Understanding interactions between populations: Individual based modelling and quantification using pair correlation functions.

Understanding the underlying mechanisms that produce the huge variety of swarming and aggregation patterns in animals and cells is fundamental in ecology, developmental biology, and regenerative medicine, to name but a few examples. Depending upon the nature of the interactions between individuals (cells or animals), a variety of different large-scale spatial patterns can be observed in their distribution; examples include cell aggregates, stripes of different coloured skin cells, etc. For the case where all individuals are of the same type (i.e., all interactions are alike), a considerable literature already exists on how the collective organisation depends on the inter-individual interactions. Here, we focus on the less studied case where there are two different types of individuals present. Whilst a number of continuum models of this scenario exist, it can be difficult to compare these models to experimental data, since real cells and animals are discrete. In order to overcome this problem, we develop an agent-based model to simulate some archetypal mechanisms involving attraction and repulsion. However, with this approach (as with experiments), each realisation of the model is different, due to stochastic effects. In order to make useful comparisons between simulations and experimental data, we need to identify the robust features of the spatial distributions of the two species which persist over many realisations of the model (for example, the size of aggregates, degree of segregation or intermixing of the two species). In some cases, it is possible to do this by simple visual inspection. In others, the features of the pattern are not so clear to the unaided eye. In this paper, we introduce a pair correlation function (PCF), which allows us to analyse multi-species spatial distributions quantitatively. We show how the differing strengths of inter-individual attraction and repulsion between species give rise to different spatial patterns, and how the PCF can be used to quantify these differences, even when it might be impossible to recognise them visually.

Identifying the necrotic zone boundary in tumour spheroids with pair-correlation functions.

Automatic identification of the necrotic zone boundary is important in the assessment of treatments on in vitro tumour spheroids. This has been difficult especially when the difference in cell density between the necrotic and viable zones of a tumour spheroid is small. To help overcome this problem, we developed novel one-dimensional pair-correlation functions (PCFs) to provide quantitative estimates of the radial distance of the necrotic zone boundary from the centre of a tumour spheroid. We validate our approach on synthetic tumour spheroids in which the position of the necrotic zone boundary is known a priori It is then applied to nine real tumour spheroids imaged with light sheet-based fluorescence microscopy. PCF estimates of the necrotic zone boundary are compared with those of a human expert and an existing standard computational method.

Endovenous 808-nm diode laser occlusion of perforating veins and varicose collaterals: a prospective study of 482 limbs.

BACKGROUND: Endovenous laser ablation (EVLA) was performed in the treatment of great and small saphenous veins (GSVs, SSVs), perforating veins (PVs), and varicose collaterals (VCs). OBJECTIVE To verify the outcome in PVs and VCs. MATERIALS AND METHODS: Four hundred eighty-two limbs of 306 patients were studied. EVLA was performed on 167 GSVs, 52 SSVs, and 534 PVs of 303 limbs and on VCs of 467 limbs; 133 GSVs were stripped, 300 of saphenofemoral junctions (SFJs) and 45 saphenopopliteal junctions (SPJs) were interrupted. Limbs were selected using duplex ultrasound examination and photographs; PVs-VCs diameter (<4 mm) and VC length were measured. EVLA was performed using a 808-nm diode laser, 0.6-mm fibers, continuous emission, 4 to 10 W, and 10 to 20 J/cm. Follow-up on 467 limbs occurred over a mean 27.5 months (range 3 months to 6 years); 98 limbs were followed up for longer than 4 years. RESULTS: Operating time range from 10 to 30 minutes per limb. Blood vaporization, thrombosis, fibrosis, and atrophy prevailed in PVs and in the large VCs (>4 mm) and massive coagulation in the smaller (<4 mm). High rate of occlusion was seen, with different rates of patent PV-VC mainly in diameter >6 mm. Thirty-nine out of 511 patent PVs (7.6%) and 96 out of 778 VCs (12-13%) were re-treated using EVLA or foam sclerotherapy. Minor complications occurred in 88 of the 778 (11%). CONCLUSIONS: EVLA of PVs and VCs is effective and faster than surgery in 2- to 6-mm PVs and VCs using an 808-nm diode laser.

Where should adolescents with ALL be treated?

Currently, 50% of adolescents with ALL are treated by adult teams and 50% by paediatric teams (following either adult or paediatric protocols). The aim of this paper is to review the results obtained with first-line chemotherapy and with haematopoietic SCT (HSCT) in adolescents with ALL. Disease biology and host factors are responsible for the differences observed between adolescents and other age categories. The outcome of adolescents with ALL after first-line chemotherapy is poorer as compared with children, although better as compared with adults. Recent studies have shown that adolescents who were enrolled in paediatric trials achieved better results than those who were enrolled in adult trials. This is most likely because of several differences, including protocol design, dose intensity and use of HSCTs, as well as better compliance to treatment and better supportive care. Disparities in the attitude towards treatment between paediatric and adult wards might also contribute to the better outcome that is observed in paediatric institutions. Indications for HSCT in children with ALL are well defined by international protocols. Only very high-risk paediatric patients are eligible for HSCT in CR1, whereas in adult trials, allogeneic or autologous HSCT are frequently offered, even to standard-risk patients in CR1. The outcome of adolescents given HSCT is poorer than in children, though better than in adults. Improving both psychosocial support during therapy and physical exercise habits represent further challenges for teams involved in the treatment of adolescents. Cooperation between paediatric and adult haematologists would surely improve the ability to recruit as many patients as possible and would promote progress in the research on adolescents. In conclusion, redefining age limits according to risk-based strategies, as well as encouraging multi-centre cooperation, should be taken into consideration to improve the outcome of this age category. Adolescents should be referred to research treatment teams that have experience in the management of paediatric ALL and they should be enrolled in international cooperative studies.

[Approach to the study of vasculitides: general aspects and classification]. / Approccio allo studio delle vasculiti: generalità e inquadramento.

Since etiology and pathogenesis of most systemic and/or isolated vasculitides are unknown, any attempt to make a rational classification of these entities is far from being perfect. Vasculitis may be a primary disease or it may be associated with connective tissue diseases, infectious diseases, neoplasms, drug assumption, allograft rejection and so on. As secondary vasculitides constitute the majority of cases, diagnosis of primary vasculitis is made by exclusion. At the present time, the 1993 Chapel Hill Consensus Conference on Nomenclature of Primary Vasculitides provides a useful guide to clinician and pathologist for evaluating a patient with an idiopathic form of vasculitis. This classification is based on the predominant size of vessels affected and describes the main clinico-pathologic features of the various clearly defined types of systemic vasculitis. Though it suffers from omissions and contradictions, in routine practice it is of great help to distinguish diseases in this intriguing chapter of pathology.

Primary pulmonary rhabdomyosarcoma: report of a case in an adult and review of the literature.

A case of primary pulmonary rhabdomyosarcoma occurring in a 62-year-old man is reported, and a review of the literature is presented. The tumor affected the left upper lobe and involved the mediastinal lymph nodes. Immunohistochemical and ultrastructural studies supported the myogenic phenotype of the neoplasm. A left pneumonectomy was performed with complete surgical removal of the tumor. Postoperative radiotherapy was carried out. The patient is currently alive and free of disease 9 months after operation. Despite the rarity of primary pulmonary rhabdomyosarcoma, this tumor should be differentiated from other poorly differentiated pulmonary neoplasms and from metastatic sarcomas.

Calretinin, thrombomodulin, CEA, and CD15: a useful combination of immunohistochemical markers for differentiating pleural epithelial mesothelioma from peripheral pulmonary adenocarcinoma.

The distinction between pleural epithelial mesothelioma and peripheral lung adenocarcinoma involving the pleura is still an important diagnostic problem for surgical pathologists. The aim of our study was to identify the most specific and sensitive markers for the positive identification of mesothelioma to select a limited, appropriate panel of antibodies to differentiate between mesothelioma and adenocarcinoma. Forty-two cases of epithelial mesotheliomas and 23 cases of pulmonary adenocarcinomas were stained with the following antibodies: anticalretinin, antithrombomodulin, anti-CD44H, and monoclonal antibody HBME-1. We also studied the value of other markers in current use: cytokeratins AE1/AE3 and CAM5.2, epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), Ber-EP4, B72.3, and CD15. Of the mesotheliomas, 42 stained for calretinin, 39 (92.8%) for thrombomodulin, 42 stained for CD44H, and 41 (97.6%) stained for HBME-1. Among negative markers, 4 (9.5%) mesothelioma cases stained for CEA, 5 (11.9%) stained for Ber-EP4, 6 (14.2%) stained for B72.3, and 2 (4.7%) stained for CD15. Of the lung adenocarcinomas, 2 (8.7%) cases showed reactivity for calretinin, 5 (21.7%) for thrombomodulin, 13 (56.5%) for CD44H, all for HBME-1, 22 (95.6%) for CEA, 22 (95.6%) for Ber-EP4, 8 (34.7%) for B72.3, and all for CD15. In conclusion, calretinin and thrombomodulin were the most specific positive mesothelial markers, whereas CD44H and HBME-1 showed high sensitivity but very low specificity. Among negative markers, we advocate the use of CEA and CD15 which were the most specific in differentiating mesotheliomas from adenocarcinomas.

Proximal long saphenous vein valves in primary venous insufficiency.

OBJECTIVE: To verify some of the previous findings of venous valves described in the literature, their pathophysiological significance and clinical implications. MATERIALS AND METHODS: The elementary components of 65 proximal valves of the long saphenous vein and their interrelationships were subjected to histopathological examination. Valves were taken from patients subjected to long saphenous vein surgical removal for varicose veins of the lower limbs. Measurements and morphological evaluations were performed by optical microscopy. RESULTS: The valvular sinus, agger and proximal portion of the cusp underwent parallel variations of thickness. Thickening of the proximal portion of cusp was related to increase in smooth muscle cells in the agger and to elastic layer dissociation. Thickening of the distal portion of cusp depended on the collagen component; sometimes it was shortened, crumpled and led to the formation of a thickened border. The vein wall in a commissural aneurysm was usually thinner than in the valvular sinus. Alterations in the intima, in the elastic membrane and in the media were found in the 98% of the valvular annulus. Ectasis and asymmetry of the venous wall were mainly related to the muscular hypoplasia of the media. CONCLUSIONS: The development of primary venous insufficiency seems to be due to the following tissue alterations: dilatation of the valvular annulus and hypotrophy of the cusp. The hemodynamic mechanical injury increases the tissue damages of both annulus and cusps. This pathophysiologic interpretation of venous insufficiency suggests the need for detailed diagnostic procedures before reparative surgery of valves.

MIB-1 proliferation index correlates with survival in pleural malignant mesothelioma.

AIMS: The purpose of this study was to establish whether the cell proliferation index assessed by the monoclonal antibody MIB-1 would correlate with survival in pleural malignant mesothelioma. METHODS AND RESULTS: We studied a series of seven long-term survivors with pleural malignant mesothelioma and a group of control cases with short-term survival. All cases showed MIB-1 positive cells, and labelling indices were expressed as percentage of cells with positive nuclear immunostaining by randomly counting 1000 tumour cells. A statistically significant difference was found between MIB-1 values in the long-term survival group and the control cases with short-term survival. CONCLUSIONS: Our results indicate that the differences in biological behaviour of malignant mesothelioma in long-term and short-term survivors may be explained in part by differences in tumour growth fraction and that proliferation index could represent an important prognostic parameter for this tumour.

19-nor-10-azasteroids: a novel class of inhibitors for human steroid 5alpha-reductases 1 and 2.

Steroid 5alpha-reductase is a system of two isozymes (5alphaR-1 and 5alphaR-2) which catalyzes the NADPH-dependent reduction of testosterone to dihydrotestosterone in many androgen sensitive tissues and which is related to several human endocrine diseases such as benign prostatic hyperplasia (BPH), prostatic cancer, acne, alopecia, pattern baldness in men and hirsutism in women. The discovery of new potent and selective 5alphaR inhibitors is thus of great interest for pharmaceutical treatment of these diseases. The synthesis of a novel class of inhibitors for human 5alphaR-1 and 5alphaR-2, having the 19-nor-10-azasteroid skeleton, is described. The inhibitory potency of the 19-nor-10-azasteroids was determined in homogenates of human hypertrophic prostates toward 5alphaR-2 and in DU-145 human prostatic adenocarcinoma cells toward 5alphaR-1, in comparison with finasteride (IC50 = 3 nM for 5alphaR-2 and approximately 42 nM for 5alphaR-1), a drug which is currently used for BPH treatment. The inhibition potency was dependent on the type of substituent at position 17 and on the presence and position of the unsaturation in the A and C rings. delta9(11)-19-Nor-10-azaandrost-4-ene-3,17-dione (or 10-azaestra-4,9(11)-diene-3,17-dione) (4a) and 19-nor-10-azaandrost-4-ene-3,17-dione (5) were weak inhibitors of 5alphaR-2 (IC50 = 4.6 and 4.4 microM, respectively) but more potent inhibitors of 5alphaR-1 (IC50 = 263 and 299 nM, respectively), whereas 19-nor-10-aza-5alpha-androstane-3,17-dione (7) was inactive for both the isoenzymes. The best result was achieved with the 9:1 mixture of delta9(11)- and delta8(9)-17beta-(N-tert-butylcarbamoyl)-19-nor-10-aza-4- androsten-3-one (10a,b) which was a good inhibitor of 5alphaR-1 and 5alphaR-2 (IC50 = 127 and 122 nM, respectively), with a potency very close to that of finasteride. The results of ab initio calculations suggest that the inhibition potency of 19-nor-10-azasteroids could be directly related to the nucleophilicity of the carbonyl group in the 3-position.

Synthesis of 5,6,6-[2H3]finasteride and quantitative determination of finasteride in human plasma at picogram level by an isotope-dilution mass spectrometric method.

Finasteride is a potent inhibitor of the enzyme steroid 5 alpha-reductase now approved as a drug for the treatment of benign prostatic hyperplasia. We describe an original method for the quantitative determination of finasteride at picogram level in human plasma by isotope-dilution gas chromatography mass spectrometry. 5,6,6-[2H3]Finasteride was synthesized with an high ratio of trideuteration (finasteride/[2H3]finasteride = 0.007) allowing its optimal use as internal standard. Plasma samples were purified in a single-step procedure on solid-phase extraction C18 columns with a recovery > or = 90%. Samples were injected in the GC-MS instrument without any derivatization and the minimum detection level of finasteride was 50 pg with a signal-to-noise ratio of 6:1. The coefficients of variation for the 5 and 10 ng/ml (plasma) concentrations were 5.8% and 4%, respectively. The method has been applied to the determination of the plasma pharmacokinetic of finasteride in five male volunteers treated with a single 5-mg dose of the drug, affording kinetic parameters which are in good agreement with the values previously reported with a different methodology. The present method results accurate, specific, sensible and reliable for a routinely determination of finasteride at picogram levels.

Mesothelioma as a risk indicator of asbestos exposure: the role of the pathologist.

Malignant mesothelioma is an uncommon tumour, which has become an important epidemiological marker for exposure to asbestos. This tumour is characterised by a wide range of microscopic features which may be classified in three histologic patterns: epithelial, mesenchimal and mixed or biphasic. Histochemical staining is often necessary to distinguish mesothelioma from carcinoma. As regards immunohistochemistry, only the use of a combination of antibodies significantly decreases the risk of false-negative results. Analytic electron microscopy techniques may also be useful, permitting the evaluation of the cumulative fiber burden in the target organ.

Pleural malignant mesothelioma in Tuscany, Italy (1970-1988): I. Anatomo-pathologic aspects.

Our investigation did not confirm the general experience that significant numbers of cases initially considered malignant mesothelioma or metastatic carcinoma are actually found to be metastatic carcinoma or malignant mesothelioma, respectively, upon deeper investigation using ancillary techniques (e.g., histochemistry, immunohistochemistry, electron microscopy). Well-trained pathologists, expert in thoraco-pulmonary pathology, have a high inter- and intra-rater agreement and significantly better results than standard hospital pathologists in correctly differentiating malignant mesothelioma from metastatic carcinoma. Therefore, epidemiologic investigations which exclude an accurate and rigorous reevaluation of the histologic slides have to be considered unreliable, unless the data come from a specialized medical center experienced in this type of pathology.

[Peripheral venous biopsy in the selection of autologous venous grafts]. / La biopsia venosa periférica en la selección de los injertos venosos autólogos.

Authors explain their experiences on the study and further clinical application of peripheral venous biopsy (dorsal food vein) as a systematic diagnose method for phlebopatic patients. Results from these experience seem to support the availability of this method to select patients candidates for an autologous venous graft in Cardiovascular Surgery. Peripheral venous biopsy, such as for the dorsal food vein, allows to individualize the possible injuries at the saphenous wall, previously its use for autologous graft; and it avoids the preliminary sample taking for biopsy. By this method, the requirement of an intraoperatory biopsy is also avoided and an eventual by-pass or substitution are better programmed.

Heterogeneity of [3H]-mepyramine binding sites in guinea pig cerebellum and lung.

The nature of histamine receptors in peripheral tissues is still controversial. However, evidence of heterogeneous classes of binding sites for [3H]-mepyramine are reported in the literature. The aim of our study was, therefore, to investigate the nature of this heterogeneity by comparing [3H]-mepyramine binding in a central tissue (cerebellum) and in a peripheral tissue (lung) obtained from guinea pigs and to assess its dependence upon the temperature of incubation. The results revealed that the [3H]-mepyramine interaction in both tissues is temperature-dependent. At 25 degrees C, the interaction between [3H]-mepyramine and the receptors was biphasic in the lung while only a single class of binding site was found in the cerebellum. At 0 degrees C, [3H]-mepyramine interacted with three binding sites in the lung and two in the cerebellum. The behaviour of the reference compounds (clemastine, promethazine and histamine) also supported this temperature-dependence. Moreover, two new compounds (DF 11062 and DF 11113), synthesized in our laboratories and endowed with antihistamine activity, can differentiate between the low affinity site seen at 25 degrees C in the lung and that seen in the cerebellum at 0 degrees C.

[External valvuloplasty of the sapheno-femoral junction]. / Valvuloplastie externe de la jonction sapheno-femorale.

Authors describe the pathophysiologic premises, technique and results obtained, in over two years, in N. 40 external valvuloplasties of the sapheno-femoral junction, performed with the following main indications: sapheno-femoral reflux and U.S. evidence of normal valve leaflets in the terminal valves of the long saphenous vein. Dilatation of the terminal segment of the long saphenous vein is reduced with the application of an external synthetic prosthesis and valvular function is restored. Good results have been obtained in N. 35 cases (87.5%). A careful pre- and peroperative procedure is necessary in order to avoid failures.

Antihistaminic/antiallergic activity of 2-dialkylaminoalkylthio(oxy)-1-substituted benzimidazoles: evaluation "in vitro" and "in vivo".

A new series of 2-dialkylamino-alkylthio(oxy)-1-substituted benzimidazoles synthesized in our laboratories was found to have promising antihistaminic activity. The results of pharmacological screening ("in vitro": radioreceptor binding and isolated organs; "in vivo": protection against mortality induced by histamine or by compound 48/80, passive cutaneous anaphylaxis, and prolongation of barbiturate-induced sleeping-time) gave clear-cut structure-activity relationships. This series of products has a general selectivity towards H1 receptors, weak antiallergic properties and negligible central effects. DF 10967 (1-ethoxyethyl-2-dimethyl-aminoethylthiobenzimidazole) was the most interesting compound, being very potent both "in vitro" (Ki = 3.2 +/- 0.8 nM) and "in vivo" (ID50 11 micrograms/kg, i.p. and 8 micrograms/kg, i.p. against histamine- and 48/80-induced mortality), with no central effects. The last finding is probably due to poor penetration into the brain (as confirmed by "in vivo" binding test with [3H]-mepyramine) and to lack of interaction with other central receptors.

Multicystic peritoneal mesothelioma. A fine structure study with special reference to the spectrum of phenotypic differentiation exhibited by mesothelial cells.

Multicystic peritoneal mesothelioma evidenced a complete spectrum of morphodifferentiation extending from classic epithelial-like surface mesothelial cells to myoid-fibroblastoid mesenchymal-like subsurface mesothelial cells. The contemporaneous presence of both epithelial- and mesenchymal-type submicroscopic features in individual cells strongly supported the concept of a holistic histogenetic/differentiative nature of surface and subsurface mesothelial cells on the one hand, and of a single origin for all serosal neoplasms, apart from their actual cytodifferentiation features, on the other. In addition, a profusion of smooth-membrane-bound intracellular collagen was found in myoid-fibroblastoid cells; this finding was interpreted to be, at least in part, due to tangential sectioning of convoluted cell surfaces enfolding extracellular collagen fibrils or to cell processes wrapping around them. A certain finalism might be seen in this event, especially considering the shorter-than-normal period length we found in collagen fibrils; the myoid-fibroblastoid cells might be hypothesized to play a contractile role in shortening collagen fibrils in a process of stroma contraction similar to wound repair or hypertrophic scarring.