size of primary tumours at diagnosis is decreasing, the likelihood of axillary involvement is also declining, so that the indications for axillary dissection are undergoing radical revision. To definitively establish the value of removing all three axillary lymph node levels (as defined by Berg) in node positive breast cancer, retrospective analysis of a large series receiving complete dissection was carried out. consecutive breast cancer patients (n=1003) with positive axillary nodes were analyzed: all received identical axillary treatment and the three levels were tagged with metal disks to facilitate recognition and pathological examination. Follow-up (mean 97 months) was exceptionally complete. The length of disease-free and overall survival were taken as the primary endpoints. The variables considered in the statistical analysis were tumour size, number of metastatic nodes, axillary invasion by level (the three classic levels), perilymphnodal invasion and age. By univariate analysis, overall and disease-free survival decreased significantly as tumour diameter, number of involved lymph nodes, and involvement by axillary level increased. Multivariate analysis assessing the relative importance of these variables when all were considered together found that they were all important independent predictive factors for survival. This study confirms the importance of tumour size and number of metastatic axillary nodes as predictors of outcome in breast cancer. In addition, the level of axillary invasion as a third independent factor of equal importance to the established indicators was identified. When axillary dissection is performed it should be complete, and all three Berg levels tagged separately, so that involvement by level can be ascertained. This provides additional important prognostic information on which to base subsequent treatment decisions.

ARF mediates recruitment of PtdIns-4-OH kinase-beta and stimulates synthesis of PtdIns(4,5)P2 on the Golgi complex

The small GTPase ADP-ribosylation factor (ARF) regulates the structure and function of the Golgi complex through mechanisms that are understood only in part, and which include an ability to control the assembly of coat complexes and phospholipase D (PLD). Here we describe a new property of ARF, the ability to recruit phosphatidylinositol-4-OH kinase-beta and a still unidentified phosphatidylinositol-4-phosphate-5-OH kinase to the Golgi complex, resulting in a potent stimulation of synthesis of phosphatidylinositol-4-phosphate and phosphatidylinositol-4,5-bisphosphate; this ability is independent of its activities on coat proteins and PLD. Phosphatidylinositol-4-OH kinase-beta is required for the structural integrity of the Golgi complex: transfection of a dominant-negative mutant of the kinase markedly alters the organization of the organelle.

Morphological changes in the Golgi complex correlate with actin cytoskeleton rearrangements

In this report we have studied the morphological changes of the Golgi complex (GC) that specifically accompany F-actin reorganizations. In starved rat RBL-2H3 tumor mast cells, the GC, that was visualized at immunofluorescence level with antibodies raised against the Golgi-resident proteins giantin, mannosidase II, or TGN-38, showed a compacted morphology with a supranuclear positioning. Concomitant to membrane ruffle formation induced by epidermal growth factor (EGF) or phorbol 12-myristate 13-acetate (PMA), and stress fiber formation induced by lysophosphatidic acid (LPA), specific GC morphological changes were observed. When cells were stimulated with EGF or PMA, the compacted GC morphology was transformed into a reticular network that was extended towards the cell periphery. When cells were incubated with LPA, the GC acquired a characteristic ring-shaped morphology. Brefeldin A (BFA) did not affect the PMA- or LPA-induced membrane ruffling and stress fiber formation, respectively, indicating that actin rearrangements occurred independent of the presence of the GC. Upon BFA removal, the presence of PMA or LPA during the recovery process induced the GC to acquire the morphological appearance described above for each agent. Moreover, the PMA- but not the LPA-induced GC rearrangements were sensitive to the actin perturbing agents cytochalasin D and jasplakinolide. When cells were preincubated with the phosphatidylinositide 3-kinase (PI3K) inhibitors wortmannin or LY294002, the PMA-induced GC morphological changes were inhibited but not membrane ruffles. Finally, the PMA-induced increase in the post-Golgi transport of glycosaminoglycans to the cell surface was not altered by cytochalasin D or jasplakinolide. Altogether, these data suggest that: (1) the shape of the GC is influenced by the 3D arrangement of actin microfilaments; (2) PI3K regulates the association of the GC with actin microfilaments; and (3) actin microfilaments are not essential for the post-Golgi transport to the plasma membrane.

Molecular cloning and functional characterization of brefeldin A-ADP-ribosylated substrate. A novel protein involved in the maintenance of the Golgi structure

Brefeldin A (BFA) is a fungal metabolite that disassembles the Golgi apparatus into tubular networks and causes the dissociation of coatomer proteins from Golgi membranes. We have previously shown that an additional effect of BFA is to stimulate the ADP-ribosylation of two cytosolic proteins of 38 and 50 kDa (brefeldin A-ADP-riboslyated substrate (BARS)) and that this effect greatly facilitates the Golgi-disassembling activity of the toxin. In this study, BARS has been purified from rat brain cytosol and microsequenced, and the BARS cDNA has been cloned. BARS shares high homology with two known proteins, C-terminal-binding protein 1 (CtBP1) and CtBP2. It is therefore a third member of the CtBP family. The role of BARS in Golgi disassembly by BFA was verified in permeabilized cells. In the presence of dialyzed cytosol that had been previously depleted of BARS or treated with an anti-BARS antibody, BFA potently disassembled the Golgi. However, in cytosol complemented with purified BARS, or even in control cytosols containing physiological levels of BARS, the action of BFA on Golgi disassembly was strongly inhibited. These results suggest that BARS exerts a negative control on Golgi tubulation, with important consequences for the structure and function of the Golgi complex.

Intraoperative examination of axillary sentinel lymph nodes in breast carcinoma patients

BACKGROUND

Routine histologic examination of axillary sentinel lymph nodes predicts axillary lymph node status and may spare patients with breast carcinoma axillary lymph node dissection. To avoid the need for two separate surgical sessions, the results of sentinel lymph node examination should be available intraoperatively. However, routine frozen-section examination of sentinel lymph nodes is liable to yield false-negative results. This study was conducted to ascertain whether extensive intraoperative examination of sentinel lymph nodes by frozen section examination would attain a sensitivity comparable to that obtained by routine histologic examination without intraoperative frozen section examination.

METHODS

In a consecutive series of 155 clinically lymph node negative breast carcinoma patients, the axillary sentinel lymph nodes were examined intraoperatively, before complete axillary lymph node dissection. The frozen sentinel lymph nodes were sectioned subserially at 50-microm intervals. For each level, one section was stained with hematoxylin and eosin and the other section immunostained for cytokeratins using a rapid immunocytochemical assay.

RESULTS

Sentinel lymph node metastases were detected in 70 of the 155 patients (45%). In 37 cases the sentinel lymph nodes were the only axillary lymph nodes with metastases. Immunocytochemistry did not increase the sensitivity of the examination. Five patients had metastases in the nonsentinel axillary lymph nodes despite having negative sentinel lymph nodes. The general concordance between sentinel and axillary lymph node status was 96.7%; the negative predictive value of intraoperative sentinel lymph node examination was 94.1%.

CONCLUSIONS

The intraoperative examination of axillary sentinel lymph nodes is effective in predicting the axillary lymph node status of breast carcinoma patients and may be instrumental in deciding whether to spare patients axillary lymph node dissection.

Morphological and biochemical analysis of the secretory pathway in melanoma cells with distinct metastatic potential

In this report, we have investigated whether alterations of the morphological and functional aspects of the biosecretory membrane system are associated with the metastatic potential of tumor cells. To this end, we have analyzed the morphology of the Golgi complex, the cytoskeleton organization and membrane trafficking steps of the secretory pathway in two human melanoma A375 cell line variants with low (A375-P) and high metastatic (A375-MM) potential. Immunofluorescence analysis showed that in A375-P cells, the Golgi complex showed a collapsed morphology. Conversely, in A375-MM cells, the Golgi complex presented a reticular and extended morphology. At the ultrastructural level, the Golgi complex of A375-P cells was fragmented and cisternae were swollen. When the cytoskeleton was analyzed, the microtubular network appeared normal in both cell variants, whereas actin stress fibers were largely absent in A375-P, but not in A375-MM cells. In addition, the F-actin content in A375-P cells was significantly lower than in A375-MM cells. These morphological differences in A375-P cells were accompanied by acceleration and an increase in the endoplasmic reticulum to Golgi and the trans-Golgi network to cell surface membrane transport, respectively. Our results indicate that in human A375 melanoma cells, metastatic potential correlates with a well-structured morphofunctional organization of the Golgi complex and actin cytoskeleton.

Comparison of radioguided excision with wire localization of occult breast lesions

BACKGROUND

Clinically occult breast lesions are found with increasing frequency as a result of the widespread use of mammographic screening.

METHODS

This study reports a new localization technique in which a small quantity of 99mTc-labelled colloidal albumin is inoculated directly into the lesion under stereotactic-radiographic or ultrasonographic guidance. Correct positioning of the inoculum is checked by scintigraphy. A gamma ray detection probe is then used to locate the lesion and guide its surgical removal. The results of this method in 30 patients were compared with those obtained using the established hook wire method in another 30 patients.

RESULTS

In the wire localization group, the mean(s.d.) distance from the lesion centre to the specimen margin was 24.5(0.4) (range 15-45) mm. For the radioguided group the figures were 13.8(0.3) (range 5-25) mm. The mean(s.d.) lesion concentricity (difference between the maximum and minimum distance from the lesion border to specimen margin) was 6.2(0.4) (range 2-15) mm in the wire localization group and 3.8(0.2) (range 1-10) mm in the radioguided group.

CONCLUSION

Use of a gamma probe allowed rapid, easy and accurate removal of occult breast lesions. In comparison to the hook wire method, radioguided removal allows reduced excision volume and better lesion centring within the specimen.

Cyclosporin A, but not FK506, increases arachidonic acid release and inhibits proliferation of pituitary corticotrope tumor cells

The selective immunosuppressants cyclosporin A (CsA) and tacrolimus (FK506) are used in the prevention of allogenic transplant rejection and in the therapy of chronic autoimmune inflammatory pathologies. Chronic treatment with CsA leads to secondary functional and trophic alterations of multiple organs and cell systems among which endocrine ones, through insofar uncharacterized mechanisms. With the recent use of FK506 there have been reports of an improved therapeutic efficacy and a reduction of side-effects, as compared to CsA. An intriguing hypothesis is that toxic damage could be due to a systemic CsA activation of arachidonic acid (AA) metabolism, through pathways as yet only partially characterized. The side-effects of both drugs have been poorly studied on cells from tissues other than blood or kidney. We have thus proceeded to study their action on AA release in corticotropic AtT-20/D16-16 cells. The results obtained are as follows: 1) during incubation times > or =12 h, basal AA release is increased by CsA, but not FK506; the acute effect (10 min) of melittin, a PLA2 activator, is significantly potentiated starting from a 30 min pretreatment with CsA but not FK506; manoalide, a PLA2 inhibitor, antagonizes the melittin potentiation of AA release by CsA whereas the inhibition of the melittin stimulus by glucocorticoids is antagonized both by CsA and FK506. 2) during longer (>2 d) incubation times, cell growth is inhibited by CsA but not FK506. These results indicate a role for CsA, not apparent for FK506, in the activation of PLA2 and in the inhibition of cell growth. They also suggest that CsA does not have a direct (i.e. not mediated by the immune system) therapeutic effect in inflammatory processes.